Diet & Nutrition

Adding powerful antioxidants to your diet may improve your eye health.

There’s no substitute for the quality of life good vision offers. Adding certain nutrients to your diet every day – either through foods or supplements – can help save your vision. Researchers have linked eye- friendly nutrients such as lutein/zeaxanthin, vitamin C, vitamin E, and zinc to reducing the risk of certain eye diseases, including macular degeneration and cataract formation.

  • Lutein & Zeaxanthin
    Lutein and zeaxanthin are important nutrients found in green leafy vegetables, as well as other foods, such as eggs. Many studies have shown that lutein and zeaxanthin reduce the risk of chronic eye diseases, including age-related macular degeneration and cataracts. (Read More)
  • Vitamin C
    Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables. Scientific evidence suggests vitamin C lowers the risk of developing cataracts, and when taken in combination with other essential nutrients, can slow the progression of age-related macular degeneration and visual acuity loss. (Read More)
  • Vitamin D
    Vitamin D is good for our bones and teeth. It aids in preventing rickets, cavities and adult

    softening of the bones. Yet today there is significant evidence that vitamin D also plays a role in helping to prevent cancer, heart disease, diabetes, (Read More)

  • Vitamin E
    Vitamin E in its most biologically active form is a powerful antioxidant found in nuts, fortified cereals and sweet potatoes. It is thought to protect cells of the eyes from damage caused by unstable molecules called free radicals which break down healthy tissue. (Read More)
  • Essential Fatty Acids
    Fats are a necessary part of the human diet. They maintain the integrity of the nervous system, fuel cells and boost the immune system. Two omega-3 fatty acids have been shown to be important for proper visual development and retinal function. (Read More)
  • Zinc
    Zinc is an essential trace mineral or ‘helper molecule.’ It plays a vital role in bringing vitamin A from the liver to the retina in order to produce melanin, a protective pigment in the eyes. Zinc is highly concentrated in the eye, mostly in the retina and choroid, the vascular tissue layer lying under the retina. (Read More)
  • Emerging Research
    In the last 20 years, eye health research has linked diet and nutrition with a decreased risk of age-related macular degeneration (AMD). (Read More)

Lutein

Lutein (LOO-teen) and zeaxanthin are important nutrients found in green leafy vegetables as well as other foods such as eggs. Many studies have shown that lutein and zeaxanthin reduce the risk of chronic eye diseases, including age-related macular degeneration (AMD) and cataracts.

AMD and cataract incidence are growing. Worldwide, more than 25 million people are affected by age-related macular degeneration and the formation of cataracts. AMD is the leading cause of blindness in people over age 55 in the Western world and the incidence is expected to triple by 2025.

Benefits to Eye Health

Lutein and zeaxanthin are carotenoids that filter harmful high-energy blue wavelengths of light and act as antioxidants in the eye, helping protect and maintain healthy cells. Of the 600 carotenoids found in nature, only two are deposited in high quantities in the retina (macula) of the eye: lutein and zeaxanthin. The quantity of lutein and zeaxanthin in the macular region of the retina can be measured as macular pigment optical density (MPOD). Recently, MPOD has become a useful biomarker for not only predicting disease but also visual function. Unfortunately, the human body does not synthesize the lutein and zeaxanthin it needs, which is the reason why green vegetables are essential to good nutrition. Daily intake of lutein and zeaxanthin through diet, nutritional supplements, or fortified foods and beverages is important for the maintenance of good eye health.

Lutein, Zeaxanthin and Cataracts

The primary function of the crystalline lens (or natural lens in the eye) is to collect and focus light on the retina. To properly provide this function throughout life, the lens must remain clear. Oxidation of the lens is a major cause of cataracts, which cloud the lens. As antioxidant nutrients neutralize free radicals (unstable molecules) associated with oxidative stress and retinal damage, lutein and zeaxanthin likely play a role in cataract prevention. In fact, a recent study demonstrated that higher dietary intakes of lutein and zeaxanthin and vitamin E was associated with a significantly decreased risk of cataract formation.

Lutein, Zeaxanthin and Age-Related Macular Degeneration

Much evidence supports the role of lutein and zeaxanthin in reducing the risk of AMD. In fact, The National Eye Institute presently is conducting a second large human clinical trial, Age-Related Eye Disease Study (AREDS2), to confirm whether supplements containing 10 mg a day of lutein and 2 mg of zeaxanthin per day affect the risk of developing AMD. Beyond reducing the risk of developing eye disease, separate studies have shown that lutein and zeaxanthin improve visual performance in AMD patients, cataract patients and individuals with good health.

The USDA Nutrient Database offers comprehensive information on raw and prepared foods.

Although there is no recommended daily intake for lutein and zeaxanthin, most recent studies show a health benefit for lutein supplementation at 10 mg/day and leaxanthin supplementation at 2 mg/day.

Food Sources

Most Western diets are low in lutein and zeaxanthin, which can be found in spinach, corn, broccoli and eggs. The following table lists foods known to be high in lutein and zeaxanthin. If you are not getting enough lutein and zeaxanthin through diet alone, consider adding supplements to your daily routine.


Vitamin C

Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables. Scientific evidence suggests vitamin C lowers the risk of developing cataracts, and when taken in combination with other essential nutrients, can slow the progression of age-related macular degeneration (AMD) and visual acuity loss.

AMD and cataract incidence are growing. Worldwide, more than 25 million people are affected by age-related macular degeneration (AMD) and the formation of cataracts. AMD is the leading cause of blindness in people over age 55 in the Western world and the incidence is expected to triple by 2025. Smoking, diabetes and the use of steroids are all risk factors for cataract formation as they all deplete the eye's lens of vitamin C.

Benefits to Eye Health

Vitamin C helps to promote healthy capillaries, gums, teeth, cartilage and the absorption of iron. Virtually all cells of the body depend on it, including those of the eye where it is actively concentrated in all tissues. Vitamin C also supports the health of ocular blood vessels. Our bodies do not synthesize the vitamin C needed, which is the reason citrus fruits and juices are essential to good nutrition. Daily intake of vitamin C through diet, nutritional supplements, or fortified foods and beverages is important for the maintenance of good eye health.

Vitamin C and Cataracts

Numerous studies have linked vitamin C intake and ocular health. A study demonstrated that women using vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that half of cataract-related surgeries could be averted by delaying the onset of cataracts for 10 years.

Other research showed that women taking a daily supplementation dosage of 364mg experienced a 57% reduction in their risk of certain types of cataracts. The research concluded that periods shorter than 10 years are insufficient to measure the influence of vitamin C upon cataract formation. Therefore, a 300mg/day intake of vitamin C appears to be the minimum point at which cataract prevention occurs.

Vitamin C and Age-Related Macular Degeneration (AMD)

The Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, was a landmark study that established AMD as a ‘nutrition-responsive disorder.’ The study showed that a 500 mg/day intake of vitamin C, taken with antioxidants beta-carotene, vitamin E and zinc supplementation, slows the progression of advanced age-related macular degeneration by about 25 percent and visual acuity loss by 19% in individuals at high-risk for the disease. Emerging science, consisting of the AREDS results and seven smaller studies, have confirmed these results.

Daily Intake*
Discover great recipes rich in Vitamin C
The USDA Nutrient Database offers comprehensive information on raw and prepared foods.

The U.S. Food and Drug Administration (FDA) has established a dietary reference intake (DRI) for vitamin C of 90mg/day for males and 75mg/day for females. It has long been recognized that people under stress require more vitamin C than the recommended daily allowance. These groups include smokers, alcoholics, diabetics, pregnant or breast feeding women, older adults, athletes and people with chronic diseases who experience environmental stress from heat, cold, or radiation. There is little scientifically documented risk in taking higher doses of vitamin C, except for incurring diarrhoea.

Food Sources

Vitamin C is found almost exclusively in fruits and vegetables, including citrus fruits such as oranges, lemons, grapefruit and limes. The table above lists foods known to be high in vitamin C antioxidants. If you are not getting enough vitamin C through diet alone, consider adding one of the widely available vitamin C supplements to your daily routine. However, always consult with a health care professional before beginning a supplementation regiment.


Vitamin D

Vitamin D deficiency has been linked to age-related macular degeneration, as well as 17 types of cancer. Vitamin D is good for our bones and teeth. It aids in preventing rickets, cavities and adult softening of the bones. Yet today there is significant evidence that vitamin D also plays a role in helping to prevent cancer, heart disease, diabetes, and age-related macular degeneration (AMD). Activated Vitamin D, also known as calciferol, is a fat-soluble essential vitamin that helps to prevent skeletal diseases by maintaining normal levels of calcium and phosphorous in the blood. Vitamin D also regulates cells, systems and organs throughout the body. It is the most potent steroid hormone in the human body, and is the only vitamin formed with the help of sunlight.

When ultraviolet B radiation is absorbed by the skin, it triggers the synthesis of vitamin D, which is stored in the liver. Before the Industrial Revolution, more than 90% of people living in Europe and North America obtained their supply of vitamin D from this sunlight-driven process. With work and life style changes over the last 100 years, the decrease in UV exposure has led to an increase in vitamin D deficiency. Today, vitamin D deficiency has been linked to 17 types of cancer, cardiovascular disease, diabetes, autism, multiple sclerosis, schizophrenia and even influenza.

You are vulnerable to the lack of sunlight if you live in a northern climate, have black or dark brown skin, work indoors, or are housebound and elderly. Infants also are considered vulnerable. Therefore, it appears that the degree of UV B sunlight exposure you receive based on the latitude in which you live, your race, and working environment (office vs. outdoor worker), can greatly affect your health. Benefits to Eye and Systemic Health Age Related Macular Degeneration A recent study presents evidence that vitamin D may protect against the onset of age-related macular degeneration (AMD). In a study of nearly 8,000 participants, those with early AMD were associated with lower blood levels of vitamin D. However, it must be noted that the authors caution additional studies are needed to confirm these findings.

Vitamin D and Cardiovascular Disease

Cardiovascular disease (CVD) is associated with many eye diseases, including AMD and glaucoma. The aetiology of cardiovascular disease is not completely understood. Yet, a recent review summarizes data supporting the hypothesis that insufficient levels of vitamin D may contribute to the worldwide high prevalence of CVD. (Zittermann A, Schleithoff SS, Koerfer R, Putting cardiovascular disease and vitamin D insufficiency into perspective, Br J Nutr. 2005 Oct;94(4):483-92 )

Juvenile Diabetes

The American Academy of Pediatrics (AAP) announced in October 2008 it has doubled the recommended amount of vitamin D for infants, children, and adolescents. The decision to increase daily dosage is an update of the 2003 AAP initiative that sought to combat childhood rickets, but clear evidence suggests a correlation of juvenile diabetes and latitude, with children in Finland having nearly 400 times the rate of juvenile diabetes compared with children living near the equator.

Obesity, Diabetes and the Metabolic Syndrome

Vitamin D deficiency is important to pre-diabetic and diabetic adults, as it lowers insulin resistance, or the ability of cells to utilize excess glucose from the bloodstream. As well, vitamin D acts as an immunosuppressant and improves pancreatic function.

Food Sources and Supplementation

There is no substitute for the sunlight-driven process of vitamin D synthesis. As a point of reference, approximately 10,000 IU of vitamin D3 is produced by one hour of midday summer full-body skin exposure for Caucasians living at southern latitudes. Season, latitude, time of day, cloud cover, smog, and applied sunscreen all affect UV B exposure. Sunscreen with a protection factor of 8 or higher blocks vitamin D synthesis. It is possible to supplement the diet with biologically inactive vitamin D found in plants and marine life. Vitamin D3 is abundant in cold water fish (i.e. red sockeye salmon, sardines or cod liver oil) along with crucial essential fatty acids. Even less vitamin D (100 IU vitamin D2 per cup) is available from the synthetic source, ergocalciferol, used to fortify milk. The most recent 2005 U.S. Department of Agriculture (USDA) Food Triangle recommends the equivalent of three 8 oz. glasses of milk each day. However, 24 ounces of vitamin D fortified milk supplies only a meagre 300 IU of the less potent plant-based and synthetic vitamin D2. There is growing consensus that milk sources are not enough to maintain overall health for Caucasians, let alone African-Americans and populations living further from the equator.

Daily Intake*
One cup of milk has 100 IU of vitamin D2, which has 70% of the effectiveness of natural vitamin D3 found in fish.

The static USDA Recommended Daily Allowance of vitamin D, regardless of race, season or geographic location, presently is:
Less than Age 50 200 IU
Age 50 400 IU
50 - 70 600 IU
70+ 800 IU


Vitamin E

Vitamin E in its most biologically active form is a powerful antioxidant found in nuts, fortified cereals and sweet potatoes. It is thought to protect cells of the eyes from damage caused by unstable molecules called free radicals, which break down healthy tissue.

AMD and cataract incidence are growing. Worldwide, more than 25 million people are affected by age-related macular degeneration (AMD) and the formation of cataracts. AMD is the leading cause of blindness in people over age 55 in the Western world and the incidence is expected to triple by 2025 as the population ages.

Benefits to Eye Health

Studies indicate that vitamin E reduces the progression of AMD and cataract formation. Vitamin E also plays a significant role in the immune system, the health of cell membranes, in DNA repair, and in other metabolic processes. The human body does not synthesize the vitamin E it needs, which is the reason nuts, salad and vegetable oils are essential to good nutrition. Daily intake of vitamin E through diet, nutritional supplements, or fortified foods and beverages is important for the maintenance of good eye health.

Vitamin E and Cataracts

Studies have indicated that cataract formation also may be delayed by supplementing the diet with vitamin E. A recent study demonstrated that higher dietary intakes of lutein and zeaxanthin and vitamin E were associated with significantly decreased risks of cataracts.

Vitamin E and Age-Related Macular Degeneration (AMD)

The Age-Related Eye Disease Study (or AREDS), sponsored by the National Eye Institute, was a landmark study that established AMD as a ‘nutrition responsive disorder.’ The study showed that a 400 IU/day intake of vitamin E, taken with antioxidants beta-carotene, vitamin C and zinc supplementation, slows the progression of advanced age-related macular degeneration (AMD) by about 25 percent in individuals at high-risk for the disease. Emerging science, consisting of the AREDS results and seven smaller studies, have confirmed these results.

Daily Intake*

Discover great recipes rich in Vitamin E
The USDA Nutrient Database offers comprehensive information on raw and prepared foods.

The U.S. Food and Drug Administration (FDA) has established a dietary reference intake (DRI) for vitamin E to be 22 IU per day for both males and females. Diets low in fat can significantly decrease vitamin E intake. In adults, symptoms of vitamin E deficiency include nerve damage, muscle weakness, poor coordination, involuntary movement of the eyes and breaking of red blood cells leading to anemia. Vitamin E is a fat soluble supplement that should not be taken in excess by anyone taking supplements or medications that have blood thinning qualities.

Food Sources

Most Western diets are low in vitamin E, which can be found in nuts, salad and vegetable oils, peanut butter, fortified cereals and sweet potatoes. The table above lists foods known to be high in vitamin E antioxidants. Always consult with a health care professional before beginning a supplementation regiment.


Essential Fatty Acids

Omega-3: DHA and EPA

Dietary fat is an important source of energy and is a necessary part of the human diet. Fatty acids are a component of fat molecules. Two families of essential fatty acids exist in nature: omega-3 and omega-6. These essential fatty acids help support the cardiovascular, reproductive, immune, and nervous systems. Two omega-3 fatty acids have been shown to be important for proper visual development and retinal function – Docosahexaenoic acid and Eicosapentaenoic acid.

Omega-3 is critical to the biological function of the human body. The human body requires omega-3 fatty acids for membrane structural integrity and fluidity, enabling cells to obtain optimum nutrition and expel waste products. These essential fatty acids are critical in the production of prostaglandins, which regulate such functions as heart rate, blood pressure, blood clotting, fertility, conception, and play a role in immune function by regulating inflammation. They also are needed for proper neural development and maturation of sensory systems.

DHA and EPA Omega-3 Fatty Acids and Eye Health

Docosahexaenoic acid (DHA) is found in the highest concentration in the retina, suggesting it has an important functional role. Eicosapentaenoic acid (EPA) is used in DHA biosynthesis. Studies in pre-term and full-term infants have suggested that a dietary supply of omega-3 fatty acids may be essential for optimal visual development. A number of studies have shown that, in animals, dietary deprivation of DHA results in visual impairment and retinal degradation. Dry eye syndrome also has been linked to omega-3 deficiency. Additionally, low levels of DHA and EPA have also been associated with eye diseases such as diabetic retinopathy, age-related macular degeneration (AMD), and retinopathy of prematurity.

Daily Intake*
Salmon (cooked) 3oz 1800
Tuna (cooked) 3oz 1300

 

Discover great recipes rich in Vitamin E
The USDA Nutrient Database offers comprehensive information on raw and prepared foods.

Typical intake of omega-3 fatty acids is 1.6 grams per day. EPA and DHA usually comprise 6% to 12 percent of this value (0.1-0.2 grams per day). This level is well below the American Heart Association recommended 0.5-1.0 grams per day of EPA + DHA. The U.S. Food and Drug Administration has stated that consuming up to 3 grams per day of DHA and EPA is generally considered as safe.

Food Sources

EPA and DHA are concentrated in fatty fish and marine mammals. For individuals who choose not to consume fish, vegetarian DHA is commercially manufactured from microalgae. Animals can convert very small amounts of DHA through consumption of α-linolenic acid, an omega-3 fatty acid found in plants, animals, and milk.

DHA and EPA are concentrated only in a small number of less-frequently consumed fish-based foods. It is possible that increasing the intake of these nutrients can reduce the risk of vascular and degenerative retinal diseases. This can be achieved through higher consumption of fatty fish such as those listed above or through omega-3 fatty acid supplements in the form of oil or capsules.


Zinc

Zinc is an essential trace mineral or "helper molecule." It plays a vital role in bringing vitamin A from the liver to the retina in order to produce melanin, a protective pigment in the eyes. Zinc is highly concentrated in the eye, mostly in the retina and choroid, the vascular tissue layer lying under the retina.

Impaired vision has been linked to zinc deficiency. A deficiency of zinc can result in poor night vision and cloudy cataracts. Other known effects of zinc deficiency include alopecia, or a loss of hair from eyebrows and eyelashes, along with mental sluggishness and increased susceptibility to infection.

Benefits to Eye Health

Zinc is recommended for individuals diagnosed as being at high-risk for age-related macular degeneration (AMD), or already experiencing the early stages of AMD. The human body does not synthesize the zinc it needs, which is the reason why red meat, seafood, poultry, eggs, wheat germ, mixed nuts, black-eyed peas, tofu, and baked beans are essential to good nutrition. Daily intake of zinc through diet, nutritional supplements, or fortified foods and beverages is important for the maintenance of good eye health.

Zinc and Age-Related Macular Degeneration

The Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, was a landmark study that established AMD as a ‘nutrition-responsive disorder.’ The study showed that a 40-80 mg/day intake of zinc, taken with antioxidants beta-carotene, vitamin E and vitamin C, slows the progression of advanced age-related macular degeneration by about 25 percent and visual acuity loss by 19 percent in individuals at high-risk for the disease. Higher levels of zinc may interfere with copper absorption, which is why the AREDS study also included a copper supplement.

Daily Intake*

 

Discover great recipes rich in Vitamin E
The USDA Nutrient Database offers comprehensive information on raw and prepared foods.

The U.S. Food and Drug Administration (FDA) has established a dietary reference intake (DRI) for zinc of 11 mg/day for males and 8 mg/day for females. The AREDS study utilized high levels of zinc (40-80 mg/day) and showed beneficial effects for those at high risk for AMD. However, because high doses of zinc may cause stomach upset, a follow-up study, AREDS2, which is currently in progress, will be testing a more moderate dose of 25 mg. Zinc supplementation has been known to interfere with copper absorption, so 2 mg/day of copper is strongly recommended for individuals supplementing their diet with zinc.

Food Sources

The table above highlights good sources for zinc, which include red meat, seafood, poultry, eggs, wheat germ, mixed nuts, black-eyed peas, tofu, and baked beans.


Emerging Research

In the last 20 years, eye health research has linked diet and nutrition with a decreased risk of age-related macular degeneration (AMD). A major clinical study of older adults concluded that taking an antioxidant vitamin or mineral supplement significantly reduced the risk of advanced AMD progression in some people. Additionally, today there is significant evidence that vitamin D plays a role in preventing AMD.

AREDS Made it Clear

The Age-Related Eye Disease Study (AREDS) was a major clinical trial sponsored by the National Eye Institute. It enrolled 3640 subjects, age 55 to 80, and was released in October 2001. This landmark study provided evidence that nutritional intervention in the form of supplements could delay the progression of AMD. The study concluded that taking an antioxidant vitamin or mineral supplement reduced the risk of advanced AMD progression by about 25% and showed a 19% reduction in visual acuity loss in some of the subjects.

The Case for Lutein and Zeaxanthin

It was not clear in the original AREDS report which vitamin, mineral or combination of nutrients was responsible for reducing the risk of AMD. When the study was planned, the lutein and zeaxanthin carotenoids that constitute the macular pigment were not assessed because they were not commercially available. Since then, several studies have provided growing evidence specific to the beneficial role of lutein and zeaxanthin intake, and their positive effect on eye health and AMD risk reduction. The AREDS Report No. 22 published in 2007 described the relationship between dietary intake of various nutrients and AMD among the AREDS subjects. This report concluded that high dietary intake of lutein and zeaxanthin is associated with a reduction in the risk of geographic atrophy, advanced AMD, and large or extensive intermediate drusen, the waste by-products of cellular metabolism (activity).

New Study Builds on Long Term Nutrient Benefits

A follow up to the original AREDS trial, AREDS2, began in June 2008. This multi-centred, five-year study builds on a multitude of existing science supporting lutein and zeaxanthin’s role in maintaining healthy eyes. It is the largest human clinical trial to evaluate lutein, zeaxanthin, and omega-3 fatty acids supplementation, and includes 4,000 patients at high risk for AMD. The study is focusing on the protective effects lutein (10 mg/day), zeaxanthin (2 mg/day) , and omega-3 fatty acids (1 g/day) have against AMD, as well as the link between nutrition and macular pigment optical density, cataract development and visual function.

Age-Related Eye Disease Study 2 (AREDS2)

Researchers with the Age-Related Eye Disease Study (AREDS) reported in 2001 that a nutritional supplement called the AREDS formulation can reduce the risk of developing advanced age-related macular degeneration (AMD). The original AREDS formulation contains vitamin C, vitamin E, beta-carotene, zinc and copper.

In 2006, the same research group, which is based at NIH's National Eye Institute, began a second study called AREDS2 to determine if they could improve the AREDS formulation. They tried adding omega-3 fatty acids, as well as the antioxidants lutein and zeaxanthin, which are in the same family of nutrients as beta-carotene. The researchers also tried substituting lutein and zeaxanthin for beta-carotene, which prior studies had associated with an increased risk of lung cancer in smokers. The study found that while omega-3 fatty acids had no effect on the formulation, lutein and zeaxanthin together appeared to be a safe and effective alternative to beta-carotene.

Adding omega-3 fatty acids did not improve a combination of nutritional supplements commonly recommended for treating age-related macular degeneration (AMD), a major cause of vision loss among older Americans, according to a study from the National Institutes of Health (NIH). The plant-derived antioxidants lutein and zeaxanthin also had no overall effect on AMD when added to the combination; however, they were safer than the related antioxidant beta-carotene, according to the study published online today in the Journal of the American Medical Association.

"Millions of older Americans take nutritional supplements to protect their sight without clear guidance regarding benefit and risk," said NEI director Paul A. Sieving, M.D., Ph.D. "This study clarifies the role of supplements in helping prevent advanced AMD, an incurable, common, and devastating disease that robs older people of their sight and independence."

The Age-Related Eye Disease Study (AREDS), which was led by NIH’s National Eye Institute and concluded in 2001, established that daily high doses of vitamins C and E, beta-carotene, and the minerals zinc and copper—called the AREDS formulation—can help slow the progression to advanced AMD. The American Academy of Ophthalmology now recommends use of the AREDS formulation to reduce the risk of advanced AMD. However, beta-carotene use has been linked to a heightened risk of lung cancer in smokers. And there have been concerns that the high zinc dose in AREDS could cause minor side effects, such as stomach upset, in some people.

In 2006 the NEI launched AREDS2, a five-year study designed to test whether the original AREDS formulation could be improved by adding omega-3 fatty acids; adding lutein and zeaxanthin; removing beta-carotene; or reducing zinc. The study also examined how different combinations of the supplements performed. Omega-3 fatty acids are produced by plants, including algae, and are present in oily fish such as salmon. Lutein and zeaxanthin are carotenoids, a class of plant-derived vitamins that includes beta-carotene; both are present in leafy green vegetables and, when consumed, they accumulate in the retina. Prior studies had suggested that diets high in lutein, zeaxanthin, and omega-3 fatty acids protect vision. Before the AREDS2 study finished, manufacturers began marketing supplements based on the study design.

In AREDS2, participants took one of four AREDS formulations daily for five years. The original AREDS included 500 milligrams vitamin C, 400 international units of vitamin E, 15 milligrams beta-carotene, 80 milligrams zinc, and two milligrams copper. Other groups took AREDS with no beta-carotene, AREDS with low zinc (25 milligrams), or AREDS with no beta-carotene and low zinc. Participants in each AREDS group also took one of four additional supplements or combinations: these included lutein/zeaxanthin (10 milligrams/2 milligrams), omega-3 fatty acids (1,000 milligrams), lutein/zeaxanthin and omega-3 fatty acids, or placebo. Progression to advanced AMD was established by examination of retina photographs or treatment for advanced AMD.

AMD breaks down cells in the layer of tissue called the retina in the back of the eye that provide sharp central vision, which is necessary for tasks such as reading, driving, and recognizing faces. Advanced AMD can lead to significant vision loss and, in the United States, is the leading cause of blindness. About 2 million Americans have advanced AMD; another 8 million are at risk.

In the first AREDS trial, participants with AMD who took the AREDS formulation were 25 percent less likely to progress to advanced AMD over the five-year study period, compared with participants who took a placebo. In AREDS2, there was no overall additional benefit from adding omega-3 fatty acids or a 5-to-1 mixture of lutein and zeaxanthin to the formulation. However, the investigators did find some benefits when they analyzed two subgroups of participants: those not given beta-carotene, and those who had very little lutein and zeaxanthin in their diets.

"When we looked at just those participants in the study who took an AREDS formulation with lutein and zeaxanthin but no beta-carotene, their risk of developing advanced AMD over the five years of the study was reduced by about 18 percent, compared with participants who took an AREDS formulation with beta-carotene but no lutein or zeaxanthin," said Emily Chew, M.D., deputy director of the NEI Division of Epidemiology and Clinical Applications and the NEI deputy clinical director. "Further analysis showed that participants with low dietary intake of lutein and zeaxanthin at the start of the study, but who took an AREDS formulation with lutein and zeaxanthin during the study, were about 25 percent less likely to develop advanced AMD compared with participants with similar dietary intake who did not take lutein and zeaxanthin."

Because carotenoids can compete with each other for absorption in the body, beta-carotene may have masked the effect of the lutein and zeaxanthin in the overall analysis, Chew said. Indeed, participants who took all three nutrients had lower levels of lutein and zeaxanthin in their blood compared to participants who took lutein and zeaxanthin without beta-carotene.

Removing beta-carotene from the AREDS formulation did not curb the formulation’s protective effect against developing advanced AMD, an important finding because several studies have linked taking high doses of beta-carotene with a higher risk of lung cancer in smokers. Although smokers were not given a formulation with beta-carotene in AREDS2, the study showed an association between beta-carotene and risk of lung cancer among former smokers. About half of AREDS2 participants were former smokers. "Removing beta-carotene simplifies things," said Wai T. Wong, M.D., Ph.D., chief of the NEI Neuron-Glia Interactions in Retinal Disease Unit and a co-author of the report. "We have identified a formulation that should be good for everyone regardless of smoking status," he said. Adding omega-3 fatty acids or lowering zinc to the AREDS formulation also had no effect on AMD progression.

More than 4,000 people, ages 50 to 85 years, who were at risk for advanced AMD participated in AREDS2 at 82 clinical sites across the country. Eye care professionals assess risk of developing advanced AMD in part by looking for yellow deposits called drusen in the retina. The appearance of small drusen is a normal part of aging, but the presence of larger drusen indicates AMD and a risk of associated vision loss. Over time, the retina begins to break down in areas where large drusen are present during a process called geographic atrophy. AMD can also spur the growth of new blood vessels beneath the retina, which can leak blood and fluid, resulting in sudden vision loss. These two forms of AMD are often referred to as dry AMD and wet AMD respectively.

In a separate study, published online today in JAMA Ophthalmology, the AREDS2 Research Group evaluated the effect of the various AREDS formulas on cataract, a common condition caused by clouding of the eye’s lens. Globally, cataract is the most common cause of blindness and is a major health problem in areas where cataract surgery is unavailable or unaffordable. About 24.4 million Americans are directly affected by cataract.

As reported in 2001, the original AREDS formulation does not protect against cataract. In AREDS2, none of the modified formulations helped reduce the risk of progression to cataract surgery, although a subgroup of participants with low dietary lutein and zeaxanthin gained some protection. "While a healthy diet promotes good eye health and general well-being, based on overall AREDS2 data, regular high doses of antioxidant supplements do not prevent cataract," Chew said.

Many factors contribute to the development of AMD and cataract, including genetics, diet, and smoking. Scientists are unsure how supplements in the AREDS formulation exert their protective effects. However, an April 2013 report in the journal Ophthalmology by the AREDS Research Group shows the beneficial effects of taking the AREDS vitamins are long-lasting. The report describes a follow-up study of AREDS participants. Those who took the AREDS formulation during the initial five-year trial were 25 to 30 percent less likely to develop advanced AMD—mostly due to a reduction in the number of neovascular, or wet, AMD cases—over the next five years, compared with participants who took placebo during AREDS. Seventy percent of all participants were taking the original AREDS formula by the end of the follow-up period.

"Long-term use of AREDS supplements appears safe and protective against advanced AMD," said Chew. "While zinc is an important component of the AREDS formulation, based on evidence from AREDS2 it is unclear how much zinc is necessary. Omega-3 fatty acids and beta-carotene clearly do not reduce the risk of progression to advanced AMD; however, adding lutein and zeaxanthin in place of beta-carotene may further improve the formulation."

The AREDS2 study results provide physicians and patients with new information about preventing vision loss from AMD. People over 60 years old should get a dilated eye exam at least once a year and should discuss with their eye care professional whether taking AREDS supplements is appropriate.

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