Antioxidants
To understand the connection between AMD and diet, it’s important to first understand what antioxidants are, and why they are important to your health.
Antioxidants are a group of vitamins, minerals, and carotenoids that form one of the human body’s first lines of defense against “free radicals”.
Free radicals are a natural by-product of the body’s metabolic process that can damage or even kill healthy cells throughout the body – including those in the eyes. One of the roles of antioxidants is to seek out and neutralize the free radicals. Antioxidants include vitamins C and E, as well as carotenoids such as beta-carotene.
Healthy, well-nourished people usually have an ample supply of antioxidants to help protect them against free radical damage. But people whose antioxidant levels are low due to unbalanced diets or other factors may be at increased risk for various diseases, including AMD.
On the other hand, ample dietary intake of antioxidants can provide powerful protection against AMD. In one study, people who ate above-average amounts of vitamins C and E, beta-carotene, and zinc reduced their risk of developing AMD by 35%. In another study, patients with early-stage AMD who consumed increased levels of antioxidants had a reduced risk for developing a more advanced form of the disease.
Omega-3
Another nutrient essential for eye health is omega-3. Omega-3 fatty acids, in particular Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA), play a number of important roles inside the retina. DHA helps repair cell damage. Its cousin EPA helps prevent the formation of fragile blood vessels, which are prone to leaking and are characteristic of wet/advanced AMD. Both DHA and EPA have anti-inflammatory properties that help protect normal cell functioning within the retina.
Omega-3 may be of special interest to AMD patients. Studies have shown that higher levels of omega-3 intake through dietary consumption of fish are associated with significantly reduced risk of disease progression. One study found that AMD patients who regularly ate more than two servings of fish per week reduced their risk of developing advanced AMD by 39%. This finding may not be surprising when you consider that fish is the primary dietary source of DHA and EPA omega-3.
Lutein, Zeaxanthin, and their Role in the Macula
The macula is the small “spot” of central vision-related cells in the center of the retina. If you could see it, it would appear yellow. This is because the macular pigment contains high levels of antioxidant carotenoids, the yellow pigments found in many fruits and vegetables. In particular, two important carotenoids – lutein and zeaxanthin (loo-teen and zee-zan-thin) – make up the bulk of the macular pigment. What’s surprising however, is that our bodies do not make their own supply of lutein. This means that our supply of these two carotenoids must come entirely from outside – from what we eat. Research is starting to show that the more we eat of foods high in lutein, the higher the density of our macular pigment. Conversely, the less lutein we consume, the lower our macular pigment density, and the higher our risk for disease. One such research study found that average levels of lutein and zeaxanthin were 32% lower in eyes affected by AMD compared to healthy eyes.
The good news is that increased intake of lutein can increase macular pigment density, even in patients diagnosed with AMD. This was demonstrated in a study in which average macular pigment density improved by 36% for AMD patients who took a lutein supplement and 43% for patients with took a supplement containing lutein and antioxidants (including beta-carotene, Vitamins C, E and zinc).
So, why is the macular pigment density so special? One very good reason is that people with low macular pigment densities have been shown to be more prone to developing AMD. In part, this could be the result of there being fewer antioxidants available to protect the macula from free radical damage. Another good reason has more recently come to light: the macular pigment may help protect against damage from blue light.
Blue Light Damage
Visible blue light, much like ultraviolet light, can’t actually be “seen”, but over time, it can cause damage to the retina, especially the important central vision-related cells in the macula. Exposure to this type of blue light has been identified as another potential risk factor for AMD.
Fortunately, the latest research indicates that the lutein and zeaxanthin in the macular pigment may absorb blue light before it can cause damage. In fact, one recent study showed that a diet rich in lutein and zeaxanthin helped reduce the risk of AMD more than four other types of diets. But unfortunately, evidence also shows that many people are actually consuming less carotenoid-rich foods. The best natural sources of lutein and zeaxanthin are colorful fruits and vegetables such as kale, spinach, and kiwi fruit— foods which do not always appear on many Canadians’ tables.
Highest Dietary Sources of Lutein and Zeaxanthin:
• Collard Greens
• Corn
• Egg Yolk
• Kale
• Kiwi Fruit
• Mustard Greens
• Orange
• Orange Peppers
• Parsley (fresh)
• Red Grapes
• Spinach
• Various Squash
• Zucchini
There’s no doubt that the best way to stock up on vital nutrients is to eat a range of healthy foods, however that can sometimes be difficult. If you don’t think you are getting enough lutein, zeaxanthin, or other important nutrients in the foods you eat, ask your eye care professional for advice on dietary supplements.
Dietary Supplements
Some eye care professionals recommend dietary supplements as a way to ensure their patients have a regular supply of the antioxidants, carotenoids, and omega-3 fatty acids that are so important to overall good health — and to the prevention of AMD as shown in the Age-Related Eye Disease Study (AREDS).
If you’re concerned that you aren’t getting enough lutein and omega-3 in your diet, you may want to consider taking them in supplement form. Supplements containing lutein and omega-3 in addition to the AREDS formulation of vitamins and minerals are available in most pharmacies. Please check with your pharmacist for a supplement option.
Sensible eating, dietary supplements (if recommended by your eye care professional), and other basic health precautions may help protect your sight from this all-too-common disorder. |
