Role for Omega-3s in Prevention of AMD?

Omega-3s May Reduce Risk of AMD in Women

While an AREDS-tested antioxidant supplement has been shown to slow progression in people with intermediate AMD, there is no recognized means of prevention for those currently free of the disease or the estimated 7.3 million Americans with early AMD.

Evidence from observational studies suggests that regular dietary intake of fish, DHA and EPA may reduce AMD risk. In fact, the randomized trial, AREDS-2, is currently evaluating whether supplemental DHA and EPA can lower the risk of progression to advanced AMD. However, the available data for early AMD are limited and inconsistent.

To increase that evidence base, a team of Harvard University researchers has examined the relationship between omega-3, fish consumption and AMD in a large cohort of women health professionals who were free of the disease at the study’s start.

The researchers now report that regular consumption of EPA, DHA and fish is associated with a 34-42% risk reduction of visually significant AMD incidence. They conclude that consistent omega-3 consumption may be of benefit in the primary prevention of AMD.

Design

In this prospective study, dietary information was obtained by food-frequency questionnaire at baseline for 39,876 health professionals who participated in the Women’s Health Study. A total of 38,022 women, 54 years of age on average and free of a diagnosis of AMD, completed the questionnaire and were followed for an average of 10 years.

The main outcome measure was incident AMD responsible for a reduction in best corrected visual acuity to 20/30 or worse, based on self-report confirmed by medical record review.

Results

A total of 235 cases of AMD, most characterized by some combination of drusen and retinal pigment epithelial changes, were confirmed during an average 10 years of follow-up.

Women in the highest 1/3 of intake for DHA, compared with those in the lowest, had a multivariate-adjusted 38% lower risk of AMD (RR 0.62, 95% confidence interval 0.44-0.87).

For EPA, women in the highest tertile had a 34% reduced risk (RR 0.66, 95% confidence interval 0.48-0.92).

Consistent with the findings for DHA and EPA, a 42% lower risk was observed in women who consumed 1 or more servings of fish weekly compared to those consuming less than 1 serving monthly (RR 0.58 95% confidence interval, 0.38-0.87).

Comments

There are many mechanisms by which omega-3s could affect AMD occurrence. For example, they have been shown to protect against the damaging effects of blue light in the parafovea.

DHA and EPA may also contribute to macular protection by modulating inflammatory and immune processes thought to play a role in AMD pathogenesis. They enhance production of resolvins and neuroprotectins—compounds thought to dampen and resolve inflammatory responses. EPA and DHA also affect the expression of signal transduction genes and genes for pro-inflammatory cytokines.

These findings by WG Christen and his colleagues are broadly consistent with previously published findings, and appear to be the strongest observational evidence to date in support of a role for omega-3 and fish intake in the primary prevention of AMD.

Because early AMD is associated with an increased risk of developing advanced AMD, these data also suggest that regular omega-3 intake could ultimately reduce the number of persons who have advanced AMD.

References

1. Christen WG et al. Dietary omega-3 Fatty Acid and Fish Intake and Incident Age-Related Macular Degeneration in Women. Archives of Ophthalmology, Published online March 14, 2011.