Is a Dietary Deficiency Disease?
By William Harris, M.D.
December 3, 2003
The incidence of Age Related Macular Degeneration (ARMD) appears to have gone up over the past fifty years. It's not clear whether there has been an absolute increase or whether it's just because the US population is growing older, but ARMD was not a common problem when I was in training 40 years ago, and my General Ophthalmology text from 1983 barely mentions it.
The choroidal neovascular "wet" form of the disease (CNV) is responsible for ~90% of the severe loss of vision in ARMD. It is caused by a growth of abnormal blood vessels under the macula (central part of the retina). These vessels leak fluid, lift the macula off its Bruch=s membrane, and cause scar tissue that attacks central vision over a period that can range from a few months to three years. It is now the leading cause of blindness in the United States with 200,000 new cases in the United States each year, usually people in their mid 70s.
Most of the research money seems directed toward drugs, genetics, laser treatment, retinal transplants, and possible autoimmune factors. However, numerous journal articles point to the role of nutrients in preventing the disease in the first place. Vitamin E appears to be concentrated in the normal macula and reduced in the abnormal. Beta-carotene (BC) not only splits to form retinal, a part of rhodopsin, the light detecting trigger of the eye, but has antioxidant properties as well. Vitamin C may also be a protective antioxidant while lutein and zeaxanthin, barely distinguishable from BC, become photo-protective elements in the Retinal Pigment Epithelium (RPE) in the back of the retina.
Here is a list of the USDA SR-13 top scorers for lutein & zeaxanthin (L&Z). Most of these are also good vitamin C, E, and BC sources but with the exception of wheat germ (vitamin E) no grain product had any at all. The first animal food, egg, came in # 50 with 55 mcg/100gm.
According to the National 5-A-Day Committee, only 36% of the U.S. public is aware they should be consuming the recommended 5 servings of fruits and vegetables daily. USDA figures show that the actual food consumption of the American public looks more like the food pyramid turned upside down with ~ 66% of Calories coming from animal foods and grains, and only 34% from vegetables and fruit. U.S. and world agriculture has always been heavily based on grains, either consumed directly, or fed to animals that are then consumed, but neither grains nor any animal food contain more than a trace of vitamins C, E, BC, lutein, or zeaxanthan. Perhaps this is the real reason that AMD is on the rise.
1. Dietary carotenoids, vitamins A, C, and E, and advanced age related macular degeneration. Eye Disease Case Control Study Group. JAMA Nov 9 1994, 272 (18) p1413 20, ISSN 0098 7484
Seddon JM; Ajani UA; Sperduto RD; et al.
A.. Adjusting for other risk factors for AMD, we found that those in the highest quintile of carotenoid intake had a 43% lower risk for AMD compared with those in the lowest quintile (odds ratio, 0.57; 95% confidence interval, 0.35 to 0.92; P for trend = .02). Among the specific carotenoids, lutein and zeaxanthin, which are primarily obtained from dark green, leafy vegetables, were most strongly associated with a reduced risk for AMD (P for trend = .001).@
2.For an excellent 65 slide description of ARMD go to:
http://www.eyesight.org/Pictorials/Pic Slide_Show/pic slide_show.html
3. Goodwin and Mercer. Introduction to Plant Biochemistry. Pergamon Press. Oxford, 1983. p99
(for the subtle differences in carotenoid molecular structures).