A varied and balanced diet should supply us with sufficient quantities of all the vitamins and trace elements needed to keep us in good health. Although there are some specific nutrients considered important for the eye and vision, these can be bought over the counter, in fact many high street Opticians will stock these as they are classed as general sales list medicines which require no supervision from a pharmacist.
The human body stores Fat-soluble vitamins, mainly in the liver or adipose tissue subsequently these types of vitamins do not need to be consumed on a daily basis, however water-soluble vitamins cannot be stored by the body so it is necessary to consume these on a regular basis as vitamins are substances that the body cannot produce. Excessive amounts of vitamins can build up and may be harmful, however the body discharges these in urine.
This was the first vitamin to be discovered, Vitamin A is categorised into two main groups; Retinoids and Carotenoids, these are also known as Performed vitamin A. Retinoids are found only in foods of animal origin, this is a fundamental element of the retinal photo-pigments, whereas Carotenoids are found in fruit and vegetables particularly brightly coloured red and yellow fruits and dark green leafy vegetables.
There are a various number of contrasting Carotenoids but only 10% of these are classed as pro-vitamins. The human body is capable of transforming these pro-vitamins to performed vitamin A.
Carotenoids are vital to the eye, these are powerful antioxidants known as lutein, zeaxanthin and lycopene. Healthy tissues can be damaged by free radicals which are produced by cell metabolism, these free radicals are broken down by the antioxidants in vitamin A. Vitamin A is associated with general maintenance of the eye, achieving a healthy epithelium and the production of mucus. Insufficient vitamin A leads to reduced night vision, susceptibility to infection and conjunctival corneal drying.
Water-soluble vitamins forming the B complex have crucial roles in cell metabolism. There are several within this group that are significant to ocular health; nutritional amblyopia has been linked to deficiency in thiamine (B1), niacin (B3), folic acid (B9), or cyanocobalamin (B12) or a combination. These vitamins along with riboflavin (B2) are important in maintaining optic nerve health. Vitamin B2 is an antioxidant that may help in preventing cataract. Vitamin B complex is present in many foods and deficiency in a normal diet is rare, but absorption by the digestve system of B1 and B12 in particular is easily unsettled by alcohol.
Vitamin C can also be referred to as ascorbic acid, its most important task within the body is it involvement in collagen production. It is an antioxidant and is necessary for wound healing and the preservation of healthy blood vessels. Vitamin C deficiency causes fatigue and bruising and in severe cases leads to the condition of scurvy.
Vitamin E is a fat-soluble antioxidant vitamin stored in adipose tissue. It is a generic term for a group of substances of which the most important is tocopherol. It is connected with the protection of cell membrances, and helps protect vitamin A from oxidation in the retina. Vitamin E is present in many foods and deficiency in a normal diet is rare but may arise in people with digestive problems who are unable to absorb dietary fats. Lack of vitamin E causes neurological problems due to poor nerve conduction.
Trace elements are less understood than vitamins but it is believed that trace elements are minerals required in small quantities to help vitamins to work. Selenium and zinc are important in the preservation of ocular health.
Selenium works with vitamin E, this has an antioxidant effect. It also helps in the functioning of the thyroid gland, the maintenance of cell membranes and possibly cancer prevention. A lack of Selenium may contribute to cataract and Age Related Macula Degeneration (ARMD).
Zinc is a critical trace element and is involved in antioxidant activity. It has a vital function in the metabolism of vitamin A and is found in the choroid and retinal receptors and may be connected in maintaining the health of the crystalline lens. Zinc deficiency causes poor wound healing and night blindness and has been linked in disease of the optic nerve.
Many studies have taken place on understanding the function of nutrition and dietary supplements and their effect on vision. Some show that dietary supplements can be beneficial while others show no benefit at all. It is considered by many experts that obtaining nutrients from food is more valuable than taking any supplement. Prospective buyers of these products should always be advised to consult their GP before starting to take supplements.
|Vitamin or Mineral||Examples of Good Food Sources||What It Does||Recommended Daily Amount (RDA) or Adequate|
|Choline (Vitamin B complex)||Milk, liver, eggs, peanuts||Plays a key role in the production of cells and neurotransmitters||
Men: 550 milligrams/day.
Women: 425 milligrams/day.
|Selenium||Organ meats, seafood, some plants (if grown in soil with selenium) Brazil nuts.||Protects cells from damage; regulates thyroid hormone||
Adults: 55 micrograms/day.
|Vitamin A||Sweet potato with peel, carrots, spinach, fortified cereals||Necessary for normal vision, immune function, reproduction||
Men: 900 micrograms/day.
Women: 700 micrograms/day.
|Vitamin B1 (Thiamin)||Whole-grain, enriched, fortified products; bread; cereals||Allows the body to process carbohydrates and some protein.||
Men: 1.2 milligrams/day.
Women: 1.1 milligrams/day.
Pregnant and breastfeeding women: 1.4 milligrams/day.
|Vitamin B2 (Riboflavin)||Milk, bread products, fortified cereals||Key in metabolism and the conversion of food into energy; helps produce red blood cells||
Men: 1.3 milligrams/day.
Women: 1.1 milligrams/day.
|Vitamin B3 (Niacin)||Meat, fish, poultry, enriched and whole-grains breads, fortified cereals||Assists in digestion and the conversion of food into energy; important in the production of cholesterol||
Men: 16 milligrams/day
Women: 14 milligrams/day.
|Vitamin B9 Folic Acid (Folate)||Dark, leafy vegetables; enriched and whole-grain breads; fortified cereals||Key for the development of cells, protein metabolism and heart health; in pregnant women, helps prevent birth defects||
Adults: 400 micrograms/day.
|Vitamin B12 (Cobalamin)||Fish, poultry, meat, fortified cereals||Important in the production of red blood cells||
Adults: 2.4 micrograms/day.
|Vitamin C||Red and green peppers, kiwis, oranges, strawberries, broccoli||Antioxidant that protects against cell damage, boosts the immune system, forms collagen in the body||
Men: 90 milligrams/day.
Women: 75 milligrams/day.
|Vitamin E (alpha-tocopherol)||Fortified cereals, sunflower seeds, almonds, peanut butter, vegetable oils||Antioxidant that protects cells against damage||
Adults (inc. pregnant women):
|Zinc||Red meats, some seafood, fortified cereals||Supports the body's immunity and nerve function; important in reproduction||
Women: 8 milligrams/day.