The soyabean is very high in protein (38%). So whole soyabeans and traditional soya foods, such as tofu, tempeh and soya milk are good protein sources. But it is not only the total amount of protein that is important, you also have to take the quality of the protein into account.

The fat content of soyabeans is approximately 20%. The soybean contains a heart-healthy balance of fatty acids, high in polyunsaturated fat (78% of total fat primarily in the form of linoleic acid) and low in saturated fat (15% of total fat).23, 24 Of course, linoleic acid when substituted for saturated fat reduces blood cholesterol levels.

Unlike other beans, there are few complex carbohydrates in soya. Soyabeans contain 10-13% carbohydrates of which sugars represent 10-12% and starch 1%. The soyabean also contains 18% fibres, a mixture of cellulosic, and noncellulosic structural components of the internal plant cell wall.

The soya bean is a good source of calcium (Ca) and contains approximately 225 mg Ca/ 100 g beans.The content of soya drinks, however, is only 12-mg/100 g, so to be a good source of calcium and obtain the same quantity as in cow’s milk, soya drinks have to be enriched with calcium.

Isoflavones belong to the ‘phyto-estrogens’, plant compounds with a chemical structure similar to the endogenous estrogen, oestradiol. The importance of this structural similarity and its possible favourable effect on hormone-dependent cancers was first discussed in the 1980s.