For many years, people suffering from dry eye disease have turned to omega-3 fatty acid supplements to help relive their symptoms. According to a new study funded by the US National Eye Institute (NEI), however, such supplements make virtually no difference.

The study was conducted at 27 centers throughout the US, and involved 535 people who had suffered moderate to severe dry eye for at least six months.

Out of those people, 349 were randomly selected to receive 3 grams of fish-derived omega-3 fatty acids per day, in five capsules. Each of these daily doses consisted of 2,000 mg of eicosapentaenoic acid (EPA) and 1,000 mg of docosahexaenoic acid (DHA) – the highest dosage ever tested for the treatment of dry eye.

The other 186 people were put in a placebo group, receiving 5-gram daily doses of olive oil in capsules identical to those used for the omega-3s. Neither the test subjects nor the researchers administering the supplements knew which people were in which group. Members of both groups were free to keep using other dry eye remedies, such as artificial tears and prescription anti-inflammatory eye drops.

After 12 months, patient-reported mean symptom scores for both groups improved, although there was no significant difference between the two in the amount of improvement – 13.9 points out of a possible 100 for the omega-3 group, and 12.5 for the placebo group. Additionally, clinicians saw no notable difference between the groups when examining participants' eyes using standardized tests.

"The trial provides the most reliable and generalizable evidence thus far on omega-3 supplementation for dry eye disease," says Maryann Redford, the NEI's program officer for clinical research. "This well-controlled investigation conducted by the independently-led Dry Eye Assessment and Management (DREAM) Research Group shows that omega-3 supplements are no better than placebo for typical patients who suffer from dry eye."

The results of the study were published this Friday in the New England Journal of Medicine.

Sources: National Eye Institute/National Institutes of Health, University of Pennsylvania School of Medicine, Mount Sinai Hospital via EurekAlert