What is the relationship between salt intake and BP levels?
A relationship between average daily salt intake and BP levels has long been recognized, leading to calls from the World Health Organization (WHO) for salt intake to be restricted to improve BP levels. Restricting salt intake clearly lowers BP by a moderate amount, as demonstrated in a systematic review of seven trials,53 most of which assessed the impact of restricting salt intake to 4 to 6 g (70 100 mmol). Overall, BP levels were reduced as compared to baseline levels: systolic BP by 4.7 mm Hg (95% CI 2.2 7.2) and diastolic BP by 2.5 mm Hg (95% CI 1.8 3.3). Moderate heterogeneity was observed in the effects on systolic BP, but this was corrected when one outlier trial was excluded. Other systematic reviews including a different group of trials have suggested similar but somewhat smaller benefits.