Classification of food: Under normal conditions, human blood and body fluids are slightly alkaline, and the pH value is kept between 7.35 and 7.45, when human health is at its best. The human body itself has a system to adjust the acid-base balance, which can ensure the acid-base balance of the human body under reasonable diet conditions. You should eat more alkaline food in your daily diet. The following introduces common acidic and alkaline concentrated foods. Acidic food: the acidity and alkalinity of food are determined by the products of food digestion, absorption and metabolism. Generally speaking, foods containing more nonmetallic elements such as fluorine, chlorine, sulfur and phosphorus are called "acidic foods". For example: meat and poultry, eggs, fish, grain, oil, peanuts, sugar, beer and so on. These foods are high in sulfur and phosphorus, which are metabolized in the human body to form sulfuric acid and phosphoric acid, which increases the acidity of body fluids. Alkaline food: Food containing more metal elements such as potassium, sodium, calcium and magnesium is called "alkaline food". For example: vegetables (white gourd, tomato, pumpkin, cucumber, radish, spinach, cabbage, cabbage, rape, celery, lotus root, onion, eggplant and potato), fruits (apples, pears, bananas, peaches, strawberries, plums, persimmons, grapes, oranges, grapefruit and lemons), beans and beans. Organic acids in these foods participate in metabolism in the body. After oxidation in the body, oxygen, carbon dioxide and water will be produced and excreted, and the remaining metal ions can increase the alkalinity of body fluids. Neutral food: the metal elements and nonmetal elements contained in food are basically balanced, and the acidity and alkalinity of metabolites are basically balanced after entering the human body, which is called "neutral food". For example: milk, asparagus and so on. Because the PH of human blood is between 7.35 and 7.45, the human body needs to remain slightly alkaline to be healthy.