Background & aims: In June 2016, South Africa implemented legislation mandating maximum sodium levels in a range of processed foods with a goal of reducing population salt intake and disease burden from hypertension. Our aim was to explore the relationship between salt and blood pressure (BP) in a subsample of the World Health Organization Study on global AGEing and adult health (SAGE) Wave 2 before implementation of legislation in South Africa.
Methods & results: Blood pressure (BP) was measured in triplicate (n = 2722; median age 56 years; 33% male) and 24-h urine collected in a nested subsample (n = 526) for sodium, potassium and creatinine analysis. Hypertension prevalence was 55% in older adults (50-plus years) and 28% in younger adults (18-49 years). Median salt intake (6.8 g/day) was higher in younger than older adults (8.6 g vs 6.1 g/day; p < 0.001), and in urban compared to rural populations (7.0 g vs 6.0 g/day; p = 0.033). Overall, 69% of participants had salt intakes above 5 g/day. Potassium intakes were generally low (median 35 mmol/day) with significantly lower intakes in rural areas and older adults. Overall, 91% of adults failed to meet the daily potassium recommendation of 90 mmol/d. Salt intakes above 5 g/day, and to a greater extent, a dietary sodium-to-potassium (Na:K) ratio above 2 mmol/mmol, were associated with significantly steeper regression slopes of BP with age.
Conclusion: These preliminary results indicate that high dietary Na:K ratio may lead to a greater increase in BP and hypertension risk with age. Interventions to increase potassium intakes alongside sodium reduction initiatives may be warranted.
Keywords: Aging; Health policy; Hypertension; Potassium; Public health; Salt; Sodium; South Africa.
Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.