Because it contains acetic acid.
Analysis of the chemical composition of vinegar, the main component is acetic acid, non-volatile acid, amino acids, sugar and so on. Therefore, vinegar disinfection and sterilization, reduce spicy taste, the protection of raw materials in the loss of vitamin C and other effects; also help digestion, improve the stomach acid environment, inhibit the propagation of harmful bacteria. So appropriate to eat vinegar for human health is good. But the first condition of the body's health is to keep the organ's normal work. When a large number of vinegar, a large number of vinegar into the body, will change the PH value of gastric juice to strengthen the acidity of the stomach, causing damage to the gastric mucosa. Healthy people a lot of vinegar can cause stomach pain, nausea, vomiting, and even lead to acute gastritis; and gastritis patients will make a lot of vinegar symptoms of stomach problems, ulcers can induce ulcers. At the same time, due to the large absorption of acetic acid will also affect the whole body's acid-base balance. This is because under normal circumstances, the human body blood, body fluid pH should be maintained between PH7.35-7.45, was weakly alkaline. Acid and alkaline food intake will affect the blood, body fluid pH. From the physiological point of view, acidic food intake too much, will cause blood, body fluids increased acidity, acidosis.
