Vitamin AD is an essential substance for human growth and development, especially for fetal development, epithelial tissue stereotypes, vision, reproductive function, bone growth and blood calcium regulation. The lack of vitamin AD, the immune function will be lower, the upper respiratory tract is easy to suffer from bacterial and viral invasion.

Vitamin A, also called retinol, is fat-soluble. It improves vision and prevents night blindness; promotes bone growth; and promotes the growth of the skin's mucous membranes, making the skin moist and supple. Lack of it will cause less water in the eyes, eye dryness and fear of light, vision loss, dry and rough skin, etc. Vitamin D, also known as sunshine vitamin, is also fat-soluble, it can promote children, adolescents, bone growth, prevention of rickets; to prevent osteoporosis in middle-aged and elderly people are to help the absorption of calcium.

Extended information:

Vitamins are a class of micro-organic substances that must be obtained from food for the maintenance of normal physiological functions in humans and animals, and play an important role in the human body growth, metabolism, Vitamins are not involved in the composition of human cells, nor do they provide energy for the body.

Vitamins are a class of organic compounds necessary for maintaining good health. These substances in the body can be neither raw materials for the composition of body tissues nor a source of energy, but a class of regulatory substances that play an important role in the metabolism of substances.

Vitamins are some of the small amount of organic compounds necessary for human and animal nutrition and growth, and play an extremely important role in the body's metabolism, growth, development, and health. If a long-term lack of certain vitamins, will cause physiological dysfunction and the occurrence of certain diseases. Generally obtained from food. There are dozens of species found at this stage, such as vitamin A, vitamin B, vitamin C and so on.

Vitamins are essential organic compounds in human metabolism. The human body is like an extremely complex chemical factory, constantly carrying out a variety of biochemical reactions. Its reaction and the catalytic effect of enzymes have a close relationship. Enzymes to produce activity, there must be coenzymes to participate. Many vitamins are known to be coenzymes of enzymes or constituent molecules of coenzymes. Vitamins are therefore important in maintaining and regulating the normal metabolism of the body. It can be assumed that the best vitamins are found in human tissues in the form of "biologically active substances".

Baidu Encyclopedia: Vitamins