Consuming too many soya products like tofu might increase the risk for memory loss, according to some studies. One study published in April 2000 in the Journal of the American College of Nutrition found that Japanese men living in Hawaii who ate the most tofu during their mid-40s to mid-60s were more likely to have dementia and Alzheimer’s as they grew older.
A study published in Dementia and Geriatric Disorders in 2008 backed this up. The researchers looked at people who ate tofu in Indonesia and found that high consumption of tofu was linked to worse memory loss. The theory is that plant chemicals which mimic the female hormone oestrogen interfere with hormone levels of natural oestrogen in the body by binding to receptors in cells. Natural estrogen is believed to protect the ageing brain but plant versions may not have this effect.
However, other medical trials show that healthy people who eat high soya diets may actually improve their memories. In one study, published in the journal Psychopharmacology in 2001, young adult men and women who ate a high-soy diet experienced substantial improvements in short-term and long-term memory and in mental flexibility. Other studies have found that isoflavone supplements from soy improve cognitive function in postmenopausal women. ‘More work needs to be done to establish the facts and who could benefit from eating soya products,’ says Abigail Wilson.