Vitamin A is a nutrient which is most beneficial for the skin. We know vitamin A by many different names such as retinoic acid, retinol, antixerophthalmic vitamin, biosterol or beta-carotene. However vitamin A is an isoprenoid polyene alcohol and these names all have different functions.
We will look at the most important: Retinol is the main form of vitamin A in diets and is solely found in animal products. Carotenes and derivatives act as provitamins or precursors of vitamin A, which is found in many plant substances. So... What is retinoic acid? It is the active form of retinol on the skin and regulates queratogenesis which is the generation process of the skin’s horny layer.
Vitamin A is a nutrient of animal origin. It’s complete nutrient form is found in oils from animal origin, butter, egg yolk, milk and meat (above all in liver) and some fish.
However carotenes (and beta-carotenes) are found in dark green vegetables, such as spinach, lettuce, cabbage and some vegetables such as pumpkin, carrots and yellow corn. You should always take into account that a considerable amount of carotenes are lost when these foods are dried in the sun, therefore we recommend that you eat them when they are fresh. We cannot be sure that the WHO recommended amount of vitamin A (750μg of retinol daily for adults) can be achieved by “only” consuming vegetables (carotenes) because the conversion to retinol is not effective.
And one more thing about beta-carotenes (precursor of vitamin A) that we need to bear in mind is that it does not accumulate, meaning that the body can only absorb the amount necessary and the rest is discarded. Therefore it’s important to know this when we plan our diet. Only vitamin A in its final structure can accumulate in the liver.