Acetone as biomarker for ketosis buildup capability - a study in healthy individuals under combined high fat and starvation diets

Prabhakar et al. Nutrition Journal (2015) 14:41 DOI 10.1186/s12937-015-0028-x RESEARCH Open Access Acetone as biomarker for ketosis buildup capability - a study in healthy individuals under combined high fat and starvation diets Amlendu Prabhakar1†, Ashley Quach1†, Haojiong Zhang1, Mirna Terrera1, David Jackemeyer1, Xiaojun Xian1, Francis Tsow1, Nongjian Tao1,3 and Erica S Forzani1,2* Abstract Background: Ketogenic diets are high fat and low carbohydrate or very low carbohydrate diets, which render high production of ketones upon consumption known as nutritional ketosis (NK). Ketosis is also produced during fasting periods, which is known as fasting ketosis (FK). Recently, the combinations of NK and FK, as well as NK alone, have been used as resources for weight loss management and treatment of epilepsy. Methods: A crossover study design was applied to 11 healthy individuals, who maintained moderately sedentary lifestyle, and consumed three types of diet randomly assigned over a three-week period. All participants completed the diets in a randomized and counterbalanced fashion. Each weekly diet protocol included three phases: Phase 1 A mixed diet with ratio of fat: (carbohydrate + protein) by mass of 0.18 or the equivalence of 29% energy from fat from Day 1 to Day 5. Phase 2- A mixed or a high-fat diet with ratio of fat: (carbohydrate + protein) by mass of approximately 0.18, 1.63, or 3.80 on Day 6 or the equivalence of 29%, 79%, or 90% energy from fat, respectively. Phase 3 - A fasting diet with no calorie intake on Day 7. Caloric intake from diets on Day 1 to Day 6 was equal to each individual’s energy expenditure. On Day 7, ketone buildup from FK was measured. Results: A statistically significant effect of Phase 2 (Day 6) diet was found on FK of Day 7, as indicated by repeated analysis of variance (ANOVA), F(2,20) = 6.73, p < 0.0058. Using a Fisher LDS pair-wise comparison, higher significant levels of acetone buildup were found for diets with 79% fat content and 90% fat content vs. 29% fat content (with p = 0.00159**, and 0.04435**, respectively), with no significant difference between diets with 79% fat content and 90% fat content. In addition, independent of the diet, a significantly higher ketone buildup capability of subjects with higher resting energy expenditure (R2 = 0.92), and lower body mass index (R2 = 0.71) was observed during FK. Keywords: Ketogenic diet, Breath ketone, Acetone, Fasting ketosis, Nutritional ketosis, Starvation Background Ketosis or ketoacidosis is a physiological state sharing an outcome of increased ketone levels in the blood due to relatively high lipid oxidation rates. Monitoring rapid and dramatic changes in ketones offers us valuable diagnoses for lipid oxidation and metabolism [1]. Several studies have clearly demonstrated that metabolic * Correspondence: † Equal contributors 1 Current address: Center for Bioelectronics and Biosensors, the Biodesign Institute, Arizona State University, 1001 S McAllister Ave., Tempe, AZ 85287, USA 2 School for Engineering of Matter, Transport, and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, AZ 85287, USA Full list of author information is available at the end of the article imbalance in type I diabetes has led to ketoacidosis (KAD) of blood, leading to elevated ketone levels with arterial pH < 7.3 and bicarbonate < 15 mEq/L, and causing arresting of major organ functions [2]. In addition to acidosis, studies have also shown that elevated ketone levels are a natural metabolic response to negative energy balance, wherein caloric intake is smaller than total energy expenditure, and the body burns stored fat to produce the needed energy [3], leading to a state of ketosis known as fasting ketosis (FK). FK has been used as an indicator of the effectiveness of weight loss [4-6]. Furthermore, ketosis also occurs in situations where caloric © 2015 Prabhakar et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Prabhakar et al. Nutrition Journal (2015) 14:41 intake equals total energy expenditure, specifically in a diet that contains high percentage of fat (>60%) and/or low carbohydrate. This state of ketosis has been referred to as nutritional ketosis (NK) [7,8]. NK has been investigated as a treatment for epilepsy because ketones are thought to provide energy to the brain, which reduces epileptic seizures [9,10]. In addition, ketosis buildup capability resulting from a combination of NK and FK has been associated with weight loss efficiency and positive health outcomes [11-13]. While KAD, FK, and NK are well-defined clinical and physiological states that can produce high levels of ketones, there are other conditions, such as exercise that can actually decrease ketone levels in the blood by using ketone as an energy source in the muscles [14,15]. For the reasons described above, ketone levels are affected by several factors, such as energy balance, diet composition, and physical activities, all of which underscore the importance of determining the accuracy of ketone levels. Previous studies, including KAD, FK, NK, and exerciserelated ketosis have significantly advanced the field of ketosis. However, analyses including characterization of analytical, physiological, and behavioral conditions are needed in the literature to improve the understanding of ketone level profiles in connection with monitoring of lipid oxidation, generation, utilization, and clearance of ketones under free-living conditions. Under ketosis or ketoacidosis, the liver metabolizes fatty acids to produce two water-soluble types of ketones: acetoacetic acid and beta-hydroxybutyric acid. A third type of ketone, i.e., acetone, is also produced by the enzymatic decarboxylation of acetoacetic acid. Due to its high vapor pressure, acetone crosses the membrane barrier into the alveoli of the lung and the airway. As a result, acetone is normally present in breath. Breath acetone has been considered a reliable indicator of ketosis in adults consuming ketogenic meals [16] and can be used to predict plasma ketone bodies in children with epilepsy who are on a ketogenic diet [17]. Most recently, breath acetone has been used as a new ketone biomarker because it is non-invasive, convenient, and an accurate reflection of the body’s ketone level [18]. In the present work, our focus is on both intermittent high-fat diets (NK) and fasting diets (FK) with an aim to: 1) evaluate the effectiveness of combined NK and FK in ketone buildup capability; and 2) study how ketone buildup capability is associated with intrinsic character (...truncated)