Assessment of fish oil containing food supplements in terms of oxidative quality and heavy metal

Fish oil supplements, rich in ω3 long-chain polyunsaturated fatty acids, are among the most widely used nutritional supplements worldwide and are regularly consumed by millions of people. Because fish oil supplements are highly susceptible to oxidative degradation and may contain heavy metals, the safety and quality of these products are extremely significant to public health. The aim of this study was to determine the fatty acid composition of top-selling fish oil dietary supplements in the markets for comparison with the claimed content on the product label, and to assess of the oxidative qualities and heavy metal contents. In this study, ten brands of fish oil capsules (K) and ten brands of fish oil syrup (S) were investigated. While all the capsule groups confirmed the label information, it was observed that one third of the syrup groups had less than the specified content. The PV of all fish oil capsules and syrups were found in the range of 1.97-2.89 mEq/kg and 2.22-18.30 mEq/kg, respectively. As for FFA values, it was observed that the K4, S6, S9 and S10 groups were above the 3% oleic acid limit recommended for high quality oils. However, TBARs values were found below 1 mg MA/kg in all groups. All fish oil supplements examined in this study were within the limits specified in terms of As (0.50-4.19 µg/g), Cd (0.14 µg/g detected for one group, K5), Cu (not detected), Fe (0.32-15.7 µg/g) and Hg (≤ 0.1 µg/g). On the other hand, two fish oil supplements from the capsule group (0.17 for K6 and 1.01 µg/g for K8) and one group from the syrup group (0.29 µg/g for S10) exceeded the recommended limit in terms of Pb (0.1 mg/kg). It can be concluded that the chemical quality of fish oils in syrup form needs to be improved and their reliability in terms of content should be increased. Considering the heavy metals, it seems important to follow up the fish oil products more strictly.