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Circulation Research Mar 2023The ketone bodies beta-hydroxybutyrate and acetoacetate are hepatically produced metabolites catabolized in extrahepatic organs. Ketone bodies are a critical cardiac... (Review)
Review
The ketone bodies beta-hydroxybutyrate and acetoacetate are hepatically produced metabolites catabolized in extrahepatic organs. Ketone bodies are a critical cardiac fuel and have diverse roles in the regulation of cellular processes such as metabolism, inflammation, and cellular crosstalk in multiple organs that mediate disease. This review focuses on the role of cardiac ketone metabolism in health and disease with an emphasis on the therapeutic potential of ketosis as a treatment for heart failure (HF). Cardiac metabolic reprogramming, characterized by diminished mitochondrial oxidative metabolism, contributes to cardiac dysfunction and pathologic remodeling during the development of HF. Growing evidence supports an adaptive role for ketone metabolism in HF to promote normal cardiac function and attenuate disease progression. Enhanced cardiac ketone utilization during HF is mediated by increased availability due to systemic ketosis and a cardiac autonomous upregulation of ketolytic enzymes. Therapeutic strategies designed to restore high-capacity fuel metabolism in the heart show promise to address fuel metabolic deficits that underpin the progression of HF. However, the mechanisms involved in the beneficial effects of ketone bodies in HF have yet to be defined and represent important future lines of inquiry. In addition to use as an energy substrate for cardiac mitochondrial oxidation, ketone bodies modulate myocardial utilization of glucose and fatty acids, two vital energy substrates that regulate cardiac function and hypertrophy. The salutary effects of ketone bodies during HF may also include extra-cardiac roles in modulating immune responses, reducing fibrosis, and promoting angiogenesis and vasodilation. Additional pleotropic signaling properties of beta-hydroxybutyrate and AcAc are discussed including epigenetic regulation and protection against oxidative stress. Evidence for the benefit and feasibility of therapeutic ketosis is examined in preclinical and clinical studies. Finally, ongoing clinical trials are reviewed for perspective on translation of ketone therapeutics for the treatment of HF.
Topics: Humans; Ketones; 3-Hydroxybutyric Acid; Epigenesis, Genetic; Ketone Bodies; Heart Failure; Ketosis
PubMed: 36996176
DOI: 10.1161/CIRCRESAHA.123.321872 -
The British Journal of Nutrition Jun 2022Obesity remains a serious relevant public health concern throughout the world despite related countermeasures being well understood (i.e. mainly physical activity and an... (Review)
Review
Obesity remains a serious relevant public health concern throughout the world despite related countermeasures being well understood (i.e. mainly physical activity and an adjusted diet). Among different nutritional approaches, there is a growing interest in ketogenic diets (KD) to manipulate body mass (BM) and to enhance fat mass loss. KD reduce the daily amount of carbohydrate intake drastically. This results in increased fatty acid utilisation, leading to an increase in blood ketone bodies (acetoacetate, 3--hydroxybutyrate and acetone) and therefore metabolic ketosis. For many years, nutritional intervention studies have focused on reducing dietary fat with little or conflicting positive results over the long term. Moreover, current nutritional guidelines for athletes propose carbohydrate-based diets to augment muscular adaptations. This review discusses the physiological basis of KD and their effects on BM reduction and body composition improvements in sedentary individuals combined with different types of exercise (resistance training or endurance training) in individuals with obesity and athletes. Ultimately, we discuss the strengths and the weaknesses of these nutritional interventions together with precautionary measures that should be observed in both individuals with obesity and athletic populations. A literature search from 1921 to April 2021 using Medline, Google Scholar, PubMed, Web of Science, Scopus and Sportdiscus Databases was used to identify relevant studies. In summary, based on the current evidence, KD are an efficient method to reduce BM and body fat in both individuals with obesity and athletes. However, these positive impacts are mainly because of the appetite suppressive effects of KD, which can decrease daily energy intake. Therefore, KD do not have any superior benefits to non-KD in BM and body fat loss in individuals with obesity and athletic populations in an isoenergetic situation. In sedentary individuals with obesity, it seems that fat-free mass (FFM) changes appear to be as great, if not greater, than decreases following a low-fat diet. In terms of lean mass, it seems that following a KD can cause FFM loss in resistance-trained individuals. In contrast, the FFM-preserving effects of KD are more efficient in endurance-trained compared with resistance-trained individuals.
Topics: Humans; Diet, Ketogenic; Body Composition; Exercise; Obesity; 3-Hydroxybutyric Acid; Carbohydrates
PubMed: 34250885
DOI: 10.1017/S0007114521002609 -
Sports Medicine (Auckland, N.Z.) Dec 2022The ketone bodies acetoacetate (AcAc) and β-hydroxybutyrate (βHB) have pleiotropic effects in multiple organs including brain, heart, and skeletal muscle by serving as... (Review)
Review
The ketone bodies acetoacetate (AcAc) and β-hydroxybutyrate (βHB) have pleiotropic effects in multiple organs including brain, heart, and skeletal muscle by serving as an alternative substrate for energy provision, and by modulating inflammation, oxidative stress, catabolic processes, and gene expression. Of particular relevance to athletes are the metabolic actions of ketone bodies to alter substrate utilisation through attenuating glucose utilisation in peripheral tissues, anti-lipolytic effects on adipose tissue, and attenuation of proteolysis in skeletal muscle. There has been long-standing interest in the development of ingestible forms of ketone bodies that has recently resulted in the commercial availability of exogenous ketone supplements (EKS). These supplements in the form of ketone salts and ketone esters, in addition to ketogenic compounds such as 1,3-butanediol and medium chain triglycerides, facilitate an acute transient increase in circulating AcAc and βHB concentrations, which has been termed 'acute nutritional ketosis' or 'intermittent exogenous ketosis'. Some studies have suggested beneficial effects of EKS to endurance performance, recovery, and overreaching, although many studies have failed to observe benefits of acute nutritional ketosis on performance or recovery. The present review explores the rationale and historical development of EKS, the mechanistic basis for their proposed effects, both positive and negative, and evidence to date for their effects on exercise performance and recovery outcomes before concluding with a discussion of methodological considerations and future directions in this field.
Topics: Humans; Ketones; Ketone Bodies; Ketosis; Acetoacetates; 3-Hydroxybutyric Acid; Dietary Supplements
PubMed: 36214993
DOI: 10.1007/s40279-022-01756-2 -
Immunity Sep 2023Environmental nutrient availability influences T cell metabolism, impacting T cell function and shaping immune outcomes. Here, we identified ketone bodies...
Environmental nutrient availability influences T cell metabolism, impacting T cell function and shaping immune outcomes. Here, we identified ketone bodies (KBs)-including β-hydroxybutyrate (βOHB) and acetoacetate (AcAc)-as essential fuels supporting CD8 T cell metabolism and effector function. βOHB directly increased CD8 T effector (Teff) cell cytokine production and cytolytic activity, and KB oxidation (ketolysis) was required for Teff cell responses to bacterial infection and tumor challenge. CD8 Teff cells preferentially used KBs over glucose to fuel the tricarboxylic acid (TCA) cycle in vitro and in vivo. KBs directly boosted the respiratory capacity and TCA cycle-dependent metabolic pathways that fuel CD8 T cell function. Mechanistically, βOHB was a major substrate for acetyl-CoA production in CD8 T cells and regulated effector responses through effects on histone acetylation. Together, our results identify cell-intrinsic ketolysis as a metabolic and epigenetic driver of optimal CD8 T cell effector responses.
Topics: 3-Hydroxybutyric Acid; Acetylation; CD8-Positive T-Lymphocytes; Histones; Ketone Bodies; Animals; Mice
PubMed: 37516105
DOI: 10.1016/j.immuni.2023.07.002 -
Alzheimer's & Dementia : the Journal of... Mar 2021Counteracting impaired brain glucose metabolism with ketones may improve cognition in mild cognitive impairment (MCI). (Randomized Controlled Trial)
Randomized Controlled Trial
INTRODUCTION
Counteracting impaired brain glucose metabolism with ketones may improve cognition in mild cognitive impairment (MCI).
METHODS
Cognition, plasma ketone response, and metabolic profile were assessed before and 6 months after supplementation with a ketogenic drink containing medium chain triglyceride (ketogenic medium chain triglyceride [kMCT]; 15 g twice/day; n = 39) or placebo (n = 44).
RESULTS
Free and cued recall (Trial 1; P = .047), verbal fluency (categories; P = .024), Boston Naming Test (total correct answers; P = .033), and the Trail-Making Test (total errors; P = .017) improved significantly in the kMCT group compared to placebo (analysis of covariance; pre-intervention score, sex, age, education, and apolipoprotein E4 as covariates). Some cognitive outcomes also correlated positively with plasma ketones. Plasma metabolic profile and ketone response were unchanged.
CONCLUSIONS
This kMCT drink improved cognitive outcomes in MCI, at least in part by increasing blood ketone level. These data support further assessment of MCI progression to Alzheimer's disease.
Topics: Aged; Beverages; Cognition; Cognitive Dysfunction; Diet, Ketogenic; Female; Humans; Ketones; Male; Neuropsychological Tests; Triglycerides
PubMed: 33103819
DOI: 10.1002/alz.12206 -
Annual Review of Nutrition Oct 2021Ketone bodies play significant roles in organismal energy homeostasis, serving as oxidative fuels, modulators of redox potential, lipogenic precursors, and signals,...
Ketone bodies play significant roles in organismal energy homeostasis, serving as oxidative fuels, modulators of redox potential, lipogenic precursors, and signals, primarily during states of low carbohydrate availability. Efforts to enhance wellness and ameliorate disease via nutritional, chronobiological, and pharmacological interventions have markedly intensified interest in ketone body metabolism. The two ketone body redox partners, acetoacetate and D-β-hydroxybutyrate, serve distinct metabolic and signaling roles in biological systems. We discuss the pleiotropic roles played by both of these ketones in health and disease. While enthusiasm is warranted, prudent procession through therapeutic applications of ketogenic and ketone therapies is also advised, as a range of metabolic and signaling consequences continue to emerge. Organ-specific and cell-type-specific effects of ketone bodies are important to consider as prospective therapeutic and wellness applications increase.
Topics: 3-Hydroxybutyric Acid; Homeostasis; Humans; Ketone Bodies; Signal Transduction
PubMed: 34633859
DOI: 10.1146/annurev-nutr-111120-111518 -
Nutrients Oct 2023In glucose-deprived conditions, ketone bodies are produced by the liver mitochondria, through the catabolism of fatty acids, and are used peripherally, as an alternative... (Review)
Review
In glucose-deprived conditions, ketone bodies are produced by the liver mitochondria, through the catabolism of fatty acids, and are used peripherally, as an alternative energy source. Ketones are produced in the body under normal conditions, including during pregnancy and the neonatal period, when following a ketogenic diet (KD), fasting, or exercising. Additionally, ketone synthesis is also augmented under pathological conditions, including cases of diabetic ketoacidosis (DKA), alcoholism, and several metabolic disorders. Nonetheless, diet is the main regulator of total body ketone concentrations. The KDs are mimicking the fasting state, altering the default metabolism towards the use of ketones as the primary fuel source. Recently, KD has gained recognition as a medical nutrition therapy for a plethora of metabolic conditions, including obesity and diabetes mellitus (DM). The present review aims to discuss the role of ketones, KDs, ketonemia, and ketonuria in DM, presenting all the available new evidence in a comprehensive manner.
Topics: Female; Pregnancy; Infant, Newborn; Humans; Ketone Bodies; Ketones; Diabetic Ketoacidosis; Ketosis; Glucose; Diet, Ketogenic; Metabolic Diseases; Diabetes Mellitus
PubMed: 37892458
DOI: 10.3390/nu15204383 -
Nutrients Apr 2022A dysregulation between energy intake (EI) and energy expenditure (EE), the two components of the energy balance equation, is one of the mechanisms responsible for the... (Review)
Review
A dysregulation between energy intake (EI) and energy expenditure (EE), the two components of the energy balance equation, is one of the mechanisms responsible for the development of obesity. Conservation of energy equilibrium is deemed a dynamic process and alterations of one component (energy intake or energy expenditure) lead to biological and/or behavioral compensatory changes in the counterpart. The interplay between energy demand and caloric intake appears designed to guarantee an adequate fuel supply in variable life contexts. In the past decades, researchers focused their attention on finding efficient strategies to fight the obesity pandemic. The ketogenic or "keto" diet (KD) gained substantial consideration as a potential weight-loss strategy, whereby the concentration of blood ketones (acetoacetate, 3-β-hydroxybutyrate, and acetone) increases as a result of increased fatty acid breakdown and the activity of ketogenic enzymes. It has been hypothesized that during the first phase of KDs when glucose utilization is still prevalent, an increase in EE may occur, due to increased hepatic oxygen consumption for gluconeogenesis and for triglyceride-fatty acid recycling. Later, a decrease in 24-h EE may ensue due to the slowing of gluconeogenesis and increase in fatty acid oxidation, with a reduction of the respiratory quotient and possibly the direct action of additional hormonal signals.
Topics: Diet, Ketogenic; Energy Metabolism; Fatty Acids; Humans; Obesity; Weight Loss
PubMed: 35565778
DOI: 10.3390/nu14091814 -
Nutrients Sep 2022Diabetic nephropathy (DN), a metabolic disease, is characterized by severe systemic metabolic disorders. A unique dietary pattern, such as intermittent fasting (IF) has... (Review)
Review
Diabetic nephropathy (DN), a metabolic disease, is characterized by severe systemic metabolic disorders. A unique dietary pattern, such as intermittent fasting (IF) has shown promising protective effects on various metabolic diseases, such as diabetes and cardiovascular and nervous system diseases. However, its role in regulating kidney disease, especially in DN, is still being investigated. Here, we summarize the current research progress, highlighting the relationship between IF and the risk factors for the progression of DN, and discuss the potential mechanisms by which IF improves renal injury in DN. Finally, we propose IF as a potential strategy to prevent and delay DN progression. Abbreviation: DN: Diabetic nephropathy; IF: Intermittent fasting; CPT1A: Carnitine palmitoyltransferase 1A; L-FABP: Liver-type fatty acid-binding protein; STZ: Streptozotocin; LDL: Low-density lipoproteins; HIIT: High-intensity interval training; CKD: Chronic kidney disease; ACEI: Angiotensin-converting enzyme inhibitors; ARB: Angiotensin receptor blockers; MDA: Malondialdehyde; mtDNA: Mitochondrial DNA; UCP3: Uncoupling protein-3; MAM: Mitochondria-associated endoplasmic reticulum membrane; PBMCs: Peripheral blood mononuclear cells; ERK1/2: Extracellular signal-regulated kinase 1/2; DRP1: Dynamin-related protein 1; β-HB: β-Hydroxybutyrate; AcAc: Acetoacetate; GEO: Gene Expression Omnibus; NCBI: National Center for Biotechnology Information; mTORC1: Mechanistic target of rapamycin complex 1; HMGCS2: 3-Hydroxy-3-methylglutaryl-CoA synthase 2; GSK3β: Glycogen synthase kinase 3β; AKI: Acute kidney injury; CMA: Chaperone-mediated autophagy; FGF21: Fibroblast growth factor 21.
Topics: Diabetic Nephropathies; Fasting; Humans; Metabolic Diseases
PubMed: 36235648
DOI: 10.3390/nu14193995