Ketone Ester Research Articles

Efficacy and safety of ketone ester infusion to prevent muscle weakness in a mouse model of sepsis-induced critical illness

In septic mice, 3-hydroxybutyrate-sodium-salt has shown to partially prevent sepsis-induced muscle weakness. Although effective, the excessive sodium load was toxic. We here investigated whether ketone ester 3-hydroxybutyl-3-hydroxybutanoate (3HHB) was a safer alternative. In a mouse model of abdominal sepsis, the effects of increasing bolus doses of 3HHB enantiomers on mortality, morbidity and muscle force were investigated (n = 376). Next, plasma 3HB- clearance after bolus d-3HHB was investigated (n = 27). Subsequently, in septic mice, the effect on mortality and muscle force of a continuous d,l-3HHB infusion was investigated (n = 72). In septic mice, as compared with placebo, muscle force was increased at 20 mmol/kg/day l-3HHB and at 40 mmol/kg/day d- and d,l-3HHB. However, severity of illness and mortality was increased by doubling the effective bolus doses. Bolus 3HHB caused a higher 3HB− plasma peak and slower clearance with sepsis. Unlike bolus injections, continuous infusion of d,l-3HHB did not increase severity of illness or mortality, while remaining effective in improving muscle force. Treatment of septic mice with the ketone ester 3HHB partly prevented muscle weakness. Toxicity of 3HHB administered as bolus was completely avoided by continuous infusion of the same dose. Whether continuous infusion of ketone esters represents a promising intervention to also prevent ICU-acquired weakness in human patients should be investigated.

Ketogenic therapy for Parkinson's disease: A systematic review and synthesis without meta-analysis of animal and human trials

ObjectiveThe aim of the present systematic review was to assess the efficacy of ketogenic therapy in Parkinson's disease (PD), using all available data from randomized controlled trials (RCTs) on humans and animal studies with PD models. DesignSystematic review of in vivo studies. MethodsStudies related to the research question were identified through searches in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, clinicaltrials.gov and the gray literature, from inception until November 2021. Rayyan was employed to screen and identify all studies fulfilling the inclusion criteria. Cochrane's revised Risk of Bias 2.0 and SYRCLE tools evaluated bias in RCTs and animal studies, respectively. An effect direction plot was developed to synthesize the evidence of the RCTs. ResultsTwelve studies were identified and included in the qualitative synthesis (4 RCTs and 8 animal trials). Interventions included ketogenic diets (KDs), supplementation with medium-chain triglyceride (MCT) oil, caprylic acid administration and ketone ester drinks. The animal research used zebrafish and rodents, and PD was toxin-induced. Based on the available RCTs, ketogenic therapy does not improve motor coordination and functioning, cognitive impairment, anthropometrics, blood lipids and glycemic control, exercise performance or voice disorders in patients with PD. The evidence is scattered and heterogenous, with single trials assessing different outcomes; thus, a synthesis of the evidence cannot be conclusive regarding the efficacy of ketogenic therapy. On the other hand, animal studies tend to demonstrate more promising results, with marked improvements in locomotor activity, dopaminergic activity, redox status, and inflammatory markers. ConclusionsAlthough animal studies indicate promising results, research on the effect of ketogenic therapy in PD is still in its infancy, with RCTs conducted on humans being heterogeneous and lacking PD-specific outcomes. More studies are required to recommend or refute the use of ketogenic therapy in PD.

Visible-Light-Catalyzed Radical-Radical Cross-Coupling Reaction of Benzyl Trifluoroborates and Carbonyl Compounds to Sterically Hindered Alcohols.

We report here an organic dye catalyzed direct radical-radical cross-coupling reaction based on the persistent free-radical effect (PRE), which is powered by visible light and does not require any external oxidants or reductants. In this reaction, benzyl trifluoroborates are oxidized by excited-state 4Cz-IPN to generate benzyl radicals, and the resulting boron trifluoride acts as a Lewis acid to reduce the reduction potential of carbonyl compounds. The dual roles of benzyl trifluoroborates enable aldehydes, ketones, diketones, and ketone esters to react with benzyl trifluoroborates to generate various sterically hindered alcohols.

Systemic Ketone Replacement Does Not Improve Survival or Cancer Cachexia in Mice With Lung Cancer.

Cachexia is a debilitating comorbidity affecting many lung cancer patients. We have previously found that cachectic mice with lung cancer have reduced serum ketone body levels due to low PPARα activity in the liver. Restoring hepatic PPARα activity with fenofibrate increased circulating ketones and delayed muscle and white adipose tissue wasting. We hypothesized that the loss of circulating ketones plays a pathophysiologic role in cachexia and performed two dietary intervention studies to test this hypothesis. In the first study, male and female mice were randomized to consume either a very low carbohydrate, ketogenic diet (KD) or normal chow (NC) after undergoing tumor induction. The KD successfully restored serum ketone levels and decreased blood glucose in cachectic mice but did not improve body weight maintenance or survival. In fact, there was a trend for the KD to worsen survival in male but not in female mice. In the second study, we compounded a ketone ester supplement into the NC diet (KE) and randomized tumor-bearing mice to KE or NC after tumor induction. We confirmed that KE was able to acutely and chronically increase ketone body abundance in the serum compared to NC. However, the restoration of ketones in the circulation was not able to improve body weight maintenance or survival in male or female mice with lung cancer. Finally, we investigated PPARα activity in the liver of mice fed KE and NC and found that animals fed a ketone ester supplement showed a significant increase in mRNA expression of several PPARα targets. These data negate our initial hypothesis and suggest that restoring ketone body availability in the circulation of mice with lung cancer does not alter cachexia development or improve survival, despite increasing hepatic PPARα activity.

Fasting or the short-term consumption of a ketogenic diet protects against antipsychotic-induced hyperglycaemia in mice.

Antipsychotic (AP) medications, such as olanzapine (OLZ), are used in the treatment of schizophrenia and a growing number of 'off-label' conditions. A single dose of OLZ causes robust increases in blood glucose within minutes of treatment. The purpose of the current study was to investigate whether interventions that increase circulating ketone bodies (fasting, β-hydroxybutyrate (βHB), ketone esters or a ketogenic diet (KD)) would be sufficient to protect against the acute metabolic side effects of OLZ. We demonstrate that fasting or the short-term consumption of a KD protects against OLZ-induced hyperglycaemia, independent of alterations in whole-body insulin action, and in parallel with a blunted rise in serum glucagon. Interestingly, the effects of fasting and KDs were not recapitulated by acutely increasing circulating concentrations of ketone bodies through treatment with βHB or oral ketone esters, approaches which increase ketone bodies to physiological or supra-physiological levels, respectively. Collectively, our findings demonstrate that fasting and the short-term consumption of a KD can protect against acute AP-induced perturbations in glucose homeostasis, whereas manipulations which acutely increase circulating ketone bodies do not elicit the same beneficial effects. KEY POINTS: Antipsychotic medications cause rapid and robust increases in blood glucose. Co-treatment approaches to offset these harmful metabolic side effects have not been identified. We demonstrate that fasting or the consumption of a short-term ketogenic diet, but not treatment with β-hydroxybutyrate or oral ketone esters, protects against acute antipsychotic-induced hyperglycaemia. The protective effects of fasting and ketogenic diets were paralleled by reductions in serum glucagon, but not improvements in whole-body insulin action.

Identifying Predictive Markers of CNS Oxygen Toxicity and Ketone Ester Effects on Latency to Seizure and Antioxidant Capacity

Hyperbaric oxygen (HBO2) is used in hyperbaric oxygen therapy and in undersea and aerospace medicine. What limits the use of HBO2 is the risk of seizures, i.e. central nervous system oxygen toxicity (CNS‐OT). In undersea medicine, the threat of CNS‐OT is what limits the time that the warfighter remains at depth while breathing HBO2. In addition, when breathing HBO2, various non‐convulsive signs and symptoms often precede onset of seizures, including bradycardia followed by tachycardia, hypothermia, and hyperventilation. We hypothesized that the early cardiorespiratory responses to HBO2 during the safe latent period could be used as predictive physiological markers (or physio‐markers) prior to the onset of CNS‐OT. Furthermore, using a ketone ester (KE) supplement, R,S‐1,3‐butanediol diacetoacetate ester, we posited that the KE would increase the antioxidant capacity and the latency time to seizure (LSz) when exposed to HBO2. Accordingly, 18 male, Sprague Dawley (SD) rats were implanted with DSI 4‐ET radio telemetry to record EEG, ECG, and respiratory EMG for offline analyses of physio‐markers. At least 1 week following surgery, each rat was placed in a hyperbaric chamber and “dived” to 5 ATA O2 (1 ATG/min) after oral gavage of either water (control group) or KE (treatment group). An additional 9 SD rats were also dived to 5 ATA O2, but not implanted with telemetry, to collect blood samples to measure antioxidant capacity with the RedoxSys® device before and after HBO2 exposure. HBO2 caused a 3‐phase hyperoxic ventilatory response: decreased respiration, transient hyperventilation, and a secondary later hyperventilation prior to seizures. Results showed that LSz increased in the KE group by 307% (controls: 6.42 ± 0.44 (n=15); KE: 22.16 ± 5.10 (n=18)). Additionally, minute ventilation and RR‐Interval (1/heart rate) were significantly different beginning ~15 minutes prior to onset of seizures. Receiver operating characteristic (ROC) analyses indicated that both hyperoxic hyperpnea and bradycardia were reliable physio‐markers for seizure prediction; that is, ROC for minute ventilation in both control and KE group, and for RR‐Interval in controls, was 1 (excellent predictor), and in the KE group was 0.84 (good predictor). However, core body temperature did not decrease significantly during HBO2 exposure and thus was not a physio‐marker for CNS‐OT. In addition, KE increased antioxidant capacity of blood from animals that were exposed to HBO2 with (p=0.0399) or without (p=0.0018) the development of CNS‐OT. In conclusion, hyperoxic hyperpnea and bradycardia can be used as predictive physio‐markers in conjunction with ketone therapy to reliably predict and delay CNS‐OT in rodents, and KE delays seizures in part by increasing overall antioxidant capacity during exposure to HBO2. Together this may enable safer and longer exposures for applications in undersea/aerospace medicine as well as hyperbaric oxygen therapies.

Mitigation of CNS oxygen toxicity seizures: evaluating the neuroprotective effects of L‐NAME versus Mitoquinone during exposure to 5 ATA O2 in freely behaving Sprague‐Dawley rats

Hyperbaric oxygen (HBO2) is breathed in HBO2 therapy and in undersea medicine; however, what limits the use of HBO2 in these situations is the risk of CNS oxygen toxicity (CNS‐OT; i.e. generalized seizures, Sz). Thus, we are interested in developing strategies that extend the duration of the safe latency period for breathing HBO2 by delaying or abolishing Sz. Increased production of reactive O2 & N2 species is involved in the neuropathology of CNS‐OT. Accordingly, we tested the following two hypotheses in male Sprague‐Dawley rats: a single predive intra peritoneal treatment given 30min before exposure to 5 ATA O2 of either 1) N(g)‐Nitro‐L‐arginine methyl ester (L‐NAME), which inhibits nitric oxide synthase (NOS) and thus nitric oxide (·NO) production, or Mitoquinone (MitoQ), which inhibits mitochondrial superoxide (·O2‐), delays Sz genesis in freely behaving, adult rats. Each rat was dived twice, separated by ≥1 week, receiving either control saline, L‐NAME (30mg/kg ip), or MitoQ (see below) in randomized order. Each rat was exposed to 1 ATA air (10‐15min), 1ATA O2 (10‐15min), compressed (1 ATG/min) to 5 ATA O2. The latency time to first Sz (LSz1) was measured from time zero (3 ATA O2) until onset of Sz at 5 ATA O2 or 60min (MitoQ) or 75min (L‐NAME), whichever came first. For L‐NAME dives, LSz1 in control dives = 10.8 ± 2.5min (avg ± SD; n=14) whereas L‐NAME delayed Sz significantly, increasing LSz1= 31.5 ± 24.3min, including 3 rats that did not seize (O) by 75min of HBO2 (Fig. 1; P= 0.0064). An additional 3 rats were surgically implanted with radio telemetric modules (4‐ET, DSI Inc.; motor cortex (ECoG) and dorsal medulla oblongata (EBulboG). Increased ECoG and EBulboG activities were delayed and blunted in rats treated with L‐NAME vs.control dives. For MitoQ dives, animal toxicity was evaluated first using up‐and‐down toxicity testing (1 ATA air). The maximum safe dose (ip) was 22g/kg MitoQ. During exposure to HBO2, MitoQ, likewise, delayed Sz or prevented Sz (n=5). Unexpectedly, however, all rats became lethargic during the dive and 3/5 rats died within 24 hr following decompression. A second up‐and‐down toxicity test was conducted using 11‐22mg/kg plus5 ATA O2. Most rats dosed with 14‐22mg/kg MitoQ and exposed to HBO2 did not Sz before 1 hr or delayed Sz; however, 11/16 died within 24 hr following decompression. By contrast, rats treated with 11mg/kg MitoQ plus HBO2 survived; however, the LSz1 was no different compared to control dives (n=2). We conclude that L‐NAME delays Sz genesis during HBO2, presumably by decreasing ·NO production and blocking ·NO‐induced cerebral hyperemia prior to Sz during HBO2. Doses of MitoQ (14‐22mg/kg) that are non‐toxic in 1 ATA air, and delay Sz during exposure to HBO2, however, become lethal when combined with HBO2. We postulate that MitoQ + HBO2 toxicity is due to unbridled ·NO production in the face of diminished production of mitochondrial ·O2‐, which normally reacts with ·NO, and thus accelerates onset of pulmonary O2 toxicity. Cocktails of L‐NAME, ketone ester, and MitoQ are currently under study as mitigation strategies for CNS‐OT.

Ketone Therapy Reduces Systemic and Organ Inflammation in Sepsis

IntroductionSepsis is the body's reaction to an infection that often causes lasting multi‐organ injury due to a dysregulated inflammatory response. Currently, there are no effective treatments to reduce inflammation during sepsis and assist in preventing the lasting inflammation‐mediated damage and thus, sepsis accounts for approximately 20% of all global causes of death. In addition, many patients who recover from sepsis have permanent damage to many organ systems which makes them more susceptible to future injury that likely affects them more severely. Thus, therapeutic strategies to reduce the inflammatory response in sepsis are needed to save lives and improve the outcomes and quality of life of those who survive sepsis. Herein, we tested the efficacy of a ketone therapy that increases circulating ketones via ketone ester supplementation. Ketones are small molecules that are normally produced by the liver and are elevated during carbohydrate‐deprived states, such as fasting or exercise. While ketones are classically known to be a metabolic source of energy, they also have non‐metabolic effects, such as inhibiting inflammation, which can be of therapeutic importance. We hypothesized that ketones have potent anti‐inflammatory effects in a mouse model of lipopolysaccharide (LPS)‐induced sepsis and that ketones can be used to mitigate the inflammation‐mediated organ damage.ObjectiveTo determine if ketone supplementation can effectively reduce inflammation and organ dysfunction/damage in a model of LPS‐induced sepsis.Methods8‐week‐old mice orally received either vehicle or a clinically tested ketone ester (KE) for 3 days. On day 3, mice were injected with saline or LPS to induce systemic inflammation and organ damage. 24 hours post‐injection, cardiac function was assessed and then mice were euthanized to assess systemic and organ inflammation from the 3 groups (control, LPS, LPS+KE).ResultsLPS‐treated mice had higher blood ketones compared to controls, suggesting that ketones may be important as an innate defense mechanism, and this response was further augmented in KE‐treated septic mice. While LPS‐treated mice had an induction of systemic pro‐inflammatory cytokines (e.g., IL‐1β, IL‐6, interferon‐γ) these cytokines were significantly lower in KE‐treated septic mice. Similarly, LPS induced numerous inflammatory markers in the heart, kidney, and liver, a large majority of which were reduced in the KE‐treated septic mice. LPS‐induced cardiac dysfunction and renal fibrosis was also significantly lower in KE‐treated septic mice. Finally, there was either no change or a reduction of ketolytic enzymes in various organs, suggesting that these protective and anti‐inflammatory effects do not depend on ketone metabolism for energy production.ConclusionTogether, these data are the first to show that ketone therapy may be a novel approach to reducing systemic and organ inflammation and dysfunction, and subsequent organ damage in a model of LPS‐induced sepsis.

A Low‐carbohydrate, Ketogenic Diet Enhances Hippocampal Mitochondrial Bioenergetics and Efficiency

Mitochondrial dysfunction and cognitive impairment are common symptoms in many neurologic and psychiatric disorders, as well as in nonpathological aging. Ketones have been suggested as therapeutic for their relevance in epilepsy as well as other neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Here we explored whether a low‐carbohydrate, ketogenic diet (KD) alters recognition memory, hippocampal mitochondrial bioenergetics, and expression of proteins involved in mitochondrial dynamics. Mature‐to‐middle‐aged adult male and female mice were placed on a lard‐based KD supplemented with an exogenous ketone ester for eight weeks. Changes in behavioral recognition memory were measured in a two‐object novel object recognition test. Hippocampal mitochondrial physiology was assessed using high‐resolution respirometry to measure changes in oxygen flux, biochemical assays to quantify ATP production, and western blot to measure changes in Drp1 expression. Here we demonstrate that the KD reduces hippocampal oxygen consumption (p=0.013), but does not alter ATP production (p=0.42) or Drp1 expression (p=0.51). These results indicate an enhancement of mitochondrial coupling and efficiency independent of mitochondrial dynamics, as changes in oxygen flux occurred without changes in Drp1 expression. Together, these findings add to growing support for the use of ketones and KDs in pathological brain states in which mitochondrial function is compromised, especially within the hippocampus.

Effects of a ketogenic diet on recognition memory and locomotor activity

Ketones are generally considered neuroprotective and may have therapeutic potential in conditions such as Alzheimer’s and other diseases in which cognition is impaired. The novel object recognition (NOR) assay is a widely‐used test of non‐spatial memory that relies, not on food reward or survival instincts, but on rodents’ innate predisposition to explore in the absence of external stimuli. Here we investigated whether a ketogenic diet (KD) enhances behavioral recognition memory. Adult‐to‐middle‐aged male and female mice were placed on a ketogenic diet supplemented with an exogenous ketone ester for eight weeks and memory was assessed in a two‐object novel object recognition test. We observed trends toward significant improvements in recognition memory (p=0.12) and velocity (p=0.066), and a significant increase in total distance traveled (p=0.047) in the KD mice compared to controls. These data suggest a KD induces beneficial locomotor adaptations, but cognitively, may be more relevant in conditions associated with more severe cognitive deficits.

Metal-free one-pot oxidative conversion: Molecular Iodine Mediated Oxidation Organic Reactions

Various oxidative compounds such as aldehyde, ketone ester, and acids can be produced in large yields by an effective iodine-mediated oxidative reaction of organic molecules. Molecular iodine is a generally available and commercially extremely inexpensive substance that induces oxidative esterification. With the comparison with different Brønsted acid catalysis, molecular iodine or iodophilic activations proceed the reaction onto a deoxygenation pathway. With only a few mol% of I2, the oxidation occurs very quickly at room temperature. This approach could also be used to transport different benzil derivatives from nonactivated alkynes, such as diaryl acetylenes. Molecular iodine with several mild reagents such as aq. NH3, ∼30% aq. H2O2 and DMSO might be used to convert various one degree alcohols, particularly benzylic alcohols, into the corresponding aromatic amides in suffiently high yields in a one-pot method. Similarly, by treating different benzylic chloride, bromide and iodide with a molecular iodine oxidation medium, the corresponding aromatic amides may be prepared in a one-pot method. The reactions in this section include transformation of several compounds into their respective oxidative products with the metal-free one-pot oxidative.

Ketone Body β-Hydroxybutyrate Prevents Myocardial Oxidative Stress in Septic Cardiomyopathy.

Septic cardiomyopathy is a life-threatening complication of severe sepsis and septic shock. Oxidative stress and mitochondrial dysfunction have been identified as significant abnormalities in septic cardiomyopathy. However, specific treatments are rare. This study aims to investigate the impact of β-hydroxybutyrate (β-OHB) on septic cardiomyopathy and explore the underlying mechanism(s). We found that pretreatment of D-β-hydroxybutyrate-(R)-1,3 butanediol monoester (ketone ester, 3 mg/g body weight, once daily) by gavage for three days elevated the levels of ketone bodies, especially that of β-hydroxybutyrate (β-OHB) in the circulation and mouse hearts, which exerted a protective effect against lipopolysaccharide (LPS, 20 mg/kg)-induced septic cardiomyopathy in mice. In addition, an LPS-stimulated macrophage-conditioned medium (MCM) was used to mimic the pathological process of septic cardiomyopathy. Mechanistically, β-OHB alleviated myocardial oxidative stress and improved mitochondrial respiratory function through the antioxidant FoxO3a/MT2 pathway activated via histone deacetylase (HDAC) inhibition, which ultimately enhanced heart performance in septic cardiomyopathy. Our results, therefore, suggested an unappreciated critical role of β-OHB in septic heart protection as well as highlighted the potential of β-OHB as a simple remedy for the septic cardiomyopathy population.

No effect of oral ketone ester supplementation on exercise capacity in patients with McArdle disease and healthy controls: A randomized placebo-controlled cross-over study.

Patients with glycogen storage disease type V (GSDV), also known as McArdle disease, have blocked glycogen breakdown due to myophosphorylase deficiency, leading to exercise intolerance, muscle pain, and risk of muscle damage. Blood‐derived ketone bodies (KBs) constitute an alternative energy source that could fuel the muscle independent of glycogenolysis. However, except for long‐time fasting or ketogenic dieting, KBs are present in low quantities. This led us to explore the effects of a drink containing exogenously produced KBs in the form of D‐β‐hydroxybutyrate esters (KE) on exercise capacity and metabolism in patients with GSDV. Eight GSDV patients and four healthy controls (HC) were included in this placebo‐controlled, cross‐over study where subjects were randomized to receive a KE drink with 395 mgKE/kg or placebo drink on two separate days 25 min before a submaximal cycle exercise test. The primary outcome was exercise capacity as indicated by heart rate response (HR) to exercise. Secondary outcomes included perceived exertion (PE) and measures of KB, carbohydrate, and fat metabolism during exercise. In GSDV, the KE drink vs. placebo increased plasma KBs and KB oxidation (p ≤ 0.0001) but did not improve exercise capacity as judged from HR (p = 0.120) and PE (p = 0.109). In addition, the KE drink lowered plasma glucose, free fatty acids, and lowered lipolytic rate and glucose rate of appearance compared with placebo. Similar results were found in the HC group. The present study indicates that an increase in KB oxidation by oral KE supplementation does not improve exercise capacity in GSDV possibly because of KB‐induced inhibition of lipolysis and liver glucose output. Thus, oral KE supplementation alone cannot be recommended as a treatment option for patients with GSDV.

Evaluation of Acute Supplementation With the Ketone Ester (R)-3-Hydroxybutyl-(R)-3-Hydroxybutyrate (deltaG) in Healthy Volunteers by Cardiac and Skeletal Muscle 31P Magnetic Resonance Spectroscopy.

In this acute intervention study, we investigated the potential benefit of ketone supplementation in humans by studying cardiac phosphocreatine to adenosine-triphosphate ratios (PCr/ATP) and skeletal muscle PCr recovery using phosphorus magnetic resonance spectroscopy (31P-MRS) before and after ingestion of a ketone ester drink. We recruited 28 healthy individuals: 12 aged 23–70 years for cardiac 31P-MRS, and 16 aged 60–75 years for skeletal muscle 31P-MRS. Baseline and post-intervention resting cardiac and dynamic skeletal muscle 31P-MRS scans were performed in one visit, where 25 g of the ketone monoester, deltaG®, was administered after the baseline scan. Administration was timed so that post-intervention 31P-MRS would take place 30 min after deltaG® ingestion. The deltaG® ketone drink was well-tolerated by all participants. In participants who provided blood samples, post-intervention blood glucose, lactate and non-esterified fatty acid concentrations decreased significantly (−28.8%, p ≪ 0.001; −28.2%, p = 0.02; and −49.1%, p ≪ 0.001, respectively), while levels of the ketone body D-beta-hydroxybutyrate significantly increased from mean (standard deviation) 0.7 (0.3) to 4.0 (1.1) mmol/L after 30 min (p ≪ 0.001). There were no significant changes in cardiac PCr/ATP or skeletal muscle metabolic parameters between baseline and post-intervention. Acute ketone supplementation caused mild ketosis in blood, with drops in glucose, lactate, and free fatty acids; however, such changes were not associated with changes in 31P-MRS measures in the heart or in skeletal muscle. Future work may focus on the effect of longer-term ketone supplementation on tissue energetics in groups with compromised mitochondrial function.

Therapeutic ketosis decreases methacholine hyperresponsiveness in mouse models of inherent obese asthma.

Obese asthmatics tend to have severe, poorly controlled disease and exhibit methacholine hyperresponsiveness manifesting in proximal airway narrowing and distal lung tissue collapsibility. Substantial weight loss in obese asthmatics or in mouse models of the condition decreases methacholine hyperresponsiveness. Ketone bodies are rapidly elevated during weight loss, coinciding with or preceding relief from asthma-related comorbidities. As ketone bodies may exert numerous potentially therapeutic effects, augmenting their systemic concentrations is being targeted for the treatment of several conditions. Circulating ketone body levels can be increased by feeding a ketogenic diet or by providing a ketone ester dietary supplement, which we hypothesized would exert protective effects in mouse models of inherent obese asthma. Weight loss induced by feeding a low-fat diet to mice previously fed a high-fat diet was preceded by increased urine and blood levels of the ketone body β-hydroxybutyrate (BHB). Feeding a ketogenic diet for 3 wk to high-fat diet-fed obese mice or genetically obese db/db mice increased BHB concentrations and decreased methacholine hyperresponsiveness without substantially decreasing body weight. Acute ketone ester administration decreased methacholine responsiveness of normal mice, and dietary ketone ester supplementation of high-fat diet-fed mice decreased methacholine hyperresponsiveness. Ketone ester supplementation also transiently induced an "antiobesogenic" gut microbiome with a decreased Fermicutes/Bacteroidetes ratio. Dietary interventions to increase systemic BHB concentrations could provide symptom relief for obese asthmatics without the need for the substantial weight loss required of patients to elicit benefits to their asthma through bariatric surgery or other diet or lifestyle alterations.

Mapping the Endogenous Ketogenic System Across Ages, Sex and Diets

Understanding how our cells maintain energy homeostasis has long been a focus of aging biology. A decline in energy metabolism is central to many age-related diseases such as Alzheimer’s disease, heart failure, frailty, and delirium. Intervening on pathways involved in energy homeostasis can extend healthy lifespan. When our primary energy substrate glucose, is scarce, our bodies use ketone bodies (i.e. beta-hydroxybutyrate, acetoacetate, acetone). Aging is associated with glucose intolerance and insulin insensitivity, yet what role ketone body metabolism might play in compensating for impaired glucose utilization in age-related diseases is understudied. Here, we investigated how the body’s endogenous ketone body production and utilization pathways are modulated by age across the lifespan of female and male C57BL/6 mice (4 mo old, 12 mo old, 22 mo old). We show how different ages have different metabolic and gene expression responses to 1-week ketogenic diet (KD) or ketone ester diet. We observed an apparently compensatory ketogenic response in older animals fed normal diet, with a stronger compensatory response driven by KD. We observed tissue-specific changes, including induction of ketone body production enzymes in the aging heart. When comparing the ketogenic capacity between sexes, females had a higher basal level and less variation with age, underscoring the importance of sexual dimorphism in metabolism. Overall, these findings suggest that older animals use ketone bodies to meet energetic demands in a normal diet context. This study supports the potential roles of ketogenic therapies such as exogenous ketones to improve energy homeostasis in conditions of aging.

Ketone Bodies Impact on Hypoxic CO2 Retention Protocol During Exercise.

Exogenous ketone esters have demonstrated the capacity to increase oxygen availability during acute hypoxic exposure leading to the potential application of their use to mitigate performance declines at high altitudes. Voluntary hypoventilation (VH) with exercise reliably reduces oxygen availability and increases carbon dioxide retention without alterations to ambient pressure or gas content. Utilizing a double-blind randomized crossover design, fifteen recreational male distance runners performed submaximal exercise (4 × 5 min; 70% VO2 Max) with VH. An exogenous ketone ester (KME; 573 mg⋅kg–1) or iso-caloric flavor matched placebo (PLA) was consumed prior to exercise. Metabolites, blood gases, expired air, heart rate, oxygen saturation, cognition, and perception metrics were collected throughout. KME rapidly elevated R-β-hydroxybutyrate and reduced blood glucose without altering lactate production. KME lowered pH, bicarbonate, and total carbon dioxide. VH with exercise significantly reduced blood (SpO2) and muscle (SmO2) oxygenation and increased cognitive mean reaction time and respiratory rate regardless of condition. KME administration significantly elevated respiratory exchange ratio (RER) at rest and throughout recovery from VH, compared to PLA. Blood carbon dioxide (PCO2) retention increased in the PLA condition while decreasing in the KME condition, leading to a significantly lower PCO2 value immediately post VH exercise (IPE; p = 0.031) and at recovery (p = 0.001), independent of respiratory rate. The KME’s ability to rapidly alter metabolism, acid/base balance, CO2 retention, and respiratory exchange rate independent of respiratory rate changes at rest, during, and/or following VH exercise protocol illustrates a rapid countermeasure to CO2 retention in concert with systemic metabolic changes.

Nutritional Ketosis as a Potential Treatment for Alcohol Use Disorder.

Alcohol use disorder (AUD) is a chronic, relapsing brain disorder, characterized by compulsive alcohol seeking and disrupted brain function. In individuals with AUD, abstinence from alcohol often precipitates withdrawal symptoms than can be life threatening. Here, we review evidence for nutritional ketosis as a potential means to reduce withdrawal and alcohol craving. We also review the underlying mechanisms of action of ketosis. Several findings suggest that during alcohol intoxication there is a shift from glucose to acetate metabolism that is enhanced in individuals with AUD. During withdrawal, there is a decline in acetate levels that can result in an energy deficit and could contribute to neurotoxicity. A ketogenic diet or ingestion of a ketone ester elevates ketone bodies (acetoacetate, β-hydroxybutyrate and acetone) in plasma and brain, resulting in nutritional ketosis. These effects have been shown to reduce alcohol withdrawal symptoms, alcohol craving, and alcohol consumption in both preclinical and clinical studies. Thus, nutritional ketosis may represent a unique treatment option for AUD: namely, a nutritional intervention that could be used alone or to augment the effects of medications.

Structure Optimization of Cellulose Nanofibers/Poly(Lactic Acid) Composites by the Sizing of AKD.

Recently, cellulose nanofibers (CNF) are used as one novel fillers to reinforce poly(lactic acid) (PLA) matrix and form PLA green nanocomposites. In the present work, alkyl ketene dimer (AKD) was used as the sizing of CNF to improve the interfacial compatibility between the hydrophilic CNF and the hydrophobic PLA. The interactions between the AKD and CNF were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), which showed the formation of ketone ester structure between AKD and the hydroxyl groups of CNF. Thermo gravimetric analysis (TGA) showed the little reduced thermal stability of the AKD-CNF/PLA composites. The AKD-CNF/PLA morphology has rough surfaces due to the incorporation of cellulose nanofibers. The mechanical properties of AKD-CNF/PLA were tested by tensile testing, which discovered more AKD-CNF content enhances stress–strain performance. The highest tensile strength of composites was obtained for PLA with 5.0 wt.% AKD-cellulose, which is almost nine times higher than that of the pure PLA.

β-Hydroxybutyrate Oxidation in Exercise Is Impaired by Low-Carbohydrate and High-Fat Availability.

Purpose: In this study, we determined ketone oxidation rates in athletes under metabolic conditions of high and low carbohydrate (CHO) and fat availability.Methods: Six healthy male athletes completed 1 h of bicycle ergometer exercise at 75% maximal power (WMax) on three occasions. Prior to exercise, participants consumed 573 mg·kg bw−1 of a ketone ester (KE) containing a 13C label. To manipulate CHO availability, athletes undertook glycogen depleting exercise followed by isocaloric high-CHO or very-low-CHO diets. To manipulate fat availability, participants were given a continuous infusion of lipid during two visits. Using stable isotope methodology, β-hydroxybutyrate (βHB) oxidation rates were therefore investigated under the following metabolic conditions: (i) high CHO + normal fat (KE+CHO); (ii) high CHO + high fat KE+CHO+FAT); and (iii) low CHO + high fat (KE+FAT).Results: Pre-exercise intramuscular glycogen (IMGLY) was approximately halved in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both p < 0.05). Blood free fatty acids (FFA) and intramuscular long-chain acylcarnitines were significantly greater in the KE+FAT vs. other conditions and in the KE+CHO+FAT vs. KE+CHO conditions before exercise. Following ingestion of the 13C labeled KE, blood βHB levels increased to ≈4.5 mM before exercise in all conditions. βHB oxidation was modestly greater in the KE+CHO vs. KE+FAT conditions (mean diff. = 0.09 g·min−1, p = 0.03; d = 0.3), tended to be greater in the KE+CHO+FAT vs. KE+FAT conditions (mean diff. = 0.07 g·min−1; p = 0.1; d = 0.3) and were the same in the KE+CHO vs. KE+CHO+FAT conditions (p < 0.05; d < 0.1). A moderate positive correlation between pre-exercise IMGLY and βHB oxidation rates during exercise was present (p = 0.04; r = 0.5). Post-exercise intramuscular βHB abundance was markedly elevated in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both, p < 0.001; d = 2.3).Conclusion: βHB oxidation rates during exercise are modestly impaired by low CHO availability, independent of circulating βHB levels.