In recent years, the occurrence of allergic diseases has increased dramatically worldwide and has been recognized by WHO as one of the most serious public health problems of the 21st century. Over the past few decades, allergic diseases have become the most common chronic disease of childhood in western industrialized countries, with a prevalence of about 1/3. In Shanghai, China, the probability of bronchial asthma in children has increased by 153% in a decade and is on a rapid growth trend. Allergic diseases have a unique developmental history, roughly through three stages, and can involve multiple organs and systems, manifesting as itchy skin, urticaria, eczema, skin mucosal edema, etc.; the digestive system can manifest as nausea, vomiting, diarrhea, abdominal distension, intestinal cramps, etc.; the respiratory system can manifest as runny nose, sneezing, nasal congestion, cough, wheezing, etc., and even serious adverse reactions such as anaphylaxis can occur. Allergic diseases often start in infants. Infant allergies mainly manifest as gastrointestinal and skin symptoms, which can include colic, non-pathological gastroesophageal reflux or vomiting, constipation, diarrhea, and eczema. Eczema and gastrointestinal symptoms are the first to appear in infancy. From 1 to 3 years of age, respiratory allergy symptoms are mainly manifested, the most typical being asthma and allergic cough, and after 3 years of age, allergic rhinitis is the most common. Asthma and rhinitis often follow a lifetime and affect the quality of life. Because allergic diseases are often persistent and frequent, there is no effective cure, and symptomatic treatment is often accompanied by significant side effects, so it poses a great burden on the quality of life of the affected children and their family members, as well as on society. Early prevention of allergies in infants and children is of great importance. The main causes of food allergy in infants are: 1. environment: pollution, food, and excessive cleaning; 2. internal environment: imbalance in the infant’s immune response and high intestinal permeability lead to allergy in infants, and there are also factors that we cannot intervene – genetic factors: parents with the same allergic symptoms: allergy risk 60 to 80%; both parents are allergic: allergy risk 40~60%; one parent is allergic: allergy risk 20~40%; both parents are not allergic: allergy risk 5~15%. 3, poor prevention: breast milk is the best nutrition for infants, and breastfeeding is advocated for infants within 4 months, but due to various reasons of mothers, some infants are not breastfed, and most mothers use ordinary cow’s milk formula to feed their babies. Milk is rich in nutrients and has a high biological value, making it the main food for infants. The protein content of milk is 3% to 4%, with casein being the main protein, accounting for 86% of the total protein content; it is this heterogeneous protein that can easily cause allergic reactions. There are more than 20,000 known allergens, and the earliest and most important allergen in infancy is milk protein, and for newborns, a drop of common milk formula can cause allergy. Even breastfed infants can be sensitized if they are occasionally exposed to milk formula. The ingestion of allogeneic proteins from regular cow’s milk formula during the first months of life is one of the major risk factors for increased allergic disease in the first years of life. Studies have now confirmed that the use of moderately hydrolyzed whey protein formulas can prevent the development of allergic diseases in infants and children. Moderately hydrolyzed protein formula, also called partially hydrolyzed protein formula, is a special high-tech process that changes large milk proteins into small milk proteins easily tolerated by infants without affecting the nutrition of milk proteins, which reduces the occurrence of allergic diseases by reducing the amount of allergens (large milk proteins) on the one hand and retains some immunogenicity on the other hand. Immunotolerance (commonly known as desensitization therapy) reduces the occurrence of allergic diseases in childhood. There is evidence that this protective effect can last up to 24 months of age and even up to 5 years of age. In foreign countries, clinical studies have been reported as early as 10 years ago recommending the use of hydrolyzed formula feeding to prevent the development of allergic diseases when breast milk is insufficient, showing that the use of specific hydrolyzed formula can reduce the risk of allergic diseases when breast milk is insufficient.