Drinking Water NaCl Is Associated With Hypertension and Albuminuria: A Panel Study.

Abstract

BACKGROUND Salt leaching into freshwater is an emerging global environmental health concern. We tested the associations between drinking water salinity and blood pressure, hypertension, and albuminuria. METHODS We conducted a 2-year panel study in 2022 and 2023 with 434 observations among 327 Daasanach adults aged >18 years in northern Kenya. Water sources were analyzed for overall salinity and ionic composition (sodium-chloride; calcium, potassium, magnesium). We measured resting blood pressure and classified hypertension stage 1 and stage 2. Urine samples were analyzed for albuminuria (≥30 mg/g albumin-to-creatinine ratio). RESULTS Drinking water salinity was driven by sodium-chloride (mean=162.6 mg/L, SD=77.1), with low concentrations of calcium, potassium, and magnesium (mean=45 mg/L, SD=13.5). Across 2022 and 2023, 40.1% of adults had at least hypertension stage 1, 13.5% had hypertension stage 2, and 42.2% had albuminuria. Using random effects linear and logistic panel regressions fully adjusted for confounders, each 100 mg/L of drinking water sodium-chloride was associated with 4.5 mm Hg (95% CI, 2.4-6.6) and 3.3 mm Hg (95% CI, 2.2-4.5) increases in systolic and diastolic blood pressure, 3.0× the odds of at least hypertension stage 1 (95% CI, 1.49-5.83), 3.6× the odds of hypertension stage 2 (95% CI, 1.93-6.81), and 2.0× the odds of albuminuria (95% CI, 1.28-3.06). Calcium, potassium, and magnesium were unassociated with any outcomes. Hypertension stage 2 (but not hypertension stage 1) was associated with 2.6× (95% CI, 1.19-5.77) the odds of albuminuria. CONCLUSIONS Drinking water sodium-chloride was associated with resting blood pressure, hypertension, and albuminuria in a population with few traditional lifestyle risk factors for chronic disease. Measuring specific salts in water helps untangle associations with hypertension.