Vitamin A is a type of unsaturated monohydric alcohol, including vitamin A1 and vitamin A2. The activity of A2 is about 40% of A1; all carotenoids that can be decomposed to form vitamin A are called provitamin A, the most important of which is β- Carotene; vitamin A is insoluble in water, stable to heat, acid and alkali, and easily destroyed by oxidation.

Physiological function

Dietary reference intake: RNI for adult males: 800 μgRAE/d; RNI for adult females: 800 μgRAE/d; UL: 3000 μgRAE/d

Effects on the body

Main food sources: livers of various animals, cod liver oil, whole milk, egg yolks. Plant foods contain only beta-carotene, and the best sources are colored vegetables

Vitamin D is a derivative of steroids, cyclopentane polyhydrophenanthrene compounds, also known as anti-rickets vitamins. The two most common forms are D3 and D2. The source of vitamin D3 in the human body is converted from 7-dehydrocholesterol in the epidermis and dermis of the skin through ultraviolet irradiation. The activity of D2 is only 1/3 of D3. Vitamin D is relatively stable to heat and alkali. Light and acid promote heptaisomerization, and fatty acid rancidity can also cause damage.

Physiological function

Dietary reference intake: RNI for adults: 10 μg/d; UL for adults: 50 μg/d

Effects on the body

Food sources: There are not many natural food sources. There are relatively many fatty fish, animal livers, egg yolks, cream and cheese.

Vitamin E, also known as tocopherol, is the general name for tocopherols and tocotrienols. There are 8 compounds of vitamin E in nature, among which α-tocopherol has the highest biological activity. Vitamin E is relatively stable to heat, light, and alkali, but high temperatures can reduce its activity.

Physiological function

Dietary Reference Intake: Adult AI: 14 mg α-TE/d

Food sources: Vitamin E can only be synthesized in plants. Vegetable oil, wheat germ, hard fruits, seeds, beans and other cereals

Vitamin K is a class of naphthoquinone compounds. There are two types of vitamin K1 and vitamin K2 in nature. It is relatively stable to heat and oxidants, and sensitive to light and alkali.

Physiological function

Dietary Reference Intake: Adult AI: 80 μg/d

Food sources: Vitamin K1 is rich in green vegetables, animal livers and fish are also high in content, meat and dairy products are moderate in content, and fruits and grains are low in content.