Sweet potatoes and carrots are excellent sources of provitamin A carotenoids that are good for your eyes. Vitamin A from animal-derived foods is called retinol. This "pre-formed" vitamin A can be used directly by the body. Good food sources of retinol vitamin A include beef and chicken liver, whole milk and cheese.
Vitamin A is a critical nutrient during the early stages of life, particularly for vision. Insufficient vitamin A is the leading cause of preventable blindness during childhood. Many kids who experience childhood blindness show remarkable improvement after more vitamin A is added to their diet.
Concentrations of preformed vitamin A are highest in liver, fish, eggs, and dairy products [1]. Most dietary provitamin A in the U.S. diet comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils [1,5,10].
Getting too much preformed vitamin A (usually from supplements or certain medicines) can cause severe headache, blurred vision, nausea, dizziness, muscle aches, and problems with coordination. In severe cases, getting too much preformed vitamin A can even lead to coma and death.
Hypervitaminosis A is a condition that occurs when a person has too much vitamin A in their body. This can happen if a person takes too many supplements or uses certain creams for acne over a prolonged period. Symptoms of hypervitaminosis A include vision problems, changes in the skin, and bone pain.
The form of vitamin A that I recommend in our Vitamin Advisor is beta-carotene in addition to other mixed carotenoids. These are precursor forms, meaning the body can make all the vitamin A it needs from beta-carotene, which is not toxic, unlike the animal forms of vitamin A.
Yet, while preformed vitamin A is effectively absorbed, stored, and hydrolyzed to form retinol, provitamin A carotenoids like β-carotene are less easily digested and absorbed, and must be converted to retinol and other retinoids by the body after uptake into the small intestine.
α-Carotene, β-carotene and β-cryptoxanthin are provitamin A carotenoids, meaning they can be converted by the body to retinol (Figure 1). Lutein, zeaxanthin, and lycopene are nonprovitamin A carotenoids because they cannot be converted to retinol (Figure 2).
Vitamin A and vision make potent allies. Carrots contain lots of beta carotene and Vitamin A, which can contribute to your eyes' health and may provide a fantastic source of eye vitamins for macular degeneration and cataracts.
Vitamin A and beta carotene
Vitamin A is essential for good vision. It is a component of the protein rhodopsin, which allows the eye to see in low-light conditions.
The results showed that high doses of antioxidants vitamin C (500 mg), vitamin E (400 IU), and beta-carotene (15 mg/25,000 IU), along with zinc (8 mg), reduced the risk of vision loss from advanced age-related macular degeneration (AMD) in some, but not all, people with this disease.
Your eye doctor may recommend eye drops containing vitamin A to alleviate dry eye symptoms. In one study, researchers compared prescription eye drops to vitamin A eye drops for dry eye relief. The participants' blurred vision and tear film were dramatically improved by both types of eye drops.
and Warnings. When taken by mouth: Vitamin A is likely safe when taken in amounts less than 10,000 units (3,000 mcg) daily. Vitamin A is available in two forms: pre-formed vitamin A (retinol or retinyl ester) and provitamin A (carotenoids). The maximum daily dose relates to only pre-formed vitamin A.
Vitamin A can exist in three forms: retinol, retinal, and retinoic acid. Many tissues requiring vitamin A store the vitamin as an ester of retinal. Vitamin A is stored as fatty acyl esters of retinol in the lacrimal gland. It is also present as retinol in the tears of rabbits and humans.
Vitamin A, also known as retinol, has several important functions. These include: helping your body's natural defence against illness and infection (the immune system) work properly. helping vision in dim light.
Synthetic vitamin A can cause birth defects. Women who are pregnant or trying to become pregnant shouldn't take this form of vitamin A. Too much vitamin A is toxic and can cause liver failure, even death.
For example, too much vitamin D can deplete your vitamin A levels. It's also been postulated that vitamin A toxicity could sometimes be caused by a vitamin D deficiency.
Think of Vitamin A as the 'family name' and Retinol is a 'member' of this Vitamin A family. Vitamin A is an essential fat-soluble vitamin. You may recognise names such as retinol, retinal, retinoic acid or retinyl ester — which are all forms of vitamin A.
Symptoms of Vitamin B Deficiencies
Vitamin B1 deficiency is often associated with alcoholism and may cause toxic optic neuropathy leading to blurred vision and a restricted visual field. Vitamin B2, B3, and B6 deficiencies are associated with dry eyes and eye infections in the front of the eye.
Vitamin A is an antioxidant that protects the cornea, or outer surface, of the eye. It also maintains function of the retina, the light-sensitive lining that converts light into nerve impulses sent to the brain. Vitamin A is especially important for scotopic (low-light) vision and color vision.
Vitamins A, C, and E are the most effective vitamins for reducing the risk of macular degeneration [13]. However, only vitamin A plays an essential role in the human retinal pigment epithelial cells, whereas vitamins C and E are known to act as antioxidants.