KORN KURATED RESEARCH

Is Your Omega-3 Supplement Rancid? It Shouldn’t Be!

Delving into fish oil quality: a study on freshness reveals common oxidation and rancidity on omega-3 supplements; highlighting the need to get omega-3 from food sources and choose fish supplements wisely.

I don’t often get into the (sea)weeds about the chemical analysis of fish oil but this study caught my eye because my students are always asking about why they burp up the taste of fish (low-quality fish oil), which fish oil to take and if it becomes rancid. 

Rancidity occurs in response to oxygen exposure, also called oxidation. According to this large study of 72 different fish oils in various forms (liquid, capsules, etc.), yes, it does! They found nearly half of the oils had oxidized, meaning they underwent chemical changes. The researchers suggest that flavored oils are meant to hide the rancid smell. Good quality oil should not smell fishy at all. 

I did some digging and was pleased to find that 3 of my favorite oils, Nordic Naturals, Barleans, and Carlson’s were among the freshest. People might supplement with Vitamin E when taking fish oil to counteract oxidation.

 Maintaining optimal levels of Omega 3 fatty acids has been well-researched and validated. In my practice, I use the Omega Quant Complete blood spot test of omega-3 levels as a dosing indicator. It is convenient as they send the text kit to your home. However, over time, the research has influenced my thinking about fish being a better source of omega-3s than supplements, which I encourage. Fish like sardines, herring, canned wild salmon, and anchovies are both inexpensive and among the best seafood to incorporate into daily diet.  

Tags: Fish oil, antioxidants, dietary supplements, multivitamins, nutraceuticals, omega-3 fatty acids

Interested in Learning More?

• Course(s): Food as Medicine
• Book(s): Nutrition Essentials For Mental Health
• Book(s): The Good Mood Kitchen

Referenced Research Publication

Journal of dietary supplements
2023, September 15
DOI: 10.1080/19390211.2023.2252064

A Multi-Year Rancidity Analysis of 72 Marine and Microalgal Oil Omega-3 Supplements

link: https://pubmed.ncbi.nlm.nih.gov/37712532/

Abstract

There exists significant heterogeneity in the 'freshness' of consumer marine- and plant-derived omega-3 (Ω3) supplements. Fears of rancidity, or the oxidation of consumer Ω3 supplements, has been debated in the literature with several prior authors reporting contradictory findings. We report the peroxide value (PV), para-anisidine value (p-AV) and total oxidation values (TOTOX) associated with 72 consumer Ω3 supplements sold in the United States sampled from 2014-2020. The effect of flavoring on the oxidation of the supplements was examined in an adjusted fixed effects model controlling for type of delivery system (enteric, liquid, animal- and vegetable-derived gelatin softgel, spray), source (algae, calamari, fish, krill, mussels), and certifications assigned by third-party organizations (e.g. USP). Overall, our results revealed that 68% (23/34) of flavored and 13% (5/38) unflavored consumer Ω3 supplements exceeded the TOTOX upper limit set by the Global Organization for EPA and DHA (GOED) voluntary monograph standard of ≤ 26, with 65% (22/34) flavored supplements and 32% (12/38) unflavored supplements failing the PV upper limit of ≤ 5 and 62% (21/34) flavored supplements exceeding the p-AV upper limit of ≤ 20. To our knowledge, no prior authors have modeled the impact of flavoring on oxidative status in 72 marine- and plant-derived Ω3 products sold in the U.S. We present our findings in this context and discuss the clinical implications related to the consumption of oxidized consumer fish oils and their effects on human health.

Reference

Hands, J. M., Anderson, M. L., Cooperman, T., & Frame, L. A. (2024). A Multi-Year Rancidity Analysis of 72 Marine and Microalgal Oil Omega-3 Supplements. Journal of dietary supplements, 21(2), 195–206.
https://doi.org/10.1080/19390211.2023.2252064