Lifting the lid on the benefits of sodium reduction legislation

A study has found that mandated sodium reductions for processed food in South Africa since 2013 have resulted in significant declines in blood pressure levels.

In 2013, South Africa became one of the first countries in the world and the first in Africa to pass regulations on sodium content. The legislation was implemented to help reduce the risk of cardiovascular disease by encouraging people to eat less salt and other sodium-rich foods.

The law required sodium content reductions on 13 food categories, including bread, cereals, fat spreads, chips, processed meats, soups, sauces and stock concentrates. By 2016, food manufacturers were required to reduce sodium content in these foods by 20 to 70%, then lower them further, by 5 to 46%, by 2019.

Published in JAMA Cardiology in February 2025, a study by researchers at Wits University and Harvard now reveals that this legislation has worked and could continue to have an impact in years to come.

The findings highlight that mandatory regulations are more effective than voluntary measures, as 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,” said Professor Steve Tollman, Director of the SAMRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt — where the study was done).

“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,” said 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.

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 and undergo lifestyle changes, and where the rural/urban divide is less well-defined.

The study was situated in this aging cohort, 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.

To assess the effectiveness of sodium regulation, the study looked at salt consumption and blood pressure among the HAALSA cohort, comprising more than 5000 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.

Gaziano notes that reductions of even one millimetre of mercury (mmHg) of blood pressure can lead to tens of thousands of deaths averted each year.

In Australia, a voluntary Partnership Reformulation Program began in July 2020, with sodium reduction targets set for 28 food categories, including bread, cheese and processed meats; and saturated fat reduction targets for five food categories.  In 2021, the program was expanded to a further 14 food categories, with sugar reduction targets for nine food categories and sodium reduction targets for five food categories. While the program has now ceased, the Australian Bureau of Statistics reported that participating companies removed 3.3 tonnes of sodium (equivalent to over 8 tonnes of table salt) and 261 tonnes of sugar from the food supply in the 2022–23 financial year.

“Most governments around the world have only encouraged or advised sodium reduction with limited effectiveness. Stricter legislation is better than a voluntary approach,” Tollman said.

“This study demonstrates that government action with accountability is able to impact not only on sodium intake but blood pressure levels as well.”

Image credit: iStock.com/Nansan Houn