Erythrocyte sodium buffering capacity status correlates with self-reported salt intake in a population from Livingstone, Zambia

Background Salt impairs endothelial function and increases arterial stiffness independent of blood pressure. The mechanisms are unknown. Recent evidence suggests that there is a possible link between salt consumption and sodium buffering capacity and cardiovascular disease but there is limited evidence in the populations living in Sub-Saharan Africa. The aim of our study was to explore the relationship between erythrocyte sodium buffering capacity and sociodemographic, clinical factors, and self-reported salt consumption at Livingstone Central Hospital. Methods We conducted a cross sectional study at Livingstone Central hospital among 242 volunteers accessing routine medical checkups. Sociodemographic and dietary characteristics were obtained along with clinical measurements to evaluate their health status. Sodium buffering capacity was estimated by erythrocyte sodium sensitivity (ESS) test. We used descriptive and inferential statistics to describe and examine associations between erythrocyte sodium sensitivity and independent variables. Results The median age (interquartile range) of the study sample was 27 (22, 42) years. 54% (n=202) and 46% (n=169) were males and females, respectively. The majority (n=150, 62%) had an ESS of >120%. High salt intake correlated positively with ESS or negatively with vascular sodium buffering capacity. Conclusions Self-reported high salt intake was associated with poor vascular sodium buffering capacity or high ESS in the majority of middle-aged Zambians living in Livingstone. The poor vascular sodium buffering capacity implies a damaged vascular glycocalyx which may potentially lead to a leakage of sodium into the interstitium. This alone is a risk factor for the future development of hypertension and cardiovascular disease. However, future studies need to validate vascular function status when using ESS testing by including established vascular function assessments to determine its pathophysiological and clinical implications. Keywords: Erythrocyte sodium sensitivity, sodium buffering capacity, vascular health, salt, red blood cells