We all know that the physical health requires adequate nutrition, and the nutrients needed by the body are mainly provided by the foods. Then, following we will introduce the best source of six kinds of important nutrients to human body.

First, amino acids
When people enter into the middle and old age, the problems of disease and aging will follow one by one. One of the reasons is that the concentration of amino acids in body fluid decreases year by year. Amino acids are widely present in our daily foods, especially the bitter foods such as bitter gourd, bitter herbs and so on.

Second, nucleic acid
Nucleic acid is the basis of the protein synthesis in human body. It plays a key role in many major life activities such as human growth, development, heredity and variation. Daily foods such as fish, onion, and mushroom are all rich in nuclear acid.

Third, phenylethylamine
Phenylethylamine is a chemical substance which is related with human emotion. If the phenylethylamine in human body is significantly reduced, people will be caught in depression. In such a case, you can eat some chocolate or bananas, which can supplement the deficiency of phenylethylamine in the blood.

Fourth,
Aspirin plays a prominent role in preventing the formation of thrombosis and myocardial infarction, so it has become one of the "guardian angels" of heart. Red wine contains a large number of aspirin. People in the Mediterranean area tend to have a strong heart. In addition to eating purslane regularly, it also because that they often drink red wine.

Fifth, enzyme
Enzyme is also the substance which is necessary in the activities of human life. When people enter into the middle or old age, their digestive function tend to decline. And this is caused by the decreasing of digestive enzyme. In addition, catalase and glutathione oxidase are much more important, which are the "main force" in hum system. Foods which contain a large amount of enzymes include mushrooms, yams, jujube, hawthorn, royal jelly, ginger and beans, leek, green pepper and so on.

Sixth, chitin
The scientific name of chitin is "chitosan", which not only has the function of enhancing the immunity of the cells in the body, but is also very effective to treat intestinal infection and food poisoning. What's more, it can also protect people from the harms of cancer, cardiovascular disease, diabetes, and liver disease. Crab is the best source of chitin.