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Nutr Metab Cardiovasc Dis. 2017 Sep;27(9):784-791. doi: 10.1016/j.numecd.2017.06.017. Epub 2017 Jul 8.

Associations between dietary salt, potassium and blood pressure in South African adults: WHO SAGE Wave 2 Salt & Tobacco.

Author information

Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa. Electronic address:
School of Medicine, University of Wollongong, New South Wales, Australia. Electronic address:
Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa; MRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, South Africa. Electronic address:
Statistical Consultation Services, North-West University, Potchefstroom, South Africa. Electronic address:
World Health Organization (WHO), Geneva, Switzerland. Electronic address:
World Health Organization (WHO), Geneva, Switzerland; University of Newcastle Research Centre for Generational Health and Ageing, Newcastle, Australia; University of Oregon, Department of Anthropology, Eugene, OR, USA. Electronic address:



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.


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.


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.


Aging; Health policy; Hypertension; Potassium; Public health; Salt; Sodium; South Africa

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