Oxidative stability of Commercial Omega-3 Supplements – A comparative study of three products available on the Swedish market

Sammanfattning

Introduction: Omega-3 fatty acid supplements are widely used as an alternative to eating oily fish. However the polyunsaturated oils they contain are highly susceptible to oxidation, which can lead to rancidity and possibly decreased quality of the supplement. Background: Despite the convenience of omega-3 supplementation, there is limited independent information on the oxidative quality of products available on the Swedish market and how everyday storage conditions affect their stability over time. Aim(s): The aim of this study was to compare initial oxidation status of three commercial omega-3 supplements (Elixir Pharma, Biosalma and Puori) and evaluate how different storage conditions affect the peroxide value (PV), anisidine value (AV) and the total oxidation value (TOTOX) over four weeks. Methods: Oxidation parameters were measured in triplicates using established titration and spectrophotometric methods from European Pharmacopoeia. Capsules were stored under four conditions: fridge (5°C), room temperature in darkness, room temperature with sunlight exposure, and elevated temperature (37°C). Results: All products, except for Puori, showed acceptable initial oxidation levels. Biosalma showed highest stability with minimal changes across conditions. Elixir Pharma exhibited moderate increases in PV and TOTOX, under warmth and sunlight. Puori displayed significantly elevated AV, likely attributed to presence of aldehydic compounds from the flavoring agents, but presented lowest PV value of all. Most values remained within GOED recommended limits (PV ≤ 5 milliequivalents peroxide oxygen per kilogram oil (meq O₂/kg), AV ≤ 20, TOTOX ≤ 26), none exceeded drastically. Conclusion: The tested commercial omega-3 supplements are generally of acceptable oxidative quality upon purchase and when stored properly, with refrigeration being most effective. Keywords: omega-3, fish oil, oxidative stability, peroxide value, anisidine value, TOTOX