Salt, Smoking, and the Risk for RA

Bret S. Stetka, MD; Björn Sundström, PhD


July 10, 2015

Editor's Note:
Smoking is known to be a major risk factor for rheumatoid arthritis (RA). Medscape recently interviewed researcher Björn Sundström, PhD, about his recent work looking at how the interaction between smoking and salt intake may contribute to RA risk.

Medscape: You recently published a study[1] exploring how smoking and salt influence RA risk. What were the objectives of your study?

Dr Sundström: Research published in 2013[2] on animal models and on human cells ex vivo have generated data on the importance of salt in the development of autoimmune diseases. The aim of our study was therefore to evaluate the impact of salt (sodium chloride) intake on the risk for development of RA.

Medscape: Can you briefly describe the methods of your research?

Dr Sundström: Patients with a verified diagnosis of RA were searched for in databases of a large screening and intervention program for risk factors for cardiovascular diseases—the Västerbotten Intervention Programme (VIP). Altogether 386 individuals were found who had stated their dietary habits before their onset of symptoms of RA. For comparison, 1886 matched controls were identified from the same database and were co-analyzed.

Medscape: What did you find about the relationship among salt, smoking, and RA?

Dr Sundström: When including all individuals, analysis of sodium intake did not yield any significant increased risk for the development of RA. However, when analyzing smokers only (cases and controls) there was a significant effect of salt intake in regard to higher odds of developing RA.

Medscape: In addition to your findings, what is known about the relationship between smoking and RA?

Dr Sundström: As we know it today, smoking is the strongest environmental risk factor for RA. The exact pathway regarding how smoking increases the risk of developing RA is not fully understood, but most of the research points to the fact that the early pathogenic processes of RA actually start in the lungs.

Medscape: Related to salt, what is known about the relationship between diet and RA? Have specific foods or dietary patterns been associated—either positively or negatively—with RA?

Dr Sundström: In general, dietary habits are not easy to assess and investigate. In particular, dietary data collected before the onset of RA is scarce; it is only present in a few cohorts worldwide with a limited number of individuals. However, as far as we know today, diet and dietary patterns, at least in the western populations studied, seem to have a rather small influence on the risk of developing RA.

Medscape: What are the clinical implications of your findings?

Dr Sundström: There is an ongoing debate today about the health issues associated with high salt consumption. Hopefully, our results draw attention to this.


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