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The Acid-Alkaline Myth: Part 1

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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).

acid alkaline, alkaline myth
Smoothies containing vegetables are alkali forming. Derkien/iStock/Thinkstock

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 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.d

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

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.

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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!

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1,191 Comments

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  1. Here is a link so we all understand what Tony Robbins point of view is.
    Tony Robbins on ALKALINITY Weight Loss and Energy

    It may also help to read this
    Acid-base balance may influence risk for insulin resistance syndrome by modulating cortisol output.”

    We have got to be careful to avoid the chicken/egg which came first debate.

    If all the interventions we suggest to improve health also make improve our ability to resolve excess acidity wouldn’t it be more honest to accept that the acid balance question needs resolving?

    Mark Sisson is another fence sitter who cannot face up to the truth
    No doubt the penny will drop eventually.

    • I’m a Mark Sisson fan, so I went to read the article you linked here. You certainly haven’t represented his position honestly. The following is the conclusion of the segment he wrote. It should be noted that he isn’t commenting on the theory in general, but rather on a particular study that claimed to find a correlation between acidic diets and diabetes– specifically that there were significant confounders that could not be accounted for.

      “So, is it the acid load causing (or preventing) the diabetes? Or is the acid load merely a representation of the diet which in turn causes (or prevents) the diabetes? Heck, it may even be that the diabetes is causing kidney disease, which in turn leads to acidosis. We don’t know for sure from this study. As the authors write in the discussion section, “this is the first prospective study to evaluate the risk of type 2 diabetes associated with scores reflecting the acid load of the diet.” What we do know is that many aspects of the overall dietary pattern of the high-acid quartile, like low magnesium, potassium, coffee, and produce intake, are consistently linked to type 2 diabetes across multiple studies. For now, that seems to be where the strongest evidence lies.”

      I don’t see any fence-sitting. I see an intelligent individual who is wise enough to determine what a study can actually tell us, and more importantly, what it can’t.

      • This is a good example of why I get so irritated with Edward Hutchison. It appears he just posts whatever he can find that sounds like it will back his point of view. In my opinion though he must not be reading these studies or understanding them and does not understand how the body really works. I feel this is why he keeps refusing to quote the parts of the studies he posts that he thinks backs his position. Instead he just posts a bunch of studies that have words in the title that sound like they will back his position and hopes that people will not read the studies. Even if they do the person will not know what in the study he thinks backs his position.

        For example, he posted a study:

        Acid-base balance may influence risk for insulin resistance syndrome by modulating cortisol output.”

        Does the study show anywhere that a diet can really influence blood pH? Not that I could find. They do mention lower potassium being a possible factor. But does potassium help with blood sugar by alkalizing? Not at all. Instead it is essential for proper insulin sensitizing of cells.

        And they talk a lot about visceral fat production due to cortisol release. Does Hutchison even realize that cortisol can be released without having anything to do with diet? Just think about something stressful and your cortisol levels will go up. If your blood sugar drops cortisol will be released. In pain? Cortisol will be released. Smoke a cigarette and your cortisol levels will go up………… So how did the researchers differentiate between cortisol rises from diet and the various other factors that can lead to a cortisol rise? Answer, they didn’t!!!

        Other things can also increase body fat such as estrogen and progesterone. Did the researchers take the body fat production from hormones in to account? Not at all.

        Bottom line is that the research paper is highly flawed and does not back his claims.

        Again, this is why if people are going to post research studies to try and back their claims they should actually read and understand those studies first.

    • It’s all based upon negative ions (minerals and antioxidants), which is the source of alkalinity. James and the Huntress seem to think that the body has an unlimited supply of alkaline minerals and antioxidants, and that an acidic diet has no effect upon the body’s ability to maintain homeostasis. The truth is that when alkaline reserves are depleted, the body begins to deteriorate. See drsircus.com and captrandall.com.

      • James is the expert, not me. And I mean that, he is that ACTUAL, in-the-lab, pH expert. Your comments here are meaningless next to his.

        Where are all of those deteriorating meat-based cultures? What aren’t they dropping like flies with such an acidic diet? ~boggles~

      • First of all minerals and antioxidants are not negative ions.

        And antioxidants do not necessarily produce alkalinity. For example, ascorbic acid is an antioxidant as is tannic acid. On the other hand, alkaline substances such as calcium hydroxide are strong radicals.

        It is virtually impossible to deplete your alkaline reserves. To start with the body’s main means of pH regulation is respiration. So it is pretty hard to develop acidosis as long as you are still breathing, which is why acidosis is so rare. And how much salt does the average American consume. Guess what sodium chloride is used to produce in the body. Stomach acid as well as alkaline sodium bicarbonate. Acidity can also be reduced by other means such as protein binding or lactate formation.

        Alkalosis is actually considered much more dangerous than acidosis since the body has less in its arsenal to deal with alkalosis.

  2. Hi Chris. As you mentioned there are tons of websites, articles and even a few studies that support notion of pH effecting the cell’s ability to absorb nutrient, we even see this in gardening, but I completely understand what you’re saying about the minimal effect these diets would have due to our body’s natural regulation of this. However, one thing I have been wondering is, any time you have a “regulator,” the external environment is what causes stress on the that system by forcing it to maintain regularity. Think of this like an Air Conditioning that is set at 70 degrees. If we are constantly running heat generating products, the AC will be forced to work much harder and this Stress on the AC causes it to break down quicker. Is it possible, that it is not the Acidic diets we eat directly, but the Stress that these diets cause on our bodies to regulate them that could be causing these issue? Thanks.

  3. You are completely in opposition with what Tony Robbins said at the Unleash the Power Within seminar I just got back from. (BTW, most life changing, amazing experience I’ve ever had.) I think I will take the word of a man who jumps and hollers on stage for 15 hours at a time without even as much as a sip of water over you. Not only that, much of what you say spits in the face of just common sense. Food intake has no affect on pH? Really? Yeah I think I will be listening to Tony on this one. 🙂

  4. There is a ton of supportive research by many DOCTORS but one in particular has been researching and practicing for about as long as Mr. Kresser has been alive. Dr. Lindsey Duncan has 30+ years of actual experience and over 40,000 clinical hours under his belt. Look him up, enlighten yourself.

  5. It could be one’s blood type that influences the type of ash left. Maybe Type O blood types need more phosphorus and sulfur in their diets from the acid ash; and maybe Type A blood types need more of the alkaline ash provided from calcium, magnesium and potassium.

    It is a strong statement that one needs to look not only at what foods a person eats, but also their blood type, life history and environment to help us understand more about how different people react to foods and why.

  6. Since making a conscious efforts to buy more alkaline and less acidic foods, I have noticed that I feel better in general. When I drink a 20 oz Coca Cola it tastes great, but as I drink the whole thing, I definitely feel worse physically, kind of a weird tired gross kind of feeling. When I drink water with fresh squeezed lime or coconut milk, I feel much better. Not because I feel good about myself or anything like that for making a “healthy” choice. I literally can feel how food makes me feel and the alkaline food scale is accurate in terms of how food makes me feel. Here’s an interesting note: peanuts are plant based food but they are quite acidic, I never knew that until recently, so I switched to almond butter instead of peanut butter, and just exactly how I used to feel kind of gross after eating a lot of peanut butter, with almond butter, the feeling is much less severe. Sounds crazy maybe to some, but I’m pretty in touch with my body. I won’t argue any nuances in the facts regarding blood pH being auto-regulated without regard to food, but I think there’s still something very valid about the alkaline diet approach, regardless of all the idiosyncracies.

    • Same here. When I changed my diet, I could feel the difference and its not placebo. Within a few days my skin literally had a glow to it. I wish people could stop fighting about who’s right and showing all the evidence they collected to prove their point. Try to get along with everyone, even when the disagree on certain stuff, and for those that truly are interested in changing their diet, do so and see and feel the evidence for yourself. Once you do, you won’t need a scientists experiment to prove anything.

      I also think that lots of people are making a fortune on selling products for us trying to improve our lifestyle. Although Almond butter is alkaline and peanut butter acidic, I could never afford it as its 4 times the price of peanut butter. Unless I sprout some almonds then plant my own tree with the sprouts which is the way the world is going eventually.

  7. As a Respiratory Therapist I have taught my patients for years that a diet high in carbohydrates increases blood CO2 levels. This decreases blood pH. Increasing respiration helps to blow off the CO2 and balance blood pH. . The kidney also produce HCO3(bicarb) which can balance pH as well. Most people don’t notice this affect, but people with severe lung disease sure do.

    This is an example of how diet can directly lower blood pH.

    • Eddie, you touch on an important point. My thoughts are that creating an alkaline environment in the kidney would help support them as they buffer blood CO2. It certainly couldn’t hurt.

    • Great point Terra!!! You are so spot on. The bicarb that is pulled in balances the pH but if we just consume highly acidic foods like sugars we are going to eventually run out of bicarb until our body withers away. We either support the intelligent design of our bodies or work against it.

      • You’ve hit the nail on the head. These people think that the body can continually neutralize acids without consuming alkaline foods. There is no other source but alkaline foods to replenish the body’s reserves. Following an Atkins diet and drinking smoothies with all the needed supplements will support a healthy body pH.

        • John Carraway: “These people think that the body can continually neutralize acids without consuming alkaline foods.”

          Most acid is the body is not neutralized. Most pH balance is maintained by respiration, which reduces carbonic acid to the normal levels, leaving sufficient carbonic acid the body needs to function properly. The second primary means the body uses to reduce excess acids in the body is through dumping hydrogen ions through the kidneys, which does not require alkaline minerals either.

          Neutralization of acids is primarily carried out through sodium bicarbonate, produced from sodium chloride found in many sources including meats and junk foods, and with carbonic acid produced continually by the body.

          John Carraway: “Following an Atkins diet and drinking smoothies with all the needed supplements will support a healthy body pH.”

          The Atkins diet is high in animal proteins and his highly processed food products that contain a lot of garbage such as dangerous artificial sweeteners. How is that healthy or alkaline?

        • Re: JoshDPT; JUNE 26, 2013 AT 6:05 AM

          Nobody had ever successfully convinced me food raises or lowers blood pH. Mr. Kresser is correct that kidneys do effect Blood pH (metabolic acidosis and alkalosis),

          Josh we were not drinking methanol or polyglycol, BUT inhaling it in Pulp Mill emissions. My Lactic acidosis progressed to Type D

        • John Carraway JAN 29, 2014 AT 8:56 PM

          You’ve hit the nail on the head. These people think that the body can continually neutralize acids without consuming alkaline foods. There is no other source but alkaline foods to replenish the body’s reserves. Following an Atkins diet …

          John a Co-worker commented who was in the same exposure of Pulp Mill emissions that he lost weight with the Atkins Diet I straight up asked him Did your pain levels drop He answered Yes because excessive carb intake will convert to Lactic acid (anaerobic glycolosis) when you have suffered Hypoxia His body felt like a piece of lead as mine also did

  8. Whatever you read regarding health , diet etc basically it all comes back to a very simple rule . For good health eat natural foods , stay away from anything that has been processed . Nothing more complicated than that .

  9. I am interested in studies showing whether an Alkalizing diet’s positive impact could come from the fact it’s FREEING your kidneys from having to work so hard to maintain blood Ph. There has to be a benefit to sparing your organs from work that wouldn’t need be done IF you were eating properly, right? No study I’ve came across ever discussed this point.

    • Doctors have been using baking soda for years to protect the kidneys, etc from acid-overload during detoxing and for recuperation. The acid/alkaline balance controls the body’s ability to function efficiently. Acidity (positive ions) must be balanced with alkalinity (negative ions) in order to maintain health.

  10. I think stomach acidity (or rather, lack of) has more to do with bone loss than an acidic diet. this would explain why high protein diets support bone health in that, it takes healthy HCL levels in the stomach to properly breakdown protein……thus the protein in the diet supports healthy stomach acidity. But everything in moderation…after a time I imagine that too much protein will stress out the body, namely the kidneys and may cause other problems.

  11. CK says in this blog that “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.”

    But the study at http://jcem.endojournals.org/content/early/2012/11/14/jc.2012-3099.abstract (Jehle, S., Henry N. Hulter, Reto Krapf. 2012. Effect of potassium citrate on bone density, microarchitecture, and fracture risk in healthy older adults without osteoporosis: A randomized controlled trial. Journal of Clinical Endocrinology and Metabolism, doi: 10.1210/jc.2012-3099.) lasted 24 months and did indicate that an alkalizing diet would be beneficial for bone health.

  12. I enjoy many of your posts. Not because I always think you are right but because you challenge commonly-held beliefs. In fact, I would suppose in many situation you are probably just as wrong as prevailing ideology. The reality is we just don’t know almost anything about the human experience. The pH hypothesis may or may not be valid. If it is, it’s likely valid for reasons neither you nor I understand. We assume well too much about correlation and observation in the medical community and as it pertains to the human experience. Albert Einstein mocked observational science. And if one truly understands science, one appreciates why. And it also explains why so much of prevailing medical science is junk science. Much more than is acknowledged. And why your challenge to why beliefs are equally invalid.

    If you or anyone else really understood the human experience, be that the body, mind or the mind-body connection, you would be able to predict outcomes rather than observe them. You cannot. I cannot. Modern medicine cannot. The number of understood and not understood factors affecting the human experience are boggling. At any moment, there are millions of processes that we know about going on within the human body. And millions of processes external to the human body that are also impacting the mind, the body and the mind-body connection.

    Certainly pH is controversial. Nothing here disproves or proves anything. Humans used to eat massive amounts of meat. Some still do. The ketogenic diet has tremendous benefits in certain situations. But humans also lived a very short period of time in our past when we ate copious amounts of meat. And they ate different meat that we have been eating for the last 50 years.

  13. Nobody had ever successfully convinced me food raises or lowers blood pH. Mr. Kresser is correct that kidneys do effect Blood pH (metabolic acidosis and alkalosis), but also breathing patterns such as hyperventilation causes respiratory acidosis and hypoventilation causes respiratory alkalosis.

    • Other way around.

      Hyperventilation leads to respiratory alkalosis from blowing off excess carbon dioxide, which in turn lowers carbonic acid levels leading to alkalosis.

      Hypoventilation leads to a build up of carbonic acid due to decreased carbon dioxide-oxygen exchange. Therefore leading to acidosis.

    • Re: JoshDPT; JUNE 26, 2013 AT 6:05 AM

      Nobody had ever successfully convinced me food raises or lowers blood pH. Mr. Kresser is correct that kidneys do effect Blood pH (metabolic acidosis and alkalosis),

      Josh we were not drinking methanol or polyglycol BUT inhaling it in Pulp Mill emissions My Metabolic (Lactic) acidosis progressed to where i suffered MELAS after eating a yogurt
      I cut out all dairy Within weeks I was off my puffers and my Fibromyalgia grew wings Apparently Lactic acid can irritate the delicate air sacs in the lungs No MD ever suggested this In fact he told me to go see a psychiatrist So back to FinnDian’s comment or as professor of Bio-Chemistry & Metabolism stating it is disgusting how little is taught to MD’s in Canada As is negligible Occupational Disease & Toxicology 1 1/2 years later i tried goat dairy products with NO complications But a slight amount of cow dairy by accident & MELAS onsets quickly

      • The metabolism pathway for methanol is: methanol –>formaldehyde –> formic acid –> water and carbon dioxide.

        Lactic acid is not a byproduct of methanol metabolism.

  14. While it’s great to find this information in this article it only confuses me as I thought the PH level in the urine came from the gut not the blood. I thought it was foods like wheat ect that also caused a higher acid level. I know some people who test their saliva and that is related to the digestive system not the blood. The reports I have read say that a high acid level causes such disease as cancer and we all want to avoid that but are we trying to stay alkaline for no reason?
    I would love to hear your thoughts on that as I don’t see that addressed above.

    • Acids do not cause cancer, nor most diseases.

      And salivary, nor urinary pH reflect blood pH. The only way to determine blood pH is with a blood test.

      Urinary pH is affected by factors such as the dumping of hydrogen ions from the blood in to the urine and by urinary tract infections as the bacteria use urease to split ammonia compounds in urine in to ammonia, which alkalizes the urine to help the bacteria to survive.

  15. Chris, is there any link between migraine and akalinity?

    The reason I ask is I occasionally suffer a migraine in my right eye, which lasts about 30-minutes, and causes like a shimmering/zigzagging effect in my eye. I can tell it’s coming on before the zigzags appear as I can’t quite focus/read text properly.

    I recently had some dental work done where calcium hydroxide was used to solve a root canal infection. Tn he calcium hydroxide was left in the root canal for 2 weeks and in that time I had the “migraine eye” every single day. Normally I’d get it once every 2-3 months! When the calcium hydroxide was removed, and the tooth filled, the migraines went to every other day, then every 3, then stopped altogether.

    Recently I’ve been using Apple Cider Vinegar to try and improve dishydrotic eczema on my hands. I think that has an alkanising effect, even though it’s acidic? I’ve had the migraine eye a couple of times since too.

    Is there a link? From n=1 it seems there is, but I can’t explain it.

    • Those are called ‘scintillating scotomas’. I get them once every few months, but have never had the follow-up migraine, and have been unable to relate them to any food I’ve consumed.

    • Calcium lowers magnesium levels. Magnesium deficiency can cause migraine. Perhaps you need a high quality magnesium like magnesium glycinate to bring levels up.

    • james, as a vendor of alkaline water systems for the last 13 years i can say I have seen results for migraine.

    • Different James here.

      Migraines result from an initial strong constriction of the blood vessels around the brain followed by rebound vasodilation leading to inflammation of the tissues. Alkalizers can cause the blood vessel constriction that precedes headaches.

      To understand this easier consider what happens during hyperventilation. The excess blowing off of carbon dioxide leads to an alkaline effect that causes the brain’s blood vessels to contract causing a decreased blood flow to the brain and we pass out. When we pass out our respiration ceases or decreases temporarily to build back up carbonic acid levels restoring blood flow to the brain.

      So not only can alkalizers lead to migraines, but so can excess calcium, which is a muscle contractor. Being that blood vessels are muscles they can also be contracted by calcium. Magnesium salts are used to treat migraines because magnesium relaxes the blood vessels by antagonizing calcium.

  16. Hi Manuel, your first reference from Wikpedia dates from 1995, the second from 1998. Below the Barzel and Massey article is a list of studies (from 1998 – 2011) citing their article.
    I checked out these references and found that several more recent studies run completely counter to the earlier articles.

    Dietary Protein: An Essential Nutrient For Bone Health J. Am. Coll. Nutr. 2005 24: 526S-536S
    http://www.jacn.org/content/24/suppl_6/526S.full

    Dietary protein and bone: a new approach to an old question Am J Clin Nutr 2009 90: 1451-1452
    http://ajcn.nutrition.org/content/90/6/1451.full
    ( This study in fact provides support for Chris’ argument ).

    Wikipedia, it seems, is rather out-of-date !

  17. According to the wikipedia:
    Diets containing high amounts of animal products, animal protein, processed foods, and other foods that induce and sustain increased acidity of body fluid may contribute to the development of osteoporosis and renal stones, loss of muscle mass, and age-related renal insufficiency due to the body’s use of calcium to buffer pH.[175][176]
    at http://en.wikipedia.org/wiki/Paleolithic_diet

    References:
    ^ Remer, T.; Manz, F. (1995). “Potential Renal Acid Load of Foods and its Influence on Urine pH”. Journal of the American Dietetic Association 95 (7): 791–797. doi:10.1016/S0002-8223(95)00219-7. PMID 7797810. edit
    ^ Uriel S. Barzel and Linda K. Massey (1998). “Excess Dietary Protein Can Adversely Affect Bone”. The Journal of Nutrition 128 (6): 1051–1053.

    • Yes, Manuel, and many other studies say the same.. but the salient point in the study i referred to and in my experience is the AMOUNT of meat you consume. Excess of anything is a problem but excess of meat is a serious acidifier, BUT absence of meat, as this thread has pointed out, may well be a recipe for longterm osteo – talking from experience of 14 years of vegetarian, now paleo.

      • Thanks, Edith, and Ian for your comments.

        Ian your previous comment was clariying. For me it is a bit confussing, as different authors, which I respect, say contradictory things, with arguments that seem to make much sense. So, it is hard to believe who is right, and who is not.

        I want to ask something, what would be a right amount of protein animal? What would be an excess, and waht would be too low ?

        At this article: http://chriskresser.com/9-steps-to-perfect-health-2-nourish-your-body Chris mentions something about the amount of fat, and about the amount of carbs, but he deones’t say anything about which amount of proteins would be healthy. So what would be too low, and what would be too high ?

        Thanks

        • Manuel, I’d heartily recommend The Art and Science of Low Carbohydrate Living which will answer that question far more expertly than I. a great read!