People can obtain fish oil naturally from eating certain types of fish or from taking supplements. Fish oil is proven to provide cardiovascular benefits such as decreasing high blood pressure and lowering the risk of a heart attack, because it contains a high concentration of beneficial omega-3 fatty acids. Eicosapentaenoic acid, or EPA, and docasahexanoic acid, or DHA, the omega-3 fatty acids in fish oil, can also interact with the immune system and might benefit people with inflammatory disorders.
Anti-Inflammatory Action
Omega-3 fatty acids reduce pain and swelling, and this is the basis for their use in the skin condition psoriasis and its frequent companion psoriatic arthritis, osteoarthritis, rheumatoid arthritis and inflammatory bowel disease, all of which involve inappropriate and damaging inflammation caused by a hyper-active immune system. Fish oil boosts the body's level of omega-3 fatty acids and helps to reduce the ratio of omega-6 to omega-3 fatty acids. A relative excess of omega-6 fatty acids promotes inflammation, while a higher level of omega-3 fatty acids helps to counteract their effects. In their 2010 paper in "Prostaglandins, Leukotrienes and Essential Fatty Acids," Dr. S. Hurst and colleagues reported that the EPA component of fish oil is more effective in fighting inflammation than DHA. MedLine rates the evidence for effectiveness of fish oil in combating psoriasis as "possibly effective", and the Mayo Clinic says that several studies show a benefit of fish oil for patients with psoriatic arthritis. Evidence for a benefit of fish oil for other inflammatory conditions, such as rheumatoid arthritis and Crohn's disease, is suggestive but not certain, according to the Mayo Clinic.
Cellular Actions
EPA and DHA in fish oil suppress the body's response to a type of immune cells called T-lymphocytes or T-cells. When the immune system malfunctions, levels of T-cells increase, contributing to inflammation. Dr. Naim Khan outlines the actions of fish oil on T-cells in a 2010 paper in "Prostaglandins, Leukotrienes and Essential Fatty Acids." The paper shows that fish oil integrates into the cell membrane of T-cells to suppress cell signaling, differentiation and proliferation and ultimately reduce inflammation. The research of Dr. Hurst and colleagues shows that fish oil suppresses cytokines, peptides that cause inflammation, activate the immune system and target cells for death. Fish oil reduced the production of the cytokines IL-1 alpha and beta and TNF-alpha, the main cytokines activated in arthritis.
Immune Suppression
At high levels, fish oil can suppress the immune system. Although fish oil supplements are generally considered safe, high doses of more than 3 g per day might be dangerous for people with already weakened immune systems, such as patients with HIV/AIDs, people taking immunosuppressant drugs or the elderly.
References
- MedLine Plus: Fish Oil
- "Prostaglandins, Leukotrienes and Essential Fatty Acids"; S. Laye; Polyunsaturated Fatty Acids, Neuroinflammation and Well-Being; April-June 2010.
- "Prostaglandins, Leukotrienes and Essential Fatty Acids"; S. Hurst et al.; Dietary Fatty Acids and Arthritis; April-June 2010.
- Mayo Clinic: Omega-3 fatty acids, fish oil, alpha-linolenic acid
- "Prostaglandins, Leukotrienes and Essential Fatty Acids"; Naim Khan; Polyunsaturated Fatty Acids in the Modulation of T-cell Signalling; April-June 2010.
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