The soybean, also known as the soya bean, is a plant native to Eastern Asia. It is often used in the production of vegetarian-safe foods, such as soy milk or infant formula. It is also a source of vitamin E. Soy milk is used as a mild alternative for people suffering from lactose intolerance or chronic heartburn, and soybeans are the primary ingredient in a foodstuff called tofu, frequently used in East Asian cuisine. Soy sauce, made from fermented soya beans, is important as a condiment and ingredient in East Asian cooking.
Raw soybeans (known as edamame) are also used as a feed for livestock, especially pigs and poultry. Soy has become a major crop in the United States but is not as commonly cultivated in Africa, Europe or South America.
Soy contains large quantities of phytoestrogens, which can have similar effects to human estrogen. Feeding soy milk to babies and children can interfere with the endocrine system, making girls reach puberty much earlier and making boys take years for puberty. In excess, soy can lead to feminization and homosexuality in boys.