The Study
Oxidation levels of North American over-the-counter n-3 (omega-3) supplements and the influence of supplement formulation and delivery form on evaluating oxidative safety
This study checked a bunch of omega-3 pills and oils in stores to see how much they had gone bad. It found that some kinds, like flavored ones or kids' gummies, tended to be more oxidized — but it didn’t change anything or test if the bad stuff hurt people. So we can only say these products looked older, not that they caused harm.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists tested 171 omega-3 supplements sold in Canada and found many had gone rancid — like old cooking oil — which could make them less healthy or even harmful.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 537 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — if your supplement is rancid, you’re not getting the health benefits and might be exposed to harmful compounds, especially if you’re a child or take it long-term.
- 2Half (50%) of the supplements had oxidation levels above safe limits; kids' supplements were worst; unflavored capsules were safest.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Nutritional Science
Year
2015
Authors
S. Jackowski, Azhar Z. Alvi, A. Mirajkar, Z. Imani, Yuliya Gamalevych, N. Shaikh, G. Jackowski
Related Content
Claims (6)
Most omega-3 supplement brands do not tell consumers if the level of oxidation in their products is above safety limits.
Half of the omega-3 supplements sold over the counter in North America in 2014 had oxidative damage levels above international safety limits, meaning the fatty acids in these products had broken down.
Omega-3 supplements in unflavored softgel capsules have less chemical breakdown from oxidation than bulk oils or flavored softgels.
Flavor additives in omega-3 supplements are linked to higher anisidine values, which can result from either oxidation of the oil or chemical interference from the flavoring compounds, making it harder to determine if the supplement is safely preserved.
Omega-3 supplements with more EPA and DHA do not oxidize more than those with less EPA and DHA.
Children's omega-3 supplements sold in North America in 2014 had higher levels of oxidation markers than other formulations because flavor additives either disrupted oxidation tests or increased chemical breakdown.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.