A new study found consuming large quantities of soy products might increase the chance of memory loss.
Researchers studied 719 elderly Indonesians living in urban and rural regions of Java, and found daily tofu consumption was associated with poor memory, particularly among the over-68s.
Scientists from the Loughborough University led the study, which is featured in the journal Dementias and Geriatric Cognitive Disorders.
In the developing world, soy products are a popular protein source for millions of people. But the soy sales are gaining ground in the west, where it is often promoted as a “super food”.
Soy products are known for their rich micronutrients called phytoestrogens, which mimic the impact of the female sex hormone estrogen. The study findings suggest phytoestrogens – in high concentration – may actually heighten the risk of dementia.
In past history, there has been some evidence phytoestrogens protected the brains of younger and middle-aged people from damage. Yet, their effect on the older brain is not as clear-cut.
Lead researcher Professor Eef Hogervorst said past research had linked estrogen therapy to a one hundred percent increase in the dementia risk for people over 65.
Hogervorst said estrogens were found to promote growth among cells, not necessarily a good thing in the ageing brain. Researchers also found high doses of estrogens promote the damage caused to cells by particles known as free radicals.
A third theory is that brain damage is actually not caused by the tofu, but by formaldehyde. A popular preservative agent used in Indonesia.
Researchers conclude more studies are needed to see if daily consumption of tofu affects other ethnic groups. However, older research has linked high soy consumption to an increased risk of dementia in older Japanese American men.
University of Oxford Professor David Smith said tofu was a complex food with many ingredients that might have an impact. But he said, “There seems to be something happening in the brain as we age which makes it react to estrogens in the opposite way to what we would expect.”
The latest study also found that eating tempe, a fermented soy product made from the whole soybean, was linked to better memory. Professor Hogervorst said the beneficial effect of tempe might be connected to the fact it contains high levels of the vitamin folate, which is known to reduce dementia risk.
“It may be that that the interaction between high levels of both folate and phytoestrogens protects against cognitive impairment.” She also stressed that eating tofu in moderation posed no health problem.
Rebecca Wood, of the Alzheimer’s Research Trust, which funded the study, said more studies were needed to find the potential risks and benefits of so-called super foods.
She said there is a desperate need to find new preventions or cures, “This kind of research into the causes of Alzheimer’s could lead scientists to new ways of preventing this devastating disease.”
Image Courtesy Sakurai Midori (Wikipedia)
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