There is a western proverb: "An apple a day keeps the doctor away." Apple has high nutritional value and contains many vitamins. Apple contains 15% carbohydrate and pectin, and is also rich in vitamins A, C, E, K and antioxidants. Apples contain polyphenols and flavonoids, which are natural chemical antioxidants, and can remove the metabolic "garbage" in the body in time and reduce the content of neutral fat in the blood. Neutral fat is the chief culprit of vascular sclerosis, which is particularly important for preventing cardiovascular and cerebrovascular diseases. Dutch medical scientists found that if 805 male subjects aged 65-84 eat 1-2 apples a day, the risk of heart disease can be reduced by half. American scientists pointed out that a medium-sized peeled apple can provide 3.9 grams of cellulose, while pectin, a soluble fiber in apples, can effectively lower cholesterol. Experiments show that people who eat two apples a day can reduce their cholesterol by 16%. A research report published by Finnish researchers shows that eating apples regularly can reduce the risk of lung cancer. They pointed out that flavonoids contained in apples are important antioxidants produced by metabolism and the main reason for reducing the incidence of lung cancer. Apples contain much more calcium than ordinary fruits, which helps to metabolize excess salt in the body. Malic acid can metabolize calories and prevent obesity in the lower body. As for soluble fiber pectin, it can solve constipation. Pectin can also promote the excretion of lead, mercury and manganese in gastrointestinal tract, regulate the blood sugar level of human body and prevent the sudden rise and fall of blood sugar. Apples have high nutritional value, but we should pay attention to chewing slowly. If an apple can be eaten within 15 minutes, the organic acids and fruit acids in the apple can kill bacteria in the mouth. So eating apples slowly is more conducive to human health.