Potassium excretion and blood pressure are associated with heart rate variability in healthy black adults: The African-PREDICT study

•Heart rate variability (HRV) is a valid non-invasive tool to determine the development of hypertension cardiovascular risk.•Imbalanced dietary Na and K intake may lead to reduced HRV and the early development of hypertension in black populations.•In the black group lower K excretion and higher Na/K ratio associated with higher parasympathetic and sympathetic activity.•Black individuals showed higher parasympathetic activity (RMSSD and HF), but lower SDNN and LF than white individuals.•A better ethnic-specific understanding of Na and K handling is required as part of preventative cardiology.