The soya bean: so small yet so mighty

Abstract

The role of diet in contributing to the incidence of coronary heart disease, cancer and other common Western diseases is attracting increasing attention. Foods which provide different biologically active compounds, such as phyto‐oestrogens, have been extensively studied and epidemiological evidence suggests that populations consuming a diet high in phyto‐oestrogens have a lower risk of these diseases. This paper reviews some of the key studies on soy isoflavones which suggest that the incorporation of soy protein into the British diet may offer important health benefits. Non‐steroidal dietary oestrogens are found in high concentrations in the traditional diets of the Far East, and by vegans who consume large amounts of soy protein. Consumption of isoflavones across Asia varies considerably and it is estimated that between 25 to 45mg of isoflavones is consumed daily, compared to as little as 5mg daily in Western countries. It is well established that modification of dietary fat, especially saturated fat, soluble fibre and total calories have a role in coronary heart disease risk. In a meta‐analysis of 38 controlled trials on soy proteins, it was concluded that significant reductions in serum and total LDL cholesterol could be achieved. A wide range of epidemiological data shows strong correlations between a diet high in soy protein and vegetables and a reduced risk of breast cancer. The incidence of osteoporosis in Japanese women is significantly lower than in Western women and dietary factors such as soy protein intake may be important in sustaining this protection.