Does vitamin A really work?


Vitamin A is actually a family of substances called retinoids that includes retinol, retinal, and retinoic acid. These are called preformed vitamin A because they are in a form that your body readily uses. Retinol is the most usable of the three forms and can be converted to both retinal and retinoic acid in your body.

Vitamin A is needed in your body for healthy vision, bone health, and robust immune system.

Preformed vitamin A is found only in foods from animal sources, such as liver and eggs, and is added to all processed milk. Plant food sources do not contain preformed vitamin A, but some do contain provitamin A carotenoid, which can be converted to retinol in your body. Carotenoids are the yellow-red pigments that give carrots, butternut squash, and cantaloupe their vibrant, deep orange color.

There are over 600 different carotenoids, but only 3 -- beta-carotene (β-carotene), beta-cryptoxanthin (β-cryptoxanthin), and alpha-carotene (α-carotene) -- can be converted to vitamin A. These three provide approximately 25 to 35 percent of the dietary vitamin A consumed by adults in the United States, with the majority of it coming from beta-carotene. Other nutritionally significant carotenoids, including lycopene, lutein, and zeaxanthin, may function as antioxidants or provide health benefits, but cannot be converted to vitamin A.
Picture of milk & carrots
Vitamin A is effective for treating vitamin A deficiency. It can also be used effectively for preventing or treating a health problem related to vitamin A deficiency, such as dry eye (xerophthalmia). However, if a person does not have vitamin A deficiency, it probably is not useful for treatment of a health condition. Before you take it, particularly in high doses, for any reason other than low-dose supplementation, as in a multivitamin, it is best to contact your doctor. Too much vitamin A in your body can result in toxicity and become life-threatening.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.