Cardiovascular disease is the leading cause of death globally, with high blood pressure being a major risk factor for premature death. Inadequate dietary potassium and excess sodium are common causes of high blood pressure.
Stady: Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis. Image Credit: Andrey_Popov / Shutterstock.com
Several previous randomized trials reported that potassium supplementation and reduced sodium intake can lower blood pressure. These blood pressure lowering effects can be found in sodium-enriched, potassium-rich salt substitutes, where the sodium chloride (NaCl) content of regular salt is replaced by potassium chloride (KCl).
Recently, the Salt Substitutes and Stroke Study (SSaSS), a five-year cluster randomized trial involving 600 villages in China, provided evidence that salt substitutes can protect against death, cardiovascular events, and stroke. SSaSS also addressed concerns regarding the adverse effect of dietary potassium supplementation and the risk of hyperkalemia. The improvement in clinical outcomes observed in SSaSS is mostly mediated by lowering of blood pressure.
new heart The journal study provides a systematic review of the effect of salt substitutes on clinical outcomes and blood pressure for all available trials. The researchers also sought to determine the consistency of the results across diverse geographic regions and populations.
The study included searches of the Embase, Cochrane, and MEDLINE databases for keywords such as low sodium salt, salt substitutes, potassium salt, and low sodium salt as of August 31, 2021.
All studies in which groups or adults were randomized to regular salt or a salt substitute were included. Mortality, blood pressure, cardiovascular events and cardiovascular mortality were the most common outcomes.
Titles and abstracts of studies were checked by one author to assess eligibility, while copies of the full text were independently reviewed by the authors. Differences between reviewers were resolved by reference with a third author.
Participant and study characteristics, as well as all results, were extracted from the records. The risk of bias was also determined for all studies independently.
Three cluster randomized trials, 17 individually randomized trials, and one step-by-step randomized trial were included in the current analysis. Of the included studies, 11 were conducted in the WHO Western Pacific Region, five in the WHO European Region, one in the WHO Southeast Asia Region, and four in the WHO Region of the Americas.
The duration of the intervention ranged from 1 to 60 months. The percentage of sodium chloride in the salt substitutes ranged from 33% to 75%, while that of sodium chloride ranged from 25% to 65%.
The mean baseline systolic blood pressure (SBP) was between 113 mm Hg and 177 mm Hg, while the mean baseline diastolic blood pressure (DBP) was between 71 mm Hg and 105 mm Hg.
The mean baseline 24-hour urinary sodium excretion was between 2.9 grams and 5.5 grams, while the mean daily 24-hour urinary potassium excretion was between 0.8 grams and 3.6 grams. The overall risk of bias was high in two studies, worrisome in eight, and low in 11.
An overall decrease of −4.61 mm Hg in SBP, along with 1.61 mm Hg in DBP, was observed with salt substitutes when compared with controls. Trial durations of less than 12 months were associated with greater reductions in DBP and SBP.
Less sodium chloride was observed in the salt substitute and increased potassium intake at baseline with greater decreases in DBP. Furthermore, these results were found to be consistent across different geographical regions and populations.
Furthermore, five studies reported effects on mortality, two on major cardiovascular events, and three on cardiovascular mortality. However, six studies reported no serious adverse effects associated with hyperkalemia, while two studies reported no effect of salt substitute on serum potassium levels.
Salt substitutes also reduced urinary excretion of sodium by −0.48 g/day and increased urinary potassium excretion by 0.45 g/day. The effect on potassium excretion was higher in European regions and lower in Southeast Asia region. Moreover, the increase in urinary potassium excretion was higher in men.
The present study demonstrated that salt substitutes can produce consistent blood pressure lowering effects across diverse populations and geographical regions without causing any severe adverse events.
Salt substitutes can be adopted in public health policies and clinical practices to reduce dietary sodium intake. Furthermore, these alternatives can increase dietary potassium intake to ultimately reduce blood pressure and prevent serious cardiovascular disease.
Complete data were not available for many of the studies, and the gray literature was not searched. An additional limitation was that the number of available trials is relatively small.
Limited data on non-hypertensive individuals makes drawing definite conclusions difficult. Finally, data on clinical outcomes were mainly obtained from a single trial.
- Yin, X., Rodgers, A., Perkovic, A., et al. (2022). Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis. heart. doi: 10.1136/heartjnl-2022-321332.