A preliminary study presented at the Society for Endocrinology annual conference in Edinburgh, UK reported that isoflavones, a type of phytoestrogen found in soy and other legumes, may protect menopausal women against osteoporosis.
The study split 200 menopausal women into two groups: one received a supplement containing soy proteins and isoflavones and the other received a supplement containing just the soy proteins.
The women took the supplements every day for 6 months, then the researchers examined blood for two markers of bone health, βCTX and P1NP. Although osteoporosis diagnosis is not based on these markers, both βCTX, a prominent marker of bone loss, and P1NP, a marker of bone formation, correlate well with the disease's presence.
The researchers reported that women in the treatment group had significantly lower levels of the βCTX when compared to women taking the control supplement.
There are qualifiers: The study was small, the results are preliminary, and it is unclear how effective markers like βCTX and P1NP are for diagnosing osteoporosis.
But it does highlight the importance of real, controlled, double-blind trials to determine the effectiveness of dietary supplements. If the science checks out on isoflavones it would be a huge benefit for the millions of women who experience osteoporosis as they go through menopause. Until then taking isoflavones, or other soy-based supplements, may lead to a false sense of health security.