Eating high levels of soy products such as tofu may increase the risk of loss of memory especially among the elderly. This conclusion was based on a Loughborough University-led study led by Professor Eef Hogervorst on 700 plus elderly Indonesians in Java. The deterioration in memory may have something to do with high levels of phytoestrogens (estrogens-like hormone from plants). It may also have something to do with formaldehyde which may be present as a preservative in tofu in Indonesia.
However, eating tempe, a fermented soy product have the opposite effect. This, says Professor Hogervorst, may be due to high levels of the vitamin folate present in tempe, a fermented soy. The vitamin folate has been shown to reduce dementia risk.
The study was funded by Alzheimer's Research Trust.