Varying quality of fish oil capsules: fatty acids and tocopherol.

OBJECTIVES: To assess the content and composition of fatty acids and tocopherols in commercially available oil capsules, and to assay thiobarbituric acid reactive substances (TBARS) as a marker of oxidation in these oils.

METHODS: Fish and seal oil capsules were analyzed for their contents of long-chain omega-3 fatty acids (DPA, EPA, and DHA), tocopherols, and malondialdehyde.

RESULTS: Large variations were found in the levels of EPA (6.5-40.9%), and DHA (8.1-26.4%), α-tocopherol (117-10282 μg/g), γ-tocopherol (406-2352 μg/g) and δ-tocopherol (127-978 μg/g). The level of malondialdehyde was very low in all capsules.

CONCLUSION: The tested samples of oil capsules showed large variation in quality with respect to long-chain n-3 polyunsaturated fatty acids and tocopherols. The low levels of malondialdehyde indicated a successful oxidation protection strategy.