Protein and Bone Health

Protein and Bone Health


Harvard’s School of Public Health explains
very nicely the mechanism by which protein can cause problems for bone health. It says,
“as your body digests protein, it releases acids into the bloodstream, which the body
neutralizes by drawing calcium from the bones. Following a high-protein diet for a few weeks
probably won’t have much effect on bone strength. Doing it for a long time, though,
could weaken bone.” Now we’ve known for a very long time that
meats, including fish, are acid forming in our body. Scientists from Columbia University,
back in 1912, analyzed acid and base forming elements in food, and noted that, “all the
meats (including fish)…show a decided excess of acid-forming elements”; all the “meats
(including fish) show [a] decided predominance of acid-forming elements.” Back in 1920, Columbia’s Department of Chemistry
also reported that adding meat to one’s diet results in increase of calcium loss in
urine, thought to be because “the added meat gave to the diet as a whole an excess of
acid-forming [over base-forming mineral] elements[.]” And what have we seen from the results of
the consumption of animal protein with regards to bones? Researchers from Yale University’s
School of Medicine looked back across a broad array of 34 prior published studies
across 16 countries, and they found these studies over time showed “a strong, positive
association” between dietary animal protein and female bone fracture rates. So, we’ve known for some time that this
association exists. We know eating a diet high in animal protein results in acidity,
and that our body leaches calcium from our bones to buffer the acid. One of the mechanisms
behind this phenomenon is that animal protein has a higher amount of sulfur-containing amino
acids, and the “sulfur-containing amino acids from animal protein lower blood pH”. So animal proteins — including meat, fish,
dairy, poultry or eggs — have higher amounts of sulfur-containing amino acids than plant
foods. As a result, when we eat diets high in animal proteins, our body produces sulfuric
acid, which increases the acidity in our bodies. One of the body’s mechanisms to neutralize
this acidity is to draw calcium from our bones (similar, for example, to when we take antacids
that are made with calcium to neutralize the acidity in our stomach associated with heartburn).
The problem is that constantly leaching calcium from our bones can reduce bone mass, making
our bones weak and more prone to fractures and osteoporosis. Moreover, the chronically
higher calcium excreted in our urine can also lead to the development of kidney stones. This Harvard study published in the American
Journal of Epidemiology followed over 80,000 women over 12 years, and found that animal
protein was associated with increased risk of forearm fracture, but no increase in risk
was observed with higher intakes of vegetable protein. It found that women who consumed
the largest amount of animal protein in the study had a 22% higher risk of fracture. Evidence
suggests that “higher protein intakes in young…women have a negative impact on radial
bone measurements”, meaning that women who consumed higher protein diets have been found
to lose bone mineral content and bone density. So we know that our body uses base stores
(including calcium from our bones) to neutralize the acidity we get from our diet. This article
from The Journal of Nutrition explains the same thing. It says, “diets that are net
acid producing…induce and sustain increased acidity of [our] body fluid. With increasing
age, the kidney’s ability to excrete daily net acid loads declines, invoking…increased
utilization of base stores ([from our] bone [and] skeletal muscle) on a daily basis to
mitigate the otherwise increasing baseline metabolic acidosis, which results in increased
calciuria and net losses of body calcium. Those effects of net acid production and its
attendant increased body fluid acidity may contribute to…osteoporosis[.]” What this
is saying is the neutralizing mechanism in our bodies of taking calcium from our bones
to deal with the higher acidity caused by our diet can contribute to osteoporosis. This journal review in The European Society
for Clinical Nutrition and Metabolism further discusses the issue, noting how problems associated
with acidity become even worse with age. “The modern Western-type diet…contains excessive
animal products, generating a state of metabolic acidosis, whose magnitude increases progressively
with aging due to the physiological decline in kidney function.” As explained in this peer-reviewed study from
the Journal of Nutrition, “The average American diet, which is high in protein and low in
fruits and vegetables, generates a large amount of acid, mainly as sulfates and phosphates.
The kidneys respond to this dietary acid challenge with net acid excretion, [and] the skeleton
supplies buffer by active resorption of bone.” The study concludes, that, “Overall, the
evidence leaves little doubt that excess acidity will create a reduction in total bone substance….
An acid-ash diet [means] a diet that creates acid in the process of its metabolism[,]”
and this article concludes, “[m]odern peoples are now eating high protein, acid-ash diets
and [are] losing their bones.” This study, published in the official journal
of the Council on Renal Nutrition of the National Kidney Foundation and the International Society
of Renal Nutrition and Metabolism, compared the net acid secretions among vegans (who
eat no animal products), lacto-ovo vegetarians (who eat no meat, but do eat dairy and eggs)
and omnivores (who eat a traditional Western diet of meat, dairy and eggs). The study found
that net acid secretion was higher in both lacto-ovo vegetarians and omnivores than in
vegans, suggesting “that higher protein intake results in more renal net acid excretion
and more acidic urine.” In addition to increased incidents of kidney stone development, higher
protein intake was also found to be associated with “increased urinary calcium excretion.”
It noted, “higher protein intake, especially animal protein, was linked to an increased
rate of bone loss and increased risk of hip and forearm fractures in women.” The study
concludes, “Because acid-base balance has significant implications for renal and bone
health, it is important…to introduce appropriate dietary modifications to prevent or treat
the conditions, including kidney stones, bone loss and/or [bone] fractures, and possibly
osteoporosis.” So to recap, eating animal proteins increases
body acidity, and one of the body’s mechanisms to neutralize this acidity is to leach calcium
from the bones. Doing this for a long time can lead to loss of bone mass and weakened
bone, increased risk of fractures and osteoporosis, as well as kidney (or renal) stones. And,
an easy way to avoid the increased risk of these problems is avoiding animal protein.

13 thoughts on “Protein and Bone Health”

  1. Nutritionfacts.org did a great video demonstrating excess calcium excretion in urine is from dietary calcium. http://youtu.be/l9XTjnvlIUI

  2. Such important info!! Thanks for your awesome work in spreading the facts.
    Wow 1912!! What they do to keep the facts hidden! urgh

  3. I have noticed, when my methionine consumption gets over 1.2 grams per day, my asthma gets triggered. If I keep the daily allowance under 1.1 grams, the lung disease is very well controlled!

    Now, I have a severe sulfur sensitivity (I can get anaphylaxis from sulfur preservatives, like sodium metabisulfite) and since the amino acid methionine contains quite a bit of sulfur, I believe it contributes to the formation of sulfur-containing compounds that trigger my asthma.

    So, I come to a hypothesis: methionine restriction as a means to control asthma?

    I'm going to have to research it:)

  4. Interesting. So people who lift weights, or do fitness and have very high animal protein intake their whole lives, should have weak bones. Which is the opposite actually. Also, the acid released from animal products can be neautralized by alkaline foods. Same veggies and fruits. Pulling calcium from bones to neutralize acid extremely drastic measure and wouldn't happen under normal conditions and balanced diet including animal products. Also, I'm sorry but I'm not gonna trust almost a century old clinical trials. Also, correlation is not causation. Now I really respect your endeavour against animal cruelty, preserving the environment etc. But we should really stop with this cherry picking experts and studies. People are not going to become vegan because you do not show the bigger picture of vegan diet. All I'm hearing is that plant based diet is flawless and is 1000x more superior to diet if it has even a little animal products in it. It's not possible. There isn't a single particular object, matter or anything on earth that would be flawless or superior in every way to the same group belonging whatever. Everything has it pros and cons. Everything. Why don't we talk about that. The cons of vegan diet and possible difficulties someone might face from it.

    Here is some more recent research you may want to read about animal protein and calcium leach from bones.

    http://www.ncbi.nlm.nih.gov/pubmed/22127335
    http://www.ncbi.nlm.nih.gov/pubmed/19419322
    http://www.ncbi.nlm.nih.gov/pubmed/11914191

    So at best, you can say that we have inconsistent data. At best. And you cannot so boldly claim that animal protein is detrimental to bone health, that it leaches Ca from bones or whatever.

  5. Any studies on high vegetable and fruit intake while consuming a high animal protein intake and the effect of calcium loss from the bones?

  6. As I understand it, a number of vegan and vegetarian RDs have reported on this idea of leeching calcium from bones is a problem only for isolated protein intake, not in the presence of whole foods. You can read more about this here: http://veganhealth.org/articles/bones. Or, watch this presentation: https://www.youtube.com/watch?v=l9XTjnvlIUI (by no friend of the dairy industry, Dr. Michael Greger)

    It's also important to note that in the Hong Kong study, the women had higher rates of osteoporosis, not lower. But, fracture rates were lower due, probably, to other factors like bone size and strength from weight-bearing exercise.

    I've been vegan for more than 6 years, and I want to see balanced information, based on the latest science. It's fine to report on information that warns about dangers of animal products, but it should also be presented with the most accurate information available and to help vegans understand that they need to understand how to get the nutrients that they need to stay healthy. For example, in the veganhealth.org review above shows that vegans who get adequate calcium, do NOT have increased fracture rates, but actually decreased. However, if they do not get adequate intake, they have increased rates.

  7. Omg… That's so worrying! We've always been said by bodybuilders athletes and channel on YT that high consumption of protein (especially animal, whey) is something good.

  8. false. Another crazy paranoic vegan theory. Bones are 50% potein continuosly turning over. We need complete animal protein.

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