Nowadays, with the continuous improvement of living conditions, food is getting richer and more expensive, does it mean that it is getting better for the baby? Infancy is the first peak of human growth and development, and nutrition is the foundation of health. The nutritional status of this period directly affects the child’s physical and intellectual development, 0-3 years old is the fastest growing period of the baby’s physical growth, at the same time, it is also the most critical period of brain development, so that many young mothers and fathers, grandparents, grandparents they are very concerned about the growth of the next generation, so they are very concerned about the nutrition of infants and young children. In terms of food, mothers and fathers are not stingy with their children, but it is under these conditions, some children still have a malnutrition phenomenon. Below, let us understand together, what are the common malnutritional diseases in infancy and childhood?Common nutritional diseases within 3 years of age are protein-calorie malnutrition, iron deficiency and iron deficiency anemia in children, vitamin D deficiency rickets, zinc deficiency. So, what are the symptoms if a baby has these diseases? Protein-calorie malnutrition is mostly characterized by mild to moderate symptoms such as low weight, wasting, and growth retardation. Iron deficiency in children will reduce the vitality of various digestive enzymes in the body, causing a decrease in the child’s appetite, and because of the abnormal sense of taste, it can cause xenophagia, and, it will cause a decline in immune function, and in recent years, research has also found that iron deficiency can cause irreversible damage to brain development. Vitamin D deficiency rickets early manifestations of night sweating, occipital baldness, restless sleep, easy night terrors, irritability, crying, further development of cranial softening, chimney door is large, the skull square, and later continue to develop, the shape of the chest skeleton abnormalities, such as chicken breast, rib ectropion, “0” legs or “X” legs, and even the spine. “0” or “X” shaped legs, and even scoliosis or kyphosis. Zinc deficiency will be manifested as low appetite, recurrent mouth ulcers, xenophagia, growth retardation, short stature, long-term zinc deficiency can affect brain development, resulting in retarded intellectual development. The lack of these nutrients will have a great impact on the baby’s development and growth, every parent wants their children to be strong, smart and lovely, and therefore will pay special attention to the child’s nutritional problems, the baby’s rapid growth and development, to meet the requirements of the baby’s nutritional growth and development, how should we go to prevent it? First of all, reasonable feeding, adhere to breastfeeding, scientific and reasonable addition of complementary foods, to avoid partiality, picky eating, and develop good eating habits, followed by regular monitoring of height, weight, head circumference, and neuropsychological development assessment (or screening). The third is active treatment when sick, but over-treatment should also be avoided. We have just talked about nutrition, this nutrition and feeding are somewhat related, they can not be said separately, because nutrition may be mostly eaten, the child is more dependent on feeding at a young age, we parents can only do scientific and reasonable feeding, in order to ensure that the child adequate nutrition. There is also such a situation, many mothers and fathers will think that the child’s growth is a very natural thing, I do not need to go too much attention, when the time to wean the weaned the meal to eat. Is this a misunderstanding? Yes, the child’s growth is to follow the laws of natural growth, but infancy is the most rapid stage of development in life, when the feeding and supplemental food to add good or bad for its physical development and health is particularly important. Once nutritional imbalance occurs, the damage caused is often irreversible. For small infants, breast milk is the best food, but the amount of breast milk has a certain limit, and with the increase in the age of infants, the nutrients contained in milk can not fully meet the needs of their growth and development. Moreover, after 4–6 months, the infant’s gastrointestinal amylase is mature and has the physiological function of digesting starchy food, therefore, it is necessary to add complementary foods for nutrient supplementation at the right time. Some parents, knowing the importance of adding complementary foods and food conversion for their children, start feeding their children rice soup or egg yolks at three months of age, while some parents think that they have enough milk and have not added any complementary foods to their children at eight or nine months of age, which, we say, are not appropriate. If you add complementary foods too early or too late, it will affect your baby’s development. less than 4 months old babies, digestive enzymes and intestinal barrier function is immature, can not accept foods other than breast milk or formula, if you add complementary foods too early, it will cause indigestion, and food allergies, and bring a lot of pressure on the immature kidneys, leaving behind hidden dangers. 6 months after the baby does not start to add complementary foods, due to the caloric and nutrient intake is insufficient, it will lead to the baby’s nutritional problems. Insufficient intake of calories and nutrients will lead to malnutrition or growth retardation. Some parents and friends can not figure out what is complementary food, that is, in addition to breast milk and formula, should give the child to eat some other things, then there are many parents think that all nutritious food should be fed to the child as much as possible, think that the more nutritious the better, which may be a common misunderstanding of the parents nowadays. For growing and developing children, a balance of nutrients is very important. Complementary food addition, that is, food conversion is one of the key elements of infant and young child nutrition, then, we parents to add food to the child, first of all, we should follow the principle: from one to many, from a small amount to the right amount, from thin to thick, from fine to coarse, at the same time, to observe the child’s digestive situation, pay attention to individual differences. Specifically, 4 months: can not add starchy food; 5 ~ 6 months: learn to eat from a small spoon of semi-fluid complementary food, should add iron-rich foods and animal and plant proteins, first add rice flour, and then add puree, puree, egg yolks, etc.; 6 ~ 7 months: feed pureed liver, pureed chicken, puree, pureed fish, pureed blood tofu, rotten rice porridge; 7 ~ 8 months: to train babies to chewing ability, and to promote the emergence of teeth. Can gradually add semi-solid food, such as cookies, cakes, bread, crushed lei, minced meat, etc.; 9 ~ 12 months: add rotten pasta, fish, tofu, wontons, dumplings and rotten rice.