Vitamin A is a fat-soluble vitamin that is good for healthy vision, skin, bones and other tissues in the body. Vitamin A often works as an antioxidant, fighting cell damage, but it also has many other uses.
There are two types of vitamin A. Preformed vitamin A, also called retinol, is found in animal products. Good sources are fortified milk, eggs, meat, cheese, liver, halibut fish oil, cream and kidneys.
Pro-vitamin A is found in plant-based foods such as fruits and vegetables, according to the U.S. National Library of Medicine (NLM). The most common type of pro-vitamin A is beta-carotene, a carotenoid that produces dark pigments in plant foods. Beta-carotene can be found in these brightly colored foods: Cantaloupe, Pink grapefruit, Apricots, Carrots, Pumpkin, Sweet potatoes, Winter squash, Dark green, leafy vegetables, Broccoli.
Retinol not only creates the pigments in the retina of the eye, according to NLM, but also is integral for good vision, especially night vision, and overall eye health. An age-related eye disease study by the National Eye Institute found that taking high levels of antioxidants, such as vitamin A, along with zinc, may reduce the risk of developing advanced age-related macular degeneration by about 25 percent. Age-related macular degeneration is the most common cause of loss of vision in the older population, said Ross.
Vitamin A also helps skin grow and repair skin.
vitamin A helps in the the formation and maintenance of teeth, bones, soft tissue, white blood cells, the immune system and mucus membranes.
Beta-carotene also acts as an antioxidant, protecting cells from free radical damage.
Around 250,000 to 500,000 children around the world with vitamin A deficiency become blind every year. Half of those children die within 12 months of losing their sight, according to the World Health Organization.
Symptoms of a severe deficiency are
- night blindness
- dry eyes,
- diarrhea and
- skin problems.
Vitamin A dosage is tricky. Too little can make a person more susceptible to disease and vision problems while too much can create many problems, as well. The recommended dietary intakes for vitamin A depend on age, gender and reproductive status. The Dietary Reference Intakes (DRI) for adult women is 700 micrograms (mcg) and for adult men it is 900 mcg per day.
“Overdose of Vitamin A is absolutely a plausible scenario given its fat soluble nature, and it has been associated with a diverse set of symptoms ranging from skin and hair loss to neurologic problems, to gastrointestinal complains. In addition, liver injury has been described in situations of long term excess,” said Greuner.