Dietary salt substitutes may lower risk of heart attack, stroke and death

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The analysis determined that using substitutes reduced the risks of early death from any cause by 11 percent, from cardiovascular disease by 13 percent, and the risks of heart attack or stroke by 11 percent. Photo credit: Getty Images

Substituting salt in your diet could help lower the risk of heart attack, stroke and death from all causes as well as cardiovascular disease, according to a review of data by Australian experts. 

Published in the peer-reviewed medical journal Heart, the researchers - from the George Institute for Global Health, the University of New South Wales, the University of Newcastle and Harbin Medical University in China - analysed the results of clinical trials and found dietary salt substitutes lowered blood pressure by around 4.6/1.6mm Hg. 

The analysis determined that using substitutes reduced the risks of early death from any cause by 11 percent, from cardiovascular disease by 13 percent, and the risks of heart attack or stroke by 11 percent. According to their research, the beneficial effects of these substitutes are likely to apply to people around the world.

Cardiovascular disease is the leading cause of death worldwide and high blood pressure is a major risk for an early death; a diet high in sodium and low in potassium is known to drive up the pressure. Around 1.28 billion people around the world have high blood pressure, although more than half of these are undiagnosed, the researchers said. 

Salt substitutes, in which a proportion of sodium chloride (NaCl) is replaced with potassium chloride (KCl), are known to help lower blood pressure; the pressure of circulating blood against the walls of blood vessels.

A recently published large study from China (Salt Substitute and Stroke Study; SSaSS) found that these dietary substitutes can cut the risk of heart attacks, stroke and early death, but it was unclear whether these benefits would apply to other parts of the world.

To shed light on this, the researchers trawled research databases looking for randomised clinical trials reporting on the effects of a salt substitute on blood pressure, cardiovascular health and early death, published up to the end of August 2021.

Blood pressure, which is measured in mmHg, 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.

The team of researchers pooled the results of 21 relevant international clinical trials involving nearly 30,000 people, carried out in Europe, the Western Pacific Region, the Americas and South-East Asia.

The study periods lasted from one month to 5 years. The proportion of sodium chloride in the salt substitutes varied from 33 percent to 75 percent; the proportion of potassium ranged from 25 percent to 65 percent.

The data analysis demonstrated that 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.

Each 10 percent lower proportion of sodium chloride in the salt substitute was associated with a 1.53 mmHg greater fall in systolic blood pressure and a 0.95 mmHg greater fall in diastolic blood pressure, the researchers added. There was no evidence that higher dietary potassium was associated with any health harms.

A pooled data analysis of the results of five of these trials, involving more than 24,000 participants, showed that salt substitutes also lowered the risks of early death.

The researchers acknowledged certain limitations to their findings, including that the studies in the pooled data analysis varied in design and there was relatively little data for people who didn't have high blood pressure.

They highlighted 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," they wrote.

"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."