Impact of adopting low sodium diet on biomarkers of inflammation and coagulation: a randomised controlled trial.

Background: A low sodium diet is an established intervention in the treatment of impaired renal function and hypertension which may modulate cardiovascular risk independent of recognised antihypertensive effects. Epidemiological data suggest that dietary sodium intake may be associated with systemic inflammation: another potential pathophysiological mechanism by which sodium intake may modify vascular disease.

Methods: We tested the hypothesis that adopting a low sodium diet may decrease biomarkers of systemic inflammation or coagulation using data from a randomised double-blind placebo-controlled trial. Participants (n=171; aged 18-65 years) in a randomised double-blind placebo-controlled trial of a low sodium diet for 6 weeks provided paired serum samples for analysis to assess the impact of adopting a low sodium diet on biomarkers of systemic inflammation and coagulation.

Results: There was a significant difference in 24-hour sodium urinary excretion between the low sodium intake and the normal sodium intake groups of 43 mmol (p<0.001). In the primary analysis there was no effect of adopting a low sodium diet on serum D-dimers, but high-sensitivity C-reactive protein (hsCRP) was reduced by 1.13 mg/L (95% confidence interval [95% CI], 0.03 to 2.22). However, after elimination of outlying high values for baseline serum hsCRP (>10 mg/L), this effect was attenuated (-0.47 mg/L; 95% CI, -1.25 to 0.31).

Conclusions: Using data from a randomised double-blind placebo-controlled trial in asthma with objective confirmation of adherence to the low sodium diet, we report that adopting a low sodium diet for 6 weeks has no effect on measures of systemic inflammation or coagulation.