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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.

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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.

References

  1. Vos T, Lim SS, Abbafati C, Abbas KM, Abbasi M, Abbasifard M, et al. Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020;396:1204–22.

    Article  Google Scholar 

  2. Afshin A, Sur PJ, Fay KA, Cornaby L, Ferrara G, Salama JS, et al. Health effects of dietary risks in 195 countries, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2019;393:1958–72.

    Article  Google Scholar 

  3. World Health Organization. Guideline: Sodium intake for adults and children: World Health Organization; 2012.

  4. Hyseni L, Green AE, Lloyd-Williams F, O’Flaherty M, Kypridemos C, McGill R, et al. Systematic review of dietary salt reduction policies: evidence for an “effectiveness hierarchy”? PLoSONE. 2016;12:e0177535.

    Article  Google Scholar 

  5. Bertram MY, Steyn K, Wentzel-Viljoen E, Tollman S, Hofman KJ. Reducing the sodium content of high-salt foods: effect on cardiovascular disease in South Africa. S Afr Med J. 2012;102:743–5.

    Article  CAS  Google Scholar 

  6. Watkins DA, Olson ZD, Verguet S, Nugent RA, Jamison DT. Cardiovascular disease and impoverishment averted due to a salt reduction policy in South Africa: an extended cost-effectiveness analysis. Health Policy Plan. 2015;31:75–82.

    Article  Google Scholar 

  7. Neal B, Wu Y, Feng X, Zhang R, Zhang Y, Shi J, et al. Effect of salt substitution on cardiovascular events and death. N Eng J Med. 2021;385:1067–77.

    Article  CAS  Google Scholar 

  8. Hofman KJ, RL Successful sodium regulation in South Africa. World Health Organization regional office for Africa; 2013.

  9. Ware LJ, Charlton K, Schutte AE, Cockeran M, Naidoo N, Kowal P. Associations between dietary salt, potassium and blood pressure in South African adults: WHO SAGE Wave 2 Salt & Tobacco. Nutr Metab Cardiovasc Dis. 2017;27:784–91.

    Article  CAS  Google Scholar 

  10. Elijovich F, Weinberger MH, Anderson CAM, Appel LJ, Bursztyn M, Cook NR, et al. Salt sensitivity of blood pressure. Hypertension. 2016;68:e7–e46.

    Article  CAS  Google Scholar 

  11. Schutte A, Botha S, Fourie C, Gafane-Matemane L, Kruger R, Lammertyn L, et al. Recent advances in understanding hypertension development in sub-Saharan Africa. J Hum Hypertens. 2017;8:491–500.

    Article  Google Scholar 

  12. Charlton KE, Steyn K, Levitt NS, Zulu JV, Jonathan D, Veldman FJ, et al. Diet and blood pressure in South Africa: Intake of foods containing sodium, potassium, calcium, and magnesium in three ethnic groups. Nutrition. 2005;21:39–50.

    Article  CAS  Google Scholar 

  13. Charlton KE, Steyn K, Levitt NS, Zulu JV, Jonathan D, Veldman FJ, et al. Ethnic differences in intake and excretion of sodium, potassium, calcium and magnesium in South Africans. Eur J Cardiovasc Prev Rehabil. 2005;12:355–62.

    Article  Google Scholar 

  14. Schutte AE, Gona PN, Delles C, Uys AS, Burger A, Mels CM, et al. The African Prospective study on the Early Detection and Identification of Cardiovascular disease and Hypertension (African-PREDICT): Design, recruitment and initial examination. Eur J Prev Cardiol. 2019;26:458–70.

    Article  Google Scholar 

  15. Williams B, Mancia G, Spiering W, Agabiti Rosei E, Azizi M, Burnier M, et al. 2018 ESC/ESH Guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Cardiology (ESC) and the European Society of Hypertension (ESH). Eur Heart J. 2018;39:3021–104.

    Article  Google Scholar 

  16. WHO/PAHO Regional Expert Group for Cardiovascular Disease Prevention through Population‐wide Dietary Salt Reduction. Protocol for population level sodium determination in 24‐hour urine samples. World Health Organization Geneva, Switzerland; 2010.

  17. Stolarz-Skrzypek K, Kuznetsova T, Thijs L, et al. FAtal and nonfatal outcomes, incidence of hypertension, and blood pressure changes in relation to urinary sodium excretion. JAMA. 2011;305:1777–85.

    Article  CAS  Google Scholar 

  18. Center for Disease Control and Prevention. Sodium reduction toolkit: a global opportunity to reduce population-level sodium intake. 2013. [Available from: http://medbox.iiab.me/modules/en-cdc/www.cdc.gov/salt/sodium_toolkit.htm.1]

  19. Stevens LA, Claybon MA, Schmid CH, Chen J, Horio M, Imai E, et al. Evaluation of the Chronic Kidney Disease Epidemiology Collaboration equation for estimating the glomerular filtration rate in multiple ethnicities. Kidney Int. 2011;79:555–62.

    Article  Google Scholar 

  20. Schultz WM, Kelli HM, Lisko JC, Varghese T, Shen J, Sandesara P, et al. Socioeconomic status and cardiovascular outcomes. Circulation. 2018;137:2166–78.

    Article  Google Scholar 

  21. World Health Organization. Global action plan for the prevention and control of noncommunicable diseases 2013-20. 2013.

  22. Swanepoel B, Malan L, Myburgh PH, Schutte AE, Steyn K, Wentzel-Viljoen E. Sodium content of foodstuffs included in the sodium reduction regulation of South Africa. J Food Composit Anal. 2017;63:73–8.

    Article  CAS  Google Scholar 

  23. Charlton KE, Corso B, Ware L, Schutte AE, Wepener L, Minicuci N, et al. Effect of South Africa’ s interim mandatory salt reduction programme on urinary sodium excretion and blood pressure. Prev Med Rep. 2021;23:101469. https://doi.org/10.1016/j.pmedr.2021.101469.

    Article  Google Scholar 

  24. Tekle DY, Santos JA, Trieu K, Thout SR, Ndanuko R, Charlton K, et al. Monitoring and implementation of salt reduction initiatives in Africa: a systematic review. J Clin Hypertens. 2020;22:1355–70.

    Article  Google Scholar 

  25. Menyanu E, Charlton KE, Ware LJ, Russell J, Biritwum R, Kowal P. Salt use behaviours of ghanaians and south africans: a comparative study of knowledge, attitudes and practices. Nutrients. 2017;9:939.

    Article  Google Scholar 

  26. Capewell S, Kypridemos C. Socioeconomic inequalities in dietary sodium intake: upstream versus downstream interventions. Am J Public Health. 2017;107:499–500.

    Article  Google Scholar 

  27. The Heart and Stroke Foundation SA. ENDORSEMENTS [Available from: https://www.heartfoundation.co.za/endorsements/].

  28. Wentzel-Viljoen E, Steyn K, Lombard C, De Villiers A, Charlton K, Frielinghaus S, et al. Evaluation of a mass-media campaign to increase the awareness of the need to reduce discretionary salt use in the South African population. Nutrients. 2017;9. https://doi.org/10.3390/nu9111238

  29. Campbell NR, He FJ, Tan M, Cappuccio FP, Neal B, Woodward M, et al. The International Consortium for Quality Research on Dietary Sodium/Salt (TRUE) position statement on the use of 24‐hour, spot, and short duration (< 24 h) timed urine collections to assess dietary sodium intake. J Clin Hypertens. 2019;21:700–9.

    Article  Google Scholar 

  30. Charlton KE, Schutte AE, Wepener L, Corso B, Kowal P, Ware LJ. Correcting for Intra-individual variability in sodium excretion in spot urine samples does not improve the ability to predict 24 h urinary sodium excretion. Nutrients. 2020;12:2026.

    Article  CAS  Google Scholar 

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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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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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