Vitamin A (Retinol) Information

Some foods contain both vitamin A (retinol and substances carotenoids) such as betacarotene that can be converted to vitamin A. Vitamin A is necessary for normal growth, bone and teeth formation, and maintaining healthy skin and the lining membranes of hollow internal organs such as the mouth and lungs. It is essential for vision in low light. It has been suggested that high intake of carotenoid-containing foods might protect against some types of cancer.

The richest sources of retinol are dairy products and liver. Yellow vegetables and fruit, and leafy vegetables, especially spinach and parsley, provide the most beta-carotene.

The earliest sign of deficiency is night blindness, followed by dryness and inflammation of the eyes. In severe, ongoing deficiency, inflammation of the cornea (transparent area in front of the coloured part of the eye) may develop and lead to blindness. Other symptoms include rough, dry skin, and increased risk of infection in lining membranes (especially respiratory and urinary). Vitamin A deficiency may cause retarded growth in children. Inadequate intake, poor absorption, or prolonged use of some lipid-lowering drugs may lead to deficiency.

Excessive intake from the diet is rare, but problems may result from supplement overdose. Symptoms include nausea, appetite loss, headache, peeling skin, hair loss, tiredness, menstrual irregularities and enlarged liver and spleen. Too much vitamin A during pregnancy may lead to birth defects. Pregnant women are advised not to take supplements except on medical advice. Eating too much carrot can cause reddish orange discoloration of the skin, but this is harmless and disappears when the diet is corrected.

Like most vitamins, Vitamin A works best in combination with other vitamins and minerals. For that reason, it is often more effective to take multi-vitamin supplements, rather than taking just a vitamin A supplement in isolation. A multi-vitamin supplement will include vitamins C, D, E, K and all the B vitamins, as well as many useful minerals, enzymes and other nutrients, all of which work together to enhance one another.