Two or more food proteins mixed with food, which contains essential amino acids to complement each other to achieve a better ratio, thereby improving protein utilization, known as the role of protein complementarity.

For example, flour and soybean and its products with food, soy protein rich in lysine can supplement the wheat protein lysine deficiency, so that the noodles, beans with food protein physiological value. There are many similar examples in life, such as the vegetarian broccoli with soy products, mushrooms, fungus, peanuts, almonds together; Lapa congee with rice, millet, red beans, mung beans, chestnuts, peanuts, jujube and other cooking, can achieve complementary role of proteins, higher than the utilization rate of protein when eating a single food.