Age-related vision loss has long stymied researchers looking for a cure, but recent studies point to a dietary solution that validates a familiar canard.
The notion that eating carrots would improve your eyesight was quite prevalent in my younger years. It had surfaced during World War II as a bit of propaganda designed to explain the success with which British anti-aircraft gunners were able to shoot down Luftwaffe fighter planes in the dark of night (it really had more to do with the Brits’ secret radar system), and it later showed up on the radar of postwar, veggie-promoting American parents. We heard it from time to time in our own kitchen, though my siblings and I didn’t need much convincing. None of us needed glasses, and carrots topped my list of least-objectionable vegetables.
It turns out that the old carrot canard does contain a morsel of truth, but until recently there’s been little serious effort to cast some needed light on dietary remedies for a condition that clouds the vision of some 11 million elderly Americans.
Age-related macular degeneration (AMD), the leading cause of vision loss among people 50 or older, attacks a small spot in the center of the retina responsible for focusing on objects directly in front of you. In the early stages of the disease, AMD sufferers may not exhibit any symptoms, but late-stage cases feature a blurry, distorted, or dark field of vision. Late-stage AMD comes in two varieties: neovascular (“wet”), in which blood vessels grow beneath the retina and leak fluids that cause swelling; and geographic (“dry”), caused by the gradual deterioration of the retina’s light-sensitive cells. The dry version is far more common, affecting about nine of 10 AMD sufferers.
Research suggests that aging is a major risk factor for AMD. It tends to affect people over 60, as well as smokers, Caucasians, and those with a family history of the disease. And a recent study out of The Ohio State University College of Optometry pointed to stress as an additional contributing cause.
There’s no proven cure for either version of late-stage AMD, but practitioners offer a few treatment options designed to slow the vision loss caused by the wet version. The most popular of these involves periodically injecting a drug into the eye that blocks abnormal blood-vessel growth. The other approach requires laser surgery.
I’m not inclined to let someone puncture my eyeball with a needle, a skepticism apparently shared by a team of scientists at the University of British Columbia, Vancouver. In a recent study published in JAMA Ophthalmology, Brennan Eadie, MD, PhD, and his colleagues found that AMD patients who submitted to seven or more of these injections were more likely to end up going under the knife for glaucoma surgery.
This is where carrots — and other low-glycemic foods — come to the rescue of needle-averse geezers like me. At least that’s what Tufts University researchers concluded after studying the effects of diet on the retinas of lab mice. “We were genuinely surprised that the retinas from the mice whose diets were switched from high- to low-glycemic-index diets midway through the study were indistinguishable from those fed low-glycemic-index diets throughout the study,” said lead study author Sheldon Rowan, PhD. “We hadn’t anticipated that dietary change might repair the accumulated damage in the RPE [retinal pigmented epithelial] so effectively.”
These results, and earlier National Eye Institute research on nutritional supplements and AMD, point to a fairly obvious connection between the gut and the retina, a theory that shouldn’t raise many eyebrows given all the research showing how well the digestive system communicates with the brain. AMD is an inflammatory disease, after all, so it’s plausible to assume that the same unbalanced collection of gut microbes that may contribute to dementia could also be messing with your vision. In fact, University of Wisconsin–Madison scientists recently identified the protein responsible for AMD as part of a family of proteins linked to Alzheimer’s.
All this suggest to me that those British propagandists maybe knew more than meets the eye about the healing power of a carrot-rich diet. And that it shouldn’t take an air raid to convince us to take their advice.