(from June, 2006) The Second Age-Related Eye Disease Study (AREDS 2)
AREDS 2 Slated to Get Underway
One of the most influential studies of the past decade is about to have a sequel. The Age-Related Eye Disease Study (AREDS), published in late 2001, was the first large-scale trial to demonstrate that supplementation with antioxidant nutrients can help slow the progression of age-related macular degeneration (AMD) and it's associated vision loss.
AREDS found that a combination of vitamins C, E, beta-carotene, zinc and copper lowered the risk of advanced AMD by 25% in high-risk patients. No effects of this antioxidant combination were observed in people without signs of the disease or with early AMD. Subjects without AMD didn't receive zinc - a mineral that also lowered the risk of AMD progressing when given alone to higher risk patients.
Lutein, Zeaxanthin and Omega-3 Fatty Acids
Now, researchers at the National Eye Institute (NEI) are gearing up to assess the impact of other nutrients that have emerged as potentially beneficial since the first AREDS study began: lutein, zeaxanthin and the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Lutein and zeaxanthin are thought to shield the macula and retina from oxidative stress generated by exposure to light.
EPA and DHA, fatty acids that are present in cold-water fish, also play important roles in the eye. According to a review by the NEI, these fatty acids lessen the effects of exposure to light, stress, inflammation and other factors. DHA is also a major component of photoreceptors (rods and cones).
When researchers analyzed the dietary intake of participants in the original AREDS trial, they found that those with the highest intake of DHA had a 50% lower risk of advanced AMD, and those consuming the most EPA had nearly the same 50% decrease in their risk of developing advanced geographic atrophy (a severe form of "dry" AMD). The investigators also studied patients' intake of lutein and zeaxanthin, finding that those with the highest intake had a 50% lower risk of developing new AMD during the trial compared to the control group. For people with high intakes and elevated blood levels of lutein and zeaxanthin, a decreased risk of both neovascular (wet AMD) and dry AMD was observed.
Wet AMD, characterized by leaky blood vessels behind the retina, is considered advanced-stage AMD, while the dry AMD develops slowly over time as light sensitive macular cells degenerate. There are several stages of dry AMD, including early, intermediate and advanced. Dry AMD is more common than the wet form, though wet AMD is usually more severe.
The Next Phase: AREDS 2
The new trial will be a multi-center, randomized study of 4000 participants aged 55 to 80 who have large drusen (yellow-white "spots under the retina) or advanced AMD in one eye. Participants will receive one of four supplements: either placebo, 10 mg of lutein along with 2 mg of zeaxanthin, 1 g of DHA and EPA, or a combination of the lutein, zeaxanthin, DHA and EPA.
AREDS 2 will start recruiting patients in 2006, with a 24-month recruiting period and 5 years of following participants. In addition, the investigators will evaluate a new version of the original AREDS supplements with a reduced level of zinc and without beta-carotene. While the main focus of AREDS II will be on AMD and cataract, the researchers also hope to learn more about the effects of EPA and DHA on mental function.
We won't know the results of AREDS 2 for a number of years. But in the meantime, it makes good sense to keep eating a diet rich in fruits and vegetables for antioxidant nutrients, especially dark green leafy veggies which are good sources of lutein, and to eat fish at least 2-3 times weekly for their heart-healthy omega-3 fats. And if your eye care practitioner has recommended that you take supplements of the original AREDS nutrients, be sure to follow that advice.
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