Vitamin B12 can promote the development and maturation of red blood cells, keep the body’s hematopoietic function in a normal state, prevent pernicious anemia, and is also an indispensable vitamin for the sound functioning of the nervous system, participating in the formation of a lipoprotein in the nervous tissue. vitamin B12 deficiency is generally caused by insufficient intake or malabsorption, etc. 1, insufficient intake: mostly due to unreasonable dietary structure. Because the human body cannot synthesize vitamin B12 by itself, it is mainly taken from animal food. If there is a lack of meat, animal offal, milk, etc. in food, vitamin B12 deficiency is easily caused; 2. Malabsorption: vitamin B12 is generally absorbed in the intestinal tract. If gastrointestinal diseases occur or gastrointestinal surgery is performed, the absorption of vitamin B12 is generally affected. Hyperthyroidism, some drugs such as metformin, colchicine, proton pump inhibitors, etc., may also affect the absorption of vitamin B12; 3, congenital vitamin B12 metabolism disorder: cobalamin transporter protein II is the main transporter protein of vitamin B12, congenital cobalamin transporter protein II deficiency can lead to vitamin B12 transporter disorder, and thus vitamin B12 deficiency. Vitamin B12 deficiency can lead to a series of symptoms, such as menstrual disorders, loss of appetite, indigestion, inflammation of the tongue, etc. Children may have abnormal mental and emotional symptoms, dull expression, less crying, less responsiveness, and sleepiness. Dietary regulation and medication are needed. It is recommended that the diet can include more foods rich in vitamin B12 and more intake of animal proteins, such as eggs, fish, shrimp, and crab-like refined meat. Vitamin B12 deficiency can also be improved by taking vitamin B12 tablets orally.