There are several different types of omega-3 polyunsaturated fatty acids, but the long-chain omega-3s, such as EPA and DHA, are the most important for therapeutic benefits. While a product may contain 1000mg of fish oil, a standard fish oil capsule will only have about 300mg of the metabolically active ingredients (120mg DHA + 180mg EPA).
What's the recommended daily intake of omega-3s?
Consumers take fish oil supplements for a range of reasons, but it's perhaps best known because it has shown promising effects of lowering inflammation, improving cognition, and lowering cardiovascular disease risk.
CHOICE research in 2013 found it's safe to consume up to 3000mg of fish oil per day, but recommendations vary depending on what you're taking it for. While 500mg DHA+EPA per day is recommended for heart disease, for arthritis relief it is 3000mg DHA+EPA per day.
The Therapeutic Goods Administration (TGA) guidelines state fish oil products must contain at least 90% of the amount of EPA and DHA they claim to contain. However, the study found that two thirds of the products only had 67% of the EPA and DHA claimed. Some had even lower levels, with one supplement having as little as 32% of the stated claim.
The TGA is aware of the research and a spokesperson said that it is "reviewing this information to see whether any action is required".
CHOICE spokesperson Tom Godfrey said if a packet has a statement about the quantity of an active ingredient then you expect to get what you pay for.
"If these products only contain 50% of the stated ingredients, and the companies have been inflating the active ingredient claims to lure in consumers then these pill producers could find themselves in hot water," he said.
"Under Australia Consumer Law it's unlawful to make false representations around the quality, composition or grade of a product. If the ACCC were to cast an eye over this research and discover that consumers had been misled, then any fishy companies might find themselves in the frying pan," he said.
Sales of omega-3 supplements exceeded $200m annually and were growing at a rate of 10% per year when we looked at the topic in depth back in 2013.
Unfortunately for consumers, the study found that the best-before date, cost and country of origin weren't indications of a supplement's quality.
The study did not identify which brands it tested.