Rheumatoid Arthritis Risk More than Doubled in Smokers with High Sodium Intake

by LMatthews on September 26, 2014

sodium smoking rheumatoid arthritis riskMany people develop spinal stenosis as a result of osteoarthritis but rheumatoid arthritis can also cause spinal narrowing, trapped nerves and spinal cord compression. Avoiding autoimmune disease is far from easy but new research from Sweden suggests that smokers would do well to avoid eating a diet high in salt if they wish to reduce their risk of rheumatoid arthritis.


This latest study looked at the effects of a high-salt diet on the incidence of rheumatoid arthritis and found that a salt-heavy diet did indeed increase the risk of RA but only in smokers. In fact, smokers with a high salt intake had twice the risk of developing RA as those with a low salt intake.

How Smoking Increase the risk of Rheumatoid Arthritis

Smoking is a significant risk factor for developing rheumatoid arthritis as it promotes inflammation, altered immune function, free radical damage, and even increased susceptibility to infection, which may provoke the autoimmune condition. It is thought that an estimated 25% of cases of RA in Sweden would not have happened had the people not been smokers, and a third of the most severe RA cases are thought to have been preventable if people did not smoke.

Previous laboratory studies and animal studies have also found that sodium can induce the production of inflammatory molecules in Th17 cells, promoting inflammation associated with the development of RA but this is the first time that researchers have looked at the link between RA and sodium intake in humans.

The researchers looked at health records and lifestyle information for almost 100,000 people in northern Sweden and isolated 386 cases of people who developed rheumatoid arthritis by 2011. They matched each of these cases to five others of a similar age and sex but who did not develop RA. Factors considered by the researchers included:


  • Dietary habits
  • Education
  • Cholesterol and triglyceride levels
  • Weight
  • Sodium
  • Smoking

They found no significant associations between sodium intake and RA development, aside from in the people who smoked. In the group of smokers, those who consumed the most sodium were 2.26 times as likely to develop RA as those with the lowest intake of sodium. In fact, smokers who ingested the least sodium had a risk of RA similar to those who did not smoke, strongly suggesting an interaction between smoking and sodium consumption in facilitating RA development.

The researchers worked out that 54% of the smoking-associated increased risk of developing RA in those eating a high sodium diet was likely to be a result of the interaction between sodium and smoking.

Anyone who smokes is not only advised to quit then, but is also advised to reduce sodium intake in the meantime. High sodium intake and smoking are both bad for joint health it seems as well as increasing the risk of heart disease and a range of other chronic conditions.

Reference

Sundström B, Johansson I, Rantapää-Dahlqvist S. Interaction between dietary sodium and smoking increases the risk for rheumatoid arthritis: results from a nested case-control study. Rheumatology (Oxford). 2014 Sep 10. pii: keu330. [Epub ahead of print]

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