Soya beans have been consumed for 3,000 years, especially in the Far East. They are extremely rich in protein, and, weight for weight, products such as soya protein isolate, soya flour and dried tofu contain more essential amino acids than meat, which makes them popular with vegans, who eat no animal produce. The soya bean is also used to make soya milk, soya oil, tofu, tempeh, and the fermented products known as miso and soya sauce.

Soya milk is the liquid left after the beans have been crushed in water and strained. In many respects the nutritional value of soya milk compares very well with cow's milk, but it is lower in calories and in calcium.

Soya products are rich in phyto-oestrogens (plant oestrogens also known as isoflavones), particularly genistein, which has tumour-inhibiting effects. A high consumption of soya products has been found to prevent prostate cancer in men and to have an oestrogen-balancing effect on women. Both problems of excess oestrogen, such as breast cancer, and problems of inadequate oestrogen, such as hot flushes, are significantly reduced.

Babies. Some speculation has recently arisen about the safety of soya-based infant formula feeds for male babies because of the phyto-oestrogen content. Since at the time of writing no research has yet been carried out to determine whether the phyto-oestrogens may interfere with a male baby's sexual development, some authorities are suggesting that to err on the side of caution, soya formula feeds should only be used in case of necessity. However the alternative of cow's milk formula feeds also poses risks due to the high rate of allergy to cow's milk. Wherever possible, breast feeding is best.

Children. Because soya milk contains much less fat than whole cow's milk, it is not recommended for very young children unless they obtain enough calories from other sources. (This applies as a general rule to all low-fat foods since children need more fat in their diet than adults do.)