Can diet and supplements preserve vision? Story Cover Cover

Devon Schuyler had a 35 per cent lower risk of developing neovascular AMD than those with the lowest intake. (Archives BEYOND the age-old admonition to ‘eat your carrots’, diet of , September 2007; 125:1225-1232.) and nutrition has not been exploited as a tool to prolong eye Another nutrient that may play a role in AMD is omega-3 health – until recently. Recent years have seen an explosion of fatty acids, which are found in cold-water fish.The Blue research on possible ways to preserve vision through Mountains Eye Study of more than 2,000 Australian adults supplement use and diet. found that those whose diets were high in omega-3 fatty This line of research has “gotten a lot of traction” since the acids, especially from fish, were less likely to develop early and eighties, said Emily Chew MD, director of epidemiology and late AMD. (Archives of Ophthalmology, July 2006, 124(7):981-6.) clinical research at the (NEI).“People A recent case-control study of more than 4,000 AREDS are very interested in it.” participants found that those who ate a diet rich in omega-3 The most exciting results came from the NEI’s own Age- fatty acids were less likely to develop neovascular AMD Related Study (AREDS), a randomised trial that (Archives of Ophthalmology, May 2007, 125:671-679). found that supplemental antioxidants and zinc could benefit An analysis of the NHANES (National Health and people with intermediate-stage or Nutrition Examination Survey) linked blood levels of vitamin advanced disease in one eye.AREDS was especially important D to a reduced risk of early AMD, although there was no because it represents one of the only times nutritional relationship to advanced AMD. Like omega-3 fatty acids, supplements have been shown to be beneficial in the vitamin D may reduce inflammation and reduce the growth of treatment of disease, notwithstanding the claims of your new blood cells in the retina. (Archives of Ophthalmology, May neighbourhood health food store. 2007;125:661-669.) Indeed, a 2006 review by the National Institutes of Health Finally, two studies of nearly 4,000 AREDS participants in Annals of Internal Medicine named just one other instance found a link between a high intake of refined carbohydrates in which supplements have been proven to prevent disease: and an increased risk of onset and progress of AMD. calcium and vitamin D for reduction of fractures in (American Journal of Clinical Nutrition, October 2007;86:1210- postmenopausal women.The review didn’t address pregnant 1218; Chiu, C-J., Milton, R.C., Klein, R., Gensler, G., and Taylor,A., women, children, or those with vitamin or mineral Association between dietary glycaemic index is related to deficiencies. progression of age-related macular degeneration:A prospective Even though few definitive studies exist, scientists have Foods rich in and zeaxanthin include , spinach, study from the Age-Related Eye Diseases Study.Am. J. Clin. Nut. found many other intriguing links between diet and collard greens, and other yellow and dark green leafy (2007) 86, 1210-8.) One hypothesis is that diets high in supplement use and healthier eyes.Antioxidants (including vegetables. refined carbohydrates boost the level of glucose in the cells, carotenoids such as beta-carotene, lutein and zeaxanthin), Inflammation is another factor that appears to play a role in increasing protein damage due to modifications by sugars or omega-3 fatty acids, and other nutrients may play a beneficial multiple diseases, including heart disease, macular their break-down products, and oxidative stress. role in conditions ranging from macular degeneration to degeneration, and dry eye. Omega-3 fatty acids, which are Although these observational studies have found some dry eye. found in cold-water fish, may help the eyes by reducing this intriguing links between specific nutrients and a reduced risk Dr Chew cautioned that most studies on diet, supplements inflammation and promoting proper blood vessel formation. of AMD, it’s impossible to know whether the relationship is and vision are observational, which makes it impossible to From antioxidants to zinc, here’s an overview of what’s truly cause-and-effect. Fortunately, a randomised trial called draw firm conclusions about what to eat or what pills to known about diet, supplement use, and vision: AREDS-2 is investigating whether supplemental lutein, take. zeaxanthin, and omega-3 fatty acids might be able to “These studies tell us that there might be something there, Age-related macular degeneration postpone the development of AMD. Enrolment has already but we still need to do well-conducted randomised Age-related macular degeneration is the leading cause of begun, and results will be available in about five years. controlled trials,” she said. vision loss in people aged 65 and older.That’s why it was so That’s because people who use supplements may be more groundbreaking when the AREDS trial found that a Diet and risk educated, have more resources, less obesity, and have a combination of vitamin C (500mg), vitamin E (400 IU), beta- healthier lifestyle than those who don’t take them – all of Observational studies have linked specific dietary patterns carotene (15mg), and zinc (80mg) with cupric oxide (2mg) and supplements to a reduced risk of cataract. For example, which might explain why they tend to have fewer eye was able to reduce the risk of disease progression for those problems. Moeller et al showed eating according to the USDA Food with intermediate AMD or advanced AMD in one eye.The Guide Pyramid reduced risk for cataract (Moeller, S.M.,Taylor, It’s also difficult to determine exactly what components of trial, which enrolled more than 4,000 adults aged 55-80, found foods might have beneficial effects. Fruits and vegetables A.,Tucker, K.L., McCullough, M.L., Chylack, L.T., Hankinson, S.E., that people with intermediate AMD who took the Willett,W.C., Jacques, P.F. Overall Adherence to the Dietary contain numerous nutrients, so components like beta- supplement had a 25 per cent reduction in the risk of carotene may be only part of the story – or may act as Guidelines for Americans is Associated with Reduced Prevalence of progression to advanced AMD over a five-year period. Early Age-Related Nuclear Lens Opacities in Women J Nutr. markers for other nutrients. Based on the results of AREDS, ophthalmologists now Although it’s too early to make specific supplement (2004)134,1812 9) and the Blue Mountains Eye Study found recommend the AREDS supplement.The combination that people who took daily multivitamins and B vitamin recommendations for most people concerned with their supplement is sold commercially and they include OcuVite vision (the major exception being certain people with AMD), supplements, especially folic acid and vitamin B12, were less PreserVision, Bausch and Lomb; ICaps,Alcon Laboratories; likely to develop (Am J Ophthalmol. 2001 what’s good for preventing cancer or cardiovascular disease Ocular Formula #2,VisiVite; and others.The supplement is may well be good for preventing vision loss.That’s because Jul;132(1):19-26). Folic acid and vitamin B12 may work by recommended to people with intermediate AMD, but not to reducing blood levels of homocysteine. the same oxidative damage that contributes to heart disease patients with early AMD. and other age-related illnesses also appears to affect the eye. A recent analysis of data from about 35,000 women in the Eating a diet rich in fruits and vegetables may also help Women’s Health Study revealed that those with the highest “When junk proteins accumulate, they create oxidative ward off AMD. In the Dietary Ancillary Study of the Eye stress and become toxic to the lens and retina,” said Allen intake of lutein and zeaxanthin from food, and vitamin E from Disease Case-Control Study, people with the highest intake of food and supplements were at decreased risk for cataracts Taylor MD, director of nutrition and vision research at Tufts lutein and zeaxanthin from foods had a reduced risk of AMD University. (Arch Ophthalmol. 2008 Jan;126(1):102-9). (JAMA, November 1994, 272:1413). In the Rotterdam study, More recently, CAREDS (Carotenoids in the Age-Related Researchers hope that ingesting antioxidants, which are people with the highest dietary intake of beta-carotene, found in fruits, vegetables, nuts and grains, might slow the Eye Disease Study) found that women with high dietary levels vitamin C and E, and zinc were at reduced risk of developing of lutein and zeaxanthin had a 23 per cent lower prevalence damage. Of particular interest are lutein and zeaxanthin, plant AMD. (JAMA. 2005 Dec 28;294(24):3101-7). More recently, a pigments that have the ability to filter damaging rays of blue of nuclear cataract than those who had low levels. (Archives of case-control study of more than 4000 AREDS participants Ophthalmology, March 2008, 126:354-364.) light and also appear to act as scavengers of free radicals. found that those with the highest dietary intake of lutein and

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Emily Chew Jeffrey Gilbard Eric Donnenfeld Allen Taylor Cover Cover

Conflicting conclusions from studies Biloba extract, and 100mg of resveratrol. Eric Donnenfeld MD, of Ophthalmic carotene is “not a suitable substitute” in Despite these promising links from Although no randomised, prospective Consultants of Long Island, said that he the treatment of retinitis pigmentosa observational studies, randomised clinical trials have shown that these recommends fish and flaxseed oil not only because it’s “not predictably converted controlled trials have told a different story. supplements are effective in the treatment for his patients with dry eye, but for those into vitamin A”. The same AREDS combination of of glaucoma, he said that animal studies undergoing cataract and refractive surgery. People with retinitis pigmentosa should antioxidants and zinc that offered some and clinical trials investigating the use of He said he believes the combination avoid vitamin E supplements because the protection against advanced AMD had no these supplements for other diseases have improves the quality of the tear film and NEI trial found that taking 400 IU of measurable effect on cataract (Archives of produced promising results. speeds healing. vitamin E a day aggravates the course of Ophthalmology, October 2001, 199:1439.) In Dr Zelefsky warns that Ginkgo Biloba the disease.Although results have been the Women’s Health Study, vitamin E had extract should be used with caution in Controlling diet to control diabetic mixed on whether DHA supplements can no effect on cataract. (Ophthalmology, people taking blood thinners as it can retinopathy help, another study by Dr Berson found 2004;111:75-84.) potentiate the effect of the blood thinner is a complication of that eating two three-ounce servings of What’s more, an Italian trial published in and cause bleeding. He also notes that poorly-controlled blood sugar, so oily fish rich in omega-3s each week may Ophthalmology produced some disturbing resveratrol has the potential to cause controlling blood sugar is the best way to slow vision loss among those taking results related to supplements and stomach upset. reduce the risk of the disease. In the vitamin A. (Archives of Ophthalmology, 2004, cataract.The trial, which randomised more Control and Complications Trial, 122:1306-1314.) than 1,000 older adults to a daily Omega-3s from fish and flax gain which studied more than 1,000 people multivitamin or a placebo, found that even support for dry eye treatment with Type 1 diabetes, people who followed What to tell patients? though the multivitamin appeared to The Women’s Health Study (WHS) found a low- diet slowed their rate of So what’s the best approach to healthy reduce the risk of nuclear cataracts by 34 that women with a higher dietary intake of retinopathy progression by one-third. eyes for the vast majority of people? A per cent, it doubled the risk of posterior omega-3 fatty acids were less likely to Another study found that people with healthy diet – meaning one that’s low in subcapsular cataract (April 2008;115:599- have dry eye syndrome. (Am J Clin Nutr. Type 2 diabetes were less likely to develop saturated , and rich in fruits, vegetables, 607). Since PSC opacities are right in the 2005 Oct;82(4):887-93). Because most diabetic retinopathy if they took wholegrains and cold-water fish. visual axis, if these results are Westerners don’t get enough omega-3 multivitamins or supplemental vitamin C Dr Chew agreed.“I tell my patients to corroborated, the utility of antioxidants fatty acids in their diet, Jeffrey Gilbard MD, and E. (Am J Clin Nutr. 2004 May;79(5): eat more fish and dark green leafy will be diminished substantially. one of the study investigators, 865-73.) vegetables,” she said.“We don’t know if it The results from AREDS-2 – which is recommends that people with dry eye Omega-3 fatty acids may also play a role will work for their eyes, but it’s good for looking at cataracts in addition to AMD – take supplemental fish oil and flaxseed oil. in retinopathy. In a 2007 study published in their overall health,” she said. will be available in 2012.This new study is “The fish and flaxseed oil work Nature Medicine, mice fed a diet rich in She was sceptical about the use of evaluating the use of lutein/zeaxanthin and synergistically against dry eye, even in omega-3 fatty acids had less blood vessel supplements for most adults.“Supplements omega-3 fatty acids for the treatment of people with Sjögren’s” said Dr Gilbard, proliferation in the retina than those fed a can’t do a great deal,” she said. AMD and cataracts, following 4,000 who is a clinical assistant professor of diet rich in omega-6 fatty acids – a finding Dr Taylor agreed, saying that he didn’t participants for five years. In the ophthalmology at Harvard Medical School that could have implications for both think “one should go about excessively meantime, Dr Chew cautioned that there’s in Boston.That’s because fish oil is rich in diabetic retinopathy and retinopathy of supplementing without demonstrating that no good evidence supplements might long-chain omega-3 fatty acids such as prematurity. In fact, the Children’s Hospital there’s some reason for doing so. But, for reduce cataracts. eicosapentaenoic acid (EPA) and in Boston has begun a clinical trial to test those with poor diets, a supplement which docosahexaenoic acid (DHA), which the effects of omega-3 supplementation in provides RDI of required nutrients may be Supplements for glaucoma? suppress inflammation of the lacrimal and premature babies, who are at elevated risk useful”. A handful of ophthalmologists are using meibomian glands, whereas flaxseed oil is of retinopathy. Many people assume that supplements supplements to treat glaucoma. Joseph rich in the short-chain omega-3 alpha- are benign, but many are risky. Fat-soluble Zelefsky MD, a clinical glaucoma fellow at linoleic acid (ALA) that improve the tear Vitamin A and omega-3 fatty acids as vitamins like A, E and K carry a risk of the New York Eye and Ear Infirmary and lipid layer. Numerous formulations are treatment for retinitis pigmentosa overdose. Beta-carotene increases the risk clinical instructor in ophthalmology at available; Dr Gilbard developed one called A randomised trial sponsored by the of lung cancer in asbestos workers and New York University, said that curcumin is TheraTears Nutrition (Advanced Vision National Eye Institute found that taking smokers. In one Chinese study, a of special interest to him and his Research) that includes fish oil, flaxseed oil 15,000 IU a day of vitamin A slowed the combination of selenium, beta-carotene, preceptor, Robert Ritch MD. Curcumin, and vitamin E at effective levels that avoid progression of retinitis pigmentosa and vitamin E increased the risk of which is derived from the spice turmeric, the side effects that can be seen at higher (Archives of Ophthalmology, 111:761-722, oesophageal cancer. In addition, high levels has been studied as an agent to prevent doses or with oxidised oils. 1993). Based on this finding, lead author of vitamin E (800 IU) may increase and treat Alzheimer’s disease.“We believe Marian Macsai MD, vice-chair of the Eliot Berson MD, a professor of mortality, although the levels used in that the inflammation in Alzheimer’s is Department of Ophthalmology at ophthalmology at Harvard Medical School, AREDS (400 IU) appear to be safe. comparable to that in glaucoma, especially Northwestern University Feinberg School said that “most non-pregnant adults aged Despite these caveats, researchers exfoliative glaucoma,” he said.As a result, of Medicine, also recommends fish and 18 and over with retinitis pigmentosa continue to search for a pill that can help he recommends the supplement for many flaxseed oil for her patients with dry eye – should take vitamin A”. preserve vision.“Sure, a proper balanced of his patients with glaucoma. either one or two one-gram capsules of Dr Berson offered several caveats. First, diet is best,” said Dr Chew.“But people Dr Zelefsky recommends additional each per day. She said that people not pregnant women should not take high- are more likely to pop a pill than they are supplements for people with normal- taking a daily multivitamin may wish to add dose vitamin A because it can cause birth to cook.” tension glaucoma. Possible factors that a vitamin E capsule because the vitamin defects. Second, physicians should monitor [email protected] contribute to normal-tension glaucoma appears to play a role in metabolising their patients’ fasting serum vitamin A and include inflammation, reduced blood flow omega-3 fatty acids. But she cautioned that liver function before beginning treatment [email protected] to the optic nerve, and oxidative damage, not only is evidence scarce that these and annually thereafter to be certain these [email protected] which is why he prescribes supplements supplements work for dry eye, side effects levels are normal. Finally, physicians should [email protected] with anti-ischemic, anti-inflammatory, and are possible. monitor bone health in patients over 49 [email protected] antioxidant properties. “They can cause flatulence, they can because high doses of vitamin A can cause [email protected] His current regimen for people with cause longer bleeding time, and they can osteoporosis.Although substituting beta- [email protected] normal-tension glaucoma comprises interfere with the action of COX-2 carotene for vitamin A avoids the bone 1200mg of curcumin, 120mg of Ginkgo inhibitors,” she said. loss problem, Dr Berson said that beta-

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