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Early evidence for the effectiveness of South Africa’s legislation on salt restriction in foods: the African-PREDICT study

Journal of Human Hypertension volume 37, pages 42–49 (2023)Cite this article

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Abstract

South Africa was among the first countries to adopt mandatory regulation in 2016 to lower the salt content in processed foods, aiming to reduce population salt intake to <5 g/day. To assess the effectiveness of this regulation in 20-30 year-old adults, we determined the change in salt intake over a mean follow-up time of 4.56-years spanning the implementation of the regulation. This observational study included baseline (2013–2016; N = 668; 24.9 ± 3 years; 47.8% black; 40.7% men) and follow-up data (2018—ongoing; N = 311; 25.4 ± 3.05 years; 51.1% black; 43.4% men) for participants of the African-PREDICT study. Salt intake was estimated from 24-h urinary sodium excretion. Median salt intake at baseline (N = 668) was 7.88 g/day (IQR: 5.67). In those followed (N = 311), salt intake reduced from baseline [median (IQR): 7.91 g/day (5.83)] to follow-up [7.26 g/day (5.30)] [unadjusted median: –0.82 g/day]. After adjusting for baseline salt intake to address regression to the mean, the mean salt reduction was –1.2 g/day. The greatest reductions were in men [mean difference: –1.47 g/day], black adults [mean difference: –2.04 g/day], and participants from low [mean difference: –1.89 g/day] or middle [mean difference: –1.84 g/day] socio-economic status groups, adjusting for baseline salt intake. Our preliminary findings suggest that South Africa’s salt regulation has been effective in lowering salt intake in young adults by ~1.2 g salt/day. Our study supports the effectiveness of upstream interventions to lower population salt intake, particularly for vulnerable groups who may typically consume more processed foods. It needs to be determined if the legislation has the anticipated population health gains.

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Fig. 1: Diagram illustrating the participant inclusion for this study.
Fig. 2: Unadjusted individual change in estimated salt intake from baseline to follow-up.
Fig. 3: Change in estimated salt intake from baseline to follow-up adjusted for baseline estimated salt intake of each respective group.
Fig. 4: Mean change in estimated salt intake of groups adjusted for baseline estimated salt intake of the total group at 7.76 g/day.

Data availability

Assignable to the informed consent given by participants, the data for this study, which is centrally managed by the data manger using REDCap, can be obtained by means of the necessary arrangements with Prof Aletta E Schutte or Prof Carina Mels from the Hypertension in Africa Research Team (HART). Potential collaborators are invited to contact the principal investigator of African-PREDICT for further information.

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Acknowledgements

We are grateful towards all individuals participating voluntarily in the study. The dedication of the support and research staff as well as students at the Hypertension Research and Training Clinic at the North-West University are also duly acknowledged.

Funding

The research funded in this manuscript is part of an ongoing larger research project financially supported by the South African Medical Research Council (SAMRC) with funds from National Treasury under its Economic Competitiveness and Support Package; the South African Research Chairs Initiative (SARChI) of the Department of Science and Technology and National Research Foundation (NRF) of South Africa (GUN 86895); SAMRC with funds received from the South African National Department of Health, GlaxoSmithKline R&D (Africa Non-Communicable Disease Open Lab grant), the UK Medical Research Council and with funds from the UK Government’s Newton Fund; as well as corporate social investment grants from Pfizer (South Africa), Boehringer-Ingelheim (South Africa), Novartis (South Africa), the Medi Clinic Hospital Group (South Africa) and in-kind contributions of Roche Diagnostics (South Africa). Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors, and therefore, the NRF does not accept any liability in this regard.

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Authors and Affiliations

  1. Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, 2520, South Africa

    Michél Strauss-Kruger & Aletta E. Schutte

  2. MRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, 2520, South Africa

    Michél Strauss-Kruger & Aletta E. Schutte

  3. Centre of Excellence for Nutrition, North-West University, Potchefstroom, 2520, South Africa

    Edelweiss Wentzel-Viljoen & Tertia Van Zyl

  4. DSI-NRF Centre of Excellence in Human Development and SAMRC/Wits Developmental Pathways for Health Research Unit, University of the Witwatersrand, Johannesburg, South Africa

    Lisa J. Ware & Aletta E. Schutte

  5. School of Medicine, Faculty of Science, Medicine and Health, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia

    Karen Charlton

  6. Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia

    Karen Charlton

  7. Pure and Applied Analytics, North-West University, Potchefstroom, 2520, South Africa

    Suria Ellis

  8. School of Population Health, University of New South Wales, Sydney, NSW, 2052, Australia

    Aletta E. Schutte

  9. The George Institute for Global Health, Sydney, NSW, 2042, Australia

    Aletta E. Schutte

Authors
  1. Michél Strauss-Kruger
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  2. Edelweiss Wentzel-Viljoen
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  3. Lisa J. Ware
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  4. Tertia Van Zyl
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Contributions

AES and MSK conceived and/designed the work that led to the submission. MSK, AES, EWV, LJW an TVZ acquired the data. AES, MSK, EWV, LJW, TVZ, KC and SE helped with the interpretation of the results. MSK drafted the first version of the manuscript and AES, EWV, LJW, TVZ, KC and SE critically revised the manuscript. All authors MSK, AES, EWV, LJW, TVZ, KC and SE approved the final version of the manuscript and agree to be accountable for all aspects of the work.

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Correspondence to Aletta E. Schutte.

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Strauss-Kruger, M., Wentzel-Viljoen, E., Ware, L.J. et al. Early evidence for the effectiveness of South Africa’s legislation on salt restriction in foods: the African-PREDICT study. J Hum Hypertens 37, 42–49 (2023). https://doi.org/10.1038/s41371-021-00653-x

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