• Fish oil – Fish oil is among the primary ways that people enhance their intake of omega-3 fats. High-quality fish oils can certainly provide many health benefits. However, this oil is weak in antioxidants. This means that as you increase your omega-3 intake through fish oil consumption, you actually increase your need for added antioxidant protection.
An analysis based on data from the Norwegian Women and Cancer Study (NOWAC) with regards to the dangers of persistent organic pollutants (POPs) in cod liver came to the conclusion that "in Norwegian women, fish liver consumption was not associated with an increased cancer risk in breast, uterus, or colon. In contrast, a decreased risk for total cancer was found."[65]
The competition between EPA and DHA during digestion and absorption and the fact that DHA appears to ‘block’ the therapeutic actions of EPA can therefore be an issue if we are looking to optimise the benefits associated with EPA (Martins 2009; Bloch & Qawasmi et al, 2011; Sublette et al, 2011). High dose, high concentration and high ratio EPA supplements increase the effectiveness in depression studies, and pure EPA-only is optimal. Depression is also a condition with an inflammatory basis, so this is likely another significant reason for EPA being the key player – its antagonistic relationship with the inflammatory omega-3 AA (arachidonic acid) is very effective at reducing inflammation.
Nielsen, G. L., Faarvang, K. L., Thomsen, B. S., Teglbjaerg, K. L., Jensen, L. T., Hansen, T. M., Lervang, H. H., Schmidt, E. B., Dyerberg, J., and Ernst, E. The effects of dietary supplementation with n-3 polyunsaturated fatty acids in patients with rheumatoid arthritis: a randomized, double blind trial. Eur J Clin Invest 1992;22(10):687-691. View abstract.
The question is whether the observed cardiovascular benefits often found among fish eaters is due solely to the oils in fish or to some other characteristics of seafood or to still other factors common to those who eat lots of fish, like eating less meat or pursuing a healthier lifestyle over all. Whatever the answer, it does not seem to be fish oil supplements.
The human body does not produce significant amounts of EPA or DHA on its own, so you must get these important nutrients from the foods you eat and the supplements you consume. If you’re looking to get the heart health benefits of omega-3s, go straight to the source of EPA and DHA. EPA and DHA are naturally found in marine sources, including fatty fish – salmon, tuna, mackerel, herring – shellfish, and marine algae.

Omega-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential nutrients that have potential preventive and therapeutic effects on psychiatric disorders, such as anxiety and depression,7-15 as well as comorbid depression and anxiety in physically ill patients,16-19 patients with coronary heart disease,20,21 and pregnant women.22,23 Preclinical data support the effectiveness of omega-3 PUFAs as treatment for anxiety disorders. Song et al24,25 found that an EPA-rich diet could reduce the development of anxiety-like behaviors in rats as well as normalize dopamine levels in the ventral striatum. In addition, Yamada et al26 showed that a high dietary omega-3 to omega-6 PUFA ratio reduced contextual fear behaviors in mice and that these effects were abolished by a cannabinoid CB1 receptor antagonist.
Cochrane lead author, Dr. Lee Hooper from the University of East Anglia, UK said: “We can be confident in the findings of this review which go against the popular belief that long-chain omega 3 supplements protect the heart. This large systematic review included information from many thousands of people over long periods.  Despite all this information, we don’t see protective effects.
For several years now, the fish oil and Alzheimer’s disease connection has been studied with consistent results. The essential fatty acids vital for brain function that are found in fish oil can not only slow cognitive decline, but can help prevent brain atrophy in older adults. A study published in the FASEB Journal looked at the health effects of four- to 17-month dietary supplementation with omega-3 fatty acids and antioxidants. The findings once again confirm the potential for fish oil to be used as a weapon to fend off the onset of cognitive decline and Alzheimer’s disease. (8)
Omega 3 fatty acids are monounsaturated fats that come from food sources—primarily cold water fish (eg, salmon, trout, tuna, mackerel, and herring)—that contain EPA (eicosapentaenoic acid) and docosahexaenoic acid (DHA). Other fatty acids are derived from plant-derived sources of food—including nuts (especially walnuts) and seeds (eg, flax, chia, sunflower)—that have primarily ALA (alpha-linolenic acid).
A certain kidney disease called IgA nephropathy. Some research shows that long-term but not short-term use of fish oil can slow the loss of kidney function in high-risk patients with IgA nephropathy. Fish oil might have greater effects when taken at higher doses. Also, it might be most effective in people with IgA nephropathy who have higher levels of protein in the urine.
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