Green Tea, Antioxidants, and the Eyes: A Guide by Natural Eye Care

green teaA large body of research shows green tea is a “super-antioxidant” that benefits the entire body, including the eyes. Eyes are highly vulnerable to oxidative stress, so any antioxidant could have ocular benefits. However, green tea contains polyphenols, potent antioxidants that also reduce inflammation. Catechins in green tea are highly absorbable by eye tissues, unlike many other antioxidants. What does the research into green tea and vision show? How much green tea do you need to get these benefits? If you do not like tea, is there an alternative?

Why Are Antioxidants Important?

Antioxidants are crucial to vision health. The eye contains many small structures, such as the retina, macula, tiny blood vessels, optic nerve, muscles, and other microscopic tissues. These tissues are highly vulnerable, given their size and our dependence on vision. Even slight damage can reduce vision or cause blindness. Free radicals can damage all tissues in the body. These roving extra electrons are the by-product of a natural oxidation processes. Oxidative stress is proving to trigger or exacerbate many diseases. Poor diet (especially trans fats found in fried foods, stick margerines, and chips), lack of exercise, and smoking increase free radicals. Therefore, antioxidants that counteract free radicals can significantly reduce the risk of age-related eye diseases such as macular degeneration, glaucoma, retinal occlusion, and retinal nerve disorders.

Green tea is high in antioxidants, including vitamins C and E. This type of tea contains the eye-crucial antioxidants lutein and zeaxanthin. Green tea has a high polyphenol content. One type of its polyphenols is called “catechins,” which have their own special antioxidant qualities.

Polyphenols in Green Tea

Green tea’s most important health-boosting chemicals are called “polyphenols.” They play key roles in reducing inflammation, destroying free radicals, and supporting signals between cells. When you consume polyphenols, your gut bacteria break them down into phenols, which are smaller molecules. They are processed by the liver, then move on to the tissues. These chemicals are highly beneficial to many tissues in the body. For example, seniors who had the highest levels of circulating polyphenols were at a 30% lower risk of death over 12 years versus those with the lowest levels.1

Catechins in Green Tea

Green tea contains large quantities of a type of polyphenols called “catechins.” Catechins have been studied closely for their health effects. Readily absorbed, catechins have been found to pass from the digestive system to the eyes.2 Green tea epigallocatechin has been shown to protect the retina from hydrogen peroxide damage (oxidization)3 and ultra-violet B light.4

How Much Green Tea to Drink?

Most of the research into green tea is based on drinking at least two to three cups per day. Try making a daily pot of green tea, carrying a thermos, or steeping individual tea bags in hot water. Many coffee shops offer large green tea drinks. Divide the number of ounces of tea by 8 to calculate how many servings you are drinking.

When brewing green tea, use boiled water that has cooled to less than 175 degrees Fahrenheit to reduce bitterness. Drink green tea straight, iced, sweetened with Stevia, or with milk or a milk substitute. Beware of sipping sugared beverages throughout the day, as this can damage teeth and increase inflammation.

If getting three cups are too difficult, try a potent green tea such as Kenyan Green Tea Crystals. Green tea supplements in capsules and green tea extracts are a short-cut to drinking cups of tea.

Green tea naturally contains caffeine. An 8-ounce drink officially contains 35mg of caffeine; however, it can be between 30mg and 50mg. A cup of brewed coffee contains 100mg to 200mg of caffeine. If caffeine keeps you awake, take it only in the morning. Decaffeinated green tea is widely available. The longer you brew the tea, the more caffeine seeps into the drink.5

Green Tea and Glaucoma

Most cases of glaucoma appear to be caused by damage to the trabecular meshwork, caused by oxidative stress. Research is starting to show that oxidative stress leads to biochemical imbalances in the systems that control blood cell circulation of the vascular endothelium.6 Therefore, antioxidants may prove important in preventing and slowing down the progression of glaucoma. A Chinese study found that the eye absorbs several catechins in green tea in significant quantities. Many antioxidants do not survive beyond the digestive tract. The antioxidants stayed active in ocular tissues for up to 20 hours.7

Macular Degeneration

Oxidative stress is a prime suspect in the triggering and progression of Age-Related Macular Degeneration (ARMD). Studies have found that a green tea substance, polyphenol epigallocatechin-3-gallate (EGCG), was 10x more powerful than vitamin E in protecting the retina from oxidative damage.8 EGCG was found to protect the retina — and therefore the macula — from ultra-violet light damage.9 Another study found that EGCG inhibited the growth of new, unwanted blood vessels associated that mark advanced “wet” macular degeneration.10

Pterygium, Meibomian Glands, and Dry Eye

pterygiumA pterygium is a small, cream-colored lump on the eye. It appears on the nasal side of the eye. People who spend a lot of time outdoors in dry, windy environments are especially susceptible. Pterygium often appears together with dry eye syndrome and meibomian gland problems. The meibomian gland plays a role in the proper functioning of the tear film. This tiny gland in the eyelid releases oil that helps prevent tear evaporation. One study found that green tea extract, applied topically to the eye, resulted in significantly better meibomian gland functioning versus controls.11 (Editor’s note: Do not put substances in your eye without your doctor’s approval.)

Cardio-Vascular Effects of Green Tea

Tiny blood vessels nourish and oxygenate the eye. People who have high blood pressure or cardiovascular disease are susceptible to blockages in blood vessels. Retinal vein occlusion is a major cause of vision loss from retinal vascular disease. Green tea was found to reduce flow-mediated dilatation of the brachial artery in just 30 minutes. The controls, caffeine and water, had no effect.12 Other studies have found that drinking 5 or more cups of green tea a day reduced the risk of death from heart attack or stroke by 26%.13 Green tea has also been shown to reduce LDL cholesterol and triglycerides.14

Green Tea May Help Sjogren’s Syndrome

The salivary and tear glands malfunction in people with Sjogren’s syndrome. White blood cells attack, making these glands less effective. Patients develop chronic dry eye. A study showed that a component of green tea (polyphenol epigallocatechin-3-gallate or EGCG) had a positive impact on salivary glands. Their total levels of autoantibodies in the blood decreased, and they had less lymphocyte infiltration. Green tea could eventually be shown to affect the eye’s tear glands too.15

Other Strengths of Green Tea

Did you know that green tea has other health benefits? According to published research, the compounds in green tea can help with:

  1. Zamora-Ros R, Rabassa M, Cherubini A, et al. High concentrations of a urinary biomarker of polyphenol intake are associated with decreased mortality in older adults. J Nutr. 2013;143(9):1445-50.
  2. Chu et al. Green Tea Catechins and Their Oxidative Protection in the Rat Eye, Journal of Agricultural and Food Chemistry, 2010; 58 (3): 1523
  3. Epigallocatechin Gallate (EGCG) Prevents H2O2-Induced Oxidative Stress in Primary Rat Retinal Pigment Epithelial Cells, D. Cia, el al, Current Eye Research, Feb, 2014.
  4. Epigallocatechin gallate eye drops protect against ultraviolet B-induced corneal oxidative damage in mice, M.H.Chen, et al., Molecular Vision, Feb. 2014
  5. HealthLine Newsletter, “How Much Caffeine is in Green Tea?”, accessed 5/7/18
  6. H. Resch, G. Garhofer, et al., Endothelial dysfunction in glaucoma, Acta Ophthalmologica, June, 2008
  7. Chi Pui Pang of the Chinese University of Hong Kong and Hong Kong Eye Hospital, study published in the April, 2010, Journal of Agricultural and Food Chemistry
  8. Brain Research. 2006 Dec 8;1124(1):176-87. Epub 2006 Nov 3. Oxidative-induced retinal degeneration is attenuated by epigallocatechin gallate. Zhang B1, Osborne NN.
  9.  Epigallocatechin Gallate (EGCG) Prevents H2O2-Induced Oxidative Stress in Primary Rat Retinal Pigment Epithelial Cells, D. Cia, el al, Current Eye Research, Feb, 2014.
  10. Molecules. 2014 Aug 13;19(8):12150-72. doi: 10.3390/molecules190812150. Epigalloccatechin-3-gallate inhibits ocular neovascularization and vascular permeability in human retinal pigment epithelial and human retinal microvascular endothelial cells via suppression of MMP-9 and VEGF activation. Lee HS. et al.
  11. M. Nejabat, S.A. Reza, M. Zadmehr, et al. Efficacy of Green Tea Extract for Treatment of Dry Eye and Meibomian Gland Dysfunction; A Double-blind Randomized Controlled Clinical Trial Study, Journal of Clinical and Diagnostical Research, February, 2017.
  12. Eur J Cardiovasc Prev Rehabil. 2008 Jun;15(3):300-5. doi: 10.1097/HJR.0b013e3282f4832f. The acute effect of green tea consumption on endothelial function in healthy individuals. Alexopoulos N, et. al.
  13. September 13, 2006. Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan. The Ohsaki Study. Shinichi Kuriyama, MD, et al. JAMA. 2006;296(10):1255-1265. doi:10.1001/jama.296.10.1255
  14. Am J Clin Nutr. 2011 Aug;94(2):601-10. doi: 10.3945/ajcn.110.010926. Epub 2011 Jun 29. Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials. Zheng XX, Xu YL
  15. March, 2007, Autoimmunity, Medical College of Georgia researchers Stephen Hsu, et al.