Individual Blood Pressure Responses to Changes in Salt Intake

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Abstract
Although group characteristics are known to influence average blood pressure response to changes in salt intake, predictability of individual responses is less clear. We examined variability and consistency of individual systolic blood pressure responses to changes in salt intake in 188 participants who ate the same diet at higher, medium, and lower (140, 104, 62 mmol/d) sodium levels for 30 days each, in random order, after 2 weeks of run-in at the higher sodium level. Regarding variability in systolic blood pressure changes over time, changes from run-in to higher sodium (no sodium level change) ranged from −24 to +25 mm Hg; 8.0% of participants decreased ≥10 mm Hg. Regarding variability in systolic blood pressure response to change in sodium intake, with higher versus lower sodium levels (78-mmol sodium difference), the range of systolic blood pressure change was −32 to +17 mm Hg; 33.5% decreased ≥10 mm Hg. Regarding consistency of response, systolic blood pressure change with run-in versus lower sodium was modestly correlated with systolic blood pressure change with higher versus medium sodium; systolic blood pressure change with higher versus lower sodium was similarly correlated with run-in versus medium sodium (combined Spearman r =0.27, P =0.002). These results show low-order consistency of response and confirm that identifying individuals as sodium responders is difficult. They support current recommendations for lower salt intake directed at the general public rather than “susceptible” individuals as one of several strategies to prevent and control adverse blood pressures widely prevalent in the adult population.