Macular Degeneration: Blind form the Western Diet
By: John McDougall M.D.
www.drmcdougall.com
Like other degenerative diseases – heart disease, stroke, arthritis – age-related macular degeneration (AMD) is due primarily to our diet and secondarily to our lifestyle – therefore easily preventable, and to some extent reversible. This form of eye disease is the leading cause of blindness in people age 64 or older living in Western countries. The severe form with impairment of vision affects 1.7 million people in the United States, with 200,000 new cases annually. Characteristically, this is a disease of progressive, painless, loss of the central vision in the macula of both eyes simultaneously. The macula is the part of the retina which provides our most acute and detailed vision, and is used for visual activities, like reading, driving, recognizing faces, watching television, and other fine work.
Multiple studies clearly show that the same risk factors that predict the development and progression of coronary artery disease (heart disease) also predict the chance of you losing your eyesight from AMD:
* Overweight people have more than twice the risk of progression of this disease from the mild form, which affects nearly 8 million people in the United States, to the severe blinding form over the next 5 years.1 Other common risk factors shared by both diseases are cigarette smoking, lack of exercise, high cholesterol, and hypertension.1
* A Diet high in all kinds fats, including animal, trans-fats (margarines, shortenings), monounsaturated fats (olive oil), and other vegetable fats, increases the risk of developing AMD by two to three times compared to a diet low in fat.2,3
* A diet low in fruits and vegetables is associated with an increased risk of AMD.4
* Vigorous physical activity decreases the risk of AMD.1
* As people in underdeveloped countries, for example Japan, Taiwan and China, switch from their native diets based on starches (like rice) to Western diets their risk of AMD increases parallel to their risk of heart disease.5
AMD is a Form of Atherosclerosis from the Western Diet
Disease of the arteries, known as atherosclerosis, is so common in Western societies that it is considered a normal part of aging. However, this disease is rare or unknown in parts of the world where people consume a diet based on starches, vegetables and fruits. The underlying mechanism involves the depositing of cholesterol and fat from the diet into the walls of the arteries.6 In smaller vessels, such as in the eye, this process results in stiffening of the walls, inflammation of the vessels, a decrease in blood flow, and finally leakage of fluids through the vessel walls into surrounding tissues. The average blood flow reduction in people with AMD is 37% compared to people without this disease.7 The end result is deprivation of oxygen and nutrients to the visual tissues of the eye found in the retina and concentrated in the macula – and the receptors of light and color (rods and cones) soon become nonfunctional and die.
Preserving Your Sight
The commercial solution to AMD is to take vitamin and mineral supplements. One recent study found supplements containing vitamins C and E, beta carotene, and zinc resulted in a 25% reduction in the risk of the intermediate stages of AMD progressing to the advanced stages within 5 years.8 Despite this one study, a more honest conclusion is: in the face of intensive marketing, high profits, doctors’ recommendations, and widespread use, no supplement has been found to be effective at preventing AMD or delaying its complications.6 (A related story of supplements failing heart disease patients is found in my August 2003 Newsletter article, “Plants, not Pills, for Vitamins and Minerals.”)
The simple, cost-free, side-effect-free, non-profitable solution for preserving your sight for a lifetime is the same one you should be presently using to preserve the circulation to your heart, brain, kidneys, etc. – a healthy low-fat, no-cholesterol diet, moderate exercise, and clean habits. As a secondary therapeutic approach for some people with elevated blood cholesterol levels (above 150 mg/dl), I recommend cholesterol-lowering medications. (More information on this subject can be found in my September 2002 newsletter article, “Cholesterol - When and How to Treat” and my June 2003 Newsletter article “Cleaning out Your Arteries.”)
Even if you have already started to lose your vision it is not too late. Treatment of blood cholesterol and triglyceride levels has been shown to improve vision in a person with very high levels of blood fat (triglycerides).9 Circulation to the eye and the rest of the body is improved immediately after switching from a high-fat to a low-fat diet.10,11 The underlying disease, atherosclerosis, is also reversible in time.12 Inflammation subsides and cholesterol and fat deposits are removed from the artery walls. The damage left from meat- and dairy-laden forks and spoons is the scarred tissue (sclerosis) that has forever lost its ability to distinguish light. The sooner you make long overdue changes in your diet the better sight you will have in your later years.
References:
1) Seddon JM. Progression of age-related macular degeneration: association with body mass index, waist circumference, and waist-hip ratio. Arch Ophthalmol. 2003 Jun;121(6):785-92.
2) Seddon JM. Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake. Arch Ophthalmol. 2003 Dec;121(12):1728-37.
3) Cho E. Prospective study of dietary fat and the risk of age-related macular degeneration. Am J Clin Nutr. 2001 Feb;73(2):209-18.
4) Mozaffarieh M. The role of the carotenoids, lutein and zeaxanthin, in protecting against age-related macular degeneration: A review based on controversial evidence.
Nutr J. 2003 Dec 112:20-30.
5) Bird AC. What is the future of research in age-related macular disease? Arch Ophthalmol. 1997 Oct;115(10):1311-3.
6) Friedman E. The role of the atherosclerotic process in the pathogenesis of age-related macular degeneration. Am J Ophthalmol. 2000 Nov;130(5):658-63.
7) Grunwald JE. Foveolar choroidal blood flow in age-related macular degeneration.
Invest Ophthalmol Vis Sci. 1998 Feb;39(2):385-90.
8) Seddon JM. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9;272(18):1413-20.
9) Nagra PK. Lipemia retinalis associated with branch retinal vein occlusion. Am J Ophthalmol. 2003 Apr;135(4):539-42.
10) Friedman M. Serum Lipids and conjunctival circulation after fat ingestion in men exhibiting type-A behavior pattern. Circulation 29:874 874-86, 1964.
11) Kuo P. The effect of lipemia upon coronary and peripheral arterial circulation in patients with essential hyperlipemia. Am J Med. 26:68, 1959.
12) Ornish D . Intensive lifestyle changes for reversal of coronary heart disease.
JAMA. 1998 Dec 16;280(23):2001-7.
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