Most Fish Oil Supplement Benefit Claims are Unfounded

The health benefits of dietary intake of fish oil supplements stems from the fact that fish oil, particularly deep cold water fishes, is rich in important omega-3 polyunsaturated fatty acids, omega-3 PUFA. The significant omega-3 PUFA are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Another beneficial source of EPA and DHA is in the oil extracted from Krill as well as from certain algae. Another less studied but nonetheless important omega-3 PUFA is docosapentaenoic acid (DPA). More detailed information on the synthesis and functions of these important omega-3 PUFA can be found here: Omega-3 & Omega-6 Fatty Acid Synthesis, Metabolism, Functions.

There are numerous clinical benefits to a diet rich in omega-3 PUFA including early development of the fetal and post-natal central nervous system and modulation of inflammatory processes that results in reductions in neuroinflammation in particular, and their role in mental health outcomes.

The composition of omega-3 PUFA in sources such as fish oil, Krill oil, and algae are distinct which contributes to the bioavailability of the EPA, DHA, and DPA from these sources. Bioavailability refers to the extent to which a substance is actually taken up from the intestines and utilized within the body. Comparisons of bioavailability of EPA and DHA from fish oil compared to Krill oil shows significant differences. The majority of EPA and DHA in fish oils are found in triglycerides, in Krill oils these PUFA are found predominantly in phospholipids. Why this is potentially of clinical significance is related to the absorption and tissue distribution of lipids derived from dietary triglycerides versus phospholipids. Upon consumption triglycerides are acted upon by pancreatic lipase yielding two molecules of free fatty acid (FFA) and a 2-monoglyceride (2-MG). Both the 2-MG and the FFA are then absorbed by the enterocytes of the intestine. On the other hand dietary phopsholipids are acted upon by pancreatic phospholipase A2 (PLA2) yielding a FFA and a lysophospholipid (lysoPL). Of significance to the source of omega-3 PUFA it has been shown that the absorption and distribution of EPA and DHA derived from dietary phospholipids is higher when compared to dietary EPA and DHA contained in triglycerides. This is in part due to the fact that DHA derived from dietary triglycerides is found at a higher concentration in the feces (i.e. wasted) compared to that derived from phospholipids.

A recent review of the claims made by various fish oil products published in the journal, JAMA Cardiology, demonstrates that these claims are vastly over stated:

Health Claims and Doses of Fish Oil Supplements in the US

The findings from evaluation of 2819 different fish oil supplements showed that only 399 used an FDA approved qualified health claim while the majority used only structure or function claims such as "promotes heart health". This is in contrast to randomized clinical trials that have shown that, since the FDA first approved a Qualified Health Claims for fish oil in 2004, there is no significant cardiovascular benefit of fish oil supplements.

The other significant finding from this evaluation was that there is a wide variability in the dose of EPA and DHA in the preparation. EPA doses varied from 135-647 mg/dose while DHA doses varied from 140-500mg/dose. This high degree of variability in dose is extremely likely to result in a high degree of variability in the efficacy, and potential safety, of a particular fish oil supplement.

TAKE HOME: It is important to be aware that food manufacturers, and health food and supplement manufacturers, have a vested interest in monetary outcomes over actual health outcomes and that one needs to do their due diligence when deciding to utilize manufactured foods and supplements, over natural foods, in their diets.