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Nutrients 2018, 10(5), 624; https://doi.org/10.3390/nu10050624

Pilot Study Examining the Influence of Potassium Bicarbonate Supplementation on Nitrogen Balance and Whole-Body Ammonia and Urea Turnover Following Short-Term Energy Restriction in Older Men

1
Nutrition, Exercise, Physiology, and Sarcopenia Laboratory, United States Department of Agriculture Jean Mayer Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
2
Bone Metabolism Laboratory, United States Department of Agriculture Jean Mayer Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
3
Division of Endocrinology, Diabetes, and Metabolism, Tufts Medical Center, Boston, MA 02111, USA
*
Author to whom correspondence should be addressed.
Received: 22 March 2018 / Revised: 10 May 2018 / Accepted: 11 May 2018 / Published: 16 May 2018
(This article belongs to the Special Issue Nutritional Prevention and Acid Base Status)
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Abstract

With aging there is a chronic low-grade metabolic-acidosis that may exacerbate negative protein balance during weight loss. The objective of this randomized pilot study was to assess the impact of 90 mmol∙day−1 potassium bicarbonate (KHCO3) versus a placebo (PLA) on 24-h urinary net acid excretion (NAE), nitrogen balance (NBAL), and whole-body ammonia and urea turnover following short-term diet-induced weight loss. Sixteen (KHCO3; n = 8, PLA; n = 8) older (64 ± 4 years) overweight (BMI: 28.5 ± 2.1 kg∙day−1) men completed a 35-day controlled feeding study, with a 7-day weight-maintenance phase followed by a 28-day 30% energy-restriction phase. KHCO3 or PLA supplementation began during energy restriction. NAE, NBAL, and whole-body ammonia and urea turnover (15N-glycine) were measured at the end of the weight-maintenance and energy-restriction phases. Following energy restriction, NAE was −9.8 ± 27.8 mmol∙day−1 in KHCO3 and 43.9 ± 27.8 mmol∙day−1 in PLA (p < 0.05). No significant group or time differences were observed in NBAL or ammonia and urea turnover. Ammonia synthesis and breakdown tended (p = 0.09) to be higher in KHCO3 vs. PLA following energy restriction, and NAE was inversely associated (r = −0.522; p < 0.05) with urea synthesis in all subjects. This pilot study suggests some benefit may exist with KHCO3 supplementation following energy restriction as lower NAE indicated higher urea synthesis. View Full-Text
Keywords: weight loss; aging; alkaline supplement; acid-base weight loss; aging; alkaline supplement; acid-base
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Margolis, L.M.; Ceglia, L.; Rivas, D.A.; Dawson-Hughes, B.; Fielding, R.A. Pilot Study Examining the Influence of Potassium Bicarbonate Supplementation on Nitrogen Balance and Whole-Body Ammonia and Urea Turnover Following Short-Term Energy Restriction in Older Men. Nutrients 2018, 10, 624.

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