Most fish oil supplements are fishy in a way that customers wish they weren't.
University of Auckland researchers tested 32 brands of omega-3 fatty acid capsules available in New Zealand pharmacies and discovered most were rancid, weak or both.
And buying an expensive or New Zealand-made brand won't help as researchers found no link between price or country of origin and quality of the product.
The study, published yesterday in the journal Scientific Reports, reveals that just three of the 32 brands contained the same concentrations of omega-3 fatty acids as listed on the label.
They also found that in over half of the products the oil had oxidised to a level higher than the recommended limit, meaning the oil was turning rancid or already off.
The findings will be of concern to the thousands of New Zealanders who take the popular supplement regularly in the hope it will improve heart health, inflammation and cognitive function.
Commenting on the results, University of Otago human nutrition specialist Professor Murray Skeaff says if the results are accurate, fish oil capsules are in good company.
"Fish oil supplements in New Zealand can be added to a long list of dietary supplements for which there are serious discrepancies between what the manufacturer claims the consumer is getting and what is actually in the supplement," Prof Skeaff said.
The rancid claim was also worrying, as it was still unclear whether the levels of oxidation revealed in the study posed a health risk for consumers, he said.
He called on researchers to publish the brand names of the fish oils supplements analysed so shoppers could find those of the highest quality.
Another specialist, Dr Matt Miller of Plant and Food Research, said while the findings were troubling it was important to remember there was still an "overwhelming body of scientific evidence" about the nutritional benefits of omega-3 supplementation.
A Commerce Commission spokesman said the watchdog has the power to investigate false claims when brought to its attention.
"Generally speaking, traders need to make sure the claims being made on product labels can be substantiated or they risk being in breach of the Fair Trading Act," he said.
source: newshub archive