Fish oil doesn’t appear to be of any help in treating multiple sclerosis, Norwegian researchers found.

In a randomized controlled trial, supplementation with omega-3 fatty acids had no effect on the number of brain lesions seen on MRI over two years compared with placebo, Oivind Torkildsen, MD, PhD, of Haukeland University Hospital in Norway, and colleagues reported online in the Archives of Neurology.

Though the Norwegian diet is usually associated with high levels of fish intake, Torkildsen told MedPage Today that serum omega-3 levels in the placebo group were low to normal, “which indicates that their fish intake was not higher than would be expected in other populations,” and that those in the supplementation group did indeed see a rise in omega-3 levels while the placebo group did not.

Smaller trials have found a potential benefit for omega-3 fatty acids, which may be active in MS because of their anti-inflammatory and neuroprotective properties. But controlled trials haven’t been able to draw any definitive conclusions, the researchers said. Still, fish oils are the most common form of complementary medicine used by MS patients, they noted. So Torkildsen and colleagues conducted a randomized, double-blind, placebo-controlled trial at 13 public neurology departments in Norway totaling 92 patients ages 18 to 55 with relapsing-remitting MS. Patients were given either 1,350 mg of eicosapentaenoic acid (EPA) and 850 mg docosahexaenoic acid (DHA) every day, or placebo. After the first 6 months of the trial, all patients were also given 44 mcg of interferon beta-1a three times a week for another 18 months. The researchers found that at all time points - 6, 9, and 24 months - there were no differences in the number of gadolinium-enhancing MRI lesions between groups. At 6 months, the median number of new lesions was three in the omega-3 group compared with two in the placebo group, which wasn’t a significant difference. Nor were there any significant between-group differences at 9 and 24 months, after patients started on interferon, they reported. In fact, the lesion rate ratio was significantly lower after interferon treatment, they said (P<0.001). "As expected, the MRI disease activity was significantly reduced when interferon beta-1a was introduced," they wrote. There were no differences in relapse rates at any time point, and the proportion of patients who had no progression in disability was 70% in both groups, the researchers wrote. Nor were there any differences in functionality, fatigue, or quality of life scores, they added. Torkildsen and colleagues confirmed that patients were getting omega-3s via blood test and found that serum fatty acid levels were indeed higher in the supplementation group (P<0.001). The study was limited because the sample size lacked the statistical power to detect small and medium treatment effect sizes. The researchers also noted that the corn oil capsules used as placebo contained 52% linoleic acid, 33% oleic acid, and 13% saturated acids - the first two of which are fatty acids with anti-inflammatory properties. The dose was minor, however, compared with a usual diet and lower than intervention studies with omega-6 acids, they said. Besides, they wrote, regular daily intake of linoleic and oleic acid in Norway is already high, so the amount in the placebo adds an insignificant amount to total intake. Overall, they concluded that omega-3 fatty acids have no beneficial effects on disease activity in MS, either as monotherapy or in combination with interferon beta-1a.