[Medical Q&A] Why is grains + beans a recommended dietary combination?

Planner: Chinese Medical Association

Reviewer: Gong Weiyan, Associate Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention

The dietary combination of grains and beans (for example, adding mung beans, red beans and other beans when cooking rice porridge) has a high nutritional value, not only because grains and beans can provide nutrients such as carbohydrates, protein, dietary fiber, vitamins, minerals, etc., but the more important reason is that the combination of these two ingredients well reflects the complementary effect of protein.

Protein is composed of amino acids. Some amino acids cannot be synthesized in the body and must be obtained from food, which are called "essential amino acids". The proportion of essential amino acids in the human body is consistent, while the proportion of essential amino acids in different foods is not the same. The closer the proportion is to the human body's amino acids, the easier it is to absorb. For example, the content of lysine (an essential amino acid for the human body) in rice is relatively low, and the content of other essential amino acids is relatively sufficient, while the content of lysine in beans such as mung beans and red beans is relatively high, and the content of methionine (an essential amino acid for the human body) is relatively low. Therefore, when cooking rice porridge, adding some mung beans, red beans and other beans can complement each other's deficiencies in essential amino acids. This mixed ingredient can make the total amino acid ratio closer to the human body model, thereby helping to improve the utilization rate of protein. This is the complementary effect of protein. Of course, the combination of grains + beans can be determined according to personal preference. For example, rice with black beans, oats with tofu, etc. are all good choices.