Study
Fishing for Answers: Is Oxidation of Fish Oil Supplements a Problem?
50% of 171 fish oil supplements exceeded voluntary oxidation limits, and 39% exceeded TOTOX safety recommendations.
Summary How often are fish oil supplements spoiled by oxidation? Show / hide ↓
Researchers tested 171 fish oil supplements from 49 brands. Oxidation means the oil has broken down after reacting with oxygen. Half the products exceeded at least one voluntary quality limit, and 39% exceeded the recommended TOTOX limit, a combined score of different oxidation measures. More than 80% of products tested in South Africa and New Zealand exceeded at least one limit, compared with 27% in the United States exceeding more than twice the recommended peroxide level. The study did not show whether taking oxidized fish oil harms people.
What this means for you: If you buy fish oil, choose a reputable brand and store it as directed, but this study cannot show that one product is safer or healthier. The health effects of oxidized fish oil remain uncertain.
moderate evidenceThis systematic review assessed oxidation levels in 171 fish oil supplements from 49 brands. The GOED voluntary standards set limits at peroxide value under 5 mEq/kg, anisidine value under 20, and TOTOX (2xPV + AV) under 26. Results: 50% of products exceeded at least one measure, and 39% exceeded the TOTOX limit. In the USA, 27% of products had more than twice recommended peroxide levels. In South Africa and New Zealand, over 80% of supplements exceeded recommended oxidation levels. The biological effects of consuming oxidized fish oil are not yet established. EFSA concluded in 2010 that information on oxidation levels and related toxicological effects in humans is lacking.
Information on the level of oxidation of fish oil and related toxicological effects in humans is lacking.
The review covered studies from multiple countries with varying testing protocols. Voluntary standards may not reflect true safety thresholds.
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