For 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).