According to a pooled data analysis of the available evidence, dietary salt substitutes lower the risk of heart attack, stroke, and death from all causes and cardiovascular disease. The findings were published on August 9 in the BMJ journal Heart.
The researchers believe that the beneficial effects of these substitutes are likely to apply to people all around the world.
High blood pressure is a significant risk factor for an early death, and cardiovascular disease is the leading cause of mortality globally. A diet high in sodium and low in potassium is known to increase blood pressure.
Around 1.28 billion people around the world have high blood pressure, although more than half of these are undiagnosed, according to the researchers.
Salt substitutes, which replace a proportion of sodium chloride (NaCl) with potassium chloride (KCl), are known to help lower blood pressure.
A recently published large study from China (Salt Substitute and Stroke Study; SSaSS) found that salt substitutes cut the risk of heart attacks, stroke, and early death. However, it was unclear whether these benefits would apply to other parts of the world.
In an effort to shed light on this, the scientists trawled research databases looking for randomized clinical trials published up to the end of August 2021 that reported on the effects of a salt substitute on blood pressure, cardiovascular health, and early death.
Blood pressure, which is measured in mm Hg, is made up of two numbers: systolic—the higher number that indicates the force at which the heart pumps blood around the body; and diastolic—the lower number that indicates arterial pressure when the heart is filling with blood.
They pooled the results of 21 relevant international clinical trials involving nearly 30,000 people. These were carried out in Europe, the Western Pacific Region, the Americas, and South-East Asia.
The study periods lasted from 1 month to 5 years. The proportion of sodium chloride in the salt substitutes varied from 33% to 75%; the proportion of potassium ranged from 25% to 65%.
According to the pooled data analysis, salt substitutes lowered blood pressure in all the participants. The overall reduction in systolic blood pressure was 4.61 mm Hg and the overall reduction in diastolic blood pressure was 1.61 mmHg.
Reductions in blood pressure seemed to be consistent, irrespective of geography, age, sex, history of high blood pressure, weight (BMI), baseline blood pressure, and baseline levels of urinary sodium and potassium.
And each 10% lower proportion of sodium chloride in the salt substitute was associated with an additional 1.53 mm Hg drop in systolic blood pressure and an additional 0.95 mm Hg drop in diastolic blood pressure. There was no indication that consuming more potassium was harmful to one’s health.
A pooled data analysis of the results of five of these trials involving more than 24,000 participants showed that salt substitutes lowered the risks of early death from any cause by 11%, from cardiovascular disease by 13%, and the risks of heart attack or stroke by 11%.
The scientists acknowledge certain limitations to their findings, including that the studies in the pooled data analysis varied in design and that there were relatively few data for people who didn’t have high blood pressure.
But they nevertheless highlight that their findings echo those of the SSaSS, the largest ever trial of a potassium-enriched salt substitute to date.
“Since blood pressure lowering is the mechanism by which salt substitutes confer their cardiovascular protection, the observed consistent blood pressure reductions make a strong case for generalisability of the cardiovascular protective effect observed in the SSaSS both outside of China and beyond,” the authors write.
“These findings are unlikely to reflect the play of chance and support the adoption of salt substitutes in clinical practice and public health policy as a strategy to reduce dietary sodium intake, increase dietary potassium intake, lower blood pressure and prevent major cardiovascular events,” the researchers conclude.
Reference: “Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis” by Xuejun Yin, Anthony Rodgers, Adam Perkovic, Liping Huang, Ka-Chun Li, Jie Yu, Yangfeng Wu, J H Y Wu, Matti Marklund, Mark D Huffman, J Jaime Miranda, Gian Luca Di Tanna, Darwin Labarthe, Paul Elliott, Maoyi Tian and Bruce Neal, 9 August 2022, Heart.