A new study published online in the journal Rheumatology today indicates that the interaction between high sodium intake and smoking is associated with a more than doubled risk of developing rheumatoid arthritis (RA).

The study, was conducted to analyze whether recent animal and human cell study results that showed a link between a high sodium intake and RA would yield similar results in a nested case-control study of data from the Västerbotten Intervention Programme (VIP).

It focused on 386 individuals who had stated their dietary habits as part of a community intervention programme a median of 7.7 years before the onset of RA symptoms. For comparison, 1886 matched controls were identified from the same database and co-analysed.

As part of the VIP, health-screening data (dietary habits, physical exercise, smoking, and other social factors) were collected, along with blood samples. The study did not find any significant association between sodium intake and the developed of RA when all the individuals were included, and so the researchers were not able to confirm their original stated hypothesis. However, when the results were stratified for current smokers, sodium intake more than doubled the risk for RA.