Content and composition of fatty acids in marine oil omega-3 supplements.

Marine oil omega-3 supplements are among the most frequently consumed dietary supplements in the United States. However, few studies have evaluated the overall fatty acid composition of these products. We investigated the content and composition of fatty acids in 46 commercially available marine oil omega-3 supplements by gas chromatography with flame ionization detection using the 200 m SLB-IL111 ionic liquid column. Seventy-three fatty acid isomers were quantified, including n-6, n-4, n-3, and n-1 polyunsaturated fatty acids and trans isomers of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3), the chromatographic separations of which we report for the first time on the 200 m SLB-IL111 column. Contents of EPA and DHA met their respective label declarations in more than 80% of the products examined. Eleven of the products (24%) carried the Food and Drug Administration's qualified health claim for EPA and DHA omega-3 fatty acids.