Many of you have probably heard of the ‘alkaline diet’. There are a few different versions of the acid-alkaline theory circulating the internet, but the basic claim is that the foods we eat leave behind an ‘ash’ after they are metabolized, and this ash can be acid or alkaline (alkaline meaning more basic on the pH scale). According to the theory, it is in our best interest to make sure we eat more alkaline foods than acid foods, so that we end up with an overall alkaline load on our body. This will supposedly protect us from the diseases of modern civilization, whereas eating a diet with a net acid load will make us vulnerable to everything from cancer to osteoporosis. To make sure we stay alkaline, they recommend keeping track of urine or saliva pH using handy pH test strips. In this two-part series, I will address the main claims made by proponents of the alkaline diet, and will hopefully clear up some confusion about what it all means for your health.

Will eating an alkaline diet make you and your bones healthier?

Foods can influence our urine pH

Before I start dismantling this theory, I want to acknowledge a couple things they get right. First, foods do leave behind acid or alkaline ash. The type of ‘ash’ is determined by the relative content of acid-forming components such as phosphate and sulfur, and alkalis such as calcium, magnesium, and potassium. (1, 2) In general, animal products and grains are acid forming, while fruits and vegetables are alkali forming. Pure fats, sugars, and starches are neutral, because they don’t contain protein, sulfur, or minerals. It’s also true that the foods we eat change the pH of our urine. (3, 4) If you have a green smoothie for breakfast, for example, your pee a few hours later will likely be more alkaline than that of someone who had bacon and eggs. As a side note, it’s also very easy to measure your urine pH, and I think this is one of the big draws of the alkaline diet. Everyone can probably agree that it’s satisfying to see concrete improvements in health markers depending on your diet, and pH testing gives people that instant gratification they desire. However, as you’ll see below, urine pH is not a good indicator of the overall pH of the body, nor is it a good indicator of general health.

Foods don’t influence our blood pH

Proponents of the alkaline diet have put forth a few different theories about how an acidic diet harms our health. The more ridiculous claim is that we can change the pH of our blood by changing the foods we eat, and that acidic blood causes disease while alkaline blood prevents it. This is not true. The body tightly regulates the pH of our blood and extracellular fluid, and we cannot influence our blood pH by changing our diet. (5, 6) High doses of sodium bicarbonate can temporarily increase blood pH, but not without causing uncomfortable GI symptoms. (7, 8) And there are certainly circumstances in which the blood is more acidic than it should be, and this does have serious health consequences. However, this state of acidosis is caused by pathological conditions such as chronic renal insufficiency, not by whether you choose to eat a salad or a burger. In other words, regardless of what you eat or what your urine pH is, you can be pretty confident that your blood pH is hovering around a comfortable 7.4. A more nuanced claim has been proposed specifically regarding bone health, and this hypothesis is addressed somewhat extensively in the scientific literature. It supposes that in order to keep blood pH constant, the body pulls minerals from our bones to neutralize any excess acid that is produced from our diet. Thus, net acid-forming diets (such as the typical Western diet) can cause bone demineralization and osteoporosis. This hypothesis, often referred to as the ‘acid-ash hypothesis of osteoporosis,’ is what I will discuss for the rest of this article. I’ll address some of the other health claims in part two.

The kidneys – not bone – regulate blood pH

While more reasonable than the first claim, the acid-ash hypothesis seems to completely disregard the vital role the kidneys play in regulating body pH. The kidneys are well equipped to deal with ‘acid ash.’ When we digest things like protein, the acids produced are quickly buffered by bicarbonate ions in the blood. (7) This reaction produces carbon dioxide, which is exhaled through the lungs, and salts, which are excreted by the kidneys. During the process of excretion, the kidneys produce ‘new’ bicarbonate ions, which are returned to the blood to replace the bicarbonate that was initially used to buffer the acid. This creates a sustainable cycle in which the body is able to maintain the pH of the blood, with no involvement from the bones whatsoever. Thus, our understanding of acid-base physiology does not support the theory that net acid-forming diets cause loss of bone minerals and osteoporosis. But just for argument’s sake, let’s say that our renal system cannot handle the acid load of the modern diet. If bones were used to buffer this excess acid, we would expect to see evidence of this taking place in clinical trials. Alas, that is not the case.

Clinical trials do not support the acid-ash hypothesis of osteoporosis

At first glance, some of the studies may look convincing, because higher acid diets often increase the excretion of calcium in the urine. Some researchers assumed that this extra calcium was coming from bone. (8) However, when calcium balance (intake minus excretion) was measured, researchers found that acid-forming diets do not have a negative effect on calcium metabolism. (9) Some studies found that supplementing with potassium salts (intended to neutralize excess acid) had beneficial effects on markers for bone health, which would tend to support the acid-ash hypothesis. However, these results were only observed in the first few weeks of supplementation, and long-term trials did not find any benefit to bone health from these alkalizing salts. (10) Finally, even though the hypothesis holds that higher intakes of protein and phosphate are acidifying and therefore detrimental to bone health, multiple studies have shown that increasing protein or phosphate intake has positive effects on calcium metabolism and on markers for bone health. (11, 12) Summarizing the clinical evidence, two different meta-analyses and a review paper all concluded that randomized controlled trials do not support the hypothesis that acidifying diets cause loss of bone mineral and osteoporosis. (13, 14, 15) So, it appears that neither physiology nor clinical trials support the acid-ash hypothesis of osteoporosis. But again, just for argument’s sake, let’s suppose that these trials are imperfect (which they are, of course; no science is perfect!), and thus we can’t depend on their conclusions. If the acid-ash hypothesis of osteoporosis were true, we would expect to see an association between net acid-producing diets and osteoporosis in observational studies. Yet again, this is not the case.

Observational studies do not support the acid-ash hypothesis of osteoporosis

Observational studies have not found a correlation between dietary acid load and bone mineral density (BMD) or fracture risk, nor have they found a correlation between urine pH and BMD or fracture risk. (16, 17, 18) Additionally, higher protein intakes are correlated with better bone health in multiple studies, even though high-protein diets are generally net acid forming. (19) In fact, animal protein in particular (the most acid-forming food of all) has been associated with better bone health. (20, 21) Imagine that! One study included in a recent meta-analysis did find an association between higher protein intake and greater risk for fracture (22), but compared to the numerous more recent studies showing the opposite, this evidence isn’t very strong. Overall, the acid-ash hypothesis of osteoporosis is not supported by physiology, clinical trials, or observational data. Hopefully I’ve given you a decent understanding of how our bodies handle pH balance, and have reassured you that you don’t need to worry about the acidity of your urine with regards to bone health. Click HERE for part two where I tackle some of the other claims of the alkaline diet!

Note: this is the sixth and final article in a series about heartburn and GERD. If you haven’t done so already, you’ll want to read Part I, Part II, Part III, and Part IVa, and Part IVb before reading this article. In this final article of the series, we're going to discuss three steps to treating heartburn and GERD without drugs. These same three steps will also prevent these conditions from developing in the first place, and keep them from returning once they're gone. To review, heartburn and GERD are not caused by too much stomach acid. They are caused by too little stomach acid and bacterial overgrowth in the stomach and intestines. Therefore successful treatment is based on restoring adequate stomach acid production and eliminating bacterial overgrowth. This can be accomplished by following the "three Rs" of treating heartburn and GERD naturally:

1. Reduce factors that promote bacterial overgrowth and low stomach acid.
2. Replace stomach acid, enzymes and nutrients that aid digestion and are necessary for health.
3. Restore beneficial bacteria and a healthy mucosal lining in the gut.

• Reduce factors that promote bacterial overgrowth and low stomach acid

Carbohydrates

As we saw in Part II and Part III, a high carbohydrate diet promotes bacterial overgrowth. Bacterial overgrowth - in particular H. pylori - can suppress stomach acid. This creates a vicious cycle where bacterial overgrowth and low stomach acid reinforce each other in a continuous decline of digestive function. It follows, then, that a low-carb (LC) diet would reduce bacterial overgrowth. To my knowledge there have only been two small studies done to test this hypothesis. The results in both studies were overwhelmingly positive. The first study was performed by Professor Yancy and colleagues at Duke University. They enrolled five patients with severe GERD that also had a variety of other medical problems, such as diabetes. Each of these patients had failed several conventional GERD treatments before being enrolled in the study. In spite of the fact that some of these patients continued to drink, smoke and engage in other GERD-unfriendly habits, in every case the symptoms of GERD were completely eliminated within one week of adopting a very low carbohydrate (VLC) diet. The second study (PDF) was performed by Yancy and colleagues a few years later. This time they examined the effects of a VLC diet on eight obese subjects with severe GERD. They measured the esophageal pH of the subjects at baseline before the study began using something called the Johnson-DeMeester score. This is a measurement of how much acid is getting back up into the esophagus, and thus an objective marker of how much reflux is occurring. They also used a self-administered questionnaire called the GSAS-ds to evaluate the frequency and severity of 15 GERD-related symptoms within the previous week. At the beginning of the diet, five of eight subjects had abnormal Johnson-DeMeester scores. All five of these patients showed a substantial decrease in their Johnson-DeMeester score (meaning less acid in the esophagus). Most remarkably, the magnitude of the decrease in Johnson-DeMeester scores is similar to what is reported with PPI treatment. In other words, in these five subjects a very low carbohydrate diet was just as effective as powerful acid suppressing drugs in keeping acid out of the esophagus. All eight individuals had evident improvement in their GSAS-ds scores. The GSAS-ds scores decreased from 1.28 prior to the diet to 0.72 after initiation of the diet. What these numbers mean is that the patients all reported significant improvement in their GERD related symptoms. Therefore, there was both objective (Johnson-DeMeester) and subjective (GSAS-ds) improvement in this study. It's important to note that obesity is an independent risk factor for GERD, because it increases intra-abdominal pressure and causes dysfunction of the lower esophageal sphincter (LES). The advantage to a low-carb diet as a treatment for GERD for those who are overweight is that LC diets are also very effective for promoting weight loss. I don't recommend VLC diets for extended periods of time, as they are unnecessary for most people. Once you have recovered your digestive function, a diet low to moderate in carbohydrates should be adequate to prevent a recurrence of symptoms. An alternative to a VLC is something called a "specific carbohydrate diet" (SCD), or the GAPS diet. In these two approaches it is not the amount of carbohydrates that is important, but the type of carbohydrates. The theory is that the longer chain carbohydrates (disaccharides and polysacharides) are the ones that feed bad bacteria in our guts, while short chain carbohydrates (monosacharides) don't pose a problem. In practice what this means is that all grains, legumes and starchy vegetables should be eliminated, but fruits and certain non-starchy root vegetables (winter squash, rutabaga, turnips, celery root) can be eaten. These are not "low-carb" diets, per se, but there is reason to believe that they may be just as effective in treating heartburn and GERD. See the resources section below for books and websites about these diets, which have been used with dramatic success to treat everything from autism spectrum disorder (ASD) to Crohn's disease. Another alternative to VLC that I increasingly use in my clinic is the Low FODMAP diet. FODMAPs are certain types of carbohydrates that are poorly absorbed by some people, particularly those with an overgrowth of bacteria in the small intestine (which, as you now know, tends to go hand-in-hand with heartburn). See this article and my book for more information. Be careful to avoid the processed low-carb foods sold in supermarkets. Instead, I suggest what is known as a "paleolithic" or "primal" approach to nutrition.

Fructose and artificial sweeteners

As I pointed out in Part II, fructose and artificial sweeteners have been shown to increase bacterial overgrowth. Artificial sweeteners should be completely eliminated, and fructose (in processed form especially) should be reduced.

Fiber

High fiber diets and bacterial overgrowth are a particularly dangerous mix. Remember, Almost all of the fiber and approximately 15-20% of the starch we consume escape absorption. Carbohydrates that escape digestion become food for intestinal bacteria. Prebiotics, which can be helpful in re-establishing a healthy bacterial balance in some patients, should probably be avoided in patients with heartburn and GERD. Several studies show that fructo-oligosaccharides (prebiotics) increase the amount of gas produced in the gut. The other problem with fiber is that it can bind with nutrients and remove them from the body before they have a chance to be absorbed. This is particularly problematic in GERD sufferers, who may already be deficient in key nutrients due to long term hypochlorydria (low stomach acid).

H. pylori

In Part III we looked at the possible relationship between H. pylori and GERD. While I think it's a contributing factor in some cases, the question of whether and how to treat it is less clear. There is some evidence that H. pylori is a normal resident on the human digestive tract, and even plays some protective and health-promoting roles. If this is true, complete eradication of H. pylori may not be desirable. Instead, a LC or specific carbohydrate diet is probably a better choice as it will simply reduce the bacterial load and bring the gut flora back into a state of relative balance. The exception to this may be in serious or long-standing cases of GERD that aren't responding to a VLC or LC diet. In this situation, it may be worthwhile to get tested for H. pylori and treat it more aggressively. Dr. Wright, author of Why Stomach Acid is Good For You, suggests using mastic (a resin from a Mediterranean and Middle Eastern variety of pistachio tree) to treat H. pylori. A 1998 in vitro study in the New England Journal of Medicine showed that mastic killed several strains of H. pylori, including some that were resistant to conventional antibiotics. Studies since then, including in vivo experiments, have shown mixed results. Mastic may be a good first-line therapy for H. pylori, with antibiotics as a second choice if the mastic treatment isn't successful.

• Replace stomach acid, enzymes and nutrients that aid digestion and are necessary for health

HCL with Pepsin

If you have an open-minded doctor, or one that is aware of the connection between low stomach acid and GERD, ask her to test your stomach acid levels. The test is quite simple. A device called a Heidelberg capsule, which consists of a tiny pH sensor and radio transmitter compressed into something resembling a vitamin capsule, is lowered into the stomach. When swallowed, the sensors in the capsule measure the pH of the stomach contents and relay the findings via radio signal to a receiver located outside the body. In cases of mild to moderate heartburn, actual testing for stomach acid production at Dr. Wright's Tahoma clinic shows that hypochlorydria occurs in over 90 percent of thousands tested since 1976. In these cases, replacing stomach acid with HCL supplements is almost always successful. Although testing actual stomach acid levels is preferable, it is not strictly necessary. There is a reasonably reliable, "low-tech" method that can be performed at home to determine whether HCL supplementation will provide a benefit. To do this test, pick up some HCL capsules that contain pepsin or acid-stable protease. HCL should always be taken with pepsin or acid-stable protease because it is likely that if the stomach is not producing enough HCL, it is also not producing enough protein digesting enzymes. To minimize side effects, start with one 650 mg capsule of HCL w/pepsin in the early part of each meal. If there are no problems after two or three days, increase the dose to two capsules at the beginning of meals. Then after another two days increase to three capsules. Increase the dose gradually in this stepwise fashion until you feel a mild burning sensation. At that point, reduce the dosage to the previous number of capsules you were taking before you experienced burning and stay at that dosage. Over time you may find that you can continue to reduce the dosage, or you may also find that you may need to increase the dosage. In Dr. Wright’s clinic, most patients end up at a dose of 5-7 650 mg capsules. In my experience, this dose is too high for many people. In fact, some have trouble with even a single 650 mg capsule. I’ve also found that the addition of cholagogues (agents which promote bile flow from the gall bladder into the small intestine) and pancreatic enzymes can help tremendously, especially in the initial stages. For these reasons, I created by own combination of HCL and enzymes called the AdaptaGest Duo. AdaptaGest Core contains acid-stable protease (to support protein digestion and complement HCL), cholagogues, and enzymes. AdaptaGest Flex contains HCL, but in a lower dose (200 mg per capsule) than is typical for standalone HCL products. This allows better fine-tuning of your HCL dosage. In my clinic, I prescribe AdaptaGest Duo for anyone struggling with heartburn and other digestive issues related to low stomach acid production. If you’d like to try it, you can order it here.

Bitters

Another way to stimulate acid production in the stomach is by taking bitter herbs. "Bitters" have been used in traditional cultures for thousands of years to stimulate and improve digestion. More recently, studies have confirmed the ability of bitters to increase the flow of digestive juices, including HCL, bile, pepsin, gastrin and pancreatic enzymes. [1. Wright, Jonathan M.D. Why Stomach Acid is Good For You. M Evans 2001. p.142] Unsurprisingly, there aren't many clinical studies evaluating the therapeutic potential of unpatentable and therefore unprofitable bitters. However, in one uncontrolled study in Germany, where a high percentage of doctors prescribe herbal medicine, gentian root capsules provided dramatic relief of GI symptoms in 205 patients. The following is a list of bitter herbs commonly used in Western and Chinese herbology:

• Barberry bark
• Caraway
• Dandelion
• Fennel
• Gentian root
• Ginger
• Globe artichoke
• Goldenseal root
• Hops
• Milk thistle
• Peppermint
• Wormwood
• Yellow dock

Bitters are normally taken in very small doses - just enough to evoke a strong taste of bitterness. Kerry Bone, a respected Western herbalist, suggests 5 to 10 drops of a 1:5 tincture of the above herbs taken in 20 mL of water. An even better option is to see a licensed herbalist who can prescribe a formula containing several of the herbs above as appropriate for your particular condition. Apple cider vinegar, lemon juice, raw (unpasteurized) sauerkraut and pickles are other time-tested, traditional remedies that often relieve the symptoms of heartburn and GERD. However, although these remedies may resolve symptoms, they do not increase nutrient absorption and assimilation to the extent that HCL supplements do. This may be important for those who have been taking acid suppressing drugs for a long period. It is also important to avoid consuming liquid during meals. Water is especially problematic, because it literally dilutes the concentration of stomach acid. A few sips of wine is probably fine, and may even be helpful. Finally, for those who have been taking acid stopping drugs for several years, it may be necessary to replace the nutrients that are not absorbed without sufficient stomach acid. These include B12, folic acid, calcium, iron and zinc. It's best to get your levels tested by a qualified medical practitioner, who can then help you replace them through nutritional changes and/or supplementation.

• Restore beneficial bacteria and a healthy mucosal lining in the gut

Probiotics

Because bacterial overgrowth is a major factor in heartburn and GERD, restoring a healthy balance of intestinal bacteria is an important aspect of treatment. Along with performing several other functions essential to digestive health, beneficial bacteria (probiotics) protect against potential pathogens through "competitive inhibition" (i.e. competing for resources). Researchers in Australia have shown that probiotics are effective in reducing bacterial overgrowth and altering fermentation patterns in the small bowel in patients with IBS. Probiotics have also been shown to be effective in treating Crohn's disease, ulcerative colitis, and other digestive conditions. Probiotics have also been shown to significantly increase cure rates of treatment for H. pylori. In my practice I always include a probiotic along with the anti-microbial treatment I do for H. pylori. I am often asked what type of probiotics I recommend. First, whenever possible I think we should always attempt to get the nutrients we need from food. This is also true for probiotics. Fermented foods have been consumed for their probiotic effects for thousands of years. What’s more, contrary to popular belief and the marketing of commercial probiotic manufacturers, foods like yogurt and kefir generally have a much higher concentration of beneficial microorganisms than probiotic supplements do. For example, even the most potent commercial probiotics claim to contain somewhere between one and five billion microorganisms per serving. (I say "claim" to contain because independent verification studies have shown that most commercial probiotics do not contain the amount of microorganisms they claim to.) Contrast that with a glass of homemade kefir, a fermented milk product, contains as many as 5 trillion beneficial microorganisms! What's more, fermented milk products like kefir and yogurt offer more benefits than beneficial bacteria alone, including minerals, vitamins, protein, amino acids, L-carnitine, fats, CLA, and antimicrobial agents. Studies have even shown that fermented milk products can improve the eradication rates of H. pylori by 5-15%. The problem with fermented milk products in the treatment of heartburn and GERD, however, is that milk is relatively high in carbohydrates. This may present a problem for people with severe bacterial overgrowth. However, relatively small amounts of kefir and yogurt are therapeutic and may be well tolerated. It's best to make kefir and yogurt at home, because the microorganism count will be much higher. Lucy's Kitchen Shop sells a good home yogurt maker, and Dom's Kefir site has exhaustive information on all things kefir. If you do buy the home yogurt maker, I suggest you also buy the glass jar that Lucy's sells to make it in (rather than using the plastic jar it comes with). If dairy doesn’t work for you, but you’d like to get the benefits of kefir, you can try making water kefir. Originating in Mexico, water kefir grains (also known as sugar kefir grains) allow for the fermentation of sugar water or juice to create a carbonated lacto-fermented beverage. You can buy water kefir grains from Cultures for Health. Another option is to eat non-dairy (and thus lower-carb) unpasteurized (raw) sauerkraut and pickles and/or drink a beverage called kombucha. Raw sauerkraut can easily be made at home, or sometimes found at farmer's markets. Bubbies brand raw pickles are sold at health food stores, as is kombucha, but both of these can also be made quite easily at home. All of that said, probiotic supplements are sometimes necessary and can play a crucial role in treatment and recovery. But not all probiotics are created alike, and in the case of small intestinal bacterial overgrowth (or SIBO, which is commonly present with GERD), certain probiotics may make things worse. SIBO often involves an overgrowth of microorganisms that produce a substance called D-lactic acid. Unfortunately, many commercial probiotics contain strains (like Lactobacillus acidophilus) that also produce D-lactic acid. That makes most commercial probiotics a poor choice for people with SIBO. Soil-based organisms do not produce significant amounts of D-lactic acid, and are a better choice for this reason. In my clinic, I use a product called Prescript Assist when treating SIBO and GERD. You can purchase it here. Other popular choices include Gut Pro from Organic 3 and D-Lactate Free Powder from Custom Probiotics. I used these in the past, but have much better success with Prescript Assist so I now use that exclusively.

Bone broth and DGL

Restoring a healthy gut lining is another important part of recovering from heartburn and GERD. Chronic stress, bacterial overgrowth, and certain medications such as steroids, NSAIDs and aspirin can damage the lining of the stomach. Since it is the mucosal lining of the stomach that protects it from its own acid, a damaged stomach lining can cause irritation, pain and ultimately, ulcers. Homemade bone broth soups are effective in restoring a healthy mucosal lining in the stomach. Bone broth is rich in collagen and gelatin, which have been shown to benefit people with ulcers. It's also high in proline, a non-essential amino acid that is an important precursor for the formation of collagen. Bone broth also contains glutamine, an important metabolic fuel for intestinal cells that has been shown to benefit the gut lining in animal studies. See this article and this one for more information about the healing power of bone broth, and how to make it. Although I prefer obtaining nutrients from food whenever possible, , as I explained above, supplements are sometimes necessary – especially for short periods. Deglycyrrhizinated licorice (DGL) has been shown to be effective in treating gastric and duodenal ulcers, and works as well in this regard as Tagamet or Zantac, with far fewer side effects and no undesirable acid suppression. In animal studies, DGL has even been shown to protect the stomach lining against damage caused by aspirin and other NSAIDs. DGL works by raising the concentration of compounds called prostaglandins, which promote mucous secretion, stabilize cell membranes, and stimulate new cell growth - all of which contributes to a healthy gut lining. Both chronic stress and use of NSAIDs suppress prostaglandin production, so it is vital for anyone dealing with any type of digestive problem (including GERD) to find ways to manage their stress and avoid the use of NSAIDs as much as possible.

Conclusion

The mainstream medical approach to treating heartburn and GERD involves taking acid stopping drugs for as long as these problems occur. Unfortunately, because these drugs not only don't address the underlying cause of these problems but may make it worse, this means that people who start taking antacid drugs end up taking them for the rest of their lives. This is a serious problem because acid stopping drugs promote bacterial overgrowth, weaken our resistance to infection, reduce absorption of essential nutrients, and increase the likelihood of developing IBS, other digestive disorders, and cancer. The manufacturers of these drugs have always been aware of these problems. When acid-stopping drugs were first introduced, it was recommended that they not be taken for more than six weeks. Clearly this prudent advice has been discarded, as it is not uncommon today to encounter people who have been on these drugs for decades - not weeks. What is especially disturbing about this is that heartburn and GERD are easily prevented and cured by making simple dietary and lifestyle changes, as I have outlined in this final article. Unfortunately, the corruption of our "disease-care" system by the financial interests of the pharmaceutical companies virtually guarantees that this crucial information will remain obscure. Drug companies make more than $7 billion a year selling acid suppressing medications. The last thing they want is for doctors and their patients to learn how to treat heartburn and GERD without these drugs. And since 2/3 of all medical research is sponsored by drug companies, it's virtually guaranteed that we won't see any large studies on the effects of a low-carb diet on acid reflux and GERD. So once again it's up to us to discover the truth and be our own advocates. I hope this series of articles has served you in that goal. I have created a "myth busing report" page for heartburn and GERD which contains an index of these articles, as well links to books and other offsite resources. If anyone you know is suffering from heartburn and GERD, please direct them to http://chriskresser.com/heartburn.

Recently, I’ve been hearing from many patients who have read Dr. Perlmutter's new book, Grain Brain, and are now concerned about their carb intake. In his book, Dr. Perlmutter suggests that dietary carbohydrates cause high blood sugar, inflammation, and other effects that lead to a “toxic brain,” which can then develop into neurological conditions such as Alzheimer’s, Parkinson’s, depression, and others. Based on this line of causality, he recommends that everyone consume a very low carb diet (<60g per day) in order to prevent neurological disease. First of all, I’d like to point out that very low carb (VLC) and ketogenic diets can be effective therapeutic tools for treating many neurological disorders. I touched on this briefly a while back in my podcast with Emily Deans, and initial studies on low-carb diets and mental health have shown promise. (1, 2, 3, 4) Because Dr. Perlmutter is a neurologist, it makes sense that he would be a proponent of low-carb diets for his patients based on these therapeutic effects.

Does eating carbs destroy your brain and lead to neurological disease?

However, recommending a low-carb diet as an intervention for sick people is very different from promoting it as a preventative measure for the entire population, which is what Dr. Perlmutter does in Grain Brain. His approach would be somewhat akin to recommending that everyone go on the Autoimmune Protocol to prevent autoimmune disease, which would be unnecessarily restrictive and unhelpful. It’s important to realize that just because a low-carb diet can help treat neurological disorders, doesn’t mean the carbs caused the disorder in the first place. While I don’t argue with the idea that refined and processed carbs like flour and sugar contribute to modern disease, there’s no evidence to suggest that unrefined, whole-food carbohydrates do. In fact, there are three compelling reasons why this is not the case.

#1 - We evolved eating whole-food carbohydrates

The first reason it doesn’t make sense that carbohydrates cause neurological disorders is that we've been eating carbs for a very long time, and we’re well adapted to digesting and metabolizing them. For instance, fruit has been part of the human diet for longer than we’ve been recognizably human, and while starch hasn’t been part of the human diet for quite as long, it’s clear that we’ve evolved mechanisms to digest and utilize it efficiently. Compared with most primates, humans have many more copies of the gene AMY1, which is essential for breaking down starches. (5) This gene is unusual in that the number of copies varies greatly between populations, with more copies present in populations that consume more starch. This indicates that starch played a significant role in our evolution, and some scientists have even argued that consumption of starch was partially responsible for the increase in our brain size. In addition to possessing the ability to break down complex carbohydrates, our bodies require glucose to function properly and maintain homeostasis. The fact that humans can produce glucose from protein is often used as an argument that we don’t need to eat glucose, but rather than viewing this as evidence that that glucose isn’t important, we might view it as evidence that glucose is so metabolically essential that we evolved a mechanism to produce it even when it’s absent from the diet.

#2 - There are many traditional cultures with high carb intake and low or nonexistent rates of neurological disease

If carbohydrates cause neurological disorders, one would expect to see high rates of dementia and similar diseases in populations where carbs constitute a significant portion of the diet. But as it turns out, many of the cultures that maintain the lowest rates of neurological and other inflammatory disease rely heavily on carbohydrate-dense dietary staples. For example, the Hadza of north-central Tanzania and the Kuna of Panama obtain a high percentage of their total calories from foods that are high in natural sugars, such as fruit, starchy tubers and honey, yet they are remarkably lean, fit and free of modern disease. (6, 7) Other examples include the Kitava in the Pacific Islands, Tukisenta in the Papa New Guinea Highlands, and the Okinawans in Japan. The Kitavan diet is 69% carb, with a high reliance on starchy tubers such as yams, and sugary tropical fruits such as banana and papaya. (8) The Okinawan diet is even more carb-heavy at 85% carbohydrate, mostly from sweet potato. (9) Finally, the Tukisenta diet is astonishingly high in carbohydrate at over 90%. (10) All of these cultures are fit and lean with practically non-existent rates of neurological disorders and other modern chronic disease. (11)

#3 - Modern research does not support the notion that ‘safe’ carbs are harmful

The claim that carbohydrates from whole-food sources cause neurological disorders is not supported by anthropological evidence. In addition, modern studies on the health effects of carb-dense foods such as fruit also fail to support Perlmutter’s hypothesis. In fact, studies overall suggest that eating whole, fresh fruit may actually decrease the risk of health issues such as obesity and diabetes, and that limiting fruit intake has no effect on blood sugar, weight loss or waist circumference. (12, 13) As you may know if you've been following my website, there is plenty of modern research demonstrating that diets rich in refined and processed carbohydrates are harmful. However, this is not due to carb content alone, and there’s no evidence that whole-food carbs have the same effect. When an author or expert recommends excluding or severely limiting one of three macronutrients that humans consume, the evidence demonstrating harm should be strong—not only because of the inconvenience of following such a restricted diet, but because extreme diets (ketogenic or VLC diets in this case) are not always harmless. In my practice I’ve seen many patients who’ve worsened on long-term VLC diets, including those with adrenal issues and poor thyroid function. Long-term VLC diets can also lead to imbalances in gut bacteria due to a lack of prebiotic fiber, which can result in digestive issues. As I've always maintained, you need to find out what works for you and tailor your diet to your specific health goals, rather than follow a canned approach. This is exactly what I’ll teach you to do in my book, Your Personal Paleo Code, which is coming out at the end of December. Have you read Grain Brain? What do you think about very low carb diets? Share your thoughts in the comments!

There are many reasons why people choose to go vegetarian or vegan. Some are compelled by the environmental impact of confinement animal feeding operations (CAFO). Others are guided by ethical concerns or religious reasons. I respect these reasons and appreciate anyone who thinks deeply about the social and spiritual impact of their food choices—even if my own exploration of these questions has led me to a different answer. But many choose a vegetarian diet is because they're under the impression that it's a healthier choice from a nutritional perspective. It is this last reason that I'd like to address in this article. For the last fifty years, we've been told that meat, eggs and animal fats are bad for us, and that we'll live longer and enjoy superior health if we minimize or avoid them. This idea has been so thoroughly drilled into our head that few people even question it anymore. In fact, if you asked the average person on the street whether a vegetarian or vegan diet is healthier than an omnivorous diet, they’d probably say yes. But is this really true? Plant-based diets emphasize vegetables, which are quite nutrient dense, and fruits, which are somewhat nutrient dense. However, they also typically include large amounts of cereal grains (refined and unrefined) and legumes, both of which are low in bioavailable nutrients and high in anti-nutrients such as phytate, and they eschew organ meats, meats, fish and shellfish, which are among the most nutrient-dense foods you can eat. (1) Vegan diets, in particular, are almost completely devoid of certain nutrients that are crucial for physiological function. Several studies have shown that both vegetarians and vegans are prone to deficiencies in B12, calcium, iron, zinc, the long-chain fatty acids EPA & DHA, and fat-soluble vitamins like A & D. Let’s take a closer look at each of these nutrients on a vegetarian or vegan diet.

Are plant-based diets missing nutrients required for optimal health? Find out!

Vitamin B12

B12 deficiency is especially common in vegetarians and vegans. I’ve covered the prevalence of B12 deficiency in vegetarians and vegans at length in another article. The takeaway is that the most recent studies using more sensitive techniques for detecting B12 deficiency have found that 68% of vegetarians and 83% of vegans are B12 deficient, compared to just 5% of omnivores. (2) Vitamin B12 works together with folate in the synthesis of DNA and red blood cells. It’s also involved in the production of the myelin sheath around the nerves, and the conduction of nerve impulses. B12 deficiency can cause numerous problems, including:

• Fatigue
• Lethargy
• Weakness
• Memory loss
• Neurological and psychiatric problems
• Anemia
• And much more…

The effects of B12 deficiency on kids are especially alarming. Studies have shown that kids raised until age 6 on a vegan diet are still B12 deficient years after adding at least some animal products to their diet. In one study, the researchers found:

…a significant association between cobalamin [B12] status and performance on tests measuring fluid intelligence, spatial ability and short-term memory” with formerly vegan kids scoring lower than omnivorous kids in each case. (3)

The deficit in fluid intelligence is particularly troubling, the researchers said, because:

…it involves reasoning, the capacity to solve complex problems, abstract thinking ability and the ability to learn. Any defect in this area may have far-reaching consequences for individual functioning.

A common myth amongst vegetarians and vegans is that it’s possible to get B12 from plant sources like seaweed, fermented soy, spirulina and brewers yeast. But plant foods said to contain B12 actually contain B12 analogs called cobamides that block the intake of, and increase the need for, true B12. (4)

Calcium

On paper, calcium intake is similar in vegetarians and omnivores (probably because both eat dairy products), but is much lower in vegans, who are often deficient. (5) However, calcium bioavailability from plant foods is affected by their levels of oxalate and phytate, which are inhibitors of calcium absorption and thus decrease the amount of calcium the body can extract from plant foods. (5a) So while leafy greens like spinach and kale have a relatively high calcium content, the calcium is not efficiently absorbed during digestion.  One study suggests that it would take 16 servings of spinach to get the same amount of absorbable calcium as an 8 ounce glass of milk. (5b) That would be 33 cups of baby spinach or around 5-6 cups of cooked spinach. There are a few vegetables listed in this paper that have higher levels of bioavailable calcium, but it’s important to note that all of the vegetables tested required multiple servings to achieve the same amount of usable calcium as one single serving of milk, cheese, or yogurt. This suggests that trying to meet your daily calcium needs from plant foods alone (rather than dairy products or bone-in fish) might not be a great strategy.

Iron

Vegetarians eat a similar amount of iron to omnivores, but as with calcium, the bioavailability of the iron in plant foods is much lower than in animal foods. Plant-based forms of iron are also inhibited by other commonly consumed substances, such as coffee, tea, dairy products, supplemental fiber, and supplemental calcium. This explains why vegetarians and vegans have lower iron stores than omnivores, and why vegetarian diets have been shown to reduce non-heme iron absorption by 70% and total iron absorption by 85%. (6, 7)

Zinc

Overt zinc deficiency is not often seen in Western vegetarians, but their intake often falls below recommendations. This is another case where bioavailability is important; many plant foods that contain zinc also contain phytate, which inhibits zinc absorption. Vegetarian diets tend to reduce zinc absorption by about 35% compared with omniovorous diet. (8) Thus, even when the diet meets or exceeds the RDA for zinc, deficiency may still occur. One study suggested that vegetarians may require up to 50% more zinc than omnivores for this reason. (9)

EPA and DHA

Plant foods do contain linoleic acid (omega-6) and alpha-linolenic acid (omega-3), both of which are considered essential fatty acids. In this context, an essential fatty acid is one that can’t be synthesized by the body and must be obtained in the diet. However, an increasing body of research has highlighted the benefits of the long-chain omega-3 fatty acids EPA & DHA. These fatty acids play a protective and therapeutic role in a wide range of diseases: cancer, asthma, depression, cardiovascular disease, ADHD, and autoimmune diseases, such as rheumatoid arthritis. While it is possible for some alpha-linolenic acid from plant foods to be converted into EPA & DHA, that conversion is poor in humans: between 5-10% for EPA and 2-5% for DHA. (10) Vegetarians have 30% lower levels of EPA & DHA than omnivores, while vegans have 50% lower EPA and nearly 60% lower DHA. (11) Moreover, the conversion of ALA to DHA depends on zinc, iron and pyridoxine—nutrients which vegetarians and vegans are less likely than omnivores to get enough of.

Fat-soluble vitamins: A and D

Perhaps the biggest problem with vegetarian and vegan diets, however, is their near total lack of two fat-soluble vitamins: A and D. Fat-soluble vitamins play numerous and critical roles in human health. Vitamin A promotes healthy immune function, fertility, eyesight and skin. Vitamin D regulates calcium metabolism, regulates immune function, reduces inflammation and protects against some forms of cancer. These important fat-soluble vitamins are concentrated, and in some cases found almost exclusively, in animal foods: primarily seafood, organ meats, eggs and dairy products. Some obscure species of mushrooms can provide large amounts of vitamin D, but these mushrooms are rarely consumed and often difficult to obtain. (This explains why vitamin D levels are 58% lower in vegetarians and 74% lower in vegans than in omnivores.) (12) The idea that plant foods contain vitamin A is a common misconception. Plants contain beta-carotene, the precursor to active vitamin A (retinol). While beta-carotene is converted into vitamin A in humans, the conversion is inefficient. (13) For example, a single serving of liver per week would meet the RDA of 3,000 IU. To get the same amount from plant foods, you’d have to eat 2 cups of carrots, one cup of sweet potatoes or 2 cups of kale every day. Moreover, traditional cultures consumed up to 10 times the RDA for vitamin A. It would be nearly impossible to get this amount of vitamin A from plant foods without juicing or taking supplements.

But don't vegetarians live longer than omnivores?

At this point you might be thinking, "Well, so what if plant-based diets are lower in some nutrients. Everyone knows vegetarians live longer than omnivores!" While it's true that some observational studies suggest that vegetarians and vegans enjoy longer lifespans, these studies were plagued by the "healthy user bias". The healthy user bias is the scientific way of saying that people who engage in one behavior that is perceived as healthy (whether it is or not) are more likely to engage in other behaviors that are healthy. For example, vegetarians tend to be more health conscious on average than general population; they are less likely to smoke or drink excessively and more likely to exercise, eat fruits and vegetables and take care of themselves. (14) Of course the flip-side is also true: those that engage in behaviors perceived to be unhealthy are more likely to engage in other unhealthy behaviors. The healthy user bias is one of the main reasons it’s so difficult to infer causality from observational studies. For example, say a study shows that eating processed meats like bacon and hot dogs increases your risk of heart disease. Let’s also say, as the healthy user bias predicts, that those who eat more bacon and hot dogs also eat a lot more refined flour (hot dog and hamburger buns), sugar and industrial seed oils, and a lot less fresh fruits, vegetables and soluble fiber. They also drink and smoke more, exercise less and generally do not take care of themselves very well. How do we know, then, that it’s the processed meat that is increasing the risk of heart disease rather than these other things—or perhaps some combination of these other things and the processed meat? One way to answer that question is to design a study that attempts to control for at least some of the healthy user bias. In other words, instead of comparing the "average" meat eater (who tends to be less health conscious) with the "average" vegetarian (who tends to be more health conscious), what happens when you compare vegetarians and omnivores that are both health-conscious? Thankfully, we have a study that did just that. It compared the mortality of people who shopped in health food stores (both vegetarians and omnivores) to people in the general population. This was a clever study design. People who shop in health food stores are more likely to be health conscious, regardless of whether they eat meat, which reduces the likelihood that the study results will be thrown off by the "healthy user bias". What did the researchers find? Both vegetarians and omnivores in the health food store group lived longer than people in the general population—not surprising given their higher level of health consciousness—but there was no survival difference between vegetarians or omnivores. Nor was there any difference in rates of heart disease or stroke between the two groups. (15) In other words, omnivores who are health conscious live just as long as vegetarians that are health conscious.

Final thoughts

With care and attention, I think it’s possible to meet nutrient needs with a vegetarian diet that includes liberal amounts of pasture-raised, full-fat dairy and eggs, with one exception: EPA and DHA. These long-chain omega fats are found exclusively in marine algae and fish and shellfish, so the only way to get them on a vegetarian diet would be to take a microalgae supplement (which contains DHA) or bend the rules and take fish oil or cod liver oil as a supplement. Still, while it may be possible to obtain adequate nutrition on a vegetarian diet, it is not optimal—as the research above indicates. I do not think it’s possible to meet nutrient needs on a vegan diet without supplements—and quite a few of them. Vegan diets are low in B12, biovailable iron and zinc, choline, vitamin A & D, calcium, and EPA and DHA. So if you’re intent on following a vegan diet, make sure you are supplementing with those nutrients. It’s worth pointing out that there are genetic differences that affect the conversion of certain nutrient precursors (like beta-carotene and alpha-linolenic acid) into the active forms of those nutrients (like retinol and EPA and DHA, respectively), and these differences may affect how long someone will be able to follow a vegetarian or vegan diet before they develop nutrient deficiencies. This explains why some people seem to do well for years on these diets, while others develop problems very quickly. From an evolutionary perspective, is difficult to justify a diet with low levels of several nutrients critical to human function. While it may be possible to address these shortcomings through targeted supplementation (an issue that is still debated), it makes far more sense to meet nutritional needs from food. This is especially important for children, who are still developing and are even more sensitive to suboptimal intake of the nutrients discussed in this article. Like all parents, vegetarians and vegans want the best for their children. Unfortunately, many are not aware of the potential for nutrient deficiencies posed by their dietary choices. I hope this article can serve as a resource for anyone on a plant-based diet, whether they choose to start eating meat (or animal products, in the case of vegans) again or not.

What do all of these diseases have in common?

• Alzheimer's, dementia, cognitive decline and memory loss (collectively referred to as "aging")
• Multiple sclerosis (MS) and other neurological disorders
• Mental illness (depression, anxiety, bipolar disorder, psychosis)
• Cardiovascular disease
• Learning or developmental disorders in kids
• Autism spectrum disorder
• Autoimmune disease and immune dysregulation
• Cancer
• Male and female infertility

Answer: they can all mimic the signs and symptoms of vitamin B12 deficiency.

B12 deficiency: an invisible epidemic

B12 deficiency isn't a bizarre, mysterious disease. It's written about in every medical textbook and its causes and effects are well-established in the scientific literature. However, B12 deficiency is far more common than most health care practitioners and the general public realize. Data from the Tufts University Framingham Offspring Study suggest that 40 percent of people between the ages of 26 and 83 have plasma B12 levels in the low normal range - a range at which many experience neurological symptoms. 9 percent had outright deficiency, and 16 percent exhibited "near deficiency". Most surprising to the researchers was the fact that low B12 levels were as common in younger people as they were in the elderly. That said, B12 deficiency has been estimated to affect about 40% of people over 60 years of age. It's entirely possible that at least some of the symptoms we attribute to "normal" aging - such as memory loss, cognitive decline, decreased mobility, etc. - are at least in part caused by B12 deficiency.

Why is B12 deficiency so under-diagnosed?

B12 deficiency is often missed for two reasons. First, it's not routinely tested by most physicians. Second, the low end of the laboratory reference range is too low. This is why most studies underestimate true levels of deficiency. Many B12 deficient people have so-called "normal" levels of B12. Yet it is well-established in the scientific literature that people with B12 levels between 200 pg/mL and 350 pg/mL - levels considered "normal" in the U.S. - have clear B12 deficiency symptoms. Experts who specialize in the diagnosis and treatment of B12 deficiency, like Sally Pacholok R.N. and Jeffery Stewart D.O., suggest treating all patients that are symptomatic and have B12 levels less than 450 pg/mL. They also recommend treating patients with normal B12, but elevated urinary methylmalonic acid (MMA), homocysteine and/or holotranscobalamin (other markers of B12 deficiency). In Japan and Europe, the lower limit for B12 is between 500-550 pg/mL, the level associated with psychological and behavioral manifestations such as cognitive decline, dementia and memory loss. Some experts have speculated that the acceptance of higher levels as normal in Japan and the willingness to treat levels considered "normal" in the U.S. explain the low rates of Alzheimer's and dementia in that country.

What is vitamin B12 and why do you need it?

Vitamin B12 works together with folate in the synthesis of DNA and red blood cells. It's also involved in the production of the myelin sheath around the nerves, and the conduction of nerve impulses. You can think of the brain and the nervous system as a big tangle of wires. Myelin is the insulation that protects those wires and helps them to conduct messages. Severe B12 deficiency in conditions like pernicious anemia (an autoimmune condition where the body destroys intrinsic factor, a protein necessary for the absorption of B12) used to be fatal until scientists figured out death could be prevented by feeding patients raw liver (which contains high amounts of B12). But anemia is the final stage of B12 deficiency. Long before anemia sets in, B12 deficiency causes several other problems, including fatigue, lethargy, weakness, memory loss and neurological and psychiatric problems. B12 deficiency occurs in four stages, beginning with declining blood levels of the vitamin (stage I), progressing to low cellular concentrations of the vitamin (stage II), an increased blood level of homocysteine and a decreased rate of DNA synthesis (stage III), and finally, macrocytic anemia (stage IV).

Why is B12 deficiency so common?

The absorption of B12 is complex and involves several steps - each of which can go wrong. Causes of B12 malabsorption include:

• intestinal dysbiosis
• leaky gut and/or gut inflammation
• atrophic gastrits or hypochlorhydria (low stomach acid)
• pernicious anemia (autoimmune condition)
• medications (especially PPIs and other acid-suppressing drugs)
• alcohol
• exposure to nitrous oxide (during surgery or recreational use)

This explains why B12 deficiency can occur even in people eating large amounts of B12-containing animal products. In fact, many of my patients that are B12 deficient are following a Paleo diet where they eat meat 2-3 times a day. In general, the following groups are at greatest risk for B12 deficiency:

• vegetarians and vegans
• people aged 60 or over
• people who regularly use PPIs or acid suppressing drugs
• people on diabetes drugs like metformin
• people with Crohn's disease, ulcerative colitis, celiac or IBS
• women with a history of infertility and miscarriage

Note to vegetarians and vegans: B12 is found ONLY in animal products

B12 is the only vitamin that contains a trace element (cobalt), which is why it's called cobalamin. Cobalamin is produced in the gut of animals. It's the only vitamin we can't obtain from plants or sunlight. Plants don't need B12 so they don't store it. A common myth amongst vegetarians and vegans is that it's possible to get B12 from plant sources like seaweed, fermented soy, spirulina and brewers yeast. But plant foods said to contain B12 actually contain B12 analogs called cobamides that block intake of and increase the need for true B12. This explains why studies consistently demonstrate that up to 50% of long-term vegetarians and 80% of vegans are deficient in B12. The effects of B12 deficiency on kids are especially alarming. Studies have shown that kids raised until age 6 on a vegan diet are still B12 deficient even years after they start eating at least some animal products. In one study, the researchers found:

...a significant association between cobalamin [b12] status and performance on tests measuring fluid intelligence, spatial ability and short-term memory" with formerly vegan kids scoring lower than omnivorous kids in each case.

The deficit in fluid intelligence is particularly troubling, the researchers said, because:

...it involves reasoning, the capacity to solve complex problems, abstract thinking ability and the ability to learn. Any defect in this area may have far-reaching consequences for individual functioning.

I recognize that there are many reasons why people choose to eat the way they do, and I respect people's right to make their own choices. I also know that, like all parents, vegetarians and vegans want the best for their children. This is why it's absolutely crucial for those that abstain from animal products to understand that there are no plant sources of B12 and that all vegans and most vegetarians should supplement with B12. This is especially important for vegetarian or vegan children or pregnant women, whose need for B12 is even greater than adults.

Treatment of B12 deficiency

One of the greatest tragedies of the B12 epidemic is that diagnosis and treatment is relatively easy and cheap - especially when compared to treatment of the diseases B12 deficiency can cause. A B12 test can be performed by any laboratory, and should be covered by insurance. If you don't have insurance, you can order it yourself from a lab like DirectLabs.com for $60. As always, adequate treatment depends on the underlying mechanism causing the problem. People with pernicious anemia or inflammatory gut disorders like Crohn's disease are likely to have impaired absorption for their entire lives, and will likely require B12 injections indefinitely. This may also be true for those with severe B12 deficiency causing neurological symptoms. Some recent studies have suggested that high dose oral or nasal administration may be as effective as injections for those with B12 malabsorption problems. However, most B12 experts still recommend injections for people with pernicious anemia and advanced B12 deficiency involving neurological symptoms. Cyanaocobalamin is the most frequently used form of B12 supplementation in the US. But recent evidence suggests that hydroxycobalamin (frequently used in Europe) is superior to cyanocobalamin, and methylcobalamin may be superior to both - especially for neurological disease. Japanese studies indicate that methylcobalamin is even more effective in treating the neurological sequelae of B12 deficiency, and that it may be better absorbed because it bypasses several potential problems in the B12 absorption cycle. On top of that, methylcobalamin provides the body with methyl groups that play an role in various biological processes important to overall health. If you suspect you have B12 deficiency, the first step is to get tested. You need an accurate baseline to work from. If you are B12 deficient, the next step is to identify the mechanism causing the deficiency. This is something you'll probably need help with from a medical practitioner. Once the mechanism is identified, the appropriate form (injection, oral, sublingual or nasal) of supplementation, the dose and the length of treatment can be selected. So, next time you or someone you know is "having a senior moment", remember: it might not be "just aging". It could be B12 deficiency.

Coconut milk is often a staple fat source for those following a Paleo diet. From a nutritional perspective, it's an excellent choice. It's high in saturated fatty acids and medium-chain triglycerides (MCT), which are both easily burned as fuel by the body. MCTs are particularly beneficial in that they don't require bile acids for digestion, and they're directly shunted to the liver via the portal vein. Coconut milk and fruit can be a great snack for Paleo folks, and coconut milk smoothies make a great Paleo breakfast choice - especially in the summer. So what could be wrong with coconut milk? Here are three things to consider.

Bisphenol-A

Bisphenol-A (BPA) is a chemical that has been used in consumer goods since the 50s. It's found in reusable drink containers, DVDs, cell phones, eyeglass lenses, automobile parts and sports equipment. While the research on BPA is still mixed (some studies indicating harm and others not), given the uncertainty I think it makes sense to avoid it whenever possible. BPA is used in the lining of certain canned foods. BPA especially leaches into canned foods that are acidic, salty or fatty, such as coconut milk, tomatoes, soup, and vegetables. Is BPA exposure common? You bet. This CDC report found BPA in the urine of 93% of adults. Perhaps most troubling is that companies like Nestle, Similac, Enfamil and PBM all use BPA in the linings of metal cans holding baby formula. This is scary in light of a recent study which found an association between neurobehavioral problems in infants and high levels of BPA in their mothers. So what's the solution here? In short, if you want to be on the safe side and reduce your exposure to BPA, you have to reduce your consumption of canned foods (including coconut milk) as much as possible. I made this recommendation in 9 Steps for Perfect Health-#3: Eat Real Food. A study published in Environmental Health Perspectives found that families who ate fresh food for three days with no canned food, and using only glass storage containers, experienced a 60% reduction of BPA in their urine. The reductions were even higher (75%) for those with the highest BPA levels at the beginning of the study. The good news, however, is that there are at least two brands of coconut milk that don't have BPA in them. One is Native Forest, which you can purchase on Amazon if it's not available at your local store. The other is Arroy-D, which is a brand imported from Thailand. You can get it here (but you have to scroll down and order the version that comes in cartons, not the cans at the top). I'm a little suspicious of Arroy-D, though, because one Thai reader mentioned that it does contain other ingredients aside from coconut milk. I don't read Thai, so I can't confirm this. If anyone out there can, please leave a comment below. Coconut milk can also be made quite easily at home, with coconut flakes, a blender and cheesecloth. Here's a video to show you how (get a load of the soundtrack). I find that blanching the coconut flakes prior to blending improves the results.

Guar gum

The other potential problem with canned coconut milk is guar gum. Guar gum is a galactomannan, which is a polysaccharide consisting of a mannose backbone with a galactose side group. It's primarily the endosperm of guar beans. Beans and legumes have a variety of compounds in them that make them difficult to digest, especially for people with digestive problems (1 in 3 Americans, from the latest statistics). In my clinical experience, many patients with gut issues improve when they remove guar gum from their diet—including canned coconut milk. Unlike BPA, there's no evidence that guar gum may cause serious harm. So, if you're able to tolerate guar gum, there's no reason to avoid it. If guar gum does give you digestive trouble, Native Forest has just released a new version of its product that doesn't contain it, and Arroy-D also does not have it. The other option, of course, is making coconut milk at home.

Fructose malabsorption

Fructose malabsorption (FM) is a digestive disorder characterized by impaired transport of fructose across the small intestine. This results in increased levels of undigested fructose in the gut, which in turn causes overgrowth of bacteria in the small intestine. Undigested fructose also reduces the absorption of water into the intestine. The clinical effects of FM include: intestinal dysbiosis, changes in motility, promotion of mucosal biofilm, and decreased levels of tryptophan, folates and zinc in the blood. Symptoms produced include bloating, gas, pain, constipation or diarrhea, vomiting and fatigue (to name a few). Recent research has also tied fructose malabsorption to depression. Lest you think this isn't a common problem, studies have shown that up to 40% of people in Western countries suffer from fructose malabsorption. Even in healthy people without fructose malabsorption, however, only about 20-25g of fructose can be properly absorbed at one sitting. Glucose assists in transport of fructose across the intestine, so in general foods with equal amounts of glucose and fructose will be better absorbed than foods with excess amounts of fructose (in relation to glucose). While fructose malabsorption can cause symptoms in anyone, those with Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD) are particularly affected. While the prevalence of FM is the same in healthy populations and those with IBS & IBD, the experience of FM appears to be more intense in the latter group. This is probably due to the increased visceral sensitivity common in IBS and IBD patients. In fact, one of the most promising clinical approaches to treating IBS & IBD right now is something called the FODMAP diet. FODMAP stands for Fermentable Oligo-, Di- and Mono-saccharides And Polyols. These include:

• fructose (fruits, honey, HFCS)
• fructans (wheat, onions)
• lactose (milk sugar)
• polyols (sugar alcohols like sorbitol, xylitol & mannitol, along with fruits like apples, pears and plums)
• galactooligosaccharides (legumes & beans, brussel sprouts, onions)
• other sweeteners like polydextrose and isomalt

Studies have found that restricting FODMAPs can significantly improve the symptoms associated with IBS, IBD and fructose malabsorption. What does this have to do with coconut milk, you ask? According to Drs. Gibson & Barrett, experts in fructose malabsorption, coconut milk is is a FODMAP and should be avoided by people with digestive conditions like IBS & IBD. According to NutritionData.com, coconut milk has very little sugar of any kind - including fructose. Nevertheless, I do have patients that cannot even tolerate homemade coconut milk (which has no guar gum in it), even though they are fine with coconut oil. I assume that they are reacting to the fructose in the coconut milk - but I can't be sure.

Recommendations

Let's bring this together into recommendations for three different groups of people:

• Women who are trying to get pregnant, pregnant or breastfeeding, children and other vulnerable populations (chronically ill): should avoid canned coconut milk products except for those that are BPA-free, like Native Forest and Arroy-D. Note: Native Forest is organic, but Arroy-D is not.
• People with digestive problems (IBS, IBD, GERD, etc.): may want to avoid coconut products entirely, except for coconut oil
• Healthy people: may be fine with canned coconut milk, provided they don't react to the guar gum, and provided they're willing to take the side of industry scientists that claim BPA doesn't cause harm in humans

Want organic coconut milk - but without the BPA and guar gum?

As of the time of this writing there is no widely available commercial brand of coconut milk that is organic and free of BPA and guar gum. The good news, however, is that with a little extra effort you can easily make this at home yourself.

• Purchase coconut cream (Let's Do Organic and Artisana are good choices) and blend with water to make coconut milk.
• Purchase shredded coconut (again, Let's Do Organic is a good choice), and follow the instructions below for making homemade coconut milk.

Homemade coconut milk instructions

Ingredients

• 4 cups water
• 1.5 - 2 cups unsweetened coconut flakes

Instructions

• Heat water until hot (but not boiling).
• Add shredded coconut and water to blender (preferably a Vitamix!) If all of the water won’t fit, you can add it in two batches.
• Blend on high for several minutes until thick and creamy.
• Pour through a colander to filter out the coconut pulp, then squeeze through a cheese cloth or nut milk bag to filter the smaller pieces of coconut.
• If you separated the water into two batches, put the strained coconut back into the blender with the second batch of water.
• Drink immediately or store in the fridge. Fresh coconut milk should be used within 3-4 days of making it for the best flavor and texture.

Many of you have probably heard of the ‘alkaline diet’. There are a few different versions of the acid-alkaline theory circulating the internet, but the basic claim is that the foods we eat leave behind an ‘ash’ after they are metabolized, and this ash can be acid or alkaline (alkaline meaning more basic on the pH scale). According to the theory, it is in our best interest to make sure we eat more alkaline foods than acid foods, so that we end up with an overall alkaline load on our body. This will supposedly protect us from the diseases of modern civilization, whereas eating a diet with a net acid load will make us vulnerable to everything from cancer to osteoporosis. To make sure we stay alkaline, they recommend keeping track of urine or saliva pH using handy pH test strips. In this two-part series, I will address the main claims made by proponents of the alkaline diet, and will hopefully clear up some confusion about what it all means for your health.

Will eating an alkaline diet make you and your bones healthier?

Foods can influence our urine pH

Before I start dismantling this theory, I want to acknowledge a couple things they get right. First, foods do leave behind acid or alkaline ash. The type of ‘ash’ is determined by the relative content of acid-forming components such as phosphate and sulfur, and alkalis such as calcium, magnesium, and potassium. (1, 2) In general, animal products and grains are acid forming, while fruits and vegetables are alkali forming. Pure fats, sugars, and starches are neutral, because they don’t contain protein, sulfur, or minerals. It’s also true that the foods we eat change the pH of our urine. (3, 4) If you have a green smoothie for breakfast, for example, your pee a few hours later will likely be more alkaline than that of someone who had bacon and eggs. As a side note, it’s also very easy to measure your urine pH, and I think this is one of the big draws of the alkaline diet. Everyone can probably agree that it’s satisfying to see concrete improvements in health markers depending on your diet, and pH testing gives people that instant gratification they desire. However, as you’ll see below, urine pH is not a good indicator of the overall pH of the body, nor is it a good indicator of general health.

Foods don’t influence our blood pH

Proponents of the alkaline diet have put forth a few different theories about how an acidic diet harms our health. The more ridiculous claim is that we can change the pH of our blood by changing the foods we eat, and that acidic blood causes disease while alkaline blood prevents it. This is not true. The body tightly regulates the pH of our blood and extracellular fluid, and we cannot influence our blood pH by changing our diet. (5, 6) High doses of sodium bicarbonate can temporarily increase blood pH, but not without causing uncomfortable GI symptoms. (7, 8) And there are certainly circumstances in which the blood is more acidic than it should be, and this does have serious health consequences. However, this state of acidosis is caused by pathological conditions such as chronic renal insufficiency, not by whether you choose to eat a salad or a burger. In other words, regardless of what you eat or what your urine pH is, you can be pretty confident that your blood pH is hovering around a comfortable 7.4. A more nuanced claim has been proposed specifically regarding bone health, and this hypothesis is addressed somewhat extensively in the scientific literature. It supposes that in order to keep blood pH constant, the body pulls minerals from our bones to neutralize any excess acid that is produced from our diet. Thus, net acid-forming diets (such as the typical Western diet) can cause bone demineralization and osteoporosis. This hypothesis, often referred to as the ‘acid-ash hypothesis of osteoporosis,’ is what I will discuss for the rest of this article. I’ll address some of the other health claims in part two.

The kidneys – not bone – regulate blood pH

While more reasonable than the first claim, the acid-ash hypothesis seems to completely disregard the vital role the kidneys play in regulating body pH. The kidneys are well equipped to deal with ‘acid ash.’ When we digest things like protein, the acids produced are quickly buffered by bicarbonate ions in the blood. (7) This reaction produces carbon dioxide, which is exhaled through the lungs, and salts, which are excreted by the kidneys. During the process of excretion, the kidneys produce ‘new’ bicarbonate ions, which are returned to the blood to replace the bicarbonate that was initially used to buffer the acid. This creates a sustainable cycle in which the body is able to maintain the pH of the blood, with no involvement from the bones whatsoever. Thus, our understanding of acid-base physiology does not support the theory that net acid-forming diets cause loss of bone minerals and osteoporosis. But just for argument’s sake, let’s say that our renal system cannot handle the acid load of the modern diet. If bones were used to buffer this excess acid, we would expect to see evidence of this taking place in clinical trials. Alas, that is not the case.

Clinical trials do not support the acid-ash hypothesis of osteoporosis

At first glance, some of the studies may look convincing, because higher acid diets often increase the excretion of calcium in the urine. Some researchers assumed that this extra calcium was coming from bone. (8) However, when calcium balance (intake minus excretion) was measured, researchers found that acid-forming diets do not have a negative effect on calcium metabolism. (9) Some studies found that supplementing with potassium salts (intended to neutralize excess acid) had beneficial effects on markers for bone health, which would tend to support the acid-ash hypothesis. However, these results were only observed in the first few weeks of supplementation, and long-term trials did not find any benefit to bone health from these alkalizing salts. (10) Finally, even though the hypothesis holds that higher intakes of protein and phosphate are acidifying and therefore detrimental to bone health, multiple studies have shown that increasing protein or phosphate intake has positive effects on calcium metabolism and on markers for bone health. (11, 12) Summarizing the clinical evidence, two different meta-analyses and a review paper all concluded that randomized controlled trials do not support the hypothesis that acidifying diets cause loss of bone mineral and osteoporosis. (13, 14, 15) So, it appears that neither physiology nor clinical trials support the acid-ash hypothesis of osteoporosis. But again, just for argument’s sake, let’s suppose that these trials are imperfect (which they are, of course; no science is perfect!), and thus we can’t depend on their conclusions. If the acid-ash hypothesis of osteoporosis were true, we would expect to see an association between net acid-producing diets and osteoporosis in observational studies. Yet again, this is not the case.

Observational studies do not support the acid-ash hypothesis of osteoporosis

Observational studies have not found a correlation between dietary acid load and bone mineral density (BMD) or fracture risk, nor have they found a correlation between urine pH and BMD or fracture risk. (16, 17, 18) Additionally, higher protein intakes are correlated with better bone health in multiple studies, even though high-protein diets are generally net acid forming. (19) In fact, animal protein in particular (the most acid-forming food of all) has been associated with better bone health. (20, 21) Imagine that! One study included in a recent meta-analysis did find an association between higher protein intake and greater risk for fracture (22), but compared to the numerous more recent studies showing the opposite, this evidence isn’t very strong. Overall, the acid-ash hypothesis of osteoporosis is not supported by physiology, clinical trials, or observational data. Hopefully I’ve given you a decent understanding of how our bodies handle pH balance, and have reassured you that you don’t need to worry about the acidity of your urine with regards to bone health. Click HERE for part two where I tackle some of the other claims of the alkaline diet!

Coconut milk is often a staple fat source for those following a Paleo diet. From a nutritional perspective, it's an excellent choice. It's high in saturated fatty acids and medium-chain triglycerides (MCT), which are both easily burned as fuel by the body. MCTs are particularly beneficial in that they don't require bile acids for digestion, and they're directly shunted to the liver via the portal vein. Coconut milk and fruit can be a great snack for Paleo folks, and coconut milk smoothies make a great Paleo breakfast choice - especially in the summer. So what could be wrong with coconut milk? Here are three things to consider.

Bisphenol-A

Bisphenol-A (BPA) is a chemical that has been used in consumer goods since the 50s. It's found in reusable drink containers, DVDs, cell phones, eyeglass lenses, automobile parts and sports equipment. While the research on BPA is still mixed (some studies indicating harm and others not), given the uncertainty I think it makes sense to avoid it whenever possible. BPA is used in the lining of certain canned foods. BPA especially leaches into canned foods that are acidic, salty or fatty, such as coconut milk, tomatoes, soup, and vegetables. Is BPA exposure common? You bet. This CDC report found BPA in the urine of 93% of adults. Perhaps most troubling is that companies like Nestle, Similac, Enfamil and PBM all use BPA in the linings of metal cans holding baby formula. This is scary in light of a recent study which found an association between neurobehavioral problems in infants and high levels of BPA in their mothers. So what's the solution here? In short, if you want to be on the safe side and reduce your exposure to BPA, you have to reduce your consumption of canned foods (including coconut milk) as much as possible. I made this recommendation in 9 Steps for Perfect Health-#3: Eat Real Food. A study published in Environmental Health Perspectives found that families who ate fresh food for three days with no canned food, and using only glass storage containers, experienced a 60% reduction of BPA in their urine. The reductions were even higher (75%) for those with the highest BPA levels at the beginning of the study. The good news, however, is that there are at least two brands of coconut milk that don't have BPA in them. One is Native Forest, which you can purchase on Amazon if it's not available at your local store. The other is Arroy-D, which is a brand imported from Thailand. You can get it here (but you have to scroll down and order the version that comes in cartons, not the cans at the top). I'm a little suspicious of Arroy-D, though, because one Thai reader mentioned that it does contain other ingredients aside from coconut milk. I don't read Thai, so I can't confirm this. If anyone out there can, please leave a comment below. Coconut milk can also be made quite easily at home, with coconut flakes, a blender and cheesecloth. Here's a video to show you how (get a load of the soundtrack). I find that blanching the coconut flakes prior to blending improves the results.

Guar gum

The other potential problem with canned coconut milk is guar gum. Guar gum is a galactomannan, which is a polysaccharide consisting of a mannose backbone with a galactose side group. It's primarily the endosperm of guar beans. Beans and legumes have a variety of compounds in them that make them difficult to digest, especially for people with digestive problems (1 in 3 Americans, from the latest statistics). In my clinical experience, many patients with gut issues improve when they remove guar gum from their diet—including canned coconut milk. Unlike BPA, there's no evidence that guar gum may cause serious harm. So, if you're able to tolerate guar gum, there's no reason to avoid it. If guar gum does give you digestive trouble, Native Forest has just released a new version of its product that doesn't contain it, and Arroy-D also does not have it. The other option, of course, is making coconut milk at home.

Fructose malabsorption

Fructose malabsorption (FM) is a digestive disorder characterized by impaired transport of fructose across the small intestine. This results in increased levels of undigested fructose in the gut, which in turn causes overgrowth of bacteria in the small intestine. Undigested fructose also reduces the absorption of water into the intestine. The clinical effects of FM include: intestinal dysbiosis, changes in motility, promotion of mucosal biofilm, and decreased levels of tryptophan, folates and zinc in the blood. Symptoms produced include bloating, gas, pain, constipation or diarrhea, vomiting and fatigue (to name a few). Recent research has also tied fructose malabsorption to depression. Lest you think this isn't a common problem, studies have shown that up to 40% of people in Western countries suffer from fructose malabsorption. Even in healthy people without fructose malabsorption, however, only about 20-25g of fructose can be properly absorbed at one sitting. Glucose assists in transport of fructose across the intestine, so in general foods with equal amounts of glucose and fructose will be better absorbed than foods with excess amounts of fructose (in relation to glucose). While fructose malabsorption can cause symptoms in anyone, those with Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD) are particularly affected. While the prevalence of FM is the same in healthy populations and those with IBS & IBD, the experience of FM appears to be more intense in the latter group. This is probably due to the increased visceral sensitivity common in IBS and IBD patients. In fact, one of the most promising clinical approaches to treating IBS & IBD right now is something called the FODMAP diet. FODMAP stands for Fermentable Oligo-, Di- and Mono-saccharides And Polyols. These include:

• fructose (fruits, honey, HFCS)
• fructans (wheat, onions)
• lactose (milk sugar)
• polyols (sugar alcohols like sorbitol, xylitol & mannitol, along with fruits like apples, pears and plums)
• galactooligosaccharides (legumes & beans, brussel sprouts, onions)
• other sweeteners like polydextrose and isomalt

Studies have found that restricting FODMAPs can significantly improve the symptoms associated with IBS, IBD and fructose malabsorption. What does this have to do with coconut milk, you ask? According to Drs. Gibson & Barrett, experts in fructose malabsorption, coconut milk is is a FODMAP and should be avoided by people with digestive conditions like IBS & IBD. According to NutritionData.com, coconut milk has very little sugar of any kind - including fructose. Nevertheless, I do have patients that cannot even tolerate homemade coconut milk (which has no guar gum in it), even though they are fine with coconut oil. I assume that they are reacting to the fructose in the coconut milk - but I can't be sure.

Recommendations

Let's bring this together into recommendations for three different groups of people:

• Women who are trying to get pregnant, pregnant or breastfeeding, children and other vulnerable populations (chronically ill): should avoid canned coconut milk products except for those that are BPA-free, like Native Forest and Arroy-D. Note: Native Forest is organic, but Arroy-D is not.
• People with digestive problems (IBS, IBD, GERD, etc.): may want to avoid coconut products entirely, except for coconut oil
• Healthy people: may be fine with canned coconut milk, provided they don't react to the guar gum, and provided they're willing to take the side of industry scientists that claim BPA doesn't cause harm in humans

Want organic coconut milk - but without the BPA and guar gum?

As of the time of this writing there is no widely available commercial brand of coconut milk that is organic and free of BPA and guar gum. The good news, however, is that with a little extra effort you can easily make this at home yourself.

• Purchase coconut cream (Let's Do Organic and Artisana are good choices) and blend with water to make coconut milk.
• Purchase shredded coconut (again, Let's Do Organic is a good choice), and follow the instructions below for making homemade coconut milk.

Homemade coconut milk instructions

Ingredients

• 4 cups water
• 1.5 - 2 cups unsweetened coconut flakes

Instructions

• Heat water until hot (but not boiling).
• Add shredded coconut and water to blender (preferably a Vitamix!) If all of the water won’t fit, you can add it in two batches.
• Blend on high for several minutes until thick and creamy.
• Pour through a colander to filter out the coconut pulp, then squeeze through a cheese cloth or nut milk bag to filter the smaller pieces of coconut.
• If you separated the water into two batches, put the strained coconut back into the blender with the second batch of water.
• Drink immediately or store in the fridge. Fresh coconut milk should be used within 3-4 days of making it for the best flavor and texture.

Many of you have probably heard of the ‘alkaline diet’. There are a few different versions of the acid-alkaline theory circulating the internet, but the basic claim is that the foods we eat leave behind an ‘ash’ after they are metabolized, and this ash can be acid or alkaline (alkaline meaning more basic on the pH scale). According to the theory, it is in our best interest to make sure we eat more alkaline foods than acid foods, so that we end up with an overall alkaline load on our body. This will supposedly protect us from the diseases of modern civilization, whereas eating a diet with a net acid load will make us vulnerable to everything from cancer to osteoporosis. To make sure we stay alkaline, they recommend keeping track of urine or saliva pH using handy pH test strips. In this two-part series, I will address the main claims made by proponents of the alkaline diet, and will hopefully clear up some confusion about what it all means for your health.

Will eating an alkaline diet make you and your bones healthier?

Foods can influence our urine pH

Before I start dismantling this theory, I want to acknowledge a couple things they get right. First, foods do leave behind acid or alkaline ash. The type of ‘ash’ is determined by the relative content of acid-forming components such as phosphate and sulfur, and alkalis such as calcium, magnesium, and potassium. (1, 2) In general, animal products and grains are acid forming, while fruits and vegetables are alkali forming. Pure fats, sugars, and starches are neutral, because they don’t contain protein, sulfur, or minerals. It’s also true that the foods we eat change the pH of our urine. (3, 4) If you have a green smoothie for breakfast, for example, your pee a few hours later will likely be more alkaline than that of someone who had bacon and eggs. As a side note, it’s also very easy to measure your urine pH, and I think this is one of the big draws of the alkaline diet. Everyone can probably agree that it’s satisfying to see concrete improvements in health markers depending on your diet, and pH testing gives people that instant gratification they desire. However, as you’ll see below, urine pH is not a good indicator of the overall pH of the body, nor is it a good indicator of general health.

Foods don’t influence our blood pH

Proponents of the alkaline diet have put forth a few different theories about how an acidic diet harms our health. The more ridiculous claim is that we can change the pH of our blood by changing the foods we eat, and that acidic blood causes disease while alkaline blood prevents it. This is not true. The body tightly regulates the pH of our blood and extracellular fluid, and we cannot influence our blood pH by changing our diet. (5, 6) High doses of sodium bicarbonate can temporarily increase blood pH, but not without causing uncomfortable GI symptoms. (7, 8) And there are certainly circumstances in which the blood is more acidic than it should be, and this does have serious health consequences. However, this state of acidosis is caused by pathological conditions such as chronic renal insufficiency, not by whether you choose to eat a salad or a burger. In other words, regardless of what you eat or what your urine pH is, you can be pretty confident that your blood pH is hovering around a comfortable 7.4. A more nuanced claim has been proposed specifically regarding bone health, and this hypothesis is addressed somewhat extensively in the scientific literature. It supposes that in order to keep blood pH constant, the body pulls minerals from our bones to neutralize any excess acid that is produced from our diet. Thus, net acid-forming diets (such as the typical Western diet) can cause bone demineralization and osteoporosis. This hypothesis, often referred to as the ‘acid-ash hypothesis of osteoporosis,’ is what I will discuss for the rest of this article. I’ll address some of the other health claims in part two.

The kidneys – not bone – regulate blood pH

While more reasonable than the first claim, the acid-ash hypothesis seems to completely disregard the vital role the kidneys play in regulating body pH. The kidneys are well equipped to deal with ‘acid ash.’ When we digest things like protein, the acids produced are quickly buffered by bicarbonate ions in the blood. (7) This reaction produces carbon dioxide, which is exhaled through the lungs, and salts, which are excreted by the kidneys. During the process of excretion, the kidneys produce ‘new’ bicarbonate ions, which are returned to the blood to replace the bicarbonate that was initially used to buffer the acid. This creates a sustainable cycle in which the body is able to maintain the pH of the blood, with no involvement from the bones whatsoever. Thus, our understanding of acid-base physiology does not support the theory that net acid-forming diets cause loss of bone minerals and osteoporosis. But just for argument’s sake, let’s say that our renal system cannot handle the acid load of the modern diet. If bones were used to buffer this excess acid, we would expect to see evidence of this taking place in clinical trials. Alas, that is not the case.

Clinical trials do not support the acid-ash hypothesis of osteoporosis

At first glance, some of the studies may look convincing, because higher acid diets often increase the excretion of calcium in the urine. Some researchers assumed that this extra calcium was coming from bone. (8) However, when calcium balance (intake minus excretion) was measured, researchers found that acid-forming diets do not have a negative effect on calcium metabolism. (9) Some studies found that supplementing with potassium salts (intended to neutralize excess acid) had beneficial effects on markers for bone health, which would tend to support the acid-ash hypothesis. However, these results were only observed in the first few weeks of supplementation, and long-term trials did not find any benefit to bone health from these alkalizing salts. (10) Finally, even though the hypothesis holds that higher intakes of protein and phosphate are acidifying and therefore detrimental to bone health, multiple studies have shown that increasing protein or phosphate intake has positive effects on calcium metabolism and on markers for bone health. (11, 12) Summarizing the clinical evidence, two different meta-analyses and a review paper all concluded that randomized controlled trials do not support the hypothesis that acidifying diets cause loss of bone mineral and osteoporosis. (13, 14, 15) So, it appears that neither physiology nor clinical trials support the acid-ash hypothesis of osteoporosis. But again, just for argument’s sake, let’s suppose that these trials are imperfect (which they are, of course; no science is perfect!), and thus we can’t depend on their conclusions. If the acid-ash hypothesis of osteoporosis were true, we would expect to see an association between net acid-producing diets and osteoporosis in observational studies. Yet again, this is not the case.

Observational studies do not support the acid-ash hypothesis of osteoporosis

Observational studies have not found a correlation between dietary acid load and bone mineral density (BMD) or fracture risk, nor have they found a correlation between urine pH and BMD or fracture risk. (16, 17, 18) Additionally, higher protein intakes are correlated with better bone health in multiple studies, even though high-protein diets are generally net acid forming. (19) In fact, animal protein in particular (the most acid-forming food of all) has been associated with better bone health. (20, 21) Imagine that! One study included in a recent meta-analysis did find an association between higher protein intake and greater risk for fracture (22), but compared to the numerous more recent studies showing the opposite, this evidence isn’t very strong. Overall, the acid-ash hypothesis of osteoporosis is not supported by physiology, clinical trials, or observational data. Hopefully I’ve given you a decent understanding of how our bodies handle pH balance, and have reassured you that you don’t need to worry about the acidity of your urine with regards to bone health. Click HERE for part two where I tackle some of the other claims of the alkaline diet!