I. Understanding lactose The chemical composition of sugars can be divided into monosaccharides, disaccharides and polysaccharides. Lactose is a disaccharide and is one-sixth as sweet as cane sugar. The difference in molecular spatial configuration makes lactose exhibit two spin isomers, alpha-lactose (α-lactose) and beta-lactose (β-lactose). Beta-lactose has nutritional value, while alpha-lactose cannot be utilized by the body. Beta-lactose is the best sugar for children to consume, and there is sufficient lactase in children’s digestive tract to decompose beta-lactose, so it can be well decomposed, digested and absorbed to use beta-lactose. Lactose is broken down into one molecule of glucose and one molecule of galactose by the enzyme disaccharidase in the human body, and is absorbed and used by the body. Human milk contains 7% lactose and milk contains 4.2% lactose. The b-lactose content in human milk is not only higher and more stable than cow or goat milk, but also does not change due to changes in the mother’s food and does not fluctuate due to changes in blood sugar. The lactose content of artificially formulated milk powder is also adjusted to a higher level with reference to the composition of breast milk. Therefore, the general infant milk powder is rich in lactose. Second, the role of lactose on the human body 1, energy supply: glucose from the decomposition is the only suitable sugar in the blood. Digestion of lactose is not as rapid as the digestion of sucrose (white sugar). Since lactose is absorbed at a slower rate than sucrose, it can provide energy for a longer period of time. Dairy products are foods that produce galactose quickly because they do not interfere with the balance of glucose in the blood and are good healing foods and weight gain diets. 2, promote the growth of lactic acid bacteria reproduction in the intestinal tract of pediatric: in the intestinal tract of beta lactose in the role of lactobacillus, lactic acid streptococcus, a variety of enzymes and certain microorganisms to generate lactic acid, beta lactic acid for pediatric gastrointestinal adjustment protection, it can inhibit the toxins produced by abnormal fermentation in the intestine caused by poisoning, but also inhibit the reproduction of harmful bacteria in the intestine. 3.Lactose is a component of glycoprotein and glycolipid, which is involved in a variety of cellular functions. Oligosaccharides in milk have anti-infective effects, therefore, breastfeeding infants, within one month of age, has a reduced chance of gastrointestinal and respiratory tract infections, and also has a protective effect on urinary tract infections. 4, promote the absorption of calcium in children; 5, the galactose provided: galactose is particularly important for children’s brain development, it can promote the production of cerebroside lipids and mucopolysaccharides, also helps the rapid regeneration of endothelial tissue, and delays the formation of atherosclerosis galactose in the intestinal tract of children is a promoter of bacterial synthesis of vitamin K and vitamin B complex. III. Types of lactose intolerance Type I: congenital lactase deficiency: It is caused by congenital deficiency or insufficient activity of lactase, the incidence of which is related to race and heredity and belongs to autosomal recessive inheritance. It means that the lactase activity of the body is low or deficient from the time the baby is born. Judgment method: no matter drinking breast milk or cow milk, it can lead to obvious diarrhea, stop feeding breast milk or replace with rice soup type food feeding, diarrhea disappears, that is, congenital lactose deficiency or low. The symptoms of diarrhea mainly appear 1 to 2 hours after breastfeeding in newborns, accompanied by abdominal distension, hyperactive bowel sounds, spasmodic diarrhea, and in severe cases, vomiting, water loss, and acidosis. The stool is watery, foamy, acidic and contains lactose. Signs: no weight gain, malnutrition, emaciation, anemia, and abdominal bulging. Type 2: Primary lactase deficiency: Human toddlers usually lose 90% of their lactose digestion by the age of 4 years, but this varies widely among individuals. Some human races have a genetic mutation on chromosome 2 that exhibits a reduced trait capable of terminating lactase, so these races are able to digest lactose throughout their lives, and the incidence varies by race and region. The incidence varies with race and region. For example, it is about 5% to 30% in white Europeans, 76% to 10% in yellow Asians, and 95% to 10% in Africa. The current situation is that most people of Western European ancestry have the mutation in their genes (meaning that they are enough to digest lactose for life), while most East Asians, sub-Saharan Africans, and native peoples of the Americas and Oceania do not have the mutation (meaning that they become lactose intolerant in adulthood). On average, 75% of people worldwide develop symptoms in adulthood, so rather than calling it a disease, it is more appropriate to refer to it as a natural condition. Type III: Secondary lactase deficiency: temporary low lactase activity due to damage to the small intestinal epithelium from various causes. Common causes include infectious diarrhea, severe malnutrition, and after high doses of cephalosporins and endocannabinoids. The lactose intolerant diarrhea occurs after enteritis when the top of the intestinal villi is damaged and the enzyme is deficient, and the diarrhea will stop only after the lower end of the villi grows upward to the top and can secrete sufficient amount of lactase, which usually takes 0.5 to 2 months. Four, lactose intolerance how to eat? 1, a small amount of multiple intake of dairy products: can reduce or not appear lactose intolerance symptoms. Even infants with lactase deficiency can tolerate a small amount of dairy (120 to 240 ml), and the general lactose limit is 12 grams in a day. No symptoms of intolerance will occur; 2. Additional lactase: It can improve the digestion and absorption of lactose. Milk can be sucked out with a breast pump, lactase added, and then bottle-fed; 3. Choose low-lactose milk formula: suitable for infants and children born with a lack of lactase or chronic diarrhea resulting in the loss of lactase from the surface layer of the intestinal mucosa. The original formula can be stopped when diarrhea occurs and directly replaced with such formula. When the diarrhea situation improves, it should be gradually replaced slowly back to the original infant formula.