The old adage ‘you are what you eat’, although its roots stretch back hundreds of years seems more relevant than ever today. With processed foods, genetically modified ingredients, additives, pesticides and foods shipped the world over, together with our busy lifestyles, eating healthy balanced diet on regular basis can be challenging.
When discussing diet and eye health (and for that matter health in general) it is important to understand that in most cases both nature (your genetics) and nurture (your environment; i.e foods you eat) are important to consider. Most people who develop lung cancer are smokers, but not all smokers get lung cancer. And not everyone who overeats develops diabetes yet they are likely increasing their risk by doing so. Think of a continuum established by your genetics and where you land on that continuum can in many cases be influenced by what we expose our bodies to. So although not all health problems will be influenced by our diet many studies suggest that making smart diet and lifestyle choices can help influence many health outcomes.
For many of my patients the extension of the concept of their diet’s affect on general health to include their diet’s influence on their eye health is difficult. This was the impetus for the article since studies clearly indicate only about 25% of us are meeting our fruit and vegetable intake recommendations, feasibly tipping the nature / nurture continuum in the wrong direction. With rates of chronic diseases such as diabetes continuing to raise in combination with our aging population it is thought that rates of low vision and blindness might double by 2030. Making healthy choices such as changing our diet can help to guard us against disease. The good news in terms of eye nutrition is that many of the choices that are good for the rest of the body are also wise choices for our eyes.
Supplements can fill dietary gaps when necessary but nutrients from food are most important. Real food sources provide nutrients in a wider variety and in combinations that can work synergistically together. For your eyes the Vitamins A, C and E, the mineral zinc, the cartenoids lutein and zeaxanthin and omega 3 fatty acids are some of the most important. It is also critical to realize that although an abundance of these vitamins in a balanced diet is good, there is such a thing as too much, especially in supplement form. Although there is plenty of evidence that eating high-antioxidant foods that contain beta-carotene is good for your health, a clear study from the US of more than 18000 smokers given beta carotene supplements over four years (the CARET study) found a 28% higher risk of lung cancer than those that received a placebo ( a fake supplement).The important message here is that there are benefits to getting vitamins in food that don’t necessarily occur in supplement form.
Two of the best antioxidants for your eyes are lutein and zeaxanthin. The body cannot make either so they have to be eaten. They are found both in your retina (the light sensing tissue at the back of your eye) and the intraocular lens (a biological lens in your eye that helps with focusing light). Dietary intake of these compounds has been shown to improve the pigment density in the important areas of your retina helping to protect these delicate tissues from damaging UV, blue light and free radicals that we get exposed to every day. Dark Leafy greens such as kale and spinach are two great sources but you’ll find them in most fruits and vegetables, especially yellow, orange and other leafy greens. In a lovely example of the above mentioned synergy, fats improve their absorption from our diet, making salads with an oil based dressing or a side of fatty fish the perfect autumn prescription.
Omega 3 fatty acids also play a significant role in eye health and have to be obtained from food or supplement sources. Although all the fatty acids are important for general health the beneficial effects of added omega-3 in our diets seems to be more critical, at least in western society. It is thought that human beings evolved on a diet with an almost even ratio of omega 6 to omega 3 yet present day average Western diets have ratios in the range of 15/1. Although the evidence is far from clear there is mounting evidence that the imbalanced ratio fosters inflammation and chronic health concerns and increasing our omega 3 intake can help to reverse some of these problems. Research and my personal clinical experience clearly indicate omega 3 supplementation has a role in the treatment of dry eye. Although dry eye is complex and usually multifactoral it almost always involves increased inflammation, which the omega 3 supplementation can help to reduce. Another place we see Omega 3 fatty acids in high concentrations in our retina helping to optimize both integrity and function and protect from inflammation and neurotoxicity. Great sources of omega 3 fatty acids are salmon or other coldwater fish, walnuts and flax seeds or oils.
The mineral zinc is highly concentrated in the eye, mostly in the retina and choroid (the vascular tissue layer under the retina). It plays a vital role in bringing vitamin A to the retina in order to produce melanin, a protective pigment in the eyes. The human body does not produce the zinc it needs, so daily intake of zinc through diet or nutritional supplements is important for the maintenance of good eye health. Red meat, seafood, poultry, eggs, mixed nuts, tofu and beans are all good sources of zinc. The most recent research clearly indicates zinc supplementation has a role to play in slowing the progression of advanced age related macular degeneration (AMD) and may benefit those at risk or in the early stages of the disease.
Vitamin A also plays an important role. In order to see properly your eye requires vitamin A to produce certain pigments in your photo sensing cells in your retina. It is also needed to keep the clear covering on your eye lubricated so you can see properly. Current research indicates it also can help slow the progression of advanced AMD when combined with other antioxidants and minerals. Vitamin A can be found in many foods including leafy green vegetables, orange vegetables and eggs.
Vitamin C is an antioxidant found in many fruits and vegetables. Scientific evidence suggests vitamin C lowers the risk of developing cataracts. Risk factors for cataracts include smoking, diabetes and steroid use, which deplete the eye's lens of vitamin C. Vitamin C helps promote healthy blood vessels and iron absorption and has been proven to be beneficial for AMD also. Good sources of vitamin C include broccoli, brussels sprouts, grapefruit, kiwi, oranges, red peppers and strawberries. Finally, but as important, we have vitamin E. Vitamin E can be found in foods like almonds, broccoli and spinach. It can also protect the cells of the eye from damaging free radicals. If left unchecked the free radicals can break down healthy cells and increase the risk for AMD and cataracts. Studies clearly show that vitamin E has a role to play in both slowing cataract development and in slowing the progression of AMD.
So clearly having adequate intake of these nutrients makes sense from an eye health standpoint but how much do we need for prevention or treatment? In my clinic I approach this question first by understanding each patients eye health and what risks they might have for future problems prior to discussing options for diet or supplementation. Specific eye conditions such as AMD have research based supplementation but more general concerns are not as clear cut. If you are interested in discussing diet and supplementation options specific to your needs I would be happy to help. Look forward to hearing from you.
Dr. Peter Roed