bones and protein
Published by Bronwyn Schweigerdt on April 21, 2009 at 3:00 AMFor those of you who have heard me talk (or write) about how osteoporosis is NOT an issue of calcium deficiency - and have found it very hard to believe, since you've heard opposing information all of your life - I have a great new study for you.
The study, titled Veganism, Bone Mineral Density, and Body Composition: a Study in Buddhist Nuns, published in Osteoporosis International Journal (April 7, 2009), found that although vegans had lower dietary calcium and protein intakes than omnivores, veganism did not have adverse effect on bone mineral density and did not alter body composition.
Researchers compared 105 postmenopausal Buddhist nuns adhering to a vegan (no meat, eggs or dairy) diet to 105 omnivorous postmenopausal women in Vietnam to see if there were differences in bone density. Even though the vegan women consumed significantly LESS calcium (as well as less protein) than the omnivorous women, there was no difference in bone density.
Researchers even stated, "Further analysis suggested that whole body BMD [Bone Mineral Density]... was positively correlated with the ratio of animal protein to vegetable protein." In other words, the higher the amount of plant protein, the less likelihood of bone loss and vice versa: the higher the animal-derived protein, the greater likelihood of bone loss.
Which brings me back to my point: osteoporosis is not due to calcium deficiency, it is due to a diet high in animal protein. In this particular study, the vegan women consumed an average of less than 400 mg of calcium a day, far from the recommended 1000-1500 mg calcium many Americans try to attain. Yet the vegan women only consumed about 35 grams/day plant protein, in contrast to omnivorous women at 62 grams/day. If you recall, animal protein is especially high in sulfuric acid, and since meat is so high in overall protein, it raises the uric acid level in our body. In order to neutralize these acids, our body leaches out calcium from the bones, which ultimately ends up in our urine (or kidneys, as kidney stones).
So what should we do to avoid bone loss? Minimize our intake of animal protein and replace it with plant protein. That means more legumes (beans, lentils, peas, nuts and seeds).
7 comments:
Love this post! I get this ALL the time from my friends and family when I say we don't drink milk and they say "But what about your calcium??" Now I know where to tell them to go....Beandiet!!!
I would be really delighted to learn that this is true, but I have a few questions I wonder if you could answer? I'm a 21-year-old female, with a small build, and am a lacto-vegetarian. Not to morally justify my choice to eat dairy but to explain my protein/calcium intake, i have a serving of dairy (fat-free, plain yogurt generally) probably 3 or 4 times a week. The rest of my diet is vegan.
Two years ago I was told I had osteopenia. How could this result from my diet if animal protein is the culprit? Are genetics a major factor? My size? Excercise (I'm a long-distance runner)?
Thanks for your help.
Dear Anonymous,
I'm no bone density expert but from what I've read, long-distance female runners often are diagnosed with osteopenia. If I recall correctly, I believe it has to do with the affect of low body fat on estrogen levels. If you are not getting your period regularly, that could be you, since estrogen plays an important role for women in maintaining bone density.
However, I have read studies where women have low bone densities at younger ages (for the same reason: low body fat/estrogen levels), yet in their postmenopausal years they do not suffer from osteoporosis, as is commonly believed to be the case.
I hope that is helpful.
Again, interesting reading! Too bad we are constantly bombarded with the wrong information from the dairy industry.
Im 47 yrs old, Latin and overweight... Its very hard for me to loss weight and I have "liver spots" on my cheeks and facial hair (not the peach fuzz kind). Could my hormones be out of balance??
Help, Cecilia
P.S. Not a vegan
Hi Bronwyn,
One thing that the Buddhist nun's were probably not eating was sugar. This also causes the blood to be acidic, leaching minerals from the bones to buffer it.
Here is a related article from the USA Today of all places. It quotes heavily from Virginia Messina RD, coauthor of The ADA Position Paper On Vegetarianism and coauthor of the classic "Becoming Vegan".
While Vietnamese Buddhist nuns seems to be doing okay American vegans with different diets and lifestyles seem to be getting brittle bones.
My intuition would be lack of *high* calcium vegetables with good absorbability ( not spinach, lettuce and typical salad greens ).
The article is interesting in that it provides a contrary viewpoint to this blog post but doesn't come off as hostile or ignorat about vegan diets:
http://www.usatoday.com/news/health/painter/2009-08-09-yourhealth10_N.htm