New research from Stanford and the University of Southern California finds that postmenopausal women who consumed 25 grams of soy daily showed no significant positive or negative differences in mental abilities from those who didn't.
The 2.5-year study (subscription required), published today in Neurology, was longer and larger than any of the previous trials on soy use. From our release:
For this work, [lead researcher Victor Henderson, MD] and his colleagues conducted the National Institutes of Health-sponsored Women’s Isoflavone Soy Health Trial, which was done between 2004 and 2008 to determine the effect of soy isoflavones on the progression of atherosclerosis and, secondarily, the effect on cognition. During this study, 350 healthy women ages 45-92 were randomized to receive daily 25 grams of isoflavone-rich soy protein (a dose comparable to that of traditional Asian diets) or a placebo. A battery of neuropsychological tests was given to the participants at the start of the study and again 2.5 years later.
Henderson and his colleagues examined changes to the composite of 14 scores and found no significant differences in global cognition — that is, overall mental abilities — from baseline to study-end between women who took the supplements and those on placebo. During a planned secondary analysis, they did identify a statistically significant difference in one of the identified cognitive factors: Women in the supplement group showed a greater improvement in visual memory (memory for faces). Henderson said this could be important, but “the finding needs to be replicated in future studies.”
These latest findings align with the largest previous study, which was published in 2004 in the Journal of the American Medical Association. In the earlier trial, researchers found that Dutch women aged 60 to 75 years who took 25.6 grams of soy protein daily did not show a significant difference in cognitive function from those who took a placebo.
Previously: Stanford biostatistician talks about saving your aging brain,Vitamins may help stem cells in the brain survive inflammatory damage and Stanford nutrition experts discuss top cancer-preventing foods
Photo by Anya Quinn