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Dörner R, Hägele FA, Müller MJ, Seidel U, Rimbach G, Bosy-Westphal A. Effect of exogenous and endogenous ketones on respiratory exchange ratio and glucose metabolism in healthy subjects. Am J Physiol Cell Physiol 2024; 326:C1027-C1033. [PMID: 38314726 DOI: 10.1152/ajpcell.00429.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/07/2024]
Abstract
This study examined the effect of exogenous ketone bodies (KB) on oxygen consumption (V̇o2), carbon dioxide production (V̇co2), and glucose metabolism. The data were compared with the effects of endogenous ketonemia during both, a ketogenic diet or fasting. Eight healthy individuals [24.1 ± 2.5 yr, body mass index (BMI) 24.3 ± 3.1 kg/m2] participated in a crossover intervention study and were studied in a whole-room indirect calorimeter (WRIC) to assess macronutrient oxidation following four 24-h interventions: isocaloric controlled mixed diet (ISO), ISO supplemented with ketone salts (38.7 g of β-hydroxybutyrate/day, EXO), isocaloric ketogenic diet (KETO), and total fasting (FAST). A physical activity level of 1.65 was obtained. In addition to plasma KB, 24-h C-peptide and KB excretion rates in the urine and postprandial glucose and insulin levels were measured. Although 24-h KB excretion increased in response to KETO and FAST, there was a modest increase in response to EXO only (P < 0.05). When compared with ISO, V̇o2 significantly increased in KETO (P < 0.01) and EXO (P < 0.001), whereas there was no difference in FAST. V̇co2 increased in EXO but decreased in KETO (both P < 0.01) and FAST (P < 0.001), resulting in 24-h respiratory exchange ratios (RER) of 0.828 ± 0.024 (ISO) and 0.811 ± 0.024 (EXO) (P < 0.05). In response to EXO there were no differences in basal and postprandial glucose and insulin levels, as well as in insulin sensitivity. When compared with ISO, EXO, and KETO, FAST increased homeostatic model assessment β-cell function (HOMA-B) (all P < 0.05). In conclusion, at energy balance exogenous ketone salts decreased respiratory exchange ratio without affecting glucose tolerance.NEW & NOTEWORTHY Our findings revealed that during isocaloric nutrition, additional exogenous ketone salts increased V̇o2 and V̇co2 while lowering the respiratory exchange ratio (RER). Ketone salts had no effect on postprandial glucose metabolism.
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Affiliation(s)
- Rebecca Dörner
- Department of Human Nutrition, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
| | - Franziska A Hägele
- Department of Human Nutrition, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
| | - Manfred J Müller
- Department of Human Nutrition, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
| | - Ulrike Seidel
- Department of Food Sciences, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
| | - Gerald Rimbach
- Department of Food Sciences, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
| | - Anja Bosy-Westphal
- Department of Human Nutrition, Institute of Human Nutrition and Food Sciences, Kiel University, Kiel, Germany
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Kephart WC, Mumford PW, Mao X, Romero MA, Hyatt HW, Zhang Y, Mobley CB, Quindry JC, Young KC, Beck DT, Martin JS, McCullough DJ, D'Agostino DP, Lowery RP, Wilson JM, Kavazis AN, Roberts MD. The 1-Week and 8-Month Effects of a Ketogenic Diet or Ketone Salt Supplementation on Multi-Organ Markers of Oxidative Stress and Mitochondrial Function in Rats. Nutrients 2017; 9:nu9091019. [PMID: 28914762 PMCID: PMC5622779 DOI: 10.3390/nu9091019] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 11/16/2022] Open
Abstract
We determined the short- and long-term effects of a ketogenic diet (KD) or ketone salt (KS) supplementation on multi-organ oxidative stress and mitochondrial markers. For short-term feedings, 4 month-old male rats were provided isocaloric amounts of KD (n = 10), standard chow (SC) (n = 10) or SC + KS (~1.2 g/day, n = 10). For long-term feedings, 4 month-old male rats were provided KD (n = 8), SC (n = 7) or SC + KS (n = 7) for 8 months and rotarod tested every 2 months. Blood, brain (whole cortex), liver and gastrocnemius muscle were harvested from all rats for biochemical analyses. Additionally, mitochondria from the brain, muscle and liver tissue of long-term-fed rats were analyzed for mitochondrial quantity (maximal citrate synthase activity), quality (state 3 and 4 respiration) and reactive oxygen species (ROS) assays. Liver antioxidant capacity trended higher in short-term KD- and SC + KS-fed versus SC-fed rats, and short-term KD-fed rats exhibited significantly greater serum ketones compared to SC + KS-fed rats indicating that the diet (not KS supplementation) induced ketonemia. In long term-fed rats: (a) serum ketones were significantly greater in KD- versus SC- and SC + KS-fed rats; (b) liver antioxidant capacity and glutathione peroxidase protein was significantly greater in KD- versus SC-fed rats, respectively, while liver protein carbonyls were lowest in KD-fed rats; and (c) gastrocnemius mitochondrial ROS production was significantly greater in KD-fed rats versus other groups, and this paralleled lower mitochondrial glutathione levels. Additionally, the gastrocnemius pyruvate-malate mitochondrial respiratory control ratio was significantly impaired in long-term KD-fed rats, and gastrocnemius mitochondrial quantity was lowest in these animals. Rotarod performance was greatest in KD-fed rats versus all other groups at 2, 4 and 8 months, although there was a significant age-related decline in performance existed in KD-fed rats which was not evident in the other two groups. In conclusion, short- and long-term KD improves select markers of liver oxidative stress compared to SC feeding, although long-term KD feeding may negatively affect skeletal muscle mitochondrial physiology.
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Affiliation(s)
- Wesley C Kephart
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
| | - Xuansong Mao
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
| | - Hayden W Hyatt
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
| | - Yufeng Zhang
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA.
| | | | - John C Quindry
- Department of Human Health Performance, University of Montana, Missoula, MT 59812, USA.
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
| | - Darren T Beck
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
| | - Jeffrey S Martin
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
| | - Danielle J McCullough
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
| | - Dominic P D'Agostino
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL 33620, USA.
| | - Ryan P Lowery
- Applied Sports Performance Institute, Tampa, FL 33607, USA.
| | - Jacob M Wilson
- Applied Sports Performance Institute, Tampa, FL 33607, USA.
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.
- Department of Cell Biology and Physiology, Edward via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36849, USA.
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