Eating high levels of some soy products - including tofu - may raise the risk of memory loss, research suggests. The Loughborough University-led study features in the journal Dementias and Geriatric Cognitive Disorders found high tofu consumption - at least once a day - was associated with worse memory, particularly among the over-68s. in the study focused on 719 elderly Indonesians living in urban and rural regions of Java.

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.

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."

1. 1. 豆腐的營養價值：

      • 豆腐是富含營養的保健食品，含有豐富的植物蛋白質。

   2. 老年人食用豆腐的注意事項：

      • 不宜天天吃：豆腐中的植物蛋白質在代謝後會產生含氮廢物，需由腎臟排出。老年人腎功能下降，過量攝取豆腐會增加腎臟負擔，可能加速腎功能衰退。

      • 不宜一次吃太多：豆製品中含有較多的蛋氨酸，在酶的作用下轉化為半胱氨酸，可能損傷動脈管壁內皮細胞，促進動脈硬化。

   3. 建議：

      • 老年人應適量食用豆腐，避免天天吃或一次攝取過多，以減少對腎臟和血管的負擔。

   總結來說，豆腐雖然營養豐富，但老年人應注意適量食用，以免對健康造成不良影響。

引用:

Java research
Hawaii research