Transcript: Dietary Prevention of Age-Related Macular Degeneration
Anyone who's ever got a sun burn knows how damaging the UV rays in sunlight can be. Imagine what those same rays are doing to the back of our eyeballs, our retinas. The eye is designed to take sunlight and focus it like a magnifying glass into the back of our eyes. Thankfully, we have a layer of cells in our eye called the retinal pigment epithelium that supports and protects our delicate retinal eyesight machinery. The layer builds up yellow plant pigments from our diet like zeaxanthin, which absorbs blue light and protects the retina from the photo-oxidative damage. The yellowing of our corneas when we get cataracts may actually be our body's defense mechanism to protect our retinas. In fact when you go and surgically remove those cataracts your risk of blindness from macular generation shoots up since you removed that protection. Instead of trading one type of vision loss for another, instead of pigmenting the front of your eye with cataracts, better to pigment the back of our eye through diet. The pigment in the back of our eye is entirely of dietary origin, thus suggesting that the most common cause of blind registration in the western world could be delayed, or even averted, with appropriate dietary modification.
Where in our diet do we get it? Well, the egg industry brags that eggs are a good source. But have six eggs a week for three months and the pigmentation in one’s eyes may barely move—and these were the high lutein free-range certified organic eggs not purchased at a supermarket, but a local farm.
Instead of getting the phytonutrients from the egg, that came from the chicken, that came from the corn and blades of grass she pecked on, what about getting it from the source—a cup of corn and a half cup of spinach a day for three months. A dramatic boost in protective eye pigment. Just to compare to the eggs, here’s the best that eggs can do. But if you cut out the middle hen, and get these nutrients from plants directly, you get up to here.
What's neat about this study is that they went back and measured the levels 3 months after the study stopped and levels were still way up here, so once you build your macular pigment up with a healthy diet, your eyeballs really try to hold on to it. Even if you go on vacation and end up eating more iceberg lettuce than spinach, your eyes will hold out until you get back.
Yes eggs can increase zeaxanthin levels in the blood, but they also raised bad cholesterol levels and risk of heart disease. "Therefore an egg yolk-based dietary strategy to increase plasma zeaxanthin cannot be recommended, and an alternative, cholesterol-free, food source is desirable, like goji berries for example, which have up to 60 times more zeaxanthin than eggs. A modest dose markedly increases levels in our body, an inexpensive, effective, safe, whole food strategy to increase zeaxanthin in the bloodstream. But we don't need it in our blood, we need it in our eyes.
So how about a double-blind randomized placebo-controlled trial? To preserve eyesight in the elderly in traditional Chinese medicine, people are often prescribed 40 to 100 goji berries a day, but here they just used about 15 berries a day for 3 months and still found it could protect against loss of pigment and prevent the buildup of what's called soft drusen, which is just debris that builds up in the back of the eye, both of which are associated with age-related macular degeneration, theleading cause of legal blindness in older men and women, affecting more than 10 million Americans. Note they gave it in milk here, so the butterfat could increase the absorption of these carotenoid pigments. A healthier way to get the same effect would just be to eat goji berries with nuts or seeds, in other words, goji trail mix.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Ariel Levitsky.
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