The Study
A Multi-Year Rancidity Analysis of 72 Marine and Microalgal Oil Omega-3 Supplements
This study checked 72 fish oil supplements and found that flavored ones were more likely to be old or spoiled. But it didn't prove that adding flavor made them spoil—it just noticed a pattern. So we can't say flavoring caused the spoilage.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists tested 72 fish oil supplements to see how much they had gone bad from air exposure.
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 530 / 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 fish oil tastes or smells rancid, it might be one of the flavored ones that failed safety standards, and you could be consuming harmful oxidized fats.
- 268% of flavored fish oil pills were too oxidized (bad), while only 13% of unflavored ones were.
- 3Flavored ones also had more signs of spoilage in three different tests.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Dietary Supplements
Year
2023
Authors
Jacob M. Hands, Mark L. Anderson, Tod Cooperman, Leigh A. Frame
Related Content
Claims (7)
Eating oxidized omega-3 fatty acids causes more harm to health than it provides benefit.
Omega-3 fatty acids in dietary supplements break down chemically when exposed to air, heat, or light during production and storage.
Most omega-3 supplement brands do not tell consumers if the level of oxidation in their products is above safety limits.
Flavored omega-3 supplements were much more likely than unflavored ones to show signs of oxidation beyond accepted safety limits in a U.S. sample of 72 products collected between 2014 and 2020.
Omega-3 supplements with added flavoring show higher levels of secondary oxidation when measured by para-anisidine value, and standard testing methods may not detect this oxidation accurately in flavored products.
In a test of 72 omega-3 supplements, 65% of flavored ones exceeded the acceptable peroxide value limit for oxidation, while only 32% of unflavored ones did.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.