Wednesday Bubble: Soy takes another hit

Posted by Liz on Aug 10, 2011 in bone health, herbal medicine, hot flash | 4 comments

We’re live!

Welcome to the new home of Flashfree! Our URL has changed but the same content that you’ve grown to know and ‘love’ is the same.

Let’s kick off http://flashfree.me with the latest and ‘greatest’ report on soy: it does not help menopausal symptoms or prevent bone loss.

Isn’t this contrary to what’s been reported previously, at least with regards to women with the ability to produce  S-equol?

In this latest nail to the soy coffin, research appearing in the Archives of Internal Medicine suggests that part of the issue in proving or disproving the utility of soy for menopause is the lack of trials of long duration, consistent use of low doses of soy isoflavones, small number of participants and too much breadth and depth of age and menopausal status. However, the SPARE trial (Soy Phytoestrogens as Replacement Estrogen), aimed to change this paradigm by examining the effect of daily 200 mg soy isoflavones in tablet form in 248 women between the age of 45 and 60. All participants had been in menopause for one to five years or for six to 12 months. These women were studied for two years, were instructed to take the active pill or placebo tablet before breakfast, and stop taking any hormones for at least six months before the study started. Calcium was supplemented in women who were taking less than 500 to 1000 mg daily. Importantly, women taking the isoflavone tablets were actually receiving a dose equal to approximately twice that normally obtained through food in Asian diets.

At the study’s end, the researchers found that women taking soy or placebo were on equal footing and that soy did not appear to prevent bone loss or reduce bone turnover. Moreover, soy did not appear to have any significant effect on hot flashes, night sweats, libido or vaginal dryness. They also say that even though women who are able to produce S-equol in their guts were likely to benefit from soy compared to women who are not, they did not see any specific benefit when these women were studied separately. Although not considered a dangerous side effect, constipation was experienced by more than a third of women taking soy.

So, what are we to think? Some studies say soy is effective, particularly among S-equol producers while others, like this well designed trial, show that it is now. However, there has been some data suggesting that the ratio of specific isoflavones may play an important role, and there is no information in the published study about this ratio other than to say that the soy supplement used is similar to those obtained in health food stores.

When it comes to soy, the verdict isn’t quite out yet, although the studies that have been conducted to date can’t seem to tease out what’s what. As always, use caution and lower your expectations. There are other non-hormonal approaches that may provide greater benefit when it comes to bone loss and menopausal hot flashes and other symptoms.

Want to read more on soy isoflavones? Check out the Flashfree archives.