Vitamin A

Vitamin A, or retinol, is an organic compound that is fundamental for the correct development and functioning of the body. It is considered essential, just like the other vitamins, but vitamin A is only necessary in relatively small amounts. This micronutrient's daily reference intake ranges between 700 and 900 micrograms, respectively for women and men. These recommendations, that not only vary according to gender but also to age, are established for healthy people of at least 18 years of age (source: Dietary Reference Intake (DRI), Food and Nutrition Board, Institute of Medicine - National Academy of Sciences).

Pre-formed vitamin A, which is the vitamin's biologically active form, is only found in foods derived from animals, such as liver and liver oil, whole milk, butter, cheese and egg yolk. Dark green leafy vegetables (e.g. broccoli, cabbage, Brussels sprouts), and colored fruits and vegetables (e.g. carrot, beet, mango and tomato) are rich in provitamin A, also known as carotene. Those with a more pronounced or darker color usually contain higher carotene concentrations. About half of the vitamin A obtained from the diet is ingested in the form of carotene, although this substance is first subjected to a conversion process in the body before it actually becomes vitamin A and can be used as such.

Most vitamins are taken in through foods, which is why it is very important to make sure that sufficient amounts of vitamin-rich foods are consumed. If necessary, resorting to supplements is also a possibility. In the case of vitamin A, food preparation often increases its bioavailability and helps with its absorption, although overcooking may do exactly the opposite, destroying the vitamin. As vitamin A is liposoluble, it is absorbed along with dietary fats. Absorbing the vitamin requires assistance from digestive enzymes. In the end, the vitamin is transported to the liver, where it is metabolized.

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