Cortese M, et al. – Researchers carried out this cohort study to examine the association between dietary sodium intake and multiple sclerosis (MS) risk. They found that higher dietary sodium intake did not increase the risk of developing MS.

• The researchers evaluated dietary sodium intake by a validated food frequency questionnaire administered every 4 years to 80,920 nurses in the Nurses' Health Study (NHS) (1984–2002) and to 94,511 in the Nurses' Health Study II (NHSII) (1991–2007), and calibrated it using data from a validation study.
• During follow-up, there were 479 new MS cases.
• Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the effect of energy-adjusted dietary sodium on MS risk, adjusting also for age, latitude of residence at age 15, ancestry, body mass index at age 18, supplemental vitamin D intake, cigarette smoking, and total energy intake in each cohort.
• They pooled the results in both cohorts using fixed effects models.

• At baseline, total dietary intake of sodium was not correlted with MS risk (highest [medians: 3.2 g/d NHS; 3.5 g/d NHSII] vs lowest [medians: 2.5 g/d NHS; 2.8 g/d NHSII] quintile: HRpooled 0.98, 95% CI 0.74–1.30, p for trend = 0.75).
• During follow-up, cumulative average sodium intake was also not correlated with MS risk (highest [medians: 3.3 g/d NHS; 3.4 g/d NHSII] vs lowest [medians: 2.7 g/d NHS; 2.8 g/d NHSII] quintile: HRpooled 1.02, 95% CI 0.76–1.37, p for trend = 0.76).
• Similar results were noted while comparing more extreme sodium intake in deciles (p for trend = 0.95).