Vitamin A deficiency: most effective dietary supplements

Vitamin A, also known as retinol, is a fat-soluble vitamin essential for many biological functions. Discovered in 1913, it was the first vitamin identified, hence its assignment to the first letter of the alphabet. Vitamin A exists in various forms in the body, such as retinol (vision), retinal (retina), retinoic acid (bones and mucous membranes), and retinyl palmitate (storage in the liver). It is essential for vision, notably the eye's adaptation to darkness, as well as for cell growth, reproduction, and immune system regulation.

Essential Role of Vitamin A

Vitamin A plays a central role in cell growth and differentiation, as well as in the transcription of certain genes and the synthesis of specific proteins. It also contributes to the formation of teeth, bones, and skin, as well as to the maintenance of the mucous membranes of the eyes, the respiratory and urinary tracts, and the intestines, which form the first line of defense against infections. Furthermore, it promotes iron absorption and helps regulate inflammatory responses thanks to its antioxidant action.

Dietary Sources of Vitamin A

The body can obtain vitamin A directly from animal-derived foods, such as liver, eggs, and dairy products. It can also convert certain carotenoids present in plants, such as carrots and spinach, into vitamin A. Carotenoids, of which beta-carotene is the best known, are considered provitamin A because they can be converted into vitamin A by the body. Major food sources also include cod liver oil, leafy green vegetables, and certain fruits such as apricots and melons.

Vitamin A Deficiency: Causes and Consequences

Vitamin A deficiency, although rare in developed countries, can lead to serious consequences. In regions of the world where nutritional intake is insufficient, vitamin A deficiency is a major cause of childhood blindness and mortality. This deficiency can be primary, due to inadequate diet, or secondary, resulting from disorders that affect the absorption, storage, or transport of vitamin A. Symptoms include impaired vision, notably night blindness, dry eyes, dry skin and brittle hair, as well as decreased immune function, increasing the risk of recurrent infections. In developed countries, deficiency is generally observed in people with diseases that compromise fat absorption, such as cystic fibrosis, Crohn's disease, or in people suffering from chronic intestinal malabsorption. In children, severe deficiency can cause growth delays and serious complications, including loss of vision that can lead to blindness if not treated.

Recommendations and Precautions

To prevent vitamin A deficiency, it is recommended to regularly consume foods rich in retinol and beta-carotene. An adequate intake of protein and zinc is also essential for vitamin A metabolism, while vitamin E can increase its absorption and storage. It is important to note that excess vitamin A can cause toxicity, particularly in the liver. Pregnant women should exercise caution, as excess vitamin A can be dangerous for fetal development. By contrast, beta-carotene does not present the same risks, because the body converts only the amount needed into vitamin A, thereby avoiding excessive storage. To ensure an adequate intake of vitamin A, it is recommended to consume about 0.8 mg per day for an adult, according to European guidelines.