The term vitamin A covers all substances or their derivatives having a similar chemical structure and biological effects. In the international chemical nomenclatures, the term retinoids is used. Of these retinoids, retinol is the most active form and is suitable for direct uptake by the body.

Carotenoids (the best-known being beta-carotene) are precursors of vitamin A, known as provitamin A. In the body (in the intestine), provitamins A are converted into vitamin A (retinol).

Vitamin A is fat-soluble, i.e. it is soluble in oil and insoluble in water. It is resistant to heat and acidity but sensitive to air (oxidation) and destroyed by light. Therefore, for maximum vitamin A retention in foods, it is best to store them away from light and air.

In the body, between 50 and 80% of vitamin A is stored in the liver and released according to the body's requirements. These reserves can cover the body's requirements for 1 to 2 years.

Roles

Vitamin A supports a normal iron metabolism. It also helps maintain normal mucosa. This vitamin helps maintain normal skin and normal eyesight. Vitamin A supports normal immune system function. It is involved in the cell specialisation process.

Table of RNI (Reference Nutrient Intakes) for vitamin A :

Age / Status	RNI for vitamin A
Infants	350 µg
Children 1 to 3 years	400 µg
Children 4 to 12 years	450 à 550 µg
Teens 13 to 19 years	700 à 800 µg
Women	600 µg
Men	800 µg
Pregnant women (> 3rd trimester)	700 µg
Breastfeeding women	950 µg
Seniors	600 à 700 µg