Oxidative stability of fish oil dietary supplements and their cytotoxic effect on cultured human keratinocytes

Commercially available fish oil supplements (FOS) are rich in n-3 polyunsaturated fatty acids (n-3 PUFAs) and have been prescribed as complementary therapy to reduce symptoms in many inflammatory skin diseases. The objective of this study was to assess the PUFAs content, oxidative stability and investigate the inhibitory effects on immortalized human keratinocytes (HaCaT) cell growth of FOS commercialized in Brazil. The fatty acids composition, analyzed by gas chromatography, was similar for all the capsules (comprising up to 30% n-3 PUFAs) and underwent no significant alteration during the storage period (9, 12, 18 and 24 months). Primary (peroxide), secondary (anisidine), and total oxidation products levels of only two FOS exceeded the maximum established by international quality standards, however, it is recommendable that the storage period should not exceed 18 months at the ambient temperature. Some products exhibited dose-dependent inhibitory effects on HaCaT proliferation.