Most fish oil supplements sold in Australia and New Zealand are lower in omega-3 fatty acids than their labels claim, research suggests.

The study, which looked at at 32 brands of fish oil capsules, found only three brands contained the same concentrations of omega-3 fatty acids listed on its label. Most of the products tested also exceeded recommended levels of oxidation markers, PV levels, AV thresholds and totox levels, the researchers reported in Scientific Reports.

The time until the best before date printed on the packaging had no relationship to the level of oxidation.

Professor Peter Clifton, Professor of Nutrition at the University of South Australia said the bulk of fish oil producers had “clearly been deceiving the public” and called for the ACCC and the TGA to get involved.

“For those members of the public trying to get an anti-inflammatory or triglyceride lowering effect from fish oil the reason the oil may not be working for them may be under-dosing, despite taking the recommended number of capsules.”

“Similarly, the high oxidation products  may be interfering with how well the pills work but we really don’t know the long term implications of high oxidation products,” he added.

Professor Murray Skeaff, Professor in Human Nutrition at the University of Otago, said the authors of the paper should publish the brand names of the fish oils supplements that were analysed so that consumers could identify the supplements of highest quality.