Systematic review and meta-analysis of randomised controlled trials on the effects of potassium supplements on serum potassium and creatinine

Objectives: High potassium intake could prevent stroke, but supplementation is considered hazardous. We assessed the effect of oral potassium supplementation on serum or plasma potassium levels and renal function. Setting: We updated a systematic review of the effects of potassium supplementation in randomised clinical trials carried out worldwide, published in 2013, extending it to July 2015. We followed the PRISMA guidelines. Participants: Any individual taking part in a potassium supplementation randomised clinical trial. Studies included met the following criteria: randomised clinical trials, potassium supplement given and circulating potassium levels reported. Intervention: Oral potassium supplementation. Primary outcome measures: Serum or plasma potassium and serum or plasma creatinine. Results: A total of 20 trials (21 independent groups) were included (1216 participants from 12 different countries). All but 2 were controlled (placebo n=16, control n=2). Of these trials, 15 were crossover, 4 had a parallel group and 1 was sequential. The duration of supplementation varied from 2 to 24 weeks and the amount of potassium given from 22 to 140 mmol/day. In the pooled analysis, potassium supplementation caused a small but significant increase in circulating potassium levels (weighted mean difference (WMD) 0.14 mmol/L, 95% CI 0.09 to 0.19, p<1x10(-5)), not associated with dose or duration of treatment. The average increase in urinary potassium excretion was 45.75 mmol/24 hours, 95% CI 38.81 to 53.69, p<1x10(-5). Potassium supplementation did not cause any change in circulating creatinine levels (WMD 0.30 mu mol/L, 95% CI -1.19 to 1.78, p=0.70). Conclusions: In short-term studies of relatively healthy persons, a moderate oral potassium supplement resulted in a small increase in circulating potassium levels and no change in renal function.