Citrate in citric acid juice has a strong bactericidal effect, which is beneficial to food hygiene, and can inhibit the crystallization of calcium salt and prevent kidney calculi. The rich aroma can alleviate the fishy smell of meat and aquatic products, make the meat tender, promote the secretion of proteolytic enzymes in the stomach and increase gastrointestinal peristalsis; Citric acid can also contract and strengthen capillaries, reduce permeability, improve coagulation function and platelets, and can be used to stop bleeding. Regular consumption of lemon can prevent hypertension and myocardial infarction. Healthy people take1~ 3g of citric acid powder orally, which can strengthen muscle working ability and reduce fatigue. It also contains hesperidin, which can regulate brain nerves and play an anti-inflammatory role. Rich in rutin, it can reduce blood cholesterol and prevent arteriosclerosis. In addition, lemon is rich in vitamin C, which can enhance vascular elasticity, help prevent and treat hypertension, prevent and eliminate skin pigmentation, and have whitening effect; It also has the function of preventing freckles and blood spots. The peel contains flavonoids, which has a strong expectorant effect, can kill a variety of pathogenic bacteria and purify the air. Foreign studies have found that a unique ingredient in lemon, namely eriocitrin, can prevent the occurrence of diabetic complications such as cataract.