Bioavailability of Potassium from Potato and Potassium Gluconate

Abstract

Potassium is a shortfall nutrient according to the 2010 Dietary Guidelines for Americans. Only 3% of Americans meet the recommended Adequate Intake of 4700 mg/d for potassium. Bioavailability of potassium has not been considered in setting requirements as no food has been tested. Among adult potato consumers potatoes provide 19-20% of potassium in the diet. The aim of this study was to compare bioavailability and dose response of potassium from non-fried white potatoes with skin with potassium gluconate. Thirty five healthy, normotensive men and women with a mean age of 29.7 (+/- 11.2) years and BMI of 24.3 (+/- 4.4) kg/m2 (mean +/- (SD)) were enrolled in this single-blind, cross-over, randomized controlled trial. Participants were randomized to 1 of 8 interventions of potassium: 0 (control repeated twice), 720 (~18.5), 1440 (~37), 2160 (~55.5) mg/day (mEq/day) consumed as a potassium gluconate supplement or white potato with skin added to the basal diet containing ~2300 mg/day (~60 mEq/day) potassium. Bioavailability of potassium was determined from AUC of serial blood draws and cumulative urinary excretion. Serum potassium AUC increased with dose (p<0.0001) and did not differ due to source (p=0.52). Cumulative 24 h urinary potassium also increased with dose (p<0.0001) and was greater with potato than supplement (p<0.0001). There were no significant sex differences. Bioavailability of potassium is as high from potatoes as from supplements. Future studies that include fecal potassium measurements will be necessary to determine whether retention varies due to source. This research was funded by the Alliance for Potato Research and Education.