Eye Sight : Your Eye and Brain Connection Think Quick and Look Sharp

By Robert Abel, Jr, MD

It is no surprise how much the eyes and the brain have in common when you realize the retina is actually an extension of the brain. Furthermore, 40 percent of the brain is devoted to processing the information that comes into the eye. A recent study indicates that the eye and brain are so intimately connected that an electrical test can detect depression through the eye. Therefore, it should also come as no surprise that the nutrients important for one are important for the other. One example is fat—that is to say, healthy fat. The brain is comprised of 60 percent essential fatty acids, while the retina has one of the highest omega-3 concentrations in the body. By incorporating a few key nutrients into your diet, you can help keep your eyes and brain at their best.

The Basics
The eye is a bag of water with two lenses, the cornea and the crystalline lens, which focus light onto the retina. The retinal photoreceptors receive the images and send them through the optic nerve to the brain. With about 1 million ganglion cells, the human retina can transmit data at approximately the rate of an Ethernet connection. Eighty percent of our sensory perception comes to us through our eyes. There are 100 times more nerve fibers devoted to vision than to hearing. The retinal receptors transform incoming light into electrical signals. While doing this, the rods and cones get oxidized and need to be immediately replenished. Since light, especially UV light, is an oxidant and the retina has the highest oxygen demand in the body, the eyes require a constant source of antioxidants. The brain is the center of thinking, breathing, heart rate, and the unconscious. The cerebral cortex governs higher thinking and puts together what we feel and how we react to it. The autonomic nervous system controls organ function and whether we become nervous or relaxed. Deep in the brain, the amygdala is the emotional center and the hippocampus regulates memories. The brain requires antioxidants and other vitamins and nutrients to function optimally. Vitamins D and E, DHA, and lutein are particularly important for both eye and brain health.

Supplemental Support
Vitamin D3 is formed when UV light meets cholesterol molecules. A recent study finds that 75 percent of American teens and adults are deficient in this important vitamin. Adequate levels of vitamin D are related to a reduced risk of insulin resistance and Type 2 diabetes, asthma, tuberculosis, cancer, and Parkinson’s disease. Vitamin D is essential for bone and heart health, and it even improves immunity. Serum levels of D are inversely associated with early macular degeneration (whereas fish intake is inversely associated with advanced macular degeneration). Vitamin D also helps protect the brain by preventing cognitive decline. Vitamin E is an important antioxidant that blocks the breakdown of essential fats in cell membranes. It’s found in the retina and the lens. Studies find that people with an adequate level of vitamin E have a reduced rate of cataract formation. Vitamin E is also associated with higher cognitive performance and memory retention. It is important to remember that natural vitamin E (d-alpha tocopherol) is significantly more potent than synthetic. Lutein is a carotenoid found in the macula (the center of the retina). It is a crucial protector against macular degeneration and cataracts. Lutein protects the rods and cones from free-radical damage caused by UV light. Like the other carotenoids, lutein is a fat-soluble nutrient that requires a small amount of cholesterol to be transported to the retina. Lutein is a powerful antioxidant that protects every cell in the body—including the brain—from the damage caused by free radicals.

Don’t Forget Healthy Fat
Only when the great apes began eating fish did the primate brain grow from 400 cubic centimeters to 1,300 to 1,500 cubic centimeters. Principally, it is the deep-water, algae-eating fatty fish like salmon, herring, and cod that provide the essential nutrient that’s necessary for the development of all organs, especially the eye and the brain. Every cell membrane in the body is made of two layers of good fats; one layer is omega-3/DHA and the other is omega-6. However, in the retina, both layers of the retinal receptor membranes and the mitochondrial membranes are made of DHA. In fact, 50 percent of the retina is comprised of that fatty acid. Omega-6 fatty acids are found in all terrestrial plants and meat from animals that feed on corn and grain. Algae and plankton are the major source of omega-3, but animals that graze freely are able to convert linolenic acid into DHA. DHA has been widely studied, and benefits include a reduced risk of depression and insulin resistance, reduced inflammation, prevention of arrhythmia and heart disease, reduced LDL cholesterol and triglycerides, and neuroportection within five hours of an ischemic stroke. DHA is essential for normal eye development and function. Deficient DHA levels contribute to macular degeneration and retinitis pigmentosa, which is caused by a progressive loss of retinal photoreceptors. DHA also offers cognitive support. Adequate levels contribute to normal development of the brain and nervous system and support memory. Infants who receive DHA supplementation in utero are found to have a higher IQ, larger head size, and better vision at age four. We are seeing much more vision loss and dementia as the nutrition value of our food decreases. Omega-6 rich food is more abundant and cheaper, and healthy fish are sometimes difficult to obtain. To assure an adequate level of DHA, a diet rich in fatty, coldwater fish or supplementation with marine oil is imperative. (For more information, see my book The DHA Story.) Add the nutrients listed above, and help protect your eyes and brain for years to come.

The DHA Story by Robert Abel, Jr., MD (Basic Health, 2002) Eye Advisory, www.eyeadvisory.com “Randomized Trial of Vitamin D Supplementation to Prevent Seasonal Influenza A in Schoolchildren” by M. Urashima et al., Am J Clin Nutr, 3/10 • “Seeing Gray when Feeling Blue? Depression Can Be Measured in the Eye of the Diseased” by E. Bubl et al., Biol Psychiatry, 2010
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