Omega-3 fatty acids are unsaturated fatty acids found in foods such as fish and flaxseed and in dietary supplements such as fish oil.[i] They are an essential nutrient, meaning that the body cannot synthesize them naturally but must derive them from food.[ii] Omega-3 fatty acids play an important role in many physiological functions, including joint health.
The three main omega-3 fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA); while EPA and DHA can be synthesized from ALA, the conversion efficiency is low and thus all three are considered “essential.”[iii] Omega-3 fats are involved in several important cellular processes, including the production of hormones that regulate blood clotting and inflammation and the formation of cell membranes.2
Omega-3 fatty acids have long been highlighted by the American Heart Association for their ability to reduce the incidence of cardiovascular events like heart attack and stroke.[iv] They are also integral for the function of the nervous system and the retina.[v] Many of these health benefits first came to light in the 1980s, when studies showed that the Greenland Inuit, whose diets are rich in seafood, have a dramatically lower incidence of cardiac and other health disorders than Western Europeans.[vi]
Additionally, omega-3 fatty acids have been shown to be an effective addition to boost joint health in treatment regimens for musculoskeletal disorders, particularly rheumatoid arthritis (RA). This is primarily due to the anti-inflammatory action of omega-3 fatty acids. RA occurs when the immune system attacks healthy cells in the joints, causing pain and inflammation.[vii] Many studies have used fish oil to demonstrate the anti-inflammatory effects of omega-3 fatty acids. For example, Espersen et al. showed that the blood plasma level of interleukin-1 beta, an inflammatory cytokine, decreases after fish oil consumption.[viii] Other mechanisms of action for the anti-inflammatory properties of omega-3 fatty acids may include the inhibition of T-cell proliferation and the reduction of antigen presentation.[ix]
A 2013 study published in the British Journal of Clinical Pharmacology argues convincingly for anti-inflammatory effects of omega-3 fatty acids. The paper[x] touches on the effect omega-3 fatty acids have on the chemotaxis, or movement, of white blood cells, which contribute to the development of arthritis when they attack the lining of the joint capsule.[xi] White blood cells are attracted to inflammatory sites by “chemo-attractants” such as the chemical LTB4.10 The author cites several studies which support the notion that fish oil supplements, and ultimately, the omega-3 fatty acids they contain, can restrict the chemotaxis of white blood cells toward chemoattractants. The mechanism of action has not yet been deduced, but the paper hypothesizes that it may involve the antagonism of receptors for chemo-attractants. The review also discusses the amount of omega-3 fatty acids needed to elicit their anti-inflammatory effects. It notes that typical consumption of “marine” omega-3 fatty acids (those coming from fish or seafood) is in the tens or low hundreds of milligrams per day.[xii] However, as Calder points out, multiple studies show that much larger amounts of omega-3 fatty acids are needed to reduce inflammation in those with chronic conditions: a study of rheumatoid arthritis showed 3.5g of EPA to be necessary to significantly reduce inflammation.[xiii] The review therefore suggests that those with inflammatory conditions take omega-3 supplements that far surpass what one would receive from a natural diet.
References
[i] “Office of Dietary Supplements – Omega-3 Fatty Acids.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services, 4 Aug. 2021, ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/.
[ii] “Omega-3 Fatty Acids: An Essential Contribution.” The Nutrition Source, Harvard T.H. Chan School of Public Health, 22 May 2019, www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/.
[iii] “Essential Fatty Acids.” Linus Pauling Institute, Oregon State University, 1 Jan. 2021, lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids.
[iv] “Fish and Omega-3 Fatty Acids.” www.heart.org, American Heart Association, www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/fish-and-omega-3-fatty-acids.
[v] Querques, G., et al. “Retina and Omega-3.” Journal of Nutrition and Metabolism, vol. 2011, 2011, pp. 1–12., doi:10.1155/2011/748361.
[vi] Kromann, N., and A. Green. “Epidemiological Studies in The Upernavik District, Greenland.” Acta Medica Scandinavica, vol. 208, no. 1-6, 2009, pp. 401–406., doi:10.1111/j.0954-6820.1980.tb01221.x.
[vii] “Rheumatoid Arthritis (Ra).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 27 July 2020, www.cdc.gov/arthritis/basics/rheumatoid-arthritis.html.
[viii] Espersen, G. T., et al. “Decreased Interleukin-1 Beta Levels in Plasma from Rheumatoid Arthritis Patients after Dietary Supplementation with n-3 Polyunsaturated Fatty Acids.” Clinical Rheumatology, vol. 11, no. 3, 1992, pp. 393–395., doi:10.1007/bf02207200.
[ix] Kostoglou-Athanassiou, I., et al. “The Effect of Omega-3 Fatty Acids On Rheumatoid Arthritis.” Mediterranean Journal of Rheumatology, vol. 31, no. 2, 2020, p. 190., doi:10.31138/mjr.31.2.190.
[x] Calder, P. C. “Omega-3 Polyunsaturated Fatty Acids and Inflammatory Processes: Nutrition or Pharmacology?” British Journal of Clinical Pharmacology, vol. 75, no. 3, 2013, pp. 645–662., doi:10.1111/j.1365-2125.2012.04374.x.
[xi] “Arthritis.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 19 July 2019, www.mayoclinic.org/diseases-conditions/arthritis/symptoms-causes/syc-20350772.
[xii] Meyer, B. J., et al. “Dietary Intakes and Food Sources of Omega-6 and Omega-3 Polyunsaturated Fatty Acids.” Lipids, vol. 38, no. 4, 2003, pp. 391–398., doi:10.1007/s11745-003-1074-0.
[xiii] Calder, P. C. “Session 3: JOINT Nutrition Society and IRISH Nutrition and Dietetic Institute Symposium ON ‘Nutrition and Autoimmune Disease’ Pufa, Inflammatory Processes and Rheumatoid Arthritis.” Proceedings of the Nutrition Society, vol. 67, no. 4, 2008, pp. 409–418., doi:10.1017/s0029665108008690.