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Excessive sodium consumption can worsen high blood pressure, which is linked to cardiovascular disease, which in turn is responsible for 20 million deaths a year globally.
Stroke, which is a type of cardiovascular disease, is also a leading cause of disability.
In response, South Africa became one of the first countries in the world and the first in Africa to pass regulations on sodium content. The idea was to encourage people to eat less salt and other sodium-rich food.
Salt and sodium are not the same. Sodium is the part of salt that raises blood pressure and leads to an increased risk of heart disease and stroke. Table salt comprises 40% sodium.
A study by researchers at Wits University and Harvard, titled “Sodium reduction legislation and urinary sodium and blood pressure in South Africa,” published in JAMA Cardiology in February 2025, now reveals that this legislation has worked and could continue to have an impressive impact in years to come.
The World Health Organization recommends less than 2 grams of salt per day; participants in this study reduced their sodium intake by 10% over seven years.
“In addition, many more people achieved the ideal sodium consumption: the number went from 7% to 17% and with every gram of sodium reduction, there was a reduction in blood pressure,” says Professor Steve Tollman, Director of the SAMRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt—where the study was done).
SA’s sodium legislation the most extensive any country has passed
The legislation has seen 13 categories of food reduce their sodium content, including bread, cereals, fat spreads, chips, processed meats, soups, sauces and stock concentrates.
By 2016, manufacturers were required to reduce sodium content in these foods between 20% and 70%, then lower them further, between 5% and 46%, by 2019.
Blood pressure reductions
“If this reduced sodium consumption remains constant over time, it could be associated with lower rates of cardiovascular disease mortality as well as of stroke, heart failure, end-stage renal disease, and vascular dementia, all of which are also associated with high blood pressure,” says Associate Professor Thomas Gaziano of the Harvard T.H Chan School of Public Health. Gaziano is also the lead and corresponding author of the study.
He notes that reductions of even 1 millimeter of mercury (mmHg) of blood pressure can lead to tens of thousands of deaths averted each year.
Tollman adds, “This kind of research insight suggests other countries can adopt similar laws and potentially see reductions in death and disability, including the US.”
Possible reversal of increased blood pressure levels linked to aging population
South Africa has a growing aging population and so-called “transitioning” societies. When an area is in transition, chronic diseases like heart disease, cancer, obesity, and diabetes replace infectious diseases as leading causes of death. This shift happens as countries develop economically and populations migrate from rural to urban settlements, undergo lifestyle changes, and where the rural/urban divide is less well-defined.
It is in this aging cohort that the study was situated, forming part of the Health and Aging in Africa: Longitudinal Studies in South Africa (HAALSA) program, a partnership between Wits, Harvard, University of Cape Town, and the Columbia University Department of Neurology.
HAALSA evaluates how policy and other drivers of health influence chronic and infectious diseases, including dementia, cardiometabolic disorders, and HIV, among South Africans ages 40 and above, in order to better understand health outcomes within an increasingly aging society.
To assess the effectiveness of sodium regulation, the study looked at salt consumption and blood pressure among the HAALSA cohort, comprising more than 5,000 adults aged 40 and above, in rural SA.
The researchers measured sodium levels in participants’ urine and took their blood pressure at three different times: in 2014, before the regulations were implemented, and again in 2018 and 2021.
“Most governments around the world have only encouraged or advised sodium reduction with limited effectiveness. Stricter legislation is better than a voluntary approach,” says Tollman. “This study demonstrates that government action with accountability is able to impact not only on sodium intake but blood pressure levels as well.”
More information:
Thomas Gaziano et al, Sodium Reduction Legislation and Urinary Sodium and Blood Pressure in South Africa, JAMA Cardiology (2025). DOI: 10.1001/jamacardio.2024.5410
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Pioneering sodium legislation linked to lower blood pressure and fewer deaths (2025, March 31)
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