Omega-3 EFAs & Fish Oil

Disclaimer: The following suggestions are presented for informational purposes only, and are not intended, nor should be taken, as medical advice. Please consult your doctor if you require medical advice on natural or supplemental forms of Omega-3 essential fatty acids.

Fish oil capsules are derived from fatty tissues of oily fish and are marine sources of Omega-3 essential fatty acids. Omega-3 EFAs are poly-unsaturated fatty acids (PUFAs).

EPA (eicosapentaenoic acid) is important to reduce cellular inflammation, while DHA (docosahexaenoic acid) is important for healthy functioning of the brain, heart and eyes.

The health benefits of fish oil are widely claimed.

Fish oil research

Current recommendations to consume fish oil to prevent cardiovascular disease are based on research conducted in the 1970’s on Inuit metabolism by Danish scientists Bang and Dyerberg. The Inuit, an indigenous hunting culture of the North American Arctic region, subsist mainly on a high-fat, Omega-3 rich diet of whale blubber, seal and fish. The researchers concluded the low rates of cardiovascular disease in the Inuit was the result of dietary Omega-3 and concluded that Omega-3 PUFAs were good for the heart.

A more recent study by Fumagalli et al. (2015) revealed that the ability of the Inuit to effectively metabolize large amounts of Omega-3 fatty acids may be due to an evolutionary adaptation to a diet high in fat rather than any inherent, protective properties of Omega-3. The researchers found these genetic variants to be much less common in other populations, suggesting that Omega-3 EFAs may not be protective for all ethnic groups.

There is a vast body of evidence from various clinical trials on fish oil supplements that failed to show any benefits to cardiovascular health.

Fish oil nutrition

Fish oil capsules may contain higher concentrations of EPA and DHA than whole fish, so taking capsules may provide higher levels of Omega-3 than could be obtained from eating whole fish. However, as revealed in this study, Omega-3 may be better absorbed from whole fish than from capsules (Visioli et al. 2003).

Some fish oil supplements are marketed as containing more Omega-3 than indicated on the label.  Albert et al. (2015) found that only 3 out of 32 brands of fish oil capsules tested for Omega-3 content were found to contain EPA and DHA levels consistent with (equal to or higher than) the amounts stated on the packaging.

Fish oil capsules may contain heavy metals and organic pollutants, including polychlorinated biphenyls (PCBs), mercury, dioxins and furans. Environmental contaminants bio-accumulate in the fatty tissues of fish, where the Omega-3 are found, so fish oil capsules contain concentrations of these contaminants however, they are not considered excessive or harmful.

The environmental impacts of fish oil

Most fish oil is derived from the fatty tissues of fish low on the marine food chain that have accumulated less mercury and other environmental toxins, usually species of forage or bait fish. Of the 179 million tonnes of fish produced in 2018, 22 million tonnes were utilized as a non-food source, namely fishmeal and fish oil (FAO 2020). Forage or bait fish are valuable in the marine food chain to facilitate energy transfer from phytoplankton to carnivorous fish to the marine organisms who feed on those fish, including cetaceans and seabirds.

Brevoortia tyrannus (Atlantic menhaden), an important forage fish and member of the herring family, is used to make fish oil. Atlantic menhaden are prey for larger fish, ospreys and eagles, and humpback whales, fin whales and dolphins (see Marine Food Webs & African Penguins under Impacts). When populations declined significantly from overfishing, the Atlantic States Marine Fisheries Commission (ASMFC) voted in 2012 to place a broad catch limit on the fishery to reduce harvests by 20%. The current stock status for this species is ‘Not Overfished’ (ASMFC 2020), suggesting the strategy has been successful.

It takes enormous amounts of energy and resources to catch fish, and additional energy and resources to turn whole fish into fish oil capsules (FAO 1986), including processing, manufacturing, transporting the capsules in glass or plastic bottles, and disposing of the empty containers. If 2-3 servings of oily fish weekly are sufficient to meet the daily requirements for Omega-3 EFAs, supplementing with fish oil is unnecessary and wasteful.

© 2016 – 2021 Seafood Free September


Albert, B., Derraik, J., Cameron-Smith, D. et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n-3 PUFA. Sci Rep 5, 7928 (2015).

Atlantic States Marine Fisheries Commission (ASMFC). Review of the interstate fishery management plan for Atlantic menhaden (Brevoortia tyrannus). 2020 Fishing Year.

Bang HO, Dyerberg J. Plasma lipids and lipoproteins in Greenlandic west coast Eskimos. Acta Med Scand. 1972 Jul-Aug;192(1-2):85-94. https://doi: 10.1111/j.0954-6820.1972.tb04782.x. PMID: 5052396.

Chris Kresser,

FAO. 1986. The production of fish meal and oil.

FAO. 2020. The State of World Fisheries and Aquaculture 2020. Sustainability in action. Rome.

Greenberg, Paul., (2018), The Omega Principle – Seafood and the Quest for a Long Life and a Healthier Planet,

Visioli, F. et al. (2003). Dietary intake of fish vs. formulations leads to higher plasma concentrations of n-3 fatty acids. Lipids 38(4): 415-418.