Omega-3 Fatty Acids in Fish Reduce RA Risk

Di Giuseppe D, Wallin A, Bottai M, et al. Long-term intake of dietary long-chain n-3 polyunsaturated fatty acids and risk of rheumatoid arthritis: a prospective cohort study of women. Ann Rheum Dis (2013) 0:1–5. doi:10.1136/annrheumdis-2013-203338 [E-pub head of print 12 Aug 2013]

Women who eat one or more servings per week of cold-water fish that are rich in omega-3 fatty acids, such as salmon and Atlantic mackerel, have a lower risk for rheumatoid arthritis (RA), according to a large prospective study from Sweden.

The seven-year study of 32,232 women over age 65 from the Swedish Mammography Cohort shows that the relative risk of RA is decreased by 52% among those with a consistently high intake of the long-chain omega-3 polyunsaturated fatty acids (PUFAs) from fish.

The results are based on self-administered food-frequency questionnaires in 1987 and 1997, listing types of fish including salmon, whitefish, char, herring and mackerel (fatty fish) and intake of cod, saithe and fish fingers (lean fish).

New cases of RA between January1, 2003 and December 31, 2010 were culled from two national registries using the women’s unique identifying numbers, revealing 205 RA cases during that period.

Omega-3 consumption was assessed in quintiles from the highest (≥0.49 g a day) to the lowest (<0.21g a day), with multivariable relative risk adjusted for cigarette smoking, alcohol intake, aspirin use, and calorie intake.

Although there was no clear dose-response relationship between omega-3 consumption and relative risk, the researchers did note a significant threshold effect. Consistent long-term intake of omega-3 fatty acids from fish higher than 0.21 g/day was associated with a 52% decreased relative risk for the development of RA. Regular long-term consumption of one or more servings of fish per week was associated with a 29% decreased relative risk.

The researchers note that dietary long-chain omega-3 PUFAs (eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA) could protect against RA through their anti-inflammatory properties. EPA is a homologue of arachidonic acid (a precursor of inflammatory eicosanoids involved in RA) and acts as a competitive substrate for the enzymes cyclo-oxygenase and lipoxygenase, which give rise to another family of eicosanoids considered to be anti-inflammatory.