Even incomplete replacement of salt with a potassium substitute had beneficial health effects in a study in rural China.

The Salt Substitute and Stroke Study (SSaSS) recently reported beneficial effects of a potassium-enriched salt on cardiovascular outcomes and death (N Engl J Med 2021; 385: 1067-1077). The investigators had provided potassium-enriched salt to villagers in rural China with instructions to replace all use of regular salt. To put the trial in perspective and to guide future implementation, it is important to determine the extent to which participants replaced regular salt with the potassium-enriched salt.

Based on urine samples from a subgroup of participants during the five-year follow up, the potassium-enriched salt group had a mean increase in 24-hour urinary potassium excretion of 0.80 g/day, equalling consumption of 8.8 g/day of potassium-enriched salt. Based on this consumption level, the projected difference in 24-hour urinary sodium excretion was −0.79 g/day. In comparison, the observed difference was −0.35 ig/day, suggesting that the intervention group replaced 72% of their baseline regular salt intake with potassium-enriched salt.

Comment: Salt-substitute (potassium for sodium) can improve health outcomes, at least in certain settings. And this paper shows that we do not need to be strident about the replacement; even partial replacement (about 70% in this trial) seemed enough to produce a benefit. It could be that even lower levels are helpful. I believe this strategy is vastly underutilised and deserves much more attention in practice and research.

Harlan M. Krumholz

Yin X, et al. The proportion of dietary salt replaced with potassium-enriched salt in the SSaSS: implications for scale-up. Hypertension 2023 Jan 11; e-pub (https://doi.org/10.1161/HYPERTENSIONAHA. 122.20115).