For the study, published in the British Medical Journal, researchers followed the diets and overall health of 92,915 Japanese men and women between the ages of 45-74 over a period of 15 years. They found that those who frequently included miso, tempeh, soy sauce and natto (an Asian dish made from fermented soybeans) on their plates benefited from a lower risk of mortality.
Women who consumed at least 46.6g of fermented soy daily were 10 per cent less likely to die compared to those who ate the smallest amounts of fermented soy products. On the other hand, men benefited most from eating at least 50.2g per day.
The researchers put this down to the fact that the products are high in fibre as well as rich in potassium and bioactive compounds. However, they did have one caveat: the reduction in mortality risk was not seen with “total soy product” consumption. Translation? Unfermented soy products (e.g. soy milk, soy beans, soy protein powders and tofu) didn’t have the same effect.
“A significant association between intake of total soy products and all cause mortality was not, however, observed,” the authors noted. “The findings should be interpreted with caution because the significant association of fermented soy products might be attenuated by unadjusted residual confounding.”