Vitamin A benefits for good vision
Vitamin A is obtained from colorful fruits and vegetables is in the form of "provitamin A" carotenoids, which are converted to retinol by the body after the food is ingested. Good food sources of provitamin A carotenoids include carrots, sweet potatoes, spinach, kale and cantaloupes.
Beta carotene is one of the most prevalent and effective provitamin A carotenoids.
Vision benefits of Vitamin A and Beta Carotene
Because vitamin A helps protect the surface of the eye (cornea), it is essential for good vision.
Studies show vitamin A eye drops are effective for the treatment of dry eyes. In fact, one study found that over-the-counter lubricating eye drops containing vitamin A were as effective for the treatment of dry eye syndrome as more expensive prescription eye drops formulated for dry eye relief.
Vitamin A eye drops also have been shown effective for the treatment of a specific type of eye inflammation called superior limbic keratoconjunctivitis.
Vitamin A, at least when in combination with other antioxidant vitamins, also appears to play a role in decreasing the risk of macular degeneration (AMD). People at high risk for the disease who took a daily multiple vitamin that included vitamin A (as beta carotene), vitamin C, vitamin E, zinc and copper had a 25 percent reduced risk of advanced AMD during a six-year period.
It also appears that a combination of vitamin A and lutein may prolong vision in people suffering from retinitis pigmentosa (RP). A recent four-year study conducted by researchers from Harvard Medical School and other prominent universities found that individuals with retinitis pigmentosa who took daily supplements of vitamin A (15,000 IU) and lutein (12 mg) had a slower loss of peripheral vision than those who did not take the combined supplements.
Because beta carotene is converted into vitamin A in the body, it's likely beta carotene (provitamin A) offers similar eye benefits as the pre-formed retinol type of vitamin A, though more research is needed to confirm this.
In early 2011, researchers at Columbia University Medical Center (New York) found that a synthetic, altered form of vitamin A might be able to slow the progression of Stargardt's disease, an inherited eye disease that causes severe vision loss in young people.
When given to mice with the same genetic defect as humans with Stargardt's disease (also called juvenile macular degeneration), the modified vitamin A inhibited the growth of clump-like deposits in the retina called "vitamin A dimers" that are associated with degenerative changes and vision loss.
Vitamin A deficiency
A lack of vitamin A causes the cornea to become very dry, leading to clouding of the front of the eye, corneal ulcers and vision loss. Vitamin A deficiency also causes damage to the retina, which also contributes to blindness.
Because vitamin A also is important for resistance to infection and a healthy immune system, vitamin A deficiency can lead to death from respiratory and other infections.
Regular Super Foods for Vitamin A
In most cases, it's best to obtain vitamins and minerals from a healthy, balanced diet. Just one cup of plant based foods as carrots, pumpkin, sweet potatos give you dose which exceeds 5-9 times daily recommended dose.
Beta carotene and other provitamin A carotenoids found in fruits and vegetables don't pose the vitamin A toxicity risk. These compounds are water-soluble and are easily eliminated from the body, so vitamin A toxicity from vegetarian food sources is rare.
Beta carotene supplements, however, may have serious risks for smokers. Two studies have found that smokers taking daily supplements containing 20 to 30 mg of beta carotene had an increased risk of lung cancer compared with smokers who did not take the supplements.
Possible toxicity reactions from long-term daily consumption of vitamin A from supplements or from animal based foods include birth defects, liver abnormalities, reduced bone mineral density that can lead to osteoporosis, and central nervous system disorders, so keep yourself in plant food side and avoid any risks.