Descriptions of Antioxidant Vitamins, Nutrients, and Minerals

Compiled by Wendy Watt, O.D.
October 25, 2000
Age-Related Macular Degeneration (AMD) is the leading cause of central vision loss in the United States today, and it is the eye disease that most often results in legal blindness. Studies have shown that AMD responds well to antioxidant vitamins, nutrients, and minerals that could prevent the deterioration of the macular part of the eye. These are described below, followed by notes on some other substances which affect the retina.
VITAMIN A (Beta-Carotene) is an unstable fat-soluble primary alcohol. It is necessary for the production and resynthesis of rhodopsin (visual purple) and may protect against (or reverse) radiation damage. It also acts as an antioxidant to scavenge radiation induced oxygen radicals and reduces lipofuscin (a component of drusen). A deficiency in vitamin A causes night blindness, xerophthalmia (an extreme dryness of the conjunctiva), keratosis (an epidermal lesion of tissue overgrowths), and infections. Vitamin A is necessary for good photoreceptor function.
VITAMIN B-1 (thiamine) is essential for growth and weight maintenance. It helps convert excess blood sugar into biological energy. Excess blood sugar is generated in vessels by x-rays and prevents a deficiency problem of mental confusion and alcohol insults. A deficiency can add to vision problems and cause beri-beri, a polyneuritis, which affects motor and sensory nerves.
VITAMIN B-2 (Riboflavin) is a water-soluble chrystalline pigment essential to the diet. Vitamin B-2 is a cofactor for the enzyme that recycles glutathione between reduced and oxidized states.
VITAMIN B-3 (Niacin) dilates blood vessels, allowing more nutrition and oxygen to the retina. It maintains the nervous system, helps metabolize protein, sugar, fat, cholesterol. It reduces high blood pressure and vascular problems in the eye.
VITAMIN B-6 (Pyridoxine) is necessary for the utilization of unsaturated fatty acids. It maintains the central nervous system. Patients with confluent soft drusen, or “pre-wet” ARMD, were found to have evidence of vitamin B6 deficiency (B. Lane, Annual Meeting of Amer Coll of Nutrition, 1991). A deficiency can also cause nutritional dermatitis and neuromuscular symptoms. There are indications that it is of importance in hemoglobin synthesis. Nearly all wet AMD patients are severely deficient in Vitamin B-6.
VITAMIN B-12 is the anti-anemia factor of liver extract and is necessary for the blood. It will aid in the prevention of pernicious anemia.
VITAMIN C (ascorbic acid) is found in high concentration in ocular tissue. It is a potent antioxidant and prevents scurvy, a condition that causes ulceration of the gums, skin, and mucous membranes. It also prevents the conversion of nitrates from tobacco smoke, smog, etc. The use of vitamin C taken at the same time as lysine will reduce harmful cholesterol in the capillaries.
VITAMIN D is necessary for producing growth in children, together with proper bone and tooth formation. It also helps retain calcium in bone.
VITAMIN E promotes healthy serum cholesterol and blood circulation. It retards cellular aging of the eyes due to oxidation. It strengthens the capillary walls and supplies oxygen to the blood, which is then carried to the eyes. Vitamin E is a blood thinner, which should be used with caution in cases of exudative (wet) macular degeneration.
VITAMIN K is a fat-soluble compound isolated from alfalfa, hog liver, fishmeal, and vegetable oils. It is essential for the formation of normal amounts of prothrombin. It is used to diminish the clotting time in patients with obstructive jaundice and to decrease the incidence of hemorrhage in the newborn.
VITAMIN P is identified as citrin and is active in increasing vascular permeability and treating purpura (skin hemorrhages).
ALPHA LIPOIC ACID, as indicated by Animal-based research, protects brain cell membranes from free radical damage and chelates some heavy metals, such as mercury. Alpha Lipoic Acid significantly reduces diabetic cataract formation and neuropathy (Annals of NY Acad of Sci, 1995).
BHT, used with vitamin E, inhibits age pigment or lipofuscin associated with senile plaques or amyloid beta protein associated with dementia and melanin loss.
BILBERRY is the Northern European cousin to the huckleberry and is now available in an extract that is attributed to preventing the breakdown of capillary walls. It increases the tissue strength and decreases inflammation. The small shrub (herb) contains anthocyanins, which mimic Vitamin P (flavinoid) activity. They reinforce collagen structures in the retina, thereby preventing free radical damage. Anthocyanins also stimulate the production of rhodopsin and iodopsin.
BIOFLAVINOIDS are plant pigments that are used by the plant to protect it from the sunÕs radiation damage. These are found in citrus fruits and berry plants, such as blue berries, huckleberries, and cherries. Bioflavinoids, especially, quercetin, are beneficial to the diabetic eye.
CAROTENE and CAROTENOIDS are yellow pigments found in the leaves of green vegetables, carrots, sweet potatoes, spinach and other vegetables, egg yolk, milk and other food stuffs. The human body is capable of converting carotene to vitamin A, which is necessary for the photoreceptor cell function of the retina. Without it, the conversion of light energy to electrical energy could not take place.
The blood contains the carotenoids beta-carotene, lutein, zeaxanthin, and lypopene, which is a fat antioxidant ten times more effective than vitamin E. HDL, the good cholesterol, is rich in the carotenoids lutein and zeaxanthin. LDL, the bad cholesterol, is low in carotenoids. The most common carotenoids in the blood are beta-carotene, lutein, and zeaxanthin. They are the lipophilic antioxidants of the blood, and are described here:
BETA-CAROTENE converts to a form of vitamin A that produces the night vision pigment, rhodopsin (in rods), and the color vision pigment (in cones). These are the photo pigments of the retina that are bleached when exposed to bright light. The bleaching causes the conversion of light energy to electrical energy and is essential to vision. Taking too much beta-carotene may cause orange to tan skin color and may be mistaken for jaundice.
LUTEIN is an antioxidant that has been shown to be associated with a reduced risk of macular degeneration and cataracts. As an antioxidant, lutein is 10 times as effective as Vitamin E. It is found in high concentrations in the macula. The macula is a central part of the retina responsible for central vision (reading, driving, handwork, etc.) and is directly behind the lens. The macula is the area of the eye that receives the most light. Lutein and zeaxanthin are deposited specifically in the macula and their function is proposed to reduce oxidation. UV light causes oxidation and oxidation may lead to AMD. Lutein, which is yellow, filters out blue light that is known to cause free radical damage to the eyes. Lutein is not made in the body and must be obtained from dietary sources and it is available in high concentrations in spinach, broccoli, and collard greens.
ZEAXANTHIN is the other carotenoid antioxidant found in the macula. Zeaxanthin and lutein block blue light, which is part of the light spectrum that allows free radical damage to the photoreceptor cells (rods and cones). By blocking the blue light, they save the rhodopsin and iodopsin pigments from damage. It is estimated that foods or supplements high in lutein and zeaxanthin eaten five times per week could significantly reduce AMD. Because both lutein and zeaxanthin are fat soluble, they should be taken with meals or olive oil to improve absorption.
COENZYME Q10 is a natural antioxidant, is a vitamin-like nutrient found in every cell of the body, and is thought to safeguard sharp thinking by protecting mitochondria, the power centers of the cells. CoQ10 supports cellular energy production by helping to create ATP, the bodyÕs primary source of stored energy. CoQ10 is known to break down cholesterol and improve circulation in capillaries in the eye.
CYSTEINE mimics the activity of taurine (see Taurine below).
FLAVINOIDS are found in deep red and blue pigments of fruits, wine, and teas and protect against oxidation and sunlight. One of their properties is to lower platelet aggregation and reduce thrombotic tendencies. Flavinoid intake is helpful in decreasing coronary artery disease in men. A flavinoid is a carotinoid pigment. The note worthy flavinoids are Ginko Biloba, Grape Seed Extract, Quecertin, and Rutin, all of which are described here:
GINKGO BILOBA is an herb flavinoid that improves arterial blood flow and enhances cellular metabolism. It increases Adenosine Tri Phosphate (ATP) levels and acts as a free radical scavenger. Ginko Biloba causes vasodilatation, both peripherally and cerebrally. Ginkgo Biloba extract has also recently been shown to promote better circulation in the eye and brain. It also increases acetylcholine levels, allowing efficient transmission of the bodyÕs electrical impulses.
GRAPE SEED EXTRACT is a flavinoid and is 50 times more powerful an antioxidant that Vitamin E. It helps vitamin C enter cells, strengthening the cell membranes and protecting the cells from oxidative damage. It enhances night vision and decreases light sensitivity (photophobia). Grape Seed and Pine Bark Extracts are excellent sources of one of these powerful bioflavonoids. An extract of Bilberry (a European blueberry related to pycnogenols) has also been demonstrated to have beneficial effects on cataracts, macular degeneration, glaucoma and diabetic retinopathy.
QUECERTIN AND RUTIN are neither vitamin or mineral. They are plant pigments that protect the eyes form sunlight damage. They are known to help protect thousands of tiny blood vessels, capillaries, in the eye. They reduce the leakage from damaged small blood vessels in the retina.
GARLIC has been shown to lower blood cholesterol and aid in fighting bacterial and fungal infections.
GLUTATHIONE is one of the bodyÕs most potent antioxidants. Low glutathione levels accompany cataract formation. When the lens proteins are damaged by free radicals, white clouding of the damaged protein appears in the crystalline lens. When this occurs, the lens is called a cataract. By taking glutathione, the rate of cataract formation is reduced. N-acetyl-cysteine (NAC), a precursor to glutathione, may be taken as a substitute.
L-GLUTATHIONE is a major cellular antioxidant. It acts directly with free radicals and supports the detoxification of free radicals by ascorbate and vitamin E.
PROANTHOCYANIN strengthens capillary walls to prevent leakage in wet AMD.
SELENIUM is a co-factor for the enzyme glutathione peroxidase, which aids in the regeneration of glutathione. It is also a major antioxidant nutrient that protects cell membranes and prevents free radical generation, thereby decreasing the risk of cancer and disease of the heart and blood vessels. Glutathione and glutathione related enzyme precursors riboflavin and selenium are protective against Age-Related Macular Degeneration (ARMD) (Sternberg, Davidson, Jones, et al. Invest Ophth Vis Sci, 1993).
SHARK CARTILAGE functions as an angiogenesis inhibitor (inhibits the development of new vessels or neovascularization). This function would be important in Wet AMD, which involves neovascularization, yet it also constricts normal retinal vessels slowing circulation to an already nutrition and oxygen starved retina. Therefore, its use with macular degeneration is questioned.
SILICA HYDRIDE is one of the most powerful antioxidant available. It is a free radical neutralizer, which has thousands of times more antioxidant power than any form of vitamin, mineral or food supplement.
TAURINE is an amino acid localized in the photoreceptor cells, stabilizes the cell membranes, and controls ion influx. As a buffer, it protects the cell from UV damage. Taurine is particularly concentrated in the photoreceptor layer of the retina and is believed to have an essential role in maintaining normal cell structure and function. Taurine has an additive effect on protecting cell membranes from oxygen damage.
BORON protects the cell from neutron radiation damage and DNA strand breaks which can lead to neuronal death, creating an enhanced risk of memory loss.
CHROMIUM is an anti-atherogenic agent and is useful in HDL cholesterol in men.
COPPER is found in the retina. The retinal pigment epithelium (RPE) is rich in copper, yet excessive copper is toxic to the retina.
MAGNESIUM is essential for the metabilization of calcium from bone and for the normal metabolism of potassium, and sodium pumps so important in keeping the eyes clear.
ZINC has a higher concentration in the eye than most other tissues. Its concentration in the RPE cells decrease with age. Because zinc is a very effective antioxidant and the elderly are at risk for zinc depletion, it should be a part of a nutritional regiment. As important as zinc is, overdosing can be a serious problem. It can decrease the levels of good cholesterol (HDL) and deplete the bodyÕs copper concentration. Zinc picolinate or citrate should be taken rather than zinc sulfate, which is poorly absorbed and has side effects. Zinc does help to reduce serum cholesterol. Patients with ARMD were found to have significantly lower zinc and vitamin E serum levels than normal eyes (Nippon Ganka Gakkai Zasshi, Mar. 1997). In 1988, Newsome et al. reported that large dose zinc (200 mg) supplementation slowed down the progression of dry ARMD and resulted in fewer neovascular events. Zinc has the ability to enhance the transport of vitamin A from the liver to the retina.
ALCOHOL and NICOTINE rob the body of antioxidants. Smokers show a 2 1/2 times greater incidence of AMD than non-smokers.
ASPIRIN is taken by many AMD patients to aid in thinning their blood. Too much aspirin may not allow adequate blood clotting and allow for excessive retinal bleeding with wet AMD. Some doctors are now substituting Bromelain as a blood thinner.
ESTROGEN at low levels in post-menopausal women predispose them to AMD. Women over age 75 are twice as likely as men to develop AMD.
SATURATED FATS and CHOLESTEROL precipitate the blockage of retinal vessels. So, we should all strive for a diet low in saturated fats and refined sugars.
All Macular Degeneration patients should strive to lead healthy lifestyles and be counseled in good nutrition practices. No significant change in nutrition should begin without professional consultation.