Chapter 152
Corn, Greens, and Goji Berries
Where are these pigments found? Because the egg industry wants to distract from the cholesterol content of eggs, it charges ahead and brags that eggs contain the pigments lutein and zeaxanthin, which protect the retina from photo-oxidative damage. And it’s true. One egg can contain up to 250 micrograms, but a serving of collard greens contains almost 18,500 micrograms, and a serving of kale tops the chart with nearly 44,700 micrograms. The yellow egg yolk is misleading: The yellow pigments are mainly in greens. (In golden autumn, when chlorophyll recedes, the yellow pigment of green leaves comes to light.)
One tablespoon of spinach contains as much pigment as eight eggs. For eye protection, 10,000 micrograms a day are recommended—about a third of a cup of spinach or 40 eggs daily. The plant pigments in eggs come via the chickens, which peck them up with the corn or blades of grass. But we can skip the chicken in the middle and get the pigments directly from corn or green leafy vegetables. On the US Department of Agriculture list, the top ten foods with these important vision nutrients are green leafy vegetables. Eggs don’t even make it into the top 100. To get to eggs you have to scroll down a few pages; then you find them right behind a few breakfast cereals, which probably made the list at all only because of the corn in their mix.
In a clinical trial, this discrepancy becomes clear. When subjects ate about six organic, high-lutein, free-range eggs each week for three months, the pigmentation in their eyes barely changed. Instead of obtaining plant pigments from eggs via the detour through chickens, the researchers then went straight to the source and administered the nutrients as plants—one cup of corn and a half cup of spinach per day—and in most subjects the protective macular pigmentation shot up in the very first month.
Three months after the subjects stopped eating corn and spinach, the pigment level was still relatively high, meaning the eyes try to hold on to macular pigment that has been built up through a healthy diet. So if we go on vacation and have to eat more iceberg lettuce than spinach, our eyes try to hang in there until we get back home.
Yellow corn contains about 70 times more lutein than white corn, but spinach contains 60 times more than yellow corn. With zeaxanthin, however, corn has the edge over green leafy vegetables. The word zeaxanthin comes from the Modern Greek zea mays, “corn,” and xanthós, “yellow.” But a few foods still beat corn. Orange bell peppers contain more than 18 times as much zeaxanthin as corn, but goji berries are unchallenged out in front, with an unbeatable level twelve times higher than orange bell peppers. In see.nf/gojis I present a randomized placebo-controlled double-blind study in which goji berries helped even people who already had macular degeneration.
At health food stores, goji berries can cost more than $20 per pound, but in Asian markets, where you can also get them as Chinese wolfberry (Lycium barbarum), they’re cheaper than raisins. I strongly recommend replacing raisins with goji berries—at breakfast in cereal, as a snack, in muffins, and everywhere else. A review concluded that goji berries are a “‘whole-food’ supplement for retinal health and to prevent and/or delay common retinal diseases.”
Optimal Absorption
Lutein and zeaxanthin are fat-soluble, so you should always eat green leafy vegetables with nuts, seeds, nut and seed butters, or other healthy fats. It tastes better, and you maximize absorption of these important macular pigments. So you can make your pesto with walnuts, whisk up a creamy tahini-based salad dressing, sprinkle steamed kale with sesame, or choose a fruit that brings the fat with it: avocados.
In see.nf/avocados I discuss all the experiments that showed how sensationally you can boost the absorption of carotenoids from vegetables when you combine avocados with salsa or salad. Steaming is another way to make the macular pigments in green leafy vegetables bioavailable, but lutein can be freed from the vegetables not only by heat. If you finely chop spinach, apparently twice as much lutein is released during digestion. And if you really break it down—into a green smoothie, pesto, or spinach purée, for example—you can even triple the bioavailability.
Plant Pigments Put to the Test
The Age-Related Eye Disease Study (AREDS) randomized thousands of men and women with at least early-stage age-related macular degeneration to take a combination of antioxidants and zinc for five years, and managed to reduce worsening to advanced macular degeneration by 25 percent. The AREDS formula quickly became the medical standard treatment for patients with age-related macular degeneration. In see.nf/areds I describe in detail all the subsequent changes to the ingredient mix. Fish oil was tried and failed, the zinc dose was lowered, and “vegetarian” amounts of lutein and zeaxanthin performed better than the original beta-carotene.
The professional ophthalmology societies and the guidelines agree that people with macular degeneration should receive such supplements, but for primary prevention they have not proven effective. The Harvard Physicians’ Health Study II even found that study participants who received a multivitamin preparation (Centrum Silver) developed macular degeneration more often than those who took a placebo. To prevent the disease from arising in the first place, a diet with “lots of green leafy vegetables” is recommended—then you don’t need dietary supplements.
To protect the eyes, everyone should include two to three servings of leafy greens in their daily diet. That means one serving with each lunch and dinner, with bonus points if you can also manage it at breakfast—for example as a green smoothie or in savory oatmeal. For fair-skinned people, green leafy vegetables are especially important, since they develop age-related macular degeneration significantly more often. This is probably due to eye color. Blue eyes let 100 times more light through, so people with blue or gray eyes are significantly more susceptible to light damage than people with brown or black eyes. (Green and light brown eyes fall somewhere in the middle.)
27 Miles of Visibility
The macular pigments lutein and zeaxanthin don’t just protect vision—they may even strengthen it. They are best at absorbing light of the wavelength that happens to correspond to the color of our planet’s sky. So anyone who fortifies their retina with lots of leafy greens can filter out the blue haze and, on a clear day from a high mountain, see 27 miles farther and make out more mountain ranges than someone who has little macular pigment.
The effect of supplements with macular pigments on visual performance in healthy normal subjects was examined in nine randomized controlled trials. All found significant improvements—in visual acuity, contrast sensitivity (important in low light), color contrast (clarity of colors), and recovery time after light exposure (the time it takes to see again after a flash of light).
Are there other foods that can improve vision in healthy people? Cocoa powder can acutely increase blood flow to the brain, so scientists investigated what a bar of dark chocolate (72 percent cocoa) and what a bar of milk chocolate (31 percent cocoa) of the same brand (Trader Joe’s) would do. Two hours after consumption, in the dark chocolate group, contrast sensitivity and visual acuity were significantly better than in the milk chocolate group, meaning they could make out small, low-contrast objects better. The researchers suspected that this might have been triggered by increased blood flow to the metabolically insatiable retina, delivering more oxygen and nutrients.