Moderate consumption of food preservatives is not harmful to the human body, but if consumed in excess, they can cause damage to the growth and reproduction of normal flora in the digestive tract. Food preservatives are generally added to food to inhibit the growth of microorganisms, reproduction and oxidation reactions and other chemical changes to prevent food spoilage for the purpose of artificial chemical synthesis. The main components of commonly used food additives are nitrite, sulfur dioxide, benzene potassium acid, sorbic acid, etc. Nitrite can combine with the body’s hemoglobin, so that it loses the ability to carry oxygen, resulting in methemoglobinemia. Sulfur dioxide can cause damage to the human lung tissue and respiratory system, while acidic substances such as potassium benzoate and sorbic acid can upset the acid-base balance in the body, thus causing a series of disorders of acid-base balance. Moderate consumption of food preservatives generally does not cause damage to the human body, but if consumed in excess will cause damage to the normal growth and reproduction of bacteria in the digestive tract, which affects the digestion, absorption and excretion of food, resulting in a series of digestive system diseases.