Supplementation for Eye Health: What Does Science Say
When thinking about improving your eye health, you may remember the old saying: "Eating carrots will help you see in the dark." There are also shelves of nutritional supplements claiming to boost your eye health, which can be overwhelming. And all this may make you think: which vitamins and minerals are the most effective?
Here, we explain the science behind the clinical trials of eye health supplements, to see which are best to support our eyes.
Lutein and zeaxanthin
Lutein and zeaxanthin are plant pigments from the carotenoid family. You'll find a high concentration of these antioxidant pigments in the macula of the eye, and they're thought to protect it from light damage. While lutein and zeaxanthin are found in foods like leafy green vegetables (kale is one of the richest sources), corn, grapes, broccoli, kiwi fruit, peas and eggs – many of us still don't eat enough in our diet, making a supplement useful.
Because lutein and zeaxanthin are found in the macula, they're often marketed as eye health supplements. They help protect against age-related macular degeneration (AMD), which damages your vision.
Studies show lutein and zeaxanthin may prevent AMD by protecting the macula from sun damage.i; Meanwhile, several trials have found lutein and zeaxanthin may be useful if your level of macular pigment is already low, and may help those who already have AMD.ii
Lutein consumers may also be less likely to develop cataracts: a condition caused by ageing which makes the lens cloudy and less transparent.iii; Taking lutein and zeaxanthin may reduce headaches and eye strain, too, if you spend a long time in front of a computer screen.iv
How much should you take?
The recommended daily allowances for lutein and zeaxanthin to improve eye health are still pending. However, the American Optometric Association suggests 10mg lutein and 2mg zeaxanthin a day.
Anthocyanidins may be helpful for eye health too. Anthocyanidins are plant pigments too, found in blue and red fruits, seeds and berries (including blueberries, bilberries, raspberries and black grapes). Thought to support the capillary walls in the eyes, there is also evidence they may prevent eye damage caused by diabetes (diabetic retinopathy).v Anthocyanidins are also available in supplement form.
How much should you take?
There is currently no recommended daily dose of anthocyanidins.
Vitamin A and beta carotene
Vitamin A is necessary for good vision. It works by helping your body produce melanin, a pigment that protects the eye. Increasing the amount of vitamin A in the diet may reduce your risk of cataracts, according to one study.vi Your risk of developing glaucoma, another common eye condition, may also lower.vii
Vitamin A is found in liver, dairy foods and cod liver oil. Too much vitamin A, however, can cause health problems and can be particularly harmful in pregnancy.
Beta carotene, on the other hand, is found in orange, red and yellow plant foods. Beta carotene is converted to vitamin A in the body, so it's considered safer because it reduces the risk of vitamin A overdose.
In the well-known study, AREDS (Age-Related Eye Disease Study),viii after including beta carotene in a multivitamin supplement that also contained vitamin C, vitamin E and zinc, they found the supplement slowed the progression of advanced AMD by 25 per cent.
Beta carotene supplements may also help prevent cataracts in people who smoke.ix
How much should you take?
Vitamin A supplements are available, but high doses can be harmful so most take it as a multivitamin. As of yet, there is no upper limit to the recommended intake of beta-carotene.
Found in vegetable oils, nuts, seeds, green leafy vegetables and fortified cereals, vitamin E is an antioxidant vitamin. Antioxidants help protect against excess free radicals, also called oxidative stress, which damages the body. According to the American Optometric Association, it protects cells in the eyes from free radical damage as well.x
How much should you take?
According to the NHS, men need 4mg of vitamin E a day and women need 3mg. However, relatively high levels of vitamin E can be taken without negative effects. In the US the adult safe upper intake level is 1,000mg a day.
Zinc, besides aiding vitamin A absorption, is found in high concentrations in the eye. Two large and well-known studies found taking a supplement containing zinc helped reduce the progression of advanced AMD - though it didn't prevent the progression of early AMD, or cataracts.xi
How much should you take?
Government dietary recommendations state women need 7mg zinc a day, and men need 9.5mg a day. If taken on an empty stomach, however, zinc supplements can occasionally cause stomach upsets. Zinc can also affect some medicines, including some antibiotics, and reduce their effectiveness.
The omega-3 fatty acids in fish oils (docosahexaenoic acid and eicosapentaenoic acids – or DHA and EPA) are polyunsaturated fats that help form the cells of your eye.
DHA is found in high concentrations in the retina. EPA and DHA were included in the AREDS2 study,xii which found a combination of nutrients including lutein, zeaxanthin, DHA, EPA, and zinc helped slow the progression of advanced AMD.
Another study found those who ate high amounts of EPA and DPA were 30 per cent less likely to develop eye diseases that affect the retina, including AMD.xiii Women who have at least one serving per week of fish, have been found to reduce their risk of developing AMD by 42 per cent.xiii
DHA and EPA may also have anti-inflammatory effects and protect against diabetic retinopathy – an eye disease affecting people with diabetes, according to a long-term observational study.xiv
Another study found taking omega-3 supplements may protect against glaucoma.xv
How much should you take?
The only official guidelines for EPA/DHA intake in the UK suggest that a healthy diet should include at least two portions of fish a week, one of which should be oily fish. In some other countries, 300 - 500mg of combined EPA and DHA are recommended, which is more or less the amount you’d find in two servings of oily fish a week. However, a typical dose of fish oil for therapeutic use can be anything between 6g and 12g daily.
It’s also worth noting that fish oil supplements vary widely in the amount of EPA and DHA they contain, and in general only a third or so of the oil is made of EPA and DHA (though this may be higher in a concentrated fish oil product).
Ginkgo biloba is often recommended to boost the circulation. It might also be helpful for AMD and glaucoma.
At least two studies taking ginkgo supplements when you already have AMD may improve your vision.xvi
A daily 120mg dose of ginkgo for eight weeks may also improve the visual field in glaucoma cases.xvii A more recent report claims it may be useful for all glaucoma patients, including those who have normal tension glaucoma.xviii
How much should you take? Standard dosages tend to be between 40 to 80mg, three times a day. However, far higher doses aren’t unusual, as ginkgo seems safe and well tolerated in high doses.
There is some concern that ginkgo may interact with blood-thinning medication, so check with your GP if you’re taking an anticoagulant such as aspirin or warfarin.
There is compelling evidence to suggest supplements help maintain healthy eyesight. Some have a protective effect, while others may slow the progression of existing eye conditions. If your diet isn’t as healthy as it could be, taking at least one eye health formulation, or a good-quality multivitamin and mineral supplement, may be beneficial.
To find out more about eye supplements and how your lifestyle could help keep your vision healthy, take a look at some of the other articles in our Vision Health Hub.
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Hammond, B.R. Jr, Wooten, B.R., Snodderly, D.M. Density of the human crystalline lens is related to the macular pigment carotenoids, lutein and zeaxanthin. Optom Vis Sci. 74:499-504. Available online: https://www.ncbi.nlm.nih.gov/pubmed/9293517
Obana, A., et al. (2015). Changes in Macular Pigment Optical Density and Serum Lutein Concentration in Japanese Subjects Taking Two Different Lutein Supplements. PLoS One. 10(10):e0139257. Available online: https://www.ncbi.nlm.nih.gov/pubmed/26451726
Stringham, J.M., Stringham, N.T., O’Brien, K.J. (2017). Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure. Foods. 6(7). Available online: https://www.ncbi.nlm.nih.gov/pubmed/28661438
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Bussel, I.I., Aref, A.A. (2014). Dietary factors and the risk of glaucoma: a review. Ther Adv Chronic Dis. 5(4):188-194. Available online: https://www.ncbi.nlm.nih.gov/pubmed/24982753
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Christen, W.G., Manson, J.E., Glynn, R.J., et al. (2003). A randomized trial of beta-carotene and age-related cataract in US physicians. Arch Ophthalmol. 121:372-378. Available online: https://www.aoa.org/patients-and-public/caring-for-your-vision/diet-and-nutrition?sso=y
AREDS Research Group, (2003). ω-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. The American Journal of Clinical Nutrition. Volume 90, Issue 6, 1 December 2009. Pages 1601–1607. Available online: https://academic.oup.com/ajcn/article/90/6/1601/4598106
Christen, W.G., et al. (2011). Dietary ω-3 Fatty Acid and Fish Intake and Incident Age-related Macular Degeneration in Women. Arch Ophthalmol. 129(7): 921–929. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134638
Sala-Vila, A., et al. (2016). Dietary Marine ω-3 Fatty Acids and Incident Sight-Threatening Retinopathy in Middle-Aged and Older Individuals With Type 2 Diabetes. JAMA Ophthalmol. 134(10):1142-1149. Available online: https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2543478
Downie, L.E., Vingrys, A.J. (2018). Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults. Transl Vis Sci Technol. 7(3): 1. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931260
Lebuisson, D.A., Leroy, L., Rigal, G. (1986). Treatment of senile macular degeneration with Ginkgo biloba extract. A preliminary double-blind, drug versus placebo study [translated from French]. Presse Med. 15:1556-1558. Available online: https://www.ncbi.nlm.nih.gov/pubmed/2947098
Fies, P., Dienel, A. (2002). Ginkgo extract in impaired vision—treatment with special extract EGb 761 of impaired vision due to dry senile macular degeneration. Wien Med Wochenschr. 152:423-426. Available online: https://www.ncbi.nlm.nih.gov/pubmed/12244891
Quaranta, L., Bettelli, S., Uva, M.G., et al. (2003). Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology. 110:359-362.
Cybulska-Heinrich, M., Mozaffarieh, J., Flammer, A.K. (2012). Ginkgo biloba: An adjuvant therapy for progressive normal and high tension glaucoma. Mol Vis. 18: 390–402.
Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.
Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.