Salt substitutes consistently beneficial for BP, survival, CV events
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Salt substitutes consistently improved BP and lowered risk for mortality, CV mortality and CV events, according to a meta-analysis published in Heart.
“These findings are unlikely to reflect the play of chance and 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,” the researchers wrote.
The researchers undertook the meta-analysis to determine the generalizability of the findings of the Salt Substitute and Stroke Study (SSaSS). As Healio previously reported, in the main results of SSaSS, switching from regular salt to a salt substitute reduced risk for stroke, CV events and death in adults in rural China with a history of stroke or at high risk for it.
For the meta-analysis, the researchers included 21 trials with 31,949 participants. Of the trials, 19 assessed effects on BP and five assessed effects on clinical outcomes.
Salt substitutes reduced systolic BP by –4.61 mm Hg (95% CI, –6.07 to –3.14) and diastolic BP by –1.61 mm Hg (95% CI, –2.42 to –0.79), according to the researchers.
The reductions in BP were consistent by region, age, sex, hypertension history, BMI, baseline 24-hour urinary sodium and baseline 24-hour urinary potassium (P for homogeneity > .05), Xuejun Yin, PhD candidate in food policy at The George Institute for Global Health, University of New South Wales, Sydney, and colleagues wrote.
Each 10% lower proportion of sodium chloride in a salt substitute was associated with a –1.53 mm Hg greater reduction in systolic BP (95% CI, –3.02 to –0.03; P = .045) and a –0.95 mm Hg greater reduction in diastolic BP (95% CI, –1.78 to –0.12; P = .025), according to the researchers.
Salt substitution was associated with reduced risk for total mortality (RR = 0.89; 95% CI, 0.85-0.94), CV mortality (RR = 0.87; 95% CI, 0.81-0.94) and CV events (RR = 0.89; 95% CI, 0.85-0.94), the researchers wrote, noting that 88% to 99% of data for clinical outcomes came from SSaSS.
“Since blood pressure lowering is the mechanism by which salt substitutes confer their cardiovascular protection, the observed consistent blood pressure reductions make a strong case for the generalizability of the cardiovascular protective effect observed in SSaSS both outside of China and beyond the SSaSS population,” Yin and colleagues wrote.
Reference:
- Dietary salt substitutes lower risk of heart attack/stroke and death. www.eurekalert.org/news-releases/961094. Published Aug. 9, 2022. Accessed Aug. 10, 2022.
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In this meta-analysis of 21 trials, consistent effects of salt substitution were observed on BP lowering across multiple geographic regions and baseline patient demographics. Salt substitutes lowered systolic BP on average by 4.6 mm Hg and diastolic BP by 1.6 mm Hg. These are clinically significant BP reductions. Consistent with this, there were also reductions in all-cause mortality, CV mortality and CV events, though this was largely driven by results from the recent large SSaSS trial conducted in China. Overall, this meta-analysis suggests that salt substitution is likely to offer significant benefit in BP lowering across diverse communities. Although there was no significant increase in hyperkalemia observed, individuals with chronic kidney disease or on medications that can raise potassium were generally excluded from these trials, so the safety remains unclear in these populations.
The vast majority of the trials in this meta-analysis, particularly the larger trials, were performed outside the United States. However, it is encouraging that the effects on BP reduction were consistent across studies in Europe, Asia, and the Americas, suggesting generalizability of the benefit of salt substitution.
I recommend that patients decrease consumption of foods with high salt content, particularly processed food, and increase intake of high-potassium foods such as fruits and vegetables. However, this can be difficult to achieve in practice. Salt substitutes can therefore be a helpful adjunctive measure, but at the present time we lack evidence on which salt substitutes are best to recommend for our patients.
It remains challenging to distinguish in salt substitution studies whether the greater benefit is derived from salt reduction or potassium supplementation. Interestingly, however, in this meta-analysis, the authors found that each 10% lower proportion of sodium chloride in the salt substitute was associated with a significant 1.53 mm Hg lowering of systolic BP. However, each 10% higher proportion of potassium chloride in the salt substitute was not significantly associated with reductions in systolic BP. This deserves further study.
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