Interest in soy as a treatment for menopausal symptoms has increased dramatically as more women seek out “natural” alternatives to hormone replacement therapy (HRT). This is certainly the case for one common menopausal complaint: forgetfulness or “fuzzy thinking.”
But the idea that soy can help menopausal women think better may be a bit fuzzy in itself, according to a recent report from the University of Southern California.
Soy, as a “phytoestrogen” is a plant source rich in estrogen-like compounds called isoflavones. These compounds mimic some of the positive actions of estrogen in humans without causing the negative effects linked to long-term HRT use such as increased risk for heart problems, stroke and some cancers.
Some research studies claim that dietary soy products improve concentration and mental funtion in menopausal women. Other clinical reports refute this finding and assert that brain function does not change in women on high-soy diets or given soy supplements compared to women given placebo treatments.
Researchers in the School of Pharmacy at the University of Southern California now offer some insights about soy and these conflicting data. Principle investigator Dr. R. Brinton and lead author Dr. L. Zhao reviewed key clinical trials published between 2000 and 2007 that focused on the use of soy for improving memory function or concentration skills in postmenopausal women.
Their analysis showed a split verdict on soy with about half the studies revealing a positive impact and half demonstrating no effect. The authors suggest several reasons for the discrepant results among the trials including differences in soy products and the age and type of study participants.
They believe “a well-designed clinical study based on standardized stable formulation (of soy) in a well-characterized study population is required in order to reach a clinical concensus.” The researchers offer specific suggestions to improve future soy studies:
•use a consistent soy product identified known to be highly effective
•test an mix of appropriate soy compounds (the various isoflavone components in soy products or foods have different levels of reported activity)
•group women by age and menopause status (some studies suggest soy is most effective in the early years of menopause)
•group women by genetic background (about 1/3 of people are naturally “high responders” to soy due to the type of intestinal bacteria they have)
•control for HRT history of participants
•control for diet variations among participants
Dr. Brinton’s group suggests that development of a soy-based treatment for memory improvement could benefit both women and men and potentially be applied to other neurological conditions like Alzheimer’s disease. Until more carefully controlled studies are carried out as the researchers suggest, it seems the power of soy for improving mental clarity during menopause remains debatable.
Link to Original Article:
Zhao, L., and RD Brinton., Nov 2007. “WHI and WHIMS Follow Up and Human Studies of Soy Isoflavones on Cognition,” Expert Review Neurotherapeutics: http://www.ncbi.nlm.nih.gov/pubmed/17997703?ordinalpos=20&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
Related Links:
File, SE et al, Mar 2005, “Cognitive Improvement after 6 Weeks of Soy Supplements in Postmenopausal Women is Limited to Frontal Lobe Function.” Menopause journal article: http://www.menopausejournal.com/pt/re/menopause/abstract.00042192-200512020-00014.htm;jsessionid=LF1YmHCj5qkj4D8xkrPqty4HQpwBs92rd1sKyGyg0X8k1K6cwGLC!-1004083789!181195629!8091!-1
Waknine, Y., July 2004. “Soy Protein Does Not Improve Cognition, BMD, or Plasma Lipids in Postmenopausal Women,” Medscape Medical News online article: http://www.medscape.com/viewarticle/482467