Fish oil supplements are popular across the UK and the US because they are rich in omega-3 fatty acids, but independent testing has found that more than 1 in 10 common fish oils are “bad”.
An analysis of 64 fish oil supplements, which are sold under 60 large US retail brands and are available globally, revealed that some stink levels were 11 times higher than recommended limits.
Labdoor, which analyzes supplements and vitamins for purity, label accuracy, and nutritional value, tested fish oils for total omega-3s, EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), vitamin D, and CLA (conjugated linoleic acid).
He also analyzed total oxidation values, which measure the freshness of each oil against optional international standards for rancidity.
Fish oil turns rancid when oxidized and can have a strong fishy taste and unpleasant odor. A number of products add flavors, such as citrus, to mask rancidity as well as the fishy taste and smell of oils.
Labdoor’s report said about 10 percent of the brands analyzed had levels of oxidized fish oil high enough to be considered spoiled.
First reported results WatchmanIt comes after a group of global studies, conducted since 2015, revealed that an average of 20 percent of fish oil products have excess oxidation.
The optional limits for oxidizing quality established by the World Organization for EPA and DHA Omega-3 (GOED) are set at 26. The higher the number, the more rancid the oil.
Previous studies have described fish oil as “hypersensitive to oxidative degradation” due to the long supply chain.
One study published in Journal of Nutritional Sciences, detailing the journey from ocean fishing to the final consumer product, noting that the main sources of fish oil come from fish caught off the coasts of Peru and Chile.
The catch is carried on a fishing vessel ashore, where it is then processed into raw 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 crude fish oil supply is destined for human consumption and is subject to additional purification and deodorization processes,” the study authors wrote.
“The end result is that consumers are at risk of purchasing an oxidized supplement, as there is little concrete information on the packaging to provide details on the source, age, and refining levels of the original oil.”
Labdoor analysis, conducted between 2014 and 2018, found that some fish oils sold under the Carlson Labs and Puritan’s Pride brand names had significantly higher rancidity scores than suggested limits.
Some products from Ocean Blue and Nature’s Answer were also found to have exceeded the limits, and half of all products tested had the GOED limit.
However, high rancidity levels do not indicate that the oils are less safe, but rather indicate a lower quality. It is still not clear whether rancid fish oil is harmful to human health, but studies have shown that it is less effective than fresh fish oil.
independent I contacted Carlson Labs, Puritan Pride, Ocean Blue, and Nature Answer for comment.