Older Vegetarians Take Note

Photo credit: artist in doing nothingDo you eat tofu and drink soy milk?  Good for you, right?  Less allergenic, right? Soy products have been promoted as health smart, with Japanese statistics for breast cancer, etc used as evidence. Some even go so far as to list tofu in their personal collection of “superfoods”. Before you throw another tofu kebab on the bbq, think about this.

Apparently people who eat a lot of certain soy products, including tofu, may be at an increased risk of memory loss, particularly in older age groups.  These are the findings of a team of scientists from two British universities and two Indonesian universities, funded by the UK Alzheimer’s Research Trust. They looked into the effects of high soy consumption in 719 elderly Indonesians (aged 52-99) living in urban and rural regions of Java.  “High consumption” meant that the people were eating soy at least twice a day.

According to the principal researcher, Professor Eef Hogervorst of Loughborough University, it may be the high levels of phytoestrogens in soy products which are having a negative  effect on the aging brain.

What’s still a bit of a mystery is that these same oestrogen compounds may actually be protective for your brain if you are younger or middle-aged.

Intriguingly, the researchers also found that consuming tempeh, a fermented soy product made from whole soy bean, is associated with reduced risk of memory loss.  Tempeh may offset the negative effects of tofu when also included in a diet containing tofu.

Possible reasons for this effect include:

  • tempeh has significant antioxidative, anti-inflammatory and anti-thrombotic effets – all these may decrease cognitive decline;
  • tempeh has high levels in folate, which is known to reduce dementia risk;
  • tempeh is a good vegetarian source of B12, which is often low in the elderly;
  • tempeh is high in genestein;
  • tofu in Indonesia may be contaminated with formaldehyde during the manufacturing process.  Formaldehyde can kill brain cells.

Other research suggests that the level of good bacteria in the gut has a big effect on phytoestrogen metabolism.  This could mean that tempeh, a fermented food, may be more beneficial, especially to older people, because of its probiotic effect. Older vegetarians who eat soy products may want to include some of these fermented varieties in their daily diet.  Note that many western countries require processing that effectively kills off the probiotic benefits of tempeh.  Including other sources of natural probiotic foods in the diet could offset this (sauerkraut, kim-chi, home-made kefir, etc). Miso, a daily component of the Japanese diet, is also a fermented soy food as is natto.  Try to get a source of traditional, unpasteurized miso.

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