CATEGORY: FOODS & NUTRIENTS
For people at high risk of dangerous heart rhythms, deliberately raising blood potassium into the high-normal range cut the combined risk of serious rhythm events, unplanned hospital stays and death by 24% in a randomized Danish trial of 1,200 adults. Over a median of just over three years, 22.7% of the high-potassium group had one of those outcomes, versus 29.2% of the group getting standard care alone.1
The Mineral That Keeps the Heart’s Wiring on Time
Potassium is one of the minerals your body uses to generate the tiny electrical impulses that time every heartbeat. Doctors have long observed that low potassium—and even levels in the lower half of the normal range—goes along with a higher risk of ventricular arrhythmias, chaotic rhythms arising in the heart’s main pumping chambers that can be fatal within minutes. What nobody had tested in a large trial, the researchers noted, was whether actively pushing potassium toward the top of the normal range would prevent those events. Every participant in this trial had an implantable cardioverter-defibrillator, a matchbox-sized device placed under the skin that detects a life-threatening rhythm and shocks the heart back into step—the clearest marker medicine has for people at high arrhythmia risk.
Food, a Supplement, or a Familiar Pill—Aimed at the Top of Normal
This was a study in which people were assigned by chance, not one that followed choices they had already made. Researchers at Danish heart centers enrolled 1,200 adults with a defibrillator whose blood potassium sat at 4.3 millimoles per liter or lower—normal, but in the lower part of the range. Half were randomly assigned to a strategy targeting a high-normal level of 4.5 to 5.0, built from three familiar tools: guidance toward potassium-rich foods, potassium supplement tablets, and—where needed—a medication in the family of spironolactone, a decades-old pill that helps the kidneys hold on to potassium instead of flushing it away. The other half continued standard care. Everyone was tracked for a median of 39.6 months, with the main outcome a combination of documented dangerous rhythm events or an appropriate shock from the defibrillator, unplanned hospitalization for rhythm problems or heart failure, and death from any cause.
Roughly Twenty-Three per Hundred Instead of Twenty-Nine
A primary outcome event occurred in 136 of 600 people in the high-potassium group and 175 of 600 in the standard-care group—22.7% versus 29.2%, or 7.3 versus 9.6 events per 100 person-years. That works out to a 24% lower risk (hazard ratio 0.76, with a 95% confidence interval of 0.61 to 0.95). Think of it like tire pressure: both groups stayed inside the recommended band, but one was kept near the top of it, where there is more margin before trouble. Notably, the strategy did not simply trade one problem for another—hospitalizations for potassium levels that drifted too high or too low were similar in the two groups.
A Strategy Run on Blood Tests, Not Guesswork
Two boundaries around this result matter. First, the trial enrolled only high-risk patients with defibrillators, so it does not show that extra potassium benefits people in general. Second, the strategy was medically supervised from start to finish: potassium levels were checked repeatedly, and doses of supplements and medication were adjusted to keep levels inside—not above—the normal range. Potassium is not a more-is-better mineral; levels above the normal range carry their own serious rhythm risks, particularly for people with kidney disease. What the trial establishes is the principle: in the highest-risk patients, where potassium sits within normal appears to matter, and moving it deliberately, with monitoring, changed outcomes.
Key Takeaways
- In 1,200 adults with implanted defibrillators, targeting high-normal potassium levels cut the combined risk of serious rhythm events, unplanned hospitalizations and death by 24% compared with standard care—22.7% versus 29.2% over about three years.
- The strategy combined potassium-rich foods, supplement tablets and, where needed, a potassium-sparing medication, all steered by regular blood tests.
- Hospitalizations for potassium levels too high or too low were similar in both groups, suggesting the supervised approach did not create a new hazard.
- The trial covered only high-risk defibrillator patients; it does not show that raising potassium helps people without those conditions.
References
- Jøns C, Zheng C, Winsløw UCG, et al. Increasing the Potassium Level in Patients at High Risk for Ventricular Arrhythmias. N Engl J Med. 2025;393(20):1979–1989. link