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26-03-2013 | Ophthalmology | Article

Supplementation shows early promise in AMD


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medwireNews: Dietary supplementation with a combination of lutein, zeaxanthin, and omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) has a range of potentially beneficial effects in people with age-related macular degeneration (AMD), results from a clinical trial have found.

The supplement significantly improved plasma antioxidant capacity, circulating macular xanthophyll levels, and optical density of the macular pigment, report Volker Böhm (Friedrich Schiller University Jena, Germany) and team in JAMA Ophthalmology.

However, they admit it remains to be determined whether the supplement can slow the progression of AMD and note that "interpretation of the present analysis remains speculative."

The LUTEGA study included 172 patients with nonexudative AMD who were randomly assigned to take either a single capsule containing 10 mg of lutein, 1 mg of zeaxanthin, 100 mg of docosahexaenoic acid, and 30 mg of eicosapentaenoic acid; a single capsule containing the same four substances but at double the dose; or a matching placebo capsule once daily for 12 months.

At baseline, all patients had comparable plasma levels of lutein and zeaxanthin. After 1 month of therapy, plasma levels of both carotenoids had risen significantly in the groups taking active treatment, but were unchanged in those taking placebo.

In the standard-dose group, plasma levels of lutein rose from 0.22 to 0.60 µmol/L and zeaxanthin levels rose from 0.045 to 0.060 µmol/L. A similar magnitude of increase was seen in the double-dose group; in both groups, levels peaked at around 1 month and were stable thereafter.

Analysis of plasma from a subgroup of 30 random participants revealed that lipophilic antioxidant capacity rose significantly among participants who took the supplement but was unchanged in those who took placebo. Hydrophilic antioxidant capacity remained the same in all patients.

Finally, the optical density of the macular pigment increased significantly, and by a similar magnitude, in the two groups that took the supplement but was unchanged in the placebo group.

Böhm and co-authors note that their findings support using the lower-dose supplement and also remark that "harmful effects associated with high-dose antioxidant supplementation cannot be ruled out (especially for smokers)."

They conclude: "With this, and the limitations of the study, no general implications for clinical practice can be given… Trials evaluating different categories of individuals (healthy people at risk for AMD and those with early, intermediate, or late stages of the disease) are required, since it seems likely that the potential protective effects of macular xanthophylls and omega-3 LC-PUFAs depend on the stage of the disease."

By Joanna Lyford, Senior medwireNews Reporter

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