Fish Oil: Storage & Stability

What affects stability

Light: exposure can speed oxidation in liquids and bulk oils.
Heat: higher temperatures can raise oxidation rates.
Oxygen: more oxygen contact can increase PV and AV over time.
Formulation: flavored liquids and bulk oils showed higher oxidation in surveys vs sealed capsules in some contexts^1,2.

North American market analysis: “Oxidation levels of North American over‑the‑counter omega‑3 supplements.” Subsets above voluntary PV/AV/TOTOX thresholds were reported at testing¹.
New Zealand survey: “Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n‑3 PUFA.” Oxidation levels and label content observations were reported².
United States dataset: “Oxidation levels in U.S. omega‑3 products 2014–2020.” Flavored products exceeded TOTOX more often than unflavored in that dataset³.

Sealed softgels can limit oxygen exposure compared to open bottles of liquids.
Opaque or amber containers can reduce light exposure.
Labels provide storage directions and expiration dates for the specific product.

Jackowski SA, et al. Oxidation levels of North American over‑the‑counter omega‑3 supplements. Journal of Nutritional Science. 2015. PMC
Albert BB, et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n‑3 PUFA. Scientific Reports. 2015. PMC
Hedayati M, et al. Oxidation levels in U.S. omega‑3 products 2014–2020. Food Science & Nutrition. 2023. PubMed

Last Updated: 3 September 2025