Swapping table salt for a potassium alternative cuts blood pressure

Replacing regular table salt with a potassium-enriched substitute reduces blood pressure and the risk of cardiovascular events, such as heart attacks and strokes, among people who are over 55 and living in care homes.

Salt contains sodium, which can increase blood pressure. Salt substitutes that replace some of this sodium with potassium may lower blood pressure, however, few studies have shown their effectiveness among people over 55. Our blood pressure and risk of cardiovascular events increases with age, so these people may have the most to gain by making the swap. There are also concerns that these substitutes may cause high levels of potassium in the blood, called hyperkalemia, which can lead to serious heart problems in some cases.

In a clinical trial made up of 1612 people who were living in 48 care facilities in China, meals were prepared with either regular salt containing 100 per cent sodium chloride or with a potassium-enriched salt substitute containing 62.5 per cent sodium chloride and 25 per cent potassium chloride, alongside other flavourings. Some of the participants also ate meals with just less salt in general. The participants were all over 55 years old, with an average age of 71.

At the start of the study, the average blood pressure of the participants was 137.5/80.5 millimetres of mercury (mmHg), with the higher number representing systolic blood pressure – the force at which your heart pumps blood around your body – and the lower number showing diastolic blood pressure – the resistance to the blood flow in the blood vessels. An ideal reading is usually considered to be between 90/60mmHg and 120/80mmHg.

Almost two-thirds of the participants had high blood pressure at the beginning of the trial.

Over two years, those living in facilities where the potassium-enriched salt substitute was introduced had an average reduction in systolic blood pressure of 7.1mmHg and in diastolic pressure of 1.9mmHg, compared with those in the regular salt group.

“This is an impressive fall in blood pressure – it’s at least what you’d expect to get if you gave everyone a [blood pressure-lowering] drug,” says Bruce Neal at the George Institute for Global Health in Sydney, Australia, who was part of the research team.

The reduction in blood pressure was associated with 1.5 fewer heart attacks, strokes and other cardiovascular events per 100 people in the salt substitute group, compared with the regular salt group.

In contrast, no reduction in the average blood pressure or number of cardiovascular events was seen in the group living in facilities that simply reduced the salt content of meals. This may be because these participants didn’t like the taste of the reduced-salt meals and therefore added salt themselves, says Neal.

The researchers also found that while those in the salt substitute group had increased blood potassium levels, this wasn’t associated with any safety concerns.

Salt substitutes are only marginally more expensive than regular salt and most people can’t taste the difference, says Neal.

“If you look at the totality of the evidence, if everyone switched from regular salt to potassium-enriched salt, we could prevent millions of premature strokes and heart attacks around the world each year,” he says.