Sodium and potassium excretion in an adult Caribbean population of African descent with a high burden of cardiovascular disease

Rachel M. Harris, Angela M. C. Rose, Ian R. Hambleton, Christina Howitt, Nita G. Forouhi, Anselm J. M. Hennis, T. Alafia Samuels, Nigel Unwin

High sodium diets with inadequate potassium and high sodium-to-potassium ratios are a known determinant of hypertension and cardiovascular disease (CVD). The Caribbean island of Barbados has a high prevalence of hypertension and mortality from CVD. Our objectives were to estimate sodium and potassium excretion, to compare estimated levels with recommended intakes and to identify the main food sources of sodium in Barbadian adults. A sub-sample (n = 364; 25-64 years) was randomly selected from the representative population-based Health of the Nation cross-sectional study (n = 1234), in 2012-13. A single 24-h urine sample was collected from each participant, following a strictly applied protocol designed to reject incomplete samples, for the measurement of sodium and potassium excretion (in mg), which were used as proxy estimates of dietary intake. In addition, sensitivity analyses based on estimated completeness of urine collection from urine creatinine values were undertaken. Multiple linear regression was used to examine differences in sodium and potassium excretion, and the sodium-to-potassium ratio, by age, sex and educational level. Two 24-h recalls were used to identify the main dietary sources of sodium. All analyses were weighted for the survey design. Mean sodium excretion was 2656 (2488-2824) mg/day, with 67% (62-73%) exceeding the World Health Organization (WHO) recommended limit of 2000 mg/d. Mean potassium excretion was 1469 (1395-1542) mg/d; < 0.5% met recommended minimum intake levels. Mean sodium-to-potassium ratio was 2.0 (1.9-2.1); not one participant had a ratio that met WHO recommendations. Higher potassium intake and lower sodium-to-potassium ratio were independently associated with age and tertiary education. Sensitivity analyses based on urine creatinine values did not notably alter these findings. In this first nationally representative study with objective assessment of sodium and potassium excretion in a Caribbean population in over 20 years, levels of sodium intake were high, and potassium intake was low. Younger age and lower educational level were associated with the highest sodium-to-potassium ratios. These findings provide baseline values for planning future policy interventions for non-communicable disease prevention.