Skip navigation

Oral potassium and blood pressure

 

Clinical bottom line

Oral potassium appears to reduce blood pressure, and the effects are larger in people with higher daily sodium intake.


Reference


PK Whelton et al. Effects of oral potassium on blood pressure. JAMA 1997 277: 1624-1632.


Systematic review

The review searched the English-language literature for studies of the effect of oral potassium on blood pressure. It used MEDLINE only. For inclusion studies had to be randomised, use oral potassium and a control group, and report mean BP changes.

Results

There were 33 trials conducted between 1981 and 1995, with a median of 32 participants (2,600 in total). One trial had an extreme change in blood pressure (reduction of over 40 mmHg of systolic BP) and was omitted. Trials lasted between four days and three years, and the amount of potassium per day was between 17 and 200 mmol.

Oral potassium resulted in an average fall in BP of 3 mmHg and 2 mmHg in systolic and diastolic BP respectively (Table 1). Somewhat larger reductions were found in trials with more than 20 mmol/day increase in urinary potassium excretion and in trials where antihypertensive drugs were not used (Table 1).

Table 1: Results of potassium supplementation on BP

Reduction in BP (mmHg)
Trials
Trials
Systolic BP
Diastolic BP
All trials
32
3.1 (1.9 to 4.3)
2.0 (0.5 to 3.4)
Trials with increased urinary excretion of potassium more than 19 mmon/day
29
4.9 (2.7 to 7.1)
2.7 (0.7 to 4.7)
Trials without antihypertensive medicines
29
4.9 (2.7 to 7.0)
2.7 (0.8 to 4.6)
All reductions were statistically significant

Smaller reductions in BP were seen in trials that were longer, larger and in white rather than black subjects. Urinary sodium excretion was an important determinant, with larger reductions in subjects with higher urinary sodium excretion (Figure 1).

Figure 1: Effect of potassium supplementation according to urinary sodium excretion


Comment

This was an eclectic group of trials, most of which tended to be small and short, and with very different situations in terms of daily potassium supplementation, daily sodium intake, and use of antihypertensive medicines. The message, if there is one, is that oral potassium appears to reduce blood pressure, and the effects are larger in people with higher daily sodium intake.