Salt substitutes for better blood pressure Original paper

High blood pressure (hypertension) is one of the leading causes of death and disease around the world. However, this condition is manageable with diet and lifestyle intervention; for example, dietary salt (sodium chloride) is one of the main factors that influences blood pressure control. Many individuals consume more sodium than is recommended, mainly through the addition of salt to food and the consumption of processed foods.

Restricting sodium intake reduces blood pressure in people with and without hypertension, but some people find sodium restriction difficult. Substituting regular salt with low-sodium alternatives (i.e., potassium chloride) may be one way to limit sodium consumption without drastically altering the taste of food. Are salt substitutes effective for lowering blood pressure and reducing cardiovascular disease burden?

This meta-analysis included 23 randomized controlled trials with a total of 32,073 participants. All of the studies investigated the effects of sodium reduction using a salt substitute, the most common of which was potassium chloride, with comparison to a control group (i.e., normal salt intake). The included studies were conducted in China (10 studies), the UK (2 studies), and Taiwan, Japan, Korea, Brazil, Finland, South Africa, the Netherlands, Italy, India, Peru, and Norway (1 study each. The studies ranged in duration from 4 weeks to 10 years.

The primary outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), urinary sodium and potassium excretion, and all-cause and cardiovascular disease mortality.

Salt substitution reduced SBP by an average of 5 mmHg and DBP by an average of 2 mmHg compared to the control group. Salt substitution also reduced 24-hour urinary sodium excretion and increased 24-hour potassium excretion compared to the control group. The 24-hour urinary sodium/potassium ratio decreased in the salt substitution group compared to the control group.

Salt substitution reduced the risk for all-cause mortality by 12% compared to the control group. Salt substitution also decreased the risk for cardiovascular mortality by 28% compared to the control group, though this difference was not statistically significant.

In subgroup analyses, salt substitution had more pronounced effects on reducing SBP in participants who were older than 60 years of age, and salt substitution reduced SBP by 6 mmHg in this age group vs. a 3 mmHg reduction in participants younger than 60. The effects of salt substitution were no different between Asian and non-Asian countries, nor were the effects modified by whether or not the participants had hypertension.

Only 4 and 5 studies included in this meta-analysis investigated the effects of salt substitutes on cardiovascular and all-cause mortality, respectively, and one particular study was highly influential for both of these outcomes. Therefore, we should be a bit cautious about concluding that salt substitutes reduce the risk for mortality due to the small number of studies that were analyzed.