Investigation of the association between coffee and risk of RA-results from the Swedish EIRA study.

BACKGROUND: Studies on the association between coffee, a modifiable lifestyle factor, and rheumatoid arthritis (RA), a chronic autoimmune disease primarily affecting the joints, have been conflicting. The aim of the present study was to study the association between coffee consumption and risk of RA in the context of different lifestyle factors. METHODS: We included 2184 cases (72% women, mean age 55 years) newly diagnosed with RA during 2005-2018 in Sweden and 4201 controls matched on age, sex, and residential area. Data on coffee consumption was collected through a food frequency questionnaire and categorized into < 2 (reference), 2-< 4, 4-< 6, and ≥ 6 cups/day. We calculated odds ratios (OR) with 95% confidence intervals (CI) for coffee consumption and risk of RA, in a crude model (taking matching factors into account), and then adjusted first for smoking and further for BMI, educational level, alcohol consumption, and physical activity. We also stratified analyses on sex, smoking, rheumatoid factor, and anti-CCP2 status. RESULTS: In the crude model, high coffee consumption was associated with increased risk of RA (OR = 1.50, 95% CI 1.20-1.88 for ≥ 6 cups/day compared to < 2 cups). After adjusting for smoking, the OR decreased and was no longer statistically significant (OR = 1.16, 95% CI 0.92-1.46) and decreased further in the full model (OR = 1.14 95% CI 0.89-1.45). This pattern held true in all strata. CONCLUSION: The findings from this large, population-based case-control study did not support a significant association between coffee consumption and risk of RA as a whole nor within different subgroups.

Is tea consumption associated with reduction of risk of rheumatoid arthritis? A Swedish case-control study.

BACKGROUND: Tea is a popular beverage around the world and has properties that can affect the immune system. The association between tea consumption and the risk of rheumatoid arthritis (RA), a chronic autoimmune disease primarily affecting the joints, is not well studied and results are conflicting. METHODS: We collected data on tea consumption for 2237 incident RA cases diagnosed 2005-2018 and 4661 controls matched on age, sex, and residential area. Tea consumption was classified into no (0 cups/day), irregular (< 1 cup/day), regular (1-2 cups/day), and high (≥ 2 cups/day) consumption, and irregular consumption was used as the reference category. Missing data on tea consumption was classified as no consumers, and sensitivity analyses were performed to test this assumption. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression, adjusting for smoking, coffee, alcohol, educational level, and body mass index. We also performed stratified analysis on sex, anti-citrullinated autoantibody (ACPA) status, and smoking habits. RESULTS: Among the cases, we found 57.3% to be ever consumers of tea with 19.7 having a high tea consumption. Corresponding figures for the controls were 58.4% ever drinkers with 22.1% high tea consumers. High tea consumption had an inverse association to the risk of RA compared to irregular consumption [OR = 0.78 (95% CI 0.66-0.92)], but the association lost statistical significance in the adjusted model [adjusted OR (adjOR) = 0.85 (95% CI 0.71-1.01)]. Among non-tea consumers, a protective effect was also observed compared to irregular consumers [adjOR = 0.82 (95% CI 0.70-0.88)], but this association did not withstand sensitivity analysis, possibly due to bias. In the ACPA-positive group and among current smokers, a protective effect of tea consumption was observed among the high tea consumers [adjOR = 0.76 (95% CI 0.62-0.94) and adjOR = 0.60 (95% CI 0.38-0.95), respectively]. CONCLUSIONS: This study suggests a protective effect of high consumption of tea, among smokers and for ACPA-positive RA. TRIAL REGISTRATION: Not applicable.

Mediterranean diet and risk of rheumatoid arthritis: a population-based case-control study.

BACKGROUND: The Mediterranean diet has been associated with lower mortality and lower risk of cardiovascular diseases and cancer. Although its components have been analysed in several studies, only one study has specifically investigated the association between Mediterranean diet and risk of rheumatoid arthritis (RA), and reported no association. METHODS: Data on 1721 patients with incident RA (cases) and 3667 controls, matched on age, gender and residential area, from the Swedish epidemiological investigation of RA (EIRA), a population-based case-control study, were analysed using conditional logistic regression. The Mediterranean diet score, ranging from 0 to 9, was calculated from a 124-item food frequency questionnaire. RESULTS: In the EIRA study (median age of participants 53 years), 24.1% of the patients and 28.2% of the controls had high adherence to the Mediterranean diet (a score between 6 and 9). After adjustments for body mass index, educational level, physical activity, use of dietary supplements, energy intake, and smoking, high adherence reduced the odds of developing RA by 21% (OR 0.79; 95% CI 0.65-0.96) as compared to low adherence (a score between 0 and 2). The OR was even lower among men (OR 0.49; 95% CI 0.33-0.73), but no significant association was found among women (OR 0.94; 95% CI 0.74-1.18). An association between high diet score and low risk of RA was observed in rheumatoid factor (RF)-positive (OR 0.69; 95% CI 0.54-0.88), but not RF-negative RA (OR 0.96; 95% CI 0.68-1.34), and in RA characterised by presence of antibodies to citrullinated peptides (ACPA), but not in ACPA-negative RA. CONCLUSIONS: In this large population-based case-control study, the Mediterranean diet score was inversely associated with risk of RA. However, an association was only found among men and only in seropositive RA.

Dietary Intake of Polyunsaturated Fatty Acids and Pain in Spite of Inflammatory Control Among Methotrexate-Treated Early Rheumatoid Arthritis Patients.

OBJECTIVE: To investigate potential associations between dietary intake of polyunsaturated fatty acids (FAs) and pain patterns in early rheumatoid arthritis (RA) patients after 3 months of methotrexate (MTX) treatment. METHODS: We included 591 early RA patients with MTX monotherapy from a population-based prospective case-control study, the Epidemiological Investigation of Rheumatoid Arthritis. Dietary data on polyunsaturated FAs (food frequency questionnaires) were linked with data on unacceptable pain (visual analog scale [VAS] >40 mm), noninflammatory/refractory pain (VAS >40 mm and C-reactive protein [CRP] level <10 mg/liter), and inflammatory pain (VAS >40 mm and CRP level >10 mg/liter) after 3 months. Statistical analysis included logistic regression. RESULTS: After 3 months of MTX treatment, 125 patients (21.2%) had unacceptable pain, of which 92 patients had refractory pain, and 33 patients had inflammatory pain. Omega-3 FA intake was inversely associated with unacceptable pain and refractory pain (odds ratio [OR] 0.57 [95% confidence interval (95% CI) 0.35-0.95] and OR 0.47 [95% CI 0.26-0.84], respectively). The omega-6:omega-3 FA ratio, but not omega-6 FA alone, was directly associated with unacceptable pain and refractory pain (OR 1.70 [95% CI 1.03-2.82] and OR 2.33 [95% CI 1.28-4.24], respectively). Furthermore, polyunsaturated FAs were not associated with either inflammatory pain or CRP level and erythrocyte sedimentation rate at followup. Omega-3 FA supplementation was not associated with any pain patterns. CONCLUSION: Omega-3 FA was inversely associated with, and the omega-6:omega-3 FA ratio was directly associated with, unacceptable and refractory pain, but not with inflammatory pain or systemic inflammation. The inverse association between omega-3 FA and refractory pain may have a role in pain suppression in RA.

Fish consumption and risk of rheumatoid arthritis: a dose-response meta-analysis.

INTRODUCTION: The association between fish consumption and rheumatoid arthritis (RA) is unclear. The aim of this paper was to summarize the available evidence on the association between fish consumption and risk of RA using a dose-response meta-analysis. METHODS: Relevant studies were identified by a search of MEDLINE and EMBASE through December 2013, with no restrictions. A random-effects dose-response meta-analysis was conducted to combine study specific relative risks. Potential non-linear relation was investigated using restricted cubic splines. A stratified analysis was conducted by study design. RESULTS: Seven studies (four case-controls and three prospective cohorts) involving a total of 174 701 participants and 3346 cases were included in the meta-analysis. For each one serving per week increment in fish consumption, the relative risk (RR) of RA was 0.96 (95% confidence interval (CI) 0.91 to 1.01). Results did not change when stratifying by study design. No heterogeneity or publication bias was observed. When fish consumption was modeled using restricted cubic splines, the risk of RA was 20 to 24% lower for 1 up to 3 servings per week of fish (RR =0.76, 95% CI: 0.57 to 1.02) as compared to never consumption. CONCLUSIONS: Results from this dose-response meta-analysis showed a non-statistically significant inverse association between fish consumption and RA.

Long-term intake of dietary long-chain n-3 polyunsaturated fatty acids and risk of rheumatoid arthritis: a prospective cohort study of women.

OBJECTIVES: 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.

Fish consumption, dietary long-chain n-3 fatty acids, and risk of type 2 diabetes: systematic review and meta-analysis of prospective studies.

OBJECTIVE: The evidence on the association between fish consumption, dietary long-chain n-3 fatty acids, and risk of type 2 diabetes is inconsistent. We therefore performed a systematic review and meta-analysis of the available prospective evidence. RESEARCH DESIGN AND METHODS: Studies were identified by searching the PubMed and EMBASE databases through 15 December 2011 and by reviewing the reference lists of retrieved articles. Prospective studies were included if they reported relative risk (RR) estimates with 95% CIs for the association between fish consumption and/or dietary long-chain n-3 fatty acids and incidence of type 2 diabetes. A dose-response random-effects model was used to combine study-specific RRs. Potential sources of heterogeneity were explored by prespecified stratifications. RESULTS: Sixteen studies involving 527,441 participants and 24,082 diabetes cases were included. Considerable statistical heterogeneity in the overall summary estimates was partly explained by geographical differences. For each serving per week increment in fish consumption, the RRs (95% CIs) of type 2 diabetes were 1.05 (1.02-1.09), 1.03 (0.96-1.11), and 0.98 (0.97-1.00) combining U.S., European, and Asian/Australian studies, respectively. For each 0.30 g per day increment in long-chain n-3 fatty acids, the corresponding summary estimates were 1.17 (1.09-1.26), 0.98 (0.70-1.37), and 0.90 (0.82-0.98). CONCLUSIONS: Results from this meta-analysis indicate differences between geographical regions in observed associations of fish consumption and dietary intake of long-chain n-3 fatty acids with risk of type 2 diabetes. In consideration of the heterogeneous results, the relationship warrants further investigation. Meanwhile, current public health recommendations on fish consumption should be upheld unchanged.