Long-term intake of dietary long-chain n-3 polyunsaturated fatty acids and risk of rheumatoid arthritis: a prospective cohort study of women.
OBJECTIVE
To analyse the association between dietary long-chain n-3 polyunsaturated fatty acids (PUFAs) and incidence of rheumatoid arthritis (RA) in middle-aged and older women from the Swedish Mammography Cohort, a population-based prospective study.


METHODS
Data on diet were collected in 1987 and 1997 via a self-administered food-frequency questionnaire (FFQ). The risk of RA associated with dietary long-chain n-3 PUFAs and fish intake was estimated using Cox proportional hazard regression models, adjusted for age, cigarette smoking, alcohol intake, use of aspirin and energy intake.


RESULTS
Among 32 232 women born 1914-1948, 205 RA cases were identified during a mean follow-up of 7.5 years (1 January 2003 to 31 December 2010; 2 41 120 person-years). An intake of dietary long-chain n-3 PUFAs (FFQ1997) of more than 0.21 g/day (lowest quintile) was associated with a 35% decreased risk of developing RA (multivariable adjusted relative risk (RR) 0.65; 95% CI 0.48 to 0.90) compared with a lower intake. Long-term intake consistently higher than 0.21 g/day (according to both FFQ1987 and FFQ1997) was associated with a 52% (95% CI 29% to 67%) decreased risk. Consistent long-term consumption (FFQ1987 and FFQ1997) of fish ≥1 serving per week compared with<1 was associated with a 29% decrease in risk (RR 0.71; 95% CI 0.48 to 1.04).


CONCLUSIONS
This prospective study of women supports the hypothesis that dietary intake of long-chain n-3 PUFAs may play a role in aetiology of RA.
Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Daniela
D
Di Giuseppe
Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Alice
A
Wallin
Division of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Matteo
M
Bottai
Clinical Epidemiology Unit, Department of Medicine, Karolinska Hospital, Stockholm, Sweden.
Johan
J
Askling
Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Alicja
A
Wolk
D000368:Aged; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000517:prevention & control*; D004032:Diet / Q000706:statistics & numerical data; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D005247:Feeding Behavior; D005260:Female; D005399:Fishes; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D017747:Seafood / Q000706:statistics & numerical data; D013548:Sweden / Q000453:epidemiology
D015525:Fatty Acids, Omega-3
Arthritis; Epidemiology; Rheumatoid Arthritis