Soybeans and milk are good sources of protein. Soybean contains plant protein, and fat is unsaturated fatty acid, which will not make people fat. Mixed milk is a good source of calcium. Although it contains sugar, the sugar content is not high, so it is nutritious and will not get fat. However, after all, it contains sugar, and drinking it at night will have a bad influence on teeth, and the quality of soybeans in soy milk should also be paid attention to. Soybean milk is called "brain-nourishing" food by western nutritionists, because soybean phospholipids contained in soybean milk can activate brain cells and improve memory and attention of the elderly. Phospholipid is one of the basic substances of human cells and an essential component of brain cells and nerve cells. The metabolism of phospholipids in organisms is related to the functional state of the brain. After people take soybean phospholipids, they hydrolyze in vivo to produce choline, glycerophosphate and fatty acids, which have strong physiological activity and nutritional value. Therefore, the elderly often take soybean phospholipids, which can improve neurochemical function and brain function and play a promoting role. Appropriate supplementation of phospholipids can reduce the degeneration and death of brain cells and enhance physical fitness. Soybean phospholipids can resist aging, but also because phospholipids have the function of protecting and repairing cells. Cell membrane is composed of phospholipids, protein and cholesterol, which is responsible for supplying substances necessary for cell life and excreting wastes during metabolism. Therefore, for the elderly, soybean phosphatide is a kind of health food which can obviously stimulate the vitality of brain cells. Taboo of soybean milk: (1) Soybean milk contains phytoestrogens, which may increase the risk of breast cancer. Therefore, if you have a family history of breast cancer, you need to ask the doctor if you can drink soy milk. (2) Beat soybean milk with eggs. After eggs are mixed with soybean milk, mucin in eggs is easy to "closely" combine with protease in soybean milk, resulting in a substance that cannot be absorbed at all. (3) Add brown sugar. When the organic acids in brown sugar combine with protein in soybean milk, it will produce a denatured precipitate, which will decompose and destroy the nutrients in brown sugar and soybean milk. Adding sugar to soybean milk will not produce the above chemical reaction.