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DGDispatch
AREDS II to Answer Questions Raised by AREDS: Presented at AAO
By Pippa Wysong
CHICAGO, IL -- October 26, 2005 -- The Age-Related Eye Diseases Study (AREDS), a large, multi-center trial which investigated the use of high-dose antioxidants on age-related macular degeneration (AMD) is coming to a close in December 2005. Researchers are now moving towards the start of AREDS II.
"As AREDS draws to a close, a number of scientific questions remain unanswered," said Emily Chew, MD, Deputy Director of Epidemiology and Clinical Research, National Eye Institute, Bethesda, Maryland, United States.
She outlined the rationale and design of AREDS II, October 14th at the American Academy of Ophthalmology (AAO).
The regimen consisted of vitamin C 500 mg, vitamin E 400 IU, beta-carotene 15 mg, zinc oxide 80 mg and cupric acid 2 mg.
AREDS demonstrated that oral supplementation with high-dose antioxidant vitamins and minerals decrease by 25% the risk of advanced AMD. After 5 years, patients on the regimen decreased by 19% their risk of moderate vision loss compared to placebo.
Other studies have suggested that people with a lower dietary intake of certain micronutrients, especially lutein and omega-3 fatty acids, have increased risks associated with AMD.
The primary objective of AREDS II is to determine whether progression to advanced AMD will decrease with oral supplementation of lutein and omega-3 fatty acids. The supplements will consist of macular xanthophyllis (lutein at 10 mg/day plus zeaxanthin at 2 mg/day), and/or omega-3 fatty acids at a total of 1 g/day.
Lutein and omega-3 "are of particular interest because of the mounting epidemiologic data that suggests that nutrients are associated with a decreased risk of AMD," Dr. Chew said. In AREDS II patients will be divided into three treatment groups plus one placebo group.
AREDS II will also attempt to refine the AREDS formulation. One change will be to remove beta-carotene from the regimen, another will be to investigate lower zinc levels in some patients.
There is concern over beta-carotene since two large trials showed it is associated with an increased risk of lung cancer among smokers. The AREDS formulation is not recommended for smokers.
As for zinc, the AREDS dose of 80 mg was initially chosen because of its reported benefits in small trials. "This is the largest dose of zinc and the longest duration of zinc supplements ever given, even though it is considered twice the upper tolerable level established by the Institute of Medicine," Dr. Chew said.
There is some concern in the scientific community that there may be a relationship between zinc and Alzheimer's Disease. On the other hand, AREDS showed a small association with decreased mortality among patients who took the high zinc dosage. In AREDS II, half the participants taking zinc will get the 80 mg dose while the other half will take 40 mg.
It is hoped that AREDS II will clarify questions about dosages as well as the use of other supplements, Dr. Chew said.
[Presentation title: AREDS II. Retina Sub-specialty Day]
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