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BMC Musculoskelet Disord. 2019 Jan 5;20(1):2. doi: 10.1186/s12891-018-2381-3.

Association of fish intake and smoking with risk of rheumatoid arthritis and age of onset: a prospective cohort study.

Author information

1
Department of Medicine, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, 60 Fenwood Road, #6016U, Boston, MA, 02115, USA. jsparks@bwh.harvard.edu.
2
Harvard Medical School, 25 Shattuck St, Boston, MA, 02115, USA. jsparks@bwh.harvard.edu.
3
Department of Nutrition, Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, MA, 02115, USA.
4
School of Public Health, University College Cork, University College, College Road, Cork, Ireland.
5
Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA.
6
Department of Medicine, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, 60 Fenwood Road, #6016U, Boston, MA, 02115, USA.
7
Harvard Medical School, 25 Shattuck St, Boston, MA, 02115, USA.
8
Department of Medicine, Channing Division of Network Medicine, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA, 02115, USA.

Abstract

BACKGROUND:

Prior studies suggest that fish may be protective for rheumatoid arthritis (RA) risk perhaps through the anti-inflammatory effect of omega-3 fatty acid, but this relationship has not been clearly established. Therefore, we investigated fish intake and RA risk by serologic status, age of onset, and smoking using a prospective cohort study with large sample size, repeated measures of dietary intake, and lengthy follow-up.

METHODS:

We studied fish intake and RA risk among 166,013 women in two prospective cohorts, the Nurses' Health Study (NHS, 1984-2014) and NHSII (1991-2015). Fish intake was assessed using food frequency questionnaires at baseline and every 4 years. Incident RA during follow-up and serologic status were determined by medical record review. Pooled Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for RA (overall and by serologic status and age at diagnosis) for fish intake frequency. We tested for a smoking-fish interaction for RA risk.

RESULTS:

During 3,863,909 person-years of follow-up, we identified 1080 incident RA cases. Increasing fish intake was not associated with all RA (≥4 servings/week: multivariable HR 0.93 [95%CI 0.67-1.28] vs. < 1 serving/month; p for trend = 0.42), seropositive RA (p for trend = 0.66), or seronegative RA (p for trend = 0.45), but had increased risk for RA diagnosed > 55 years old (p for trend = 0.037). Among women ≤55 years old, frequent fish intake (vs. infrequent) had HRs (95%CIs) of: 0.73 (0.52-1.02) for all RA, 0.85 (0.55-1.32) for seropositive RA, and 0.55 (0.32-0.94) for seronegative RA. Ever smokers with infrequent fish intake had highly elevated risk for RA onset ≤55 years (HR 2.59, 95%CI 1.65-4.06), while ever smokers with frequent fish intake had modestly elevated RA risk (HR 1.29, 95%CI 1.07-1.57; vs. never smokers/frequent fish intake; p for smoking-fish interaction = 0.039).

CONCLUSION:

In this large prospective cohort study, we found no clear protective effect of fish or marine omega-3 fatty acid intake on RA risk, overall or by serologic status. We found that fish intake attenuated the strong association of smoking for RA diagnosed ≤55 years of age, but this requires further study.

KEYWORDS:

Diet; Epidemiology; Fish; Inflammation; Omega-3 fatty acids; Rheumatoid arthritis; Smoking

PMID:
30611246
PMCID:
PMC6320647
DOI:
10.1186/s12891-018-2381-3
[Indexed for MEDLINE]
Free PMC Article

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