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

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 mmHg (95% CI, 2.4–6.6) and 3.3 mmHg (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.