Diet and Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the #1 cause of blindness for people who are age 55 years or older in the United States. By 2020 it is estimated that perhaps 3 million Americans will have late-stage AMD in which there is a significant loss of their central vision.

In effect they have a blind spot in the middle of their visual field making reading, driving, and face recognition difficult if not impossible.About 90% have what doctors call the “dry” form of the disease for which there is no effective drugs or surgical treatments. The much less common “wet” form of AMD can be slowed with surgery including laser treatments but there is no lasting cure.The macular is the central part of the retina with densely packed cone cells that allow for detailed color vision in the center of your visual field. It is protected from ultraviolet and even blue light waves that can damage these cone cells by a pigmented layer. Certain plant chemicals such as lutein and zeaxanthin are found in this pigmented layer. They help screen out UV rays and excessive blue wavelength light that can damage the cone cells directly or perhaps by forming free radicals. As most Americans age, much of this pigmented layer wears out and the cone cells become increasingly susceptible to the damaging effect of sunlight as well as chemicals found in the blood. Vitamins C & E, and perhaps other antioxidant phytochemicals, appear to slow down the disease process. By contrast smoking, diabetes, dyslipidemia, and high blood pressure all increase the risk of AMD.Data from the Nurses’ Health Study found that the 20% with the highest fat intakes were 54% more likely to develop AMD over time than the 20% of nurses with lowest fat intake.1However, growing evidence indicates some dietary fat sources are protective. Indeed, data from this earlier study found omega-3 fatty acids from fish cut the risk of AMD. More recently two studies from Australia confirmed the potential protective role of eating more fish rich in omega-3s. One study that followed 2,454 subjects for 10 years found that one serving of fish per week cut the risk of early AMD by 31%.They also observed that eating 1-2 servings of nuts per week was associated with a 35% reduced risk of early AMD.2 The authors conclude “…. Our findings support the hypothesis that increased omega-3 polyunsaturated fatty acids and regular consumption of fish and/or nuts in the diet may protect against the development of early AMD. These fatty acids may protect the eyes by preventing the buildup of plaque in the arteries or reducing inflammation, blood vessel formation and oxygen-related cell damage in the retina.”In another study that examined the impact of different types of fat on the risk of developing AMD, Dr. Chong followed 6,734 people aged 58 to 69 for about 10 years. She found the 25% consuming the most trans fat had a 76% increased risk of developing AMD compared to the 25% consuming the least trans fat during that time. These researchers also observed that regular consumption of olive oil was associated with a 52% reduced risk of developing AMD even though monounsaturated fat it self was not associated with AMD risk. This suggests that perhaps antioxidant phytochemicals such as polyphenols found that in extra virgin olive oil might help reduce damage to the macular. They also observed a reduced risk of AMD with more omega-3s. The authors conclude: “A diet low in trans-unsaturated fat and rich in omega-3 fatty acids and olive oil may reduce the risk of AMD.”3Bottom Line: A little of the right fat is good. This includes fat from extra virgin olive oil, nuts and omega-3 rich fish (salmon, trout, tuna, mackerel). It just takes one to two servings of each per week according to recent studies. By including these fats in your diet in small amounts while largely avoiding fats from meat and dairy products and refined oils, you are assured of an adequate intake of essential fatty acids without getting so much total fat that promotes weight, diabetes, CVD, some cancers as well as AMD.

By James J. Kenney, PhD, RD, FACNReferences:1 Am J Clin Nutr 2001;73:209-182 Arch Ophthalmol 2009;127:656-653 Arch Ophthalmol 2009;127:674-80