Can changing the salt in a kitchen reduce strokes?

In a large randomised trial, the answer was yes. Among 20,995 high-risk adults in rural China, strokes occurred at a rate of 29.14 per 1,000 person-years when households used potassium-enriched salt, compared with 33.65 per 1,000 person-years with regular salt. The rate ratio was 0.86, with a 95% confidence interval from 0.77 to 0.96.

The intervention was neither a tablet nor an instruction to cook without salt. It was a substitute made from 75% sodium chloride and 25% potassium chloride. That distinction explains both the likely benefit and the reason it does not suit every person.

What the stroke trial changed

The Salt Substitute and Stroke Study, known as SSaSS, recruited people from 600 villages. Participants qualified because they had already had a stroke, or because they were at least 60 and had high blood pressure. Their average age was 65.4 years. Almost three quarters had a previous stroke and 88.4% had hypertension.

Researchers randomly assigned whole villages, rather than individual participants, to receive the potassium-enriched product or continue regular salt. The trial was open label: people knew which salt they used. Follow-up averaged 4.74 years.

Stroke was the prespecified primary outcome. Major cardiovascular events occurred at 49.09 per 1,000 person-years with the substitute and 56.29 with regular salt, a rate ratio of 0.87. Death from any cause occurred at 39.28 versus 44.61 per 1,000 person-years, a rate ratio of 0.88. These were clinical events, not changes in a laboratory marker.

The absolute rates also show why the population is central. This was a group with substantial starting risk, living in communities where much of the dietary sodium came from salt added at home. The trial did not enrol healthy, low-risk Australians whose main sodium exposure comes from bread, packaged meals, sauces or restaurant food.

Two minerals moved in opposite directions

Ordinary table salt is sodium chloride. Sodium helps regulate fluid balance and nerve and muscle function, but a high intake can raise blood pressure in susceptible people. Potassium has several opposing effects, including increasing sodium excretion through the kidneys and influencing the tension of blood-vessel walls.

A potassium-enriched substitute changes both sides of that balance: less sodium enters with each gram of salt, while potassium intake rises. The trial was not designed to separate how much benefit came from each part.

A Cochrane review of 26 randomised trials included 34,961 adults. Compared with regular salt, lower-sodium substitutes reduced systolic blood pressure by an average of about 4.8 mmHg and diastolic pressure by 2.4 mmHg. Systolic pressure is the higher number in a blood-pressure reading; it reflects pressure while the heart contracts.

The review judged the evidence for blood-pressure lowering moderately certain. Evidence for clinical events was also graded as moderate, but most events came from SSaSS. The consistency between lower blood pressure and fewer strokes strengthens the interpretation without making the Chinese event rates universal.

The safety result needs its denominator

The kidneys normally remove excess potassium. When kidney function is impaired, or when certain medicines reduce potassium excretion, blood potassium can rise. A marked rise, called hyperkalaemia, can disturb the heart’s electrical rhythm.

In SSaSS, serious adverse events attributed to hyperkalaemia occurred at 3.35 per 1,000 person-years with the substitute and 3.30 with regular salt. The rate ratio was 1.04, with a confidence interval from 0.80 to 1.37. That comparison did not show an increase, but it does not prove safety for people the trials excluded.

Across the evidence base, studies generally excluded people with kidney disease and those taking potassium-sparing diuretics or potassium supplements. Hyperkalaemia was also reported inconsistently. A reassuring average result in a screened trial population cannot be extended to someone whose kidneys or medicines make potassium harder to clear.

Why the WHO recommendation is conditional

In 2025, the World Health Organization suggested that adults who choose to use table salt replace regular salt with a lower-sodium substitute containing potassium. It was a conditional recommendation, not a direction for every household. It excludes children, pregnant women, people with kidney impairment and others whose potassium excretion may be compromised.

The wording also applies to discretionary salt—the salt added during cooking or at the table. It does not cover sodium already present in manufactured food or meals prepared elsewhere. This is particularly relevant in Australia. The Heart Foundation reports that the average Australian consumes about 9 grams of salt a day, compared with its recommended maximum of 5 grams, while most of that sodium comes from processed food.

A different salt in the shaker may alter only a small share of intake for one household and a large share for another. Product composition varies as well. “Low sodium” on a label does not by itself state how much potassium chloride is present or whether the product resembles the 75/25 mixture tested in SSaSS.

The useful clinical question comes before the switch

Potassium-enriched salt sits at an unusual intersection of food policy and individual medicine. At population level, reformulating salt could lower blood pressure without requiring people to sustain a complex new behaviour. At individual level, the same intervention asks several concrete questions.

How much salt is actually added at home? Is blood pressure high, and what is the person’s cardiovascular risk? Is kidney function impaired? Do current medicines affect potassium? Which product is being considered, and would changing it preserve iodised salt intake?

SSaSS showed that a modest change to a frequently used ingredient can alter hard cardiovascular outcomes in a high-risk population. The memorable result is fewer strokes, not a universal kitchen instruction. The evidence fits best when the source of sodium, the person’s starting risk and their ability to excrete potassium are all made explicit.

Sources

Evidence note: This Insight is general education, not individual medical or dietary advice. It does not recommend changing salt, potassium intake or medicines. Kidney function, medicines, blood pressure and cardiovascular risk require assessment by a qualified clinician.