Soy not helpful for post-menopausal women, says study

New research has cast further doubt on claims that menopausal and postmenopausal women can benefit from consuming soy.

The research, undertaken by Stanford University and the University of Southern California, found that those who consumed 25 grams of soy daily showed no significant positive or negative differences in mental abilities from those who didn’t.

The study, published in the most recent issue of Neurology, is said to have been longer and larger than any of the previous trials on soy use.

Soy has been researched previously for its potential health benefits for menopausal and post-menopausal women. Soy beans contain phytoestrogens, naturally occurring compounds that act like oestrogen in the body; oestrogen declines in women of this age, a decline that is said to result in a range of symptoms including hot flushes and bone loss.

These studies concluded that soy did not have a beneficial effect on menopause symptoms.

However, a study published in Menopause: The Journal of the North American Menopause Association in April, reviewed 19 previous studies that examined more than 1,200 women. It noted that, while some studies concluded that soy was beneficial while others concluded that it was not, on balance, the effect of consuming soy was positive.

For this study, researchers were looking to determine the effect of soy isoflavones on the progression of atherosclerosis and, secondarily, the effect on cognition.

During the study, 350 healthy women aged 45-92 were given 25 grams of isoflavone-rich soy protein (a dose comparable to that of traditional Asian diets) or a placebo over a period of 2.5 years. A battery of neuropsychological tests was given to the participants at the start of the study and again at the end.

During a planned secondary analysis, the researchers 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). They said, however, that further work would need to be done to verify this finding.

These latest findings align with the largest previous study, in which 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.