Revealed: many common omega-3 fish oil supplements are ‘rancid’

Independent tests find that a number of products on the market use oxidised oils, with the rancidity often masked by flavourings

More than one in 10 fish oil supplements tested from among 60 large retail brands are rancid, while nearly half are just under the recommended maximum limit, according to independent tests.

Conducted over several years by Labdoor, which analyses vitamins and supplements based on criteria such as purity, label accuracy and nutritional value, the tests measured common US-branded fish oils, available globally, against international voluntary standards of rancidity.