The use of dietary salt substitutes lower the risk of heart attack, stroke, and death from all causes and cardiovascular disease, according to a group of international researchers.
The findings from their analysis of the available evidence, suggests the beneficial effects of these substitutes are likely to apply to people all around the world, they said in the journal Heart.
The researchers noted that a diet high in sodium and low in potassium was known to drive up blood pressure, with hypertension affecting around 1.28 billion people around the world.
They also highlighted that salt substitutes, in which a proportion of sodium chloride (NaCl) is replaced with potassium chloride (KCl), were known to help lower blood pressure.
A recent Chinese study – the Salt Substitute and Stroke Study (SSaSS) – found salt substitutes cut the risk of heart attacks, stroke, and early death.
But it was unclear whether the benefits seen in SSaSS, the largest ever trial of a potassium-enriched salt substitute to date, applied globally or just to China.
To investigate, the researchers reviewed 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.
They 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 five years. The proportion of sodium chloride in the salt substitutes varied from 33% to 75%, while the proportion of potassium ranged from 25% to 65%.
The analysis showed that salt substitutes lowered blood pressure in all the participants. The overall reduction in systolic blood pressure was 4.61mmHg and 1.61mmHg for diastolic blood pressure.
Reductions in blood pressure seemed to be consistent, irrespective of other factors, like geography, age, sex, history of hypertension, weight and baseline levels of urinary sodium and potassium.
In addition, each 10% lower proportion of sodium chloride in the salt substitute was associated with a 1.53mmHg greater fall in systolic blood pressure and a 0.95mmHg greater fall in diastolic pressure.
There was no evidence that higher dietary potassium was associated with any health harms, said the researchers from Australia, China, Sweden, Peru, the UK and the US.
A more detailed look at the results of five of the trials, involving 24,000 participants, found salt substitutes lowered the risk of early death from any cause by 11%, from cardiovascular disease by 13%, and the risks of heart attack or stroke by 11%.
The researchers, some of whom were from Imperial College of Science Technology and Medicine, highlighted that their findings echoed those of the SSaSS.
“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 said.
“These findings… 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,” they added.
Tracy Parker, a heart health dietitian at the British Heart Foundation, said: “This research is a helpful reminder to cut the amount of salt we have in our diets and to look for alternatives.”
“However, while low salt substitutes have less sodium than regular salt, they still contain potassium which may not be suitable for some people with a heart problem and other existing health conditions.”
Ms Parker noted that, overall, it was better to “just eat less salt”.