Seeing and Understanding
We intuitively know that there is a link between seeing and understanding. Our language is replete with expressions equating the two. We might say, “focus on what I am saying” meaning “pay attention”, or “do you see what I mean?” We often refer to a “man of vision” or “woman of vision” and we clearly are not speaking of their eyesight. Rather we are referring to an enlightened understanding, puns intended.
There are over 600 carotenoids in nature. Beautiful fall colors result when chlorophyll fades away in the leaves (since it is not needed for photosynthesis at the end of the growing season) and the beautifully colored carotenoids are exposed.
Of the 600 carotenoids only about 20 are found in the human diet. Lycopene is the most abundant and gives tomatoes their red color. Lutein and zeaxanthin are the most important for vision but are sadly deficient in most diets. Jay Leno has said, “Who needs Al Quaeda when we have the American diet?” Lutein and zeaxanthin are yellow and orange and those colors are critical for their beneficial effect upon vision. The colors appear as they do because they absorb the shorter wavelengths of light and reflect longer wavelengths (the ones you see) that are yellow and orange. Ultraviolet rays are the shortest wavelengths and therefore have the most energy and cause the most damage to ocular and epidermal tissue by damaging the DNA of the cells. Lutein and zeaxanthin also have an antioxidant effect, helping to prevent free radical damage.
Lutein and zeaxanthin are so important to the eye that these two pigments are concentrated at 500 -1000 times more in the retina than any other tissue of the body. The other organ of the body that also requires a high concentration of those two pigments is the brain. This week, on a beautiful fall day in Boston, I attended the Ocular Nutrition Society Annual Meeting. Elizabeth J. Johnson, PhD, presented the results of one of her research projects demonstrating that individuals that have a relatively high amount of lutein and zeaxanthin in the retina ALSO have a higher amount in the brain AND that it is protective of higher cognitive function. Mini Mental State Examinations scores ( a standard test of cognitive function) were higher in older adults that had higher amounts of lutein and zeaxanthin in their brains. Specifically they were better at global cognition, executive function, memory and recognition.
DHA, found in fish oil, is the other nutrient that is important for brain function and works synergistically with the lutein and zeaxanthin. The sum of the two working together is greater that the individual parts.
Is there a best diet to preserve your vision and your brain? Eat plenty of sardines (or your favorite cold water fish) and leafy greens such as kale or spinach. Bright yellow/ orange vegetables like orange or yellow peppers are also high in lutein/zeaxanthin. Incidentally, marigold petals are the commercial source for lutein and zeaxanthin. Fortunately, excellent supplements are available that make it possible for anyone to get these nutrients in the quantity that they need.
Unfortunately, many inferior products exist, and fall far short of their hyped marketing claims. For example, many products claim they have lutein, but only have a fraction of the 6-12 mg a day that is required. I recommend that the amount of DHA (found as an EPA/DHA combination) should be at least 400 mg per day. ( I personally take 4 capsules a day of a Super Omega 3 supplement that contains about 1600 mg day of EPA and 800 mg day of DHA.)
