Soy and Your Bones
A new study published in the Archives of Internal Medicine in September 2005 found that intake of soy food was associated with a significantly lower risk of bone fracture, particularly among early post-menopausal women. Researchers studied associations between soy consumption and bone fractures in more than 24,000 postmenopausal Chinese women averaging 60 years of age. After following these women for 4 1/2 years, researchers found that the women in the highest soy intake group (13g soy protein daily) were at a 35 - 37 percent lowered risk of bone fractures than women in the lowest intake group (5g soy protein).
Editor's Note: Soy and Osteoporosis
Many soy foods are naturally high in calcium as this mineral is added as a coagulating agent. In addition, soy also contains magnesium and boron, which are important in bone health.
In addition, isoflavones in soy foods may inhibit the breakdown of bones. Daidzein, a type of isoflavone, is actually very similar to the drug ipriflavone, which is used throughout Europe and Asia to treat osteoporosis.
A study completed by Erdman in the early 1990's inspired the many studies that followed to investigate the possible benefits of soy on bone health. Erdman's study focused on post-menopausal women who consumed 40 g of isolated soy protein daily for 6 months. Erdman found that these women had significantly increased bone mineral density as compared to the controls.
A recent study published in 2003 by the Oklahoma State University showed that soy protein was more effective in bone formation and retention of calcium inside the body (excreting less calcium in urine) compared to milk protein. In addition, researchers also found that the benefits of soy on bone health were more pronounced in postmenopausal women who were not on hormone replacement therapy.
Soy and Osteoporosis - the bottom line
There is no doubt that soy has a role in maintaining healthy bones and may even help to prevent bone loss in postmenopausal women. However, it is still not clear whether the benefits are due to its soy protein, or its isoflavones daidzein and genistein, or the combination of them. The best approach is to include soy foods such as tofu, tempeh, soy milk, edamame etc in your diet instead of taking isolated soy supplements. Many brands of soy milk are now fortified with calcium. Hence, one glass of fortified soy milk provides an equivalent amount of calcium from a glass of cow's milk.
With the increasing public concerns regarding genetically modified foods, look for soy products which use non-genetically modified soy crops in their production.