Do Salt Substitutes Lower Stroke Risk and Mortality? Study Investigates Possibility

Stroke is a leading cause of death and disability worldwide, with an estimated recurrence rate of 10% within one year and 15% within five years among stroke survivors.

In China, the recurrence rates are even higher, reaching 17% at one year and 41% at five years, largely due to the high prevalence of hypertension. Since high sodium intake contributes to hypertension, reducing sodium while increasing potassium intake has been suggested as a strategy for stroke prevention.

The Salt Substitute and Stroke Study, an open-label, randomized clinical trial, was conducted in 600 villages in northern China with 20,995 participants. Prior findings from this study demonstrated that salt substitutes could reduce the risk of stroke, cardiovascular events, and premature death. The new secondary analysis aimed to assess the impact of salt substitutes specifically on recurrent stroke and mortality among stroke survivors.

The study included 15,249 participants who had self-reported a previous stroke. They were randomly assigned to either an intervention group, which received a salt substitute (75% sodium chloride and 25% potassium chloride), or a control group, which continued using regular salt. Over a median follow-up period of 61 months, 2,735 recurrent strokes and 3,242 deaths were recorded.

The findings revealed that consuming salt substitutes led to a modest but significant reduction in systolic blood pressure (−2.05 mm Hg). Stroke recurrence rates were 16% in the intervention group compared to 19% in the control group, reflecting a 14% reduction in risk.

This effect was more pronounced for haemorrhagic stroke than for ischaemic stroke. Additionally, the intake of salt substitutes was associated with a 12% reduction in all-cause mortality and a 21% decrease in stroke-related deaths.

Notably, no significant difference in hyperkalemia (high potassium levels) was observed between the groups, confirming the safety of salt substitutes.

The researchers emphasized that salt substitutes offer a low-cost, effective dietary intervention for stroke survivors. "The study provides clear evidence that salt substitutes can safely reduce the risk of recurrent stroke and death," the researchers noted. They added that these benefits were independent of factors such as age, sex, education, body mass index, blood pressure, diabetes status, and use of antihypertensive medications.

The study also underscores the role of blood pressure reduction in stroke prevention. "A reduction of even 1 mm Hg in systolic blood pressure has been linked to a 5% decrease in stroke risk," the researchers pointed out. Given that salt substitutes led to an average reduction of 2.05 mm Hg, their protective effect against stroke is significant.

The findings are particularly relevant for rural Chinese populations, where sodium intake is high due to home-cooked meals and potassium intake is low due to limited fruit and vegetable consumption. "Our study suggests that simple dietary changes, such as replacing regular salt with a salt substitute, could have a profound impact on stroke prevention in these communities," the researchers stated.

Despite its strong findings, the researchers acknowledged some limitations. Since the Salt Substitute and Stroke Study was open-label, participants were aware of their salt allocation, which could have influenced behaviour. Furthermore, as this was a secondary analysis, the results should be considered exploratory.

Nevertheless, the study provides robust evidence supporting salt substitutes as a feasible and scalable intervention for stroke prevention. "Given the substantial burden of stroke worldwide, our findings highlight a simple yet impactful strategy for reducing stroke recurrence and mortality," the authors concluded.