From a personal perspective, the main causes of vitamin deficiency are as follows: Insufficient content in the diet
The main reasons are poor economic conditions, a monotonous diet, and picky eating, which makes the intake of vitamins in the diet unable to meet the body's needs. In some regions where food is monotonous (such as a corn-based diet), it is easy to develop diseases caused by a lack of certain vitamins (such as pellagra). Impaired absorption
More common in patients with digestive system diseases, factors such as accelerated intestinal motility, obstruction of the digestive or biliary tract, reduced absorption area, and long-term diarrhea can reduce the absorption and storage of vitamins. Suppression of intestinal bacterial growth
If the use of bactericidal drugs suppresses the bacteria in the digestive tract, the amount of vitamin synthesis will be reduced, leading to a deficiency of certain vitamins (such as K, B', B:). Increased excretion
The main reasons are increased excretion due to factors such as lactation, excessive sweating, and long-term use of large amounts of diuretics. Accelerated destruction
The main reason may be that drugs and other factors cause vitamins to be destroyed more quickly in the body. Increased requirement
Due to physiological and pathological needs, an increased requirement combined with insufficient intake can also lead to vitamin deficiency. For example, children in the growth period, pregnant and lactating women, workers engaged in heavy physical labor and special types of work, and patients with long-term high fever and chronic wasting diseases all have higher vitamin requirements than the average person.