Fish oil or snake oil?

There is a massive amount of research surrounding the potential therapeutic benefits of omega-3 polyunsaturated fatty acids (n-3 PUFAs). The main active n-3 PUFA compounds are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The fish oil entry on Examine.com is a substantial compendium on the subject, with over 700 references.

Oily fish typically have a high concentration of n-3 PUFAs, but many people also consume a fish oil supplement to increase their n-3 PUFA intake. Typical reasons for supplementing with fish oil include increasing cognition^[1], decreasing risk for cardiovascular disease^[2], and decreasing levels of inflammation^[3]. Despite the impressive amount of research done on fish oil, conflicting results are still a concern to both consumers and the medical community. This study may provide a piece of the puzzle as to why this may be happening.

A New Zealand research group performed a diagnostic survey of commercially available fish oil products that were all domestically acquired. The goal was to put the label accuracy of commercial fish oil supplements to the test. Do these commercial fish oil capsules have the listed amount of n-3 PUFAs? What is the level of oxidized PUFAs within each sample?