Can Soy Help Women Think?

The traditional Asian diet has been celebrated for their health benefits, but a recent study challenges one common aspect of this praise.

According to researcher Victor Henderson, M.D., M.S., "soy is a staple of many traditional Asian diets and has been thought possibly to improve cognition in postmenopausal women. Our study found long-term use of soy protein neither improved nor impaired overall cognition."

The study, published in the American Academy of Neurology’s medical journal, showed that intake of soy supplementation did not have a measurable effect on general cognition over time.

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The double-blind, long-term study followed 313 postmenopausal women for two and a half years. One group received 25 grams of soy protein a day in the form of an isoflavone-rich supplement.

Isoflavone is a phytoestrogen produced by the soybean plant. The treatment was meant to mirror the type and amount of soy protein found in the typical Asian diet.

The control group received a milk placebo matched for protein.

The subjects’ global cognition (measured by the results of 14 neuropsychological tests) was measured at the beginning of the study to determine a baseline and again after two and a half years to check for any change.

The study saw no significant change between the two groups in global cognition, signifying that the supplementation of soy did not affect overall mental functioning.

One of the factors tested, visual memory, did seem to improve in the soy isoflavone test group by about 13% more than the control milk protein group, leading the authors to suggest that this one factor of cognition may be improved by a soy-rich diet.

However, Timothy Harlan, M.D., internist with the Tulane University School of Medicine, and nutrition expert also known as “Dr. Gourmet,” preached caution in an interview with dailyRx.

“Studies like these are interesting but it is difficult for us to draw significant conclusion from them given that the intervention was with a supplement and not real food,” said Dr. Harlan.

More research, and perhaps studies focusing on whole foods, are needed to determine conclusively the effect of soy on the brain.