Background There is a growing interest in the role of lifestyle factors, such as dietary habits and alcohol consumption, in development of rheumatoid arthritis (RA). The methodology in analysing dietary factors have in recent years improved through the development of scoring methods of dietary patterns creating new possibilities to evaluate the impact of diet.
Objectives To investigate whether alcohol and diet, assessed as both macronutrients and dietary patterns, increased the risk of subsequent development of RA through a nested case-control design in the Västerbotten Intervention Program (VIP) cohort.
Methods The study included 386 individuals (271 women, 115 men) who previously had stated their dietary habits as part VIP before the onset of symptoms of RA. For comparison, 1886 matched controls were identified from the same database. Diet was assessed as food groups, as macronutrients and as scores of dietary patterns, namely the carbohydrate-restricted diet score, the Mediterranean diet score and the healthy diet indicator score. Analyses where performed using logistic regression, reporting Odds Ratios (OR) with 95% confidence intervals (CI) on tertiles with the lowest category as reference. Subgroup analyses were conducted on the cases stratified for human leukocyte antigen shared epitope (HLA-SE) and for development of rheumatoid factor (RF) and antibodies against cyclic citrullinated peptides (anti-CCP) positive RA.
Results When analysing dietary patterns, consumption of food groups and different macronutrients a significant association was only found in the highest tertile for a carbohydrate restricted diet among anti-CCP positive RA (OR=1.38, 95% CI 1.01-1.90, as well as in the highest tertile of protein consumption among smokers (OR=1.80, 95% CI 1.09-2.95). However, after additional adjustment for sodium intake these associations lost significance. No association between alcohol consumption and risk for RA could be observed.
Conclusions There were no significant associations of the dietary patterns studied on the risk for development of RA in this cohort. Neither were there any associations to the risk for RA with alcohol consumption and on diet examined as macronutrients.
Disclosure of Interest None declared