Switching to Potassium Salt Substitute Cuts Hypertension 40% in Older Adults With Normal Blood Pressure, With No Increase in Low Blood Pressure

Does a salt substitute, in which part of the salt (sodium chloride) is replaced with potassium chloride, matter for people whose blood pressure is normal? The question has been debated because of concerns that the effect might be small or might even cause low blood pressure. Researchers at the Peking University Clinical Research Institute in China examined it using data from the DECIDE-Salt trial in older adults living in nursing homes and published the results in JACC.

Methods

DECIDE-Salt is a large cluster-randomized trial in which 48 nursing homes in China were randomized as units and followed for 2 years. The researchers did a post hoc analysis of 611 older adults whose blood pressure was normal at the start. The salt substitute was composed of 62.5% sodium chloride, 25% potassium chloride and 12.5% flavoring ingredients.

The incidence of hypertension in the salt substitute group (313 people) was 11.7 per 100 person-years, lower than the 24.3 in the regular salt group (298 people), with an adjusted hazard ratio of 0.60. Hypotension did not differ, at 9.0 vs. 9.7. Systolic blood pressure rose by an average of 7.0 mmHg in the regular salt group but barely changed in the salt substitute group, for an 8.0 mmHg difference in systolic blood pressure between the two groups.

However, this is a post hoc analysis rather than the originally planned primary analysis, and the results are limited to older adults in Chinese nursing homes, where meals are managed. People with kidney disease and others with reduced potassium excretion are at risk of hyperkalemia, so caution is needed in applying it across the board.