Discuss Ways to Decrease AMD Risk Factors With Patients
By Leo Semes, OD, FAAO
The number of blind persons in the United States is projected to increase by 70 percent to 1.6 million by 2020, with a similar rise projected for low vision (Congdon et al, 2004). This prophecy is from an article published nearly eight years ago. How and can we make a dent in those numbers?
The role of nutrition and diet has become the focus of a number of studies including the Age-Related Eye Disease Study Research Group (AREDS, 2005) and the ongoing AREDS 2. To date, what guidelines are there for patient recommendations?
Consistent recommendations include the following:
• Pro-inflammatory fatty acids from food intake activate the complement cascade that results in oxidative damage to cell membranes. This may be counteracted by reducing reactive oxidative species in the outer retina with dietary modification or selected supplement intake.
• Zinc may play a protective role by interrupting the complement cascade.
• Omega-3 fatty acids may reduce up-regulation of C-reactive protein (CRP).
• Beta-carotene has been suggested to be beneficial in the AREDS as it is inversely related to CRP and other pro-inflammatory levels (Ho et al, 2011; Mozaffarian and Wu, 2011; San-Giovanni et al, 2007).
Nutrition and Supplements
Eating a healthy diet should be the base of any preventive strategy. Recommending reduction of pro-inflammatory foods is a good start. This includes minimizing intake of sugars, trans fats, red meat, processed flour products, and artificial food additives (Seddon et al, 2003). Making these recommendations may be difficult, and patients may expect to reverse the effects of decades of poor nutrition with supplements. Improving the diet may short-circuit the inflammatory cascade that is thought to initiate macular changes.
While no nutritional supplement can replace a proper diet, some suggestions may be reasonable. The Rotterdam study recommends an antioxidant cocktail including vitamins C and E, betacarotene, lutein/zeaxanthin, zinc, and omega-3s via either dietary intake or supplements (Ho et al, 2011). While beta-carotene is controversial, omega-3s are emerging as significant anti-inflammatory components in the diet. Early evidence from the AREDS 2 study suggests their significance (Mozaffarian and Wu, 2011; Bressler et al, 2003). The American College of Cardiology recommends that adults consume at least 250mg/day of long-chain n-3 PUFA (polyunsaturated fatty acids) or at least two servings/week of oily fish (Mozaffarian and Wu, 2011). What is good for the circulatory system will likely prove to benefit the retina. While AREDS 2 eliminates beta-carotene, one arm includes 1000mg long-chain n-3 PUFA as well as lutein/zeaxanthin. Lutein and zeaxanthin are included for their antioxidant properties as well as so-called filtration effects from deposition in the macula's inner layers.
Changing the Future
We can emphasize the wellknown alterable risk factors for AMD including smoking and zinc deficiency. We should also recommend protection for those at highest risk of environmental sunlight exposure and follow the recommendations for diet outlined here. The impact of the original AREDS formulation alone has been estimated to be significant (Bresler et al, 2003). Let's keep the pressure on. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #195.
|Dr. Semes is a professor of optometry at the UAB School of Optometry. He is also a consultant or advisor to Alcon, Allergan, Optovue, and Zeiss.|