Fish oil supplements they are popular in the UK and US because they are rich in omega-3 fatty acids, but independent tests have found that more than 1 in 10 common fish oils are “rancid”.
Analysis of 64 fish oil supplements, sold under 60 major US retail brands and available worldwide, revealed that some had rancidity levels 11 times higher than recommended limits.
Labdoor, which tests vitamins and supplements for purity, label accuracy, and nutritional value, tried fish oils for total omega-3 content, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), vitamin D, and CLA (conjugated linoleic acid).
It also analyzed total oxidation values, which measure the freshness of each oil against international voluntary standards for rancidity.
Fish oil becomes rancid when oxidized and can be characterized by a strong fishy taste and a sour, unpleasant odor. Several products add flavors, such as citrus, to mask rancidity, as well as the fishy taste and smell of the oils.
About 10 percent of the brands tested had levels of oxidized fish oil high enough to be considered rancid, according to the Labdoor report.
The results, first reported by The Guardian, come after a combination of global studies, conducted since 2015, revealed an average of 20 percent of fish oil products have excessive oxidation.
The voluntary oxidative quality limits created by the Global Organization for EPA and DHA Omega-3 (GOED) are set at 26. The higher the number, the more rancid the oil.
Fish oil has been labeled by previous studies as “extremely susceptible to oxidative degradation” due to its long supply chain.
A study, published in the Journal of Nutritional Science, detailed the journey from ocean capture to final consumer product, noting that the main sources of fish oil come from fish caught off the coast of Peru and Chile.
The catch is transported by fishing boat to shore, where it is then processed into crude fish oil, along with other fish products. The oil is stored in large tanks before being shipped around the world for further refining.
“Less than 25 percent of the total supply of crude fish oil goes to human consumption and undergoes further refinement and deodorization,” the study authors wrote.
“The end result is that consumers are at risk of purchasing an oxidized supplement, for which there is little tangible information on the packaging that provides details about the original source, age and refinement levels of the oil.”
Labdoor’s analysis, conducted between 2014 and 2018, found that some fish oils sold under the Carlson Labs and Puritan’s Pride brand names had degrees of rancidity significantly higher than suggested limits.
Some Ocean Blue and Nature’s Answer products were also found to exceed limits, with half of all products tested bordering the GOED limit.
However, higher levels of rancidity do not indicate that the oils are less safe, but rather of lower quality. It is not clear whether rancid fish oil is harmful to human health, but studies have shown that it is less effective than fresh fish oil.
the independent has contacted Carlson Labs, Puritan’s Pride, Ocean Blue, and Nature’s Answer for comment.
