維他命A功效、食物來源、保健品推薦

Vitamin A is the name of a fat-soluble retinol-like substance that is stable to heat, acids and alkalis and is easily oxidised. There are two types of vitamin A. Vitamin A alcohol, which is found only in animal foods, is the original form of vitamin A. Carotenoids, which can be ingested from either plant or animal foods, are converted to retinol in the body at levels that vary from person to person. Vitamin A contains photoreceptors (i.e., retinoids) that help create the retina, which is important for night vision; promotes growth and development; and maintains normal skin and mucous membranes and a functioning immune system.

Related reading:Learn about vitamin A and its effects

Common uses of Vitamin A

Vitamin A is one of the vitamins required by the human body and can be obtained through diet.

Health benefits of Vitamin A

The important physiological functions of vitamin A include:

1. Helps maintain good eyesight

Vitamin A can maintain normal visual responses and helps relieve dry eyes, maintain healthy night vision, and address some age-related macular degeneration problems.

2. Promotes growth and development

Retinol can promote the production of glycoproteins, which can promote development, make bones stronger, and maintain the health of teeth, gums, skin, and hair.

3. Helps maintain normal immunity

In particular, the body's resistance to respiratory problems helps maintain respiratory health.

4. It can maintain the integrity and health of the epithelial structure.

It can prevent dryness and keratinization of the skin and mucous membranes, and when used topically, it can help treat acne, pustules, and skin ulcers.

Vitamin A deficiency

Vitamin A deficiency may be caused by insufficient vitamin A intake, fat malabsorption, or liver problems. A lack of vitamin A can lead to stunted growth, impaired immune and hematopoietic function, and can also affect eye health and damage vision.

Excessive intake of vitamin A

Vitamin A should not be taken in excess. A single large dose of vitamin A (more than 200,000 mg) can cause blurred vision, nausea, vomiting, and dizziness. Long-term daily intake of more than 10,000 micrograms of oral vitamin A can cause headaches, nausea, skin allergies, diarrhea, joint and bone pain, birth defects, thinning of bones, and liver damage.

Vitamin A and common medications

1. Orlistat can reduce the absorption of vitamin A, other fat-soluble vitamins, and beta-carotene, thus lowering plasma concentration.
2. Taking vitamin A derivatives and vitamin A together can lead to excessive vitamin A intake and cause side effects.
3. Taking anticoagulants and vitamin A together can increase the risk of bleeding.
4. Taking bexarotine with vitamin A supplements may increase the likelihood of side effects, such as itchy and dry skin.