Overview:
Vitamin A is the name of a group of fat-soluble retinoids, primarily retinol and retinyl esters.
Vitamin A is the generic term for a group of fat-soluble compounds highly important for human health.
It’s recommended that men get 900 mcg, women 700 mcg and children and adolescents 300–600 mcg of vitamin A per day.
Vitamin A compounds are found in both animal and plant foods and come in two different forms: preformed vitamin A and provitamin A.
Preformed vitamin A is known as the active form of the vitamin, which your body can use just as it is. It’s found in animal products including meat, chicken, fish and dairy and includes the compounds retinol, retinal and retinoic acid.
Provitamin A carotenoids — alpha-carotene, beta-carotene and beta-cryptoxanthin — are the inactive form of the vitamin found in plants. These compounds are converted to the active form in your body. For example, beta-carotene is converted to retinol (an active form of vitamin A) in your small intestine.
Overview of Benefits:
Vitamin A is involved in immune function, cellular communication, growth and development, and male and female reproduction. Vitamin A supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, eyes, and other organs. It is also critical for vision as an essential component of rhodopsin, the light-sensitive protein in the retina that responds to light entering the eye, and because it supports the normal differentiation and functioning of the conjunctival membranes and cornea
Positive Health Applications:
The vitamin is needed to convert light that hits your eye into an electrical signal that can be sent to your brain. In fact, one of the first symptoms of vitamin A deficiency can be night blindness, known as nyctalopia.
Night blindness occurs in people with vitamin A deficiency, as the vitamin is a major component of the pigment rhodopsin. Rhodopsin is found in the retina of your eye and extremely sensitive to light. People with this condition can still see normally during the day, but have reduced vision in darkness as their eyes struggle to pick up light at lower levels.
In addition to preventing night blindness, eating adequate amounts of beta-carotene may help slow the decline in eyesight that some people experience as they age.
Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. Though its exact cause is unknown, it’s thought to be the result of cellular damage to the retina, attributable to oxidative stress. The Age-Related Eye Disease Study found that giving people over the age of 50 with some eyesight degeneration an antioxidant supplement (including beta-carotene) reduced their risk of developing advanced macular degeneration by 25%