Hypertension guidelines must include salt substitues: research

Hypertension treatment guidelines must include recommendations on low-sodium potassium-enriched salt, according to a global team of researchers.

High levels of sodium intake and low levels of potassium intake are widespread, and both are linked to high blood pressure (hypertension) and greater risk of stroke, heart disease and premature death. Using a salt substitute where part of the sodium chloride is replaced with potassium chloride addresses both problems at once, suggest researchers.

Salt and substitutes

A global collaboration of researchers from the US, Australia, Japan, South Africa and India reviewed 32 separate hypertension treatment guidelines - two from global organisations, five from regional organisations and 25 from country organisations — published from 1 January 2013 to 21 June 2023. The research has been published in the American Heart Association’s journal Hypertension.

They found all guidelines referred to sodium reduction, with most recommending reducing salt intake. Many also recommended increasing dietary potassium intake, but only two — the Chinese and European guidelines — made a specific recommendation for using potassium-enriched salt.

Professor Garry Jennings, Chief Medical Advisor at the National Heart Foundation said as many as one in three Australian adults have high blood pressure — equivalent to 6.8 million people.

“It’s concerning that we have not made much progress in lowering that figure in the last decade, despite all the tools at our disposal. We know that reducing sodium and increasing potassium helps improve blood pressure control, but people find it hard to make the necessary changes to their diet.”

Mean global sodium intake was recently estimated to be 4.3 g/day, or about 10.8 g/day of salt — more than double the WHO recommendation for adults of less than 2000 mg/day sodium (equivalent to <5 g/day).   In Australia and New Zealand, most people also consume excessive amounts of sodium — the estimated average is about 3600 mg/day.   Sodium reduction is listed as a ‘best-buy’ chronic disease intervention by the WHO, proposing that all member states reduce mean population intake by 30% by 2025.

Guidelines and recommendations

Professor Alta Schutte, at The George Institute for Global Health and UNSW Sydney, said that despite data from randomised controlled trials demonstrating the health benefits of potassium-enriched, sodium-reduced salt substitutes, they are rarely used.

“We found current clinical guidelines offer incomplete and inconsistent recommendations about the use of these salt substitutes,” she said.

“Given the wealth of evidence available, we feel it’s time to include salt substitutes in treatment guidelines to help address spiralling rates of uncontrolled high blood pressure around the world and reduce preventable deaths.”

The study authors proposed the following wording for inclusion in clinical guidelines for blood pressure control:

• Strong recommendation for patients with hypertension — Potassium-enriched salt with a composition of approximately 75% sodium chloride and 25% potassium chloride should be recommended to all patients with hypertension, unless they have advanced kidney disease, are using a potassium supplement, are using a potassium sparing diuretic or have another contra-indication.
• Conditional recommendation for the general population — If you have to add salt to foods, potassium-enriched salt with a composition of approximately 75% sodium chloride and 25% potassium chloride can be recommended for use by the general population in settings where there is a low likelihood that people with advanced kidney disease (stage 4-5) will be undiagnosed by the health system and contraindications to use can be printed on product packaging.
   

Potassium-enriched salt can be used at home and in commercial settings as a direct replacement for regular salt (sodium chloride) when seasoning, preserving or manufacturing foods. Importantly, while other salt reduction strategies make foods taste less salty, switching to potassium-enriched salt is undetectable by most people.

“Unwanted taste effects are the main reason why efforts to reduce salt intake have failed for more than two decades. The willingness of patients to keep using potassium-enriched salt removes that barrier, which is why it can be a game-changer,” Schutte added.

Barriers to uptake

Jennings said that while potassium-enriched salt substitutes could provide a simple solution, a shift in the food environment would be needed to fully realise the benefits.

“We would need to see low-sodium, potassium-enriched salts more widely available on supermarket shelves across the country, but they would also need to be affordable for most Australians.”

Another barrier to uptake has been concerns about causing elevated levels of potassium in the blood (hyperkalaemia) in people with advanced kidney disease.

Professor Bruce Neal, Executive Director at The George Institute Australia and Professor of Clinical Epidemiology at Imperial College London, said it is clear that patients with advanced kidney disease should not use potassium-enriched salts, but this applies to a very small proportion of the population, and these patients are already advised to avoid salt.

“No issues with serious harm from hyperkalaemia were recorded in any of the trials to date, though all were done in clinical settings. Our recommendation for use in hypertension is based on patients being managed by a healthcare worker. Healthcare workers know not to recommend potassium-enriched salt in the presence of kidney disease and risks for these patients can be avoided.”

The authors argued that given potassium-enriched salt substitution is one of the few dietary interventions patients comply with long-term, it is logical to at least consider the use of potassium-enriched salt for all those with hypertension.

“We strongly encourage clinical guideline bodies to review their recommendations about the use of potassium-enriched salt substitutes at the earliest opportunity — if the world switched from using regular salt to potassium-enriched it would prevent millions of strokes and heart attacks every year at very low cost,” Schutte said.

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