Switching from regular salt to a low-sodium salt substitute has major public health benefits, including a reduction in stroke, cardiovascular events, and death, a new landmark study shows.
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The Salt Substitute and Stroke Study (SSaSS) was conducted in 21,000 people with a history of stroke or high blood pressure in rural China, with half of them using a lower-sodium salt substitute instead of regular salt.
Results showed that after 5 years, those using the salt substitute had a 14% reduction in stroke, a 13% reduction in major cardiovascular events, and a 12% reduction in death. These benefits were achieved without any apparent adverse effects.
The trial was presented by Bruce Neal, MB, George Institute for Global Health, Sydney, Australia, on Aug. 29 at the virtual European Society of Cardiology (ESC) Congress 2021. They were simultaneously published online in the New England Journal of Medicine.
“This is one of the largest dietary intervention trials ever conducted and has shown very clear evidence of protection against stroke, cardiovascular events, and premature death, with no adverse effects with a very simple and low-cost intervention,” Dr. Neal concluded. “This is a very easy thing to work into the diet. You just replace regular salt with a substitute that looks and tastes almost identical,” he added.
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Addressing the issue of whether these results are generalizable to other populations, Dr. Neal said, “We believe the results are relevant to everyone who eats salt.
“The way the body manages sodium and potassium and their association with blood pressure is highly consistent across different populations,” he said. “Almost everyone, with the exception of a few people with serious kidney disease, should be avoiding salt or switching to a salt substitute and expect to see some benefit of this.”
Commentators at the ESC presentation lauded the study as “magnificent,” with “extraordinary” results and “very powerful implications.”
Designated discussant, hypertension expert Bryan Williams, MD, University College London, said the SSaSS was “probably the most important study with regards to public health that we will see.” He described the reductions in stroke, cardiovascular events, and death as “extraordinary for such a simple intervention.”
Dr. Williams added: “Those who have doubted the benefits of salt restriction must now admit they were wrong. The debate stops here. The data are in. Global health interventions to implement these findings must now begin.”
He also highlighted the large number of events in the trial. “This was a large, pragmatic, long-duration study in a high-risk population, and with 5,000 cardiovascular events it gives enormous power to show benefits.”
Chair of the ESC session, Barbara Casadei, MD, DPhil, John Radcliffe Hospital, Oxford (England), said the SSaSS “will change the way we think about salt and be remembered for years to come.”
Noting that the benefits were seen in all subgroups across the study, Bertram Pitt, MD, University of Michigan, Ann Arbor, was particularly excited about the stroke reduction seen in patients with diabetes, noting that several recent trials of new diabetes drugs have not managed to show a reduction in stroke.
“For patients with diabetes, this is a really important intervention,” he stated.
However, an editorial accompanying the NEJM publication gave a somewhat less enthusiastic response to the study than the ESC commentators.
Julie R. Ingelfinger, MD, deputy editor of the journal, points out that serial monitoring of potassium levels was not performed in the trial, so it is possible that hyperkalemic episodes were not detected, and persons with a history of medical conditions that may be associated with hyperkalemia were not studied.
She also noted that because the salt substitute was distributed to families, it would have been instructive to have data on the household members without risk factors, but no such data were obtained.
“Overall, the SSaSS provides some intriguing hints, but wider effectiveness is hard to predict, given limited generalizability,” she concluded.