The use of salt substitutes may result in lower blood pressure and improved cardiovascular outcomes, according to a new study out of China.
Salt
Cardiovascular disease is more common among the elderly, and high blood pressure is a major risk factor. Millions of people die as a result of this condition each year.
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High blood pressure commonly results from a diet that is low in potassium and rich in sodium. The bulk of sodium intake by people globally (about 90 percent) is in the form of sodium chloride or table salt. Cutting down sodium intake is critical for reducing the risks of high blood pressure and cardiovascular disease.
Salt substitutes reduced blood pressure and led to fewer cardiovascular events among subjects in this new study. The findings are based on experiments that were carried out in dozens of elderly care facilities in China.
This research appeared in the journal Nature Medicine. Another article was published by Rachael M. McLean in the same journal assessing the findings of the study, including its shortcomings.
Exploring the relevance of salt substitutes
The research team, led by researchers from Peking University, included 48 elderly care facilities in their study. Researchers selected the said facilities because of a tendency for higher sodium levels in diets around the regions.
There were 1,612 subjects in all, comprising 1,230 males and 382 females. The team cluster-randomized these people who were given meals that contained a salt substitute, regular salt, or slowly restricted salt for two years. The salt substitute was composed of 62.5% sodium chloride (NaCl) and 25% potassium chloride (KCl).
Compared to regular salt, the salt substitute led to a 7.1-mmHg reduction in systolic blood pressure. Diets containing salt substitutes were also associated with a 1.9-mmHg lower diastolic blood pressure.
In addition, mean serum potassium increased from the intake of salt substitutes. There was also more frequent biochemical hyperkalemia, although this was not linked to adverse clinical effects. The salt substitute diet produced fewer cardiovascular events, but there was no effect on overall mortality.
The restricted salt diet had no impact on systolic blood pressure, however. It was also associated with a higher rate of mortality.
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This research also provides some promise of safety based on the assessment of 1,086 subjects with blood assays during follow-up.
Study limitations
The design of the Peking University-led study was somehow faulty. For example, researchers depended on people who prepared meals and managers at the chosen facilities in their attempt to compare the salt substitute to gradually reduced salt, and they failed. It is possible that those staff members may have been defiant to the “intrusion” by the research team and so did not reduce salt in meals.
It also appears that proper research ethics were probably not fully adhered to by the researchers. Subjects were said to have detected a salt reduction in their meals, suggesting they might be unaware of their participation in the study.
Probably, kitchen staff who did not reduce salt in meals did so because the subjects complained after detecting a change.
However, it might not entirely be a case of subjects not giving their consent and so going ahead to add salt to their meals. There could have been a change of mind after the initial consent.
It is, therefore, impossible to determine from this study what effects salt reduction will produce solely on elderly health.
Worthy of note still are the findings that salt substitutes could prove a helpful strategy for lowering blood pressure. They may also assist in reducing the incidence of cardiovascular disease.
References
Yuan, Y., Jin, A., Neal, B. et al. Salt substitution and salt-supply restriction for lowering blood pressure in elderly care facilities: a cluster-randomized trial. Nat Med 29, 973–981 (2023). https://doi.org/10.1038/s41591-023-02286-8
McLean, R.M. Benefits of salt substitution in care facilities for the elderly. Nat Med 29, 789–790 (2023). https://doi.org/10.1038/s41591-023-02279-7
