PERSPECTIVES WITH DR ALAN BARCLAY
EATING FOR HEALTHY EYES
The risk of developing eye disease increases as we age, potentially undermining our quality of life. The most common eye diseases associated with ageing are:
- Age-related cataracts, a clouding of the normally clear lens of the eye, are a leading cause of vision impairment and blindness.
- Diabetic retinopathy is associated with diabetes and is a major cause of visual impairment and blindness. It develops when persistently high blood glucose levels damage the small blood vessels in the retina.
- Dry eye disease/syndrome occurs when the eyes don’t make enough tears to stay lubricated. This can make the eyes feel irritated, and in some cases, can also cause vision problems.
- Glaucoma, which may cause poor eyesight and can lead to blindness, occurs when the eye’s optic nerve is damaged due to increased pressure in the eye.
- Macular degeneration (also known as age-related macular degeneration or AMD) is a leading cause of blindness and severe vision loss. It refers to a group of degenerative diseases of the retina – in particular the macula, which is responsible for central and fine-detail vision.
Eye health goes hand-in-hand with general health. But because of the eye’s constant exposure to light and its high rate of metabolism, some nutrients are especially important.
The eye is particularly susceptible to oxidative damage, and oxidation and inflammation are implicated in the development of all of the common eye diseases associated with ageing. There is some evidence that dietary antioxidants and anti-inflammatories may help decrease the risk of age-related eye disease. This includes vitamin A, beta-carotene, lutein and zeaxanthin, and vitamins C and E; selenium and zinc; omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid; and omega-6 fatty acid, gamma-linolenic acid.
Vitamin A is essential for maintaining your eyes’ light-sensing cells (photoreceptors). Insufficient vitamin A may lead to night blindness, dry eyes or blindness, depending on the severity of the deficiency. Liver, egg yolks, and full-cream dairy products are all good sources.
Beta-carotene, a red-orange pigment, can be converted into vitamin A in the small intestine. It’s found in relatively large amounts in fruits and vegetables like cantaloupe/rockmelon, apricots (fresh or dried), orange-fleshed sweet potatoes, kale, spinach, and carrots.
Lutein and zeaxanthin are yellow carotenoid antioxidants known as macular pigments that function as a natural sunscreen. They are concentrated in the macula, the central part of the retina, which is a layer of light-sensitive cells on the back wall of the eye. Consuming foods rich in lutein and zeaxanthin can reduce the risk of chronic eye diseases including age-related macular degeneration and cataracts. Kale, spinach, parsley, green peas, lettuce, squash, Brussels sprouts and pistachios are among the best sources. Egg yolks, broccoli, pumpkin, asparagus and sweet corn are also good sources. Carotenoids are better absorbed when eaten with fats or oils, so dress your vegetables and salads.
Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables. There is some evidence it lowers the risk of developing cataracts. When taken in combination with other essential nutrients, it can slow the progression of age-related macular degeneration and visual acuity loss. Many fruits and vegetables are rich in vitamin C including berries, broccoli, Brussels sprouts, cabbage, cantaloupe/rockmelon, cauliflower, capsicum/bell peppers, citrus fruits, guavas and tomatoes.
Vitamin E is a group of fat-soluble antioxidants that protect fatty acids from harmful oxidation and thus protect cells in the eyes from unstable molecules called free radicals, which break down healthy tissue. Almonds, peanuts, sunflower seeds, and vegetable oils like safflower oil and wheat-germ oil are some of the best dietary sources of vitamin E.
Selenium is a powerful antioxidant. When combined with carotenoids and vitamins C and E, it can help reduce the risk of advanced age-related macular degeneration. Foods rich in selenium include seafood (shrimps/prawns, crab, salmon, halibut), poultry and eggs, Brazil nuts, enriched noodles, and brown rice (depending where it is grown). Zinc is a part of many essential enzymes. It plays a vital role in bringing vitamin A from the liver to the retina 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. It also appears to be involved in the formation of visual pigments in the retina. For this reason, zinc deficiency may lead to night blindness. Good sources include meat, seafood (fish and shellfish), poultry, dairy milk and yoghurt and peanuts.
Omega-3 fatty acids (eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA) are important for eye health. DHA is found in high amounts in the retina, where it may help maintain eye function, and help decrease oxidative stress and inflammation. It’s also important for brain and eye development during infancy. DHA deficiency may impair vision, especially in children. The best dietary sources are oily seafood like salmon, trout, herring, sardines, crab and shrimps/prawns.
Gamma-linolenic acid (GLA) is an omega-6 fatty acid that appears to have anti-inflammatory properties. Sources include evening primrose oil and hemp seed oil.
Carbohydrates (sugars and starches) have the greatest impact on our blood glucose levels. Consuming too much carbohydrate overall or too many high GI carbohydrates can lead to persistently high blood glucose levels and increase your risk of developing diabetic retinopathy, macular oedema, cataracts and glaucoma.
Talk to an Accredited/Registered dietitian to find out how much carbohydrate is right for you, and enjoy the low or lower GI varieties including quality wholegrains (e.g., grainy bread, al dente wholewheat pasta), legumes (beans, lentils and chickpeas), fruit and veggies (apples, pears, corn, peas, sweet potato, butternut pumpkin), dairy milk and yoghurt.
PUTTING IT ALL ON YOUR PLATE:
To help maintain optimal eye health, eat more fruits and vegetables, enjoy moderate amounts of quality meat, seafood and/or poultry and make most of low or lower GI carbohydrates.
Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).
Contact: You can follow him on Twitter or check out his website.