In the news: Higher Plasma DHA & EPA + DHA Tied to Lower Risk of Early AMD

Background: DHA, EPA and Early AMD

Over the last two decades, there has been increasing interest in the role of the long-chain fatty acids DHA and EPA in the development and prevention of age-related macular degeneration (AMD). DHA is a major structural component of retinal photoreceptor membranes as well as retinal vascular tissue, and ocular tissue from deceased donors with a history of AMD has shown a significant reduction in DHA compared to age-matched controls.

Additionally, several case-control, cross-sectional, and large cohort studies have reported an association between dietary DHA and EPA and reduced risk for developing AMD and/or AMD progression.

Despite this large body of evidence, the Age-Related Eye Disease Study 2 (AREDS 2) found no risk reduction (beyond that of the AREDS 1 formula) for progression to advanced AMD with DHA and EPA supplementation. AREDS2, however, included only people with intermediate AMD in both eyes or intermediate AMD in one eye and advanced AMD in the other.

The relationship of the omega-3 fatty acids and early AMD remains unclear.

To shed more light on this relationship, researchers from the University of Minnesota, University of Wisconsin and Wake Forest School of Medicine examined the association between DHA and EPA and AMD in a multi-ethnic population.

Notably, the study(1) represents the first to show a link between omega-3 fatty acids and AMD risk in a racially diverse population.

Design and Methods

This prospective study was conducted among participants of the Multi-ethnic Study of Atherosclerosis (MESA). MESA is a multi-center, cohort study designed to identify risk factors for cardiovascular disease in four ethnic groups: white, African American, Hispanic/Latino, and Chinese descent aged 45 – 84 years, and without cardio-vascular disease.

The study population included all MESA participants with baseline polyunsaturated fatty acid (PUFA) measurements and retinal photography at exam 5 (n = 3,772). Fundus photographs were assessed for AMD using a standard grading protocol. Relative risk regression determined associations between PUFA levels and AMD.

Results

Two hundred fourteen participants were determined to have early AMD, of which 46% were non-white.

The researchers found a significant association between increasing plasma DHA levels and increasing DHA + EPA levels with reduced risk for early AMD. EPA levels alone were not significantly associated with AMD.

Specifically, individuals in the two highest quartiles for DHA levels had a 40 – 50% risk reduction for early AMD, and AMD risk declined with increasing quartiles of DHA. Similarly for DHA+EPA, the highest two quartiles showed a risk reduction ranging from 41 – 53% for early AMD.

Comment

Several aspects of this study lend credence to its findings. First, most prior studies on DHA/EPA and AMD have relied on dietary intake estimates (often underestimated), rather than direct plasma measurements of PUFAs (more accurate). Additionally, the multi-ethnic make-up of the participants makes the findings more applicable to the general population.

References

1. Karger AB, et al. Association of plasma ω-3 fatty acids with early age-related macular degeneration in the Multi-Ethnic Study of Atherosclerosis (MESA). Retina. Epub March 9, 2022.