Tofu may raise risk of memory loss

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[from http://news.bbc.co.uk/2/hi/talking_point/7490202.stm]

 

Tofu 'may raise risk of dementia'

Story from BBC NEWS

Published: 2008/07/04 15:36:38 GMT

 

 

Eating high levels of some soy products - including tofu - may raise the

risk of memory loss, research suggests.

 

The study focused on 719 elderly Indonesians living in urban and rural

regions of Java.

 

The researchers found high tofu consumption - at least once a day - was

associated with worse memory, particularly among the over-68s.

 

The Loughborough University-led study features in the journal Dementias

and Geriatric Cognitive Disorders.

 

Soy products are a major alternative protein source to meat for many

people in the developing world.

 

But soy consumption is also on the increase in the west, where it is

often promoted as a " superfood " .

 

Soy products are rich in micronutrients called phytoestrogens, which

mimic the impact of the female sex hormone oestrogen.

 

There is some evidence that they may protect the brains of younger and

middle-aged people from damage - but their effect on the ageing brain is

less clear.

 

The latest study suggests phytoestrogens - in high quantity - may

actually heighten the risk of dementia.

 

Lead researcher Professor Eef Hogervorst said previous research had

linked oestrogen therapy to a doubling of dementia risk in the over-65s.

 

 

She said oestrogens - and probably phytoestrogens - tended to promote

growth among cells, not necessarily a good thing in the ageing brain.

 

Alternatively, high doses of oestrogens might promote the damage caused

to cells by particles known as free radicals.

 

A third theory is that damage is caused not by the tofu, but by

formaldehyde, which is sometimes used in Indonesia as a preservative.

 

The researchers admit that more research is required to ascertain

whether the same effects are found in other ethnic groups.

 

However, previous research has also linked high tofu consumption to an

increased risk of dementia in older Japanese American men.

 

Fermented product

 

Professor David Smith, of the University of Oxford, said tofu was a

complex food with many ingredients which might have an impact.

 

However, he said: " There seems to be something happening in the brain as

we age which makes it react to oestrogens 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 soy bean, was associated with better memory.

 

Professor Hogervorst said the beneficial effect of tempe might be

related to the fact that 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 there was no suggestion that eating tofu in

moderation posed a problem.

 

Rebecca Wood, of the Alzheimer's Research Trust, which funded the study,

said more research was needed to pin down the potential risks and

benefits of so-called superfoods.

 

However, she said: " This kind of research into the causes of Alzheimer's

could lead scientists to new ways of preventing this devastating

disease.

 

" As over half a million people have Alzheimer's in the UK today, there

is a desperate need to find a new prevention or cure. "

 

===============

 

See also:

 

Cited journal article:

" High Tofu Intake Is Associated with Worse Memory in Elderly Indonesian

Men and Women "

Vol. 26, No. 1 of the journal Dementia and Geriatric Cognitive Disorders

(online now, in print end of July 2008)

E. Hogervorst, A. Yesufu, P. Kreager, T. Sadjimim, T.B. Rahardjo.

To view Abstract online,

http://content.karger.com/ProdukteDB/produkte.asp?doi=141484 & hl=1 & q=Tofu

 

http://en.wikipedia.org/wiki/Tofu

 

Lack of folic acid dementia link (BBC News, 5 Feb 08):

http://news.bbc.co.uk/2/hi/health/7226872.stm