Vitamins and minerals perform many vital biological functions in your body, including providing structure for your bones, assist enzymes in metabolic reactions, maintain proper vision, support your immune system and heal wounds. However, too much or too little of certain vitamins and minerals can cause damage to your eyesight, according to dietitian Ellen Coleman, former nutrition consultant for the Los Angeles Lakers.
Vitamin A
Vitamin A is well-known for maintaining healthy eyesight and nightvision. If you have a deficiency of vitamin A, you eyes would not be able to adapt to changes of light, especially transitioning from light to dark environments. According to the Linus Pauling Institute, vitamin A deficiency causes a reduced production of rhodopsin, which is a compound in the retina responsible for detecting small amounts of light. It also causes changes the normal shape of the conjunctiva and cornea of the eye, which leads to blindness.
Copper
Copper is a mineral that assists enzymes in food metabolism, formation of red blood cells, bone and connective tissues and forming the hormone epinephrine. If your body has excess copper, your liver absorbs it and excretes it in bile for elimination from the body. However, if you have Wilson's disease, a rare hereditary disorder, your liver does not absorb enough copper to excrete it in the bile, according to Merck Medical Library. The copper then accumulates in various parts of your body, including your brain, liver and eyes. People with this disease should avoid foods that are high in copper for the rest of their lives, such as legumes, nuts and mushrooms.
Zinc
Zinc is a mineral that assists enzymes in initiating reactions like spark plugs in a car engine. It also helps vitamin A in forming rhodopsin and improving nightvision. Zinc deficiency causes age-related macular degeneration, or ARMD, that occurs mostly in elderly adults, according to the "Journal of the American College of Nutrition." This disease causes the center of your vision to appear blurry yet your peripheral vision remains normal. Zinc deficiency also leads to blindness because the mineral is needed to maintain a healthy retina.
Recommended Intake
To avoid vitamin A or zinc deficiency, the Linus Pauling Institute recommends that you take at least 3000 micrograms of vitamin A and 40 milligrams of zinc daily. One microgram equals to 1000 milligrams. If you have Wilson's disease, you should keep your daily copper intake no more than 1.0 mg a day, suggests Dr. Frank Jackson of Jackson Siegelbaum Gastroenterology.
Sources
The Linus Pauling Institute recommends that you obtain vitamin A from citrus fruits, dark green leafy vegetables, liver and fortified milk and cereals. Good sources of zinc include oysters, crab, beef, poultry, nuts, seeds and legumes. If you have Wilson's disease, avoid avocados, lamb, pork, salmon, certain fruits and vegetables, mushrooms and beans.
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