By Dr. Mercola
While most accept deteriorating vision as a natural part of aging, it’s really more of a side effect of our modern lifestyle. Aging does not automatically equate to failing vision, provided you’ve properly nourished your eyes through the years.
Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly, followed by cataracts. Both of these conditions are largely driven by free radical damage, and may in many cases be largely preventable through antioxidant-rich foods such as those listed in the table below.
|Astaxanthin||Animal-based omega-3 fat (found in wild-caught Alaskan salmon).|
|Anthocyanins (found in blueberries, bilberries, and black currants)||Vitamin D|
|Lutein and zeaxanthin||Bioflavonoids (found in tea, cherries, and citrus fruits)|
The Importance of Kale and Other Leafy Greens
Studies have shown that a diet rich in dark leafy greens helps support eye health, especially vegetables rich in carotenoids like zeaxanthin and lutein. Zeaxanthin is an antioxidant carotenoid found in your retina, but it cannot be made by your body, so you must get it from your diet.
Lutein is found in your macular pigment, which helps protect your central vision, and aids in blue light absorption.
Both zeaxanthin and lutein are also found in high concentrations in your macula lutea –the small central part of your retina responsible for detailed central vision. Together, they’re believed to serve two primary roles:
- To absorb excess photon energy
- Quench free-radicals before they damage your lipid membranes
While there’s no recommended daily intake for lutein and zeaxanthin, studies have found health benefits for lutein at a dose of 10 mg per day, and at 2 mg/day for zeaxanthin.
Lutein and zeaxanthin are primarily found in green leafy vegetables, with kale and (cooked) spinach topping the list of lutein-rich foods (see more extensive list below). You’ll also find these nutrients in orange- and yellow-colored fruits and vegetables. (The word lutein actually comes from the Latin word “luteus,” which means “yellow.”)
According to one 1998 study in the British Journal of Ophthalmology, orange pepper had the highest amount of zeaxanthin of the 33 fruits and vegetables tested. According to the authors:
“Most of the dark green leafy vegetables, previously recommended for a higher intake of lutein and zeaxanthin, have 15-47 percent of lutein, but a very low content (0-3 percent) of zeaxanthin. Our study shows that fruits and vegetables of various colors can be consumed to increase dietary intake of lutein and zeaxanthin.”
Following is a list of lutein-rich foods. Most of these also contain zeaxanthin, albeit in lesser quantities than lutein.
Lutein Content of Foods
|Food||Mg / serving|
|Kale (raw)||26.5 / 1 cup|
|Kale (cooked)||23.7 / 1 cup|
|Spinach (cooked)||20.4 / 1 cup|
|Collards (cooked)||14.6 / 1 cup|
|Turnip greens (cooked)||12.2 / 1 cup|
|Green peas (cooked)||4.1 / 1 cup|
|Spinach (raw)||3.7 / 1 cup|
|Corn (cooked)||1.5 / 1 cup|
|Broccoli (raw)||1.3 / 1 cup|
|Romaine lettuce (raw)||1.1 / 1 cup|
|Green beans (cooked)||0.9 / 1 cup|
|Broccoli (cooked)||0.8 / 1/2 cup|
|Papaya (raw)||0.3 / 1 large|
|Egg||0.2 / 1 large|
|Orange (raw)||0.2 / 1 large|
|U.S. Department of Agriculture, Agricultural Research Service, USDA Nutrient Data Laboratory. 2005. USDA National Nutrient Database for Standard Reference, Release 20 (2007), Nutrient Data Laboratory Home Page|
Combining Veggies with Eggs Significantly Boost Nutrient Absorption
Egg yolk is a source of both lutein and zeaxanthin along with healthy fat and protein, and while the total amount of carotenoids is lower than many vegetables, they’re in a highly absorbable, nearly ideal form. According to recent research, adding a couple of eggs to your salad can also increase the carotenoid absorption from the whole meal as much as ninefold. As reported by Time Magazine:
“Researchers at Purdue University in Indiana served 16 subjects three different varieties of the dish: an eggless salad, a salad with 1½ scrambled eggs, and a salad with three scrambled eggs. There was a threefold to ninefold increase in carotenoid absorption from the salad containing the most eggs…”
It’s interesting to note such a significant effect despite the fact that they served the eggs scrambled, as this is one of theworst ways to eat your eggs. Overcooking your eggs tends to oxidize the cholesterol in them, which promotes inflammation. The less you cook your eggs the better.
Also consider the quality of your eggs. Ideally, opt for organically-raised, free-range pastured eggs. Not only do they tend to have a better nutritional profile, by opting for pastured eggs you’ll also avoid pesticide exposure and genetically modified organisms (GMOs). The vast majority of commercially available eggs come from confined animal feeding operations (CAFOs), where the hens are not permitted to forage on pasture. Instead, they’re typically fed a diet of corn and soy, the vast majority of which is genetically engineered (GE). Factory farmed eggs are also far more prone to cause foodborne illness caused by Salmonella contamination.
If you live in an urban area, visiting a local health food store is typically the quickest route to finding high-quality local egg sources. Your local farmers market is another source for fresh free range eggs. Cornucopia.org also offers a helpful organic egg scorecard that rates egg manufacturers based on 22 criteria that are important for organic consumers. You can tell the eggs are free range by the color of the egg yolk.
Foraged hens produce eggs with bright orange yolks, indicative of higher amounts of lutein and zeaxanthin. Dull, pale yellow yolks are a sure sign you’re getting eggs from caged hens that are not allowed to forage for their natural diet. Another way to boost absorption of lutein from your vegetables is to add some raw organic butter or healthy oil such as olive or coconut oil to your salad.
Astaxanthin—a Powerful Promoter of Eye Health
Astaxanthin is produced by the microalgae Haematococcus pluvialis when its water supply dries up, forcing it to protect itself from ultraviolet radiation. There are only two main sources of astaxanthin: the microalgae that produce it, and the sea creatures that consume the algae (such as salmon and shellfish). Compelling evidence suggests this potent antioxidant may be among the most important nutrients for the prevention of blindness. It’s a much more powerful antioxidant than both lutein and zeaxanthin, and has been found to have protective benefits against a number of eye-related problems, including:
|Cataracts||Age-related macular degeneration (ARMD)||Cystoid macular edema|
|Diabetic retinopathy||Glaucoma||Inflammatory eye diseases (i.e., retinitis, iritis, keratitis, and scleritis)|
|Retinal arterial occlusion||Venous occlusion|
Dr. Mark Tso, now of the Wilmer Eye Institute at Johns Hopkins University, but who was my boss when I worked at the University of Illinois Eyebank in the1970s, has demonstrated that astaxanthin easily crosses into the tissues of your eye and exerts its effects safely and with more potency than any of the other carotenoids, without adverse reactions. Specifically, Tso determined astaxanthin could help ameliorate or prevent light-induced damage, photoreceptor cell damage, ganglion cell damage, and damage to the neurons of the inner retinal layers. Astaxanthin also helps maintain appropriate eye pressure levels that are already within the normal range, and supports your eyes’ energy levels and visual acuity.
Other researchers have since confirmed Dr. Tso’s finding that astaxanthin is the most powerful antioxidant ever discovered for eye health, giving your eyes an additional layer of long-term protection. Depending on your individual situation, you may want to take an astaxanthin supplement. I recommend starting with 4 mg per day.
Wild-Caught Alaskan Salmon—a Source of Both Astaxanthin and Omega-3
Wild-caught Alaskan salmon is also a good source of astaxanthin, but you may not be able to eat enough of it to reap optimal clinical results. That said, salmon is also an excellent source of healthy omega-3 fat, which provides structural support to cell membranes that boost eye health and protect retinal function. According to previous research, those with the highest intake of animal-based omega-3 fats have a 60 percent lower risk of advanced macular degeneration, compared to those who consume the least.
A 2009 study also found that those with the highest consumption of omega-3 fats were 30 percent less likely to progress to the advanced form of the disease over a 12-year period, and a second study published in 2009 also found that those with diets high in omega-3 fats along with vitamin C, vitamin E, zinc, lutein, and zeaxanthin, had a lower risk of macular degeneration.
Avoid farmed salmon however. Not only are they typically fed synthetic astaxanthin, Norwegian researchers have also raised serious concerns about high levels of contaminants in farm-raised salmon. Salmon labeled “Atlantic Salmon” typically comes from fish farms and is best avoided. The two designations you want to look for are: “Alaskan salmon,” and “sockeye salmon,” as Alaskan sockeye is not allowed to be farmed. Canned salmon labeled “Alaskan Salmon” is also good bet, and tends to be less expensive than salmon steaks.
Other Dietary Basics for Optimal Eyesight
Besides eating plenty of carotenoids-rich vegetables, organic pastured egg yolks, and omega-3 and astaxanthin-rich salmon, another really important dietary aspect is to normalize your blood sugar, as excessive sugar in your blood can pull fluid from the lens of your eye, affecting your ability to focus. It can also damage the blood vessels in your retina, thereby obstructing blood flow. To keep your blood sugar in a healthy range, follow my comprehensive nutrition guidelines, avoid processed foods as they tend to be loaded with processed fructose, and be sure to exercise regularly.
Trans fats also have an adverse effect on your eye health, and may contribute to macular degeneration by interfering with omega-3 fats in your body. Fortunately, the US Food and Drug Administration is moving toward removing trans fat from the list of food ingredients that are generally recognized as safe (GRAS), but trans fat can still be found in many processed foods and baked goods, including margarine, shortening, fried foods like French fries, fried chicken and doughnuts, cookies, pastries, and crackers.
Beware that heated vegetable oils may be just as, if not more, harmful than trans fat, as very harmful oxidation products are created. This is yet another reason for avoiding processed foods and food from fast food restaurants. Also avoid artificial sweeteners, as vision problems are actually one of the many potential acute symptoms of aspartame poisoning.
*Article originally appeared at Mercola.