Treatment of Parkinson disease with diet-induced hyperketonemia: a feasibility study

The Gut Microbiota in Parkinson Disease: Interactions with Drugs and Potential for Therapeutic Applications

The concept of a 'microbiota-gut-brain axis' has recently emerged as an important player in the pathophysiology of Parkinson disease (PD), not least because of the reciprocal interaction between gut bacteria and medications. The gut microbiota can influence levodopa kinetics, and conversely, drugs administered for PD can influence gut microbiota composition. Through a two-step enzymatic pathway, gut microbes can decarboxylate levodopa to dopamine in the small intestine and then dehydroxylate it to m-tyramine, thus reducing availability. Inhibition of bacterial decarboxylation pathways could therefore represent a strategy to increase levodopa absorption. Other bacterial perturbations common in PD, such as small intestinal bacterial overgrowth and Helicobacter pylori infection, can also modulate levodopa metabolism, and eradication therapies may improve levodopa absorption. Interventions targeting the gut microbiota offer a novel opportunity to manage disabling motor complications and dopa-unresponsive symptoms. Mediterranean diet-induced changes in gut microbiota composition might improve a range of non-motor symptoms. Prebiotics can increase levels of short-chain fatty acid-producing bacteria and decrease pro-inflammatory species, with positive effects on clinical symptoms and levodopa kinetics. Different formulations of probiotics showed beneficial outcomes on constipation, with some of them improving dopamine levels; however, the most effective dosage and duration and long-term effects of these treatments remain unknown. Data from faecal microbiota transplantation studies are preliminary, but show encouraging trends towards improvement in both motor and non-motor outcomes.This article summarises the most up-to-date knowledge in pharmacomicrobiomics in PD, and discusses how the manipulation of gut microbiota represents a potential new therapeutic avenue for PD.

The interplay between glucose and ketone bodies in neural stem cell metabolism

Glucose is the primary energy source for neural stem cells (NSCs), supporting their proliferation, differentiation, and quiescence. However, the high demand for glucose during brain development often exceeds its supply, leading to the utilization of alternative energy sources including ketone bodies. Ketone bodies, including β-hydroxybutyrate, are short-chain fatty acids produced through hepatic ketogenesis and play a crucial role in providing energy and the biosynthetic components for NSCs when required. The interplay between glucose and ketone metabolism influences NSC behavior and fate decisions, and disruptions in these metabolic pathways have been linked to neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Additionally, ketone bodies exert neuroprotective effects on NSCs and modulate cellular responses to oxidative stress, energy maintenance, deacetylation, and inflammation. As such, understanding the interdependence of glucose and ketone metabolism in NSCs is crucial to understanding their roles in NSC function and their implications for neurological conditions. This article reviews the mechanisms of glucose and ketone utilization in NSCs, their impact on NSC function, and the therapeutic potential of targeting these metabolic pathways in neurological disorders.

The Interplay of Sports and Nutrition in Neurological Health and Recovery

This comprehensive review explores the dynamic relationship between sports, nutrition, and neurological health. Focusing on recent clinical advancements, it examines how physical activity and dietary practices influence the prevention, treatment, and rehabilitation of various neurological conditions. The review highlights the role of neuroimaging in understanding these interactions, discusses emerging technologies in neurotherapeutic interventions, and evaluates the efficacy of sports and nutritional strategies in enhancing neurological recovery. This synthesis of current knowledge aims to provide a deeper understanding of how lifestyle factors can be integrated into clinical practices to improve neurological outcomes.

A randomized feasibility trial of medium chain triglyceride-supplemented ketogenic diet in people with Parkinson's disease

BACKGROUND

A ketogenic diet (KD) may benefit people with neurodegenerative disorders marked by mitochondrial depolarization/insufficiency, including Parkinson's disease (PD).

OBJECTIVE

Evaluate whether a KD supplemented by medium chain triglyceride (MCT-KD) oil is feasible and acceptable for PD patients. Furthermore, we explored the effects of MCT-KD on blood ketone levels, metabolic parameters, levodopa absorption, mobility, nonmotor symptoms, simple motor and cognitive tests, autonomic function, and resting-state electroencephalography (rsEEG).

METHODS

A one-week in-hospital, double-blind, randomized, placebo-controlled diet (MCT-KD vs. standard diet (SD)), followed by an at-home two-week open-label extension. The primary outcome was KD feasibility and acceptability. The secondary outcome was the change in Timed Up & Go (TUG) on day 7 of the diet intervention. Additional exploratory outcomes included the N-Back task, Unified Parkinson's Disease Rating Scale, Non-Motor Symptom Scale, and rsEEG connectivity.

RESULTS

A total of 15/16 subjects completed the study. The mean acceptability was 2.3/3, indicating willingness to continue the KD. Day 7 TUG time was not significantly different between the SD and KD groups. The nonmotor symptom severity score was reduced at the week 3 visit and to a greater extent in the KD group. UPDRS, 3-back, and rsEEG measures were not significantly different between groups. Blood ketosis was attained by day 4 in the KD group and to a greater extent at week 3 than in the SD group. The plasma levodopa metabolites DOPAC and dopamine both showed nonsignificant increasing trends over 3 days in the KD vs. SD groups.

CONCLUSIONS

An MCT-supplemented KD is feasible and acceptable to PD patients but requires further study to understand its effects on symptoms and disease.

TRIAL REGISTRATION

Trial Registration Number NCT04584346, registration dates were Oct 14, 2020 - Sept 13, 2022.

Perspective: The Impact of Fasting and Caloric Restriction on Neurodegenerative Diseases in Humans

Neurodegenerative diseases (NDs) are characterized by the progressive functional and structural denaturation of neurons in the central and peripheral nervous systems. Despite the wide range of genetic predispositions, the increased emergence of these disorders has been associated with a variety of modifiable risk factors, including lifestyle factors. Diet has been shown to influence cognitive alterations in the elderly population with age-related brain pathologies, and specific dietary interventions might, therefore, confer preservatory protection to neural structures. Although Mediterranean and ketogenic diets have been studied, no clear guidelines have been implemented for the prevention or treatment of ND in clinical practice. Murine models have shown that intermittent fasting and caloric restriction (CR) can counteract disease processes in various age-related disorders, including NDs. The objective of this perspective is to provide a comprehensive, comparative overview of the available primary intervention studies on fasting and CR in humans with ND and to elucidate possible links between the mechanisms underlying the effects of fasting, CR, and the neuropathology of ND. We also included all currently available studies in older adults (with and without mild cognitive impairment) in which the primary endpoint was cognitive function to provide further insights into the feasibility and outcomes of such interventions. Overall, we conclude that nutritional intervention trials focusing on fasting and CR in humans with ND have been neglected, and more high-quality studies, including longitudinal clinical intervention trials, are urgently needed to elucidate the underlying immune-metabolic mechanisms in diet and ND.

Role of ketogenic diet in neurodegenerative diseases focusing on Alzheimer diseases: The guardian angle

The ketogenic diet (KD) is a low-carbohydrate, adequate protein and high-fat diet. KD is primarily used to treat refractory epilepsy. KD was shown to be effective in treating different neurodegenerative diseases. Alzheimer disease (AD) is the first common neurodegenerative disease in the world characterized by memory and cognitive impairment. However, the underlying mechanism of KD in controlling of AD and other neurodegenerative diseases are not discussed widely. Therefore, this review aims to revise the fundamental mechanism of KD in different neurodegenerative diseases focusing on the AD. KD induces a fasting-like which modulates the central and peripheral metabolism by regulating mitochondrial dysfunction, oxidative stress, inflammation, gut-flora, and autophagy in different neurodegenerative diseases. Different studies highlighted that KD improves AD neuropathology by regulating synaptic neurotransmission and inhibiting of neuroinflammation and oxidative stress. In conclusion, KD improves cognitive function and attenuates the progression of AD neuropathology by reducing oxidative stress, mitochondrial dysfunction, and enhancing neuronal autophagy and brain BDNF.

Ketogenic therapy towards precision medicine for brain diseases

Precision nutrition and nutrigenomics are emerging in the development of therapies for multiple diseases. The ketogenic diet (KD) is the most widely used clinical diet, providing high fat, low carbohydrate, and adequate protein. KD produces ketones and alters the metabolism of patients. Growing evidence suggests that KD has therapeutic effects in a wide range of neuronal diseases including epilepsy, neurodegeneration, cancer, and metabolic disorders. Although KD is considered to be a low-side-effect diet treatment, its therapeutic mechanism has not yet been fully elucidated. Also, its induced keto-response among different populations has not been elucidated. Understanding the ketone metabolism in health and disease is critical for the development of KD-associated therapeutics and synergistic therapy under any physiological background. Here, we review the current advances and known heterogeneity of the KD response and discuss the prospects for KD therapy from a precision nutrition perspective.

Nutrition, Immunity and Aging: Current Scenario and Future Perspectives in Neurodegenerative Diseases

Aging is a gradual decline of physiological function and tissue homeostasis and, in many instances, is related to increased (neuro)-degeneration, together with inflammation, becoming one of the most important risks for developing neurodegenerative diseases. Certain individual nutrients or foods in combination may counteract aging and associated neurodegenerative diseases by promoting a balance between the pro- and anti-inflammatory responses. Thus, nutrition could represent a powerful modulator of this fine balance, other than a modifiable risk factor to contrast inflammaging. This narrative review explores from a broad perspective the impact of nutrition on the hallmarks of aging and inflammation in Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis Syndrome (ALS), starting from nutrients up to single foods and complex dietary patterns.

A Potential Role for the Ketogenic Diet in Alzheimer's Disease Treatment: Exploring Pre-Clinical and Clinical Evidence

Given the remarkable progress in global health and overall quality of life, the significant rise in life expectancy has become intertwined with the surging occurrence of neurodegenerative disorders (NDs). This emerging trend is poised to pose a substantial challenge to the fields of medicine and public health in the years ahead. In this context, Alzheimer's disease (AD) is regarded as an ND that causes recent memory loss, motor impairment and cognitive deficits. AD is the most common cause of dementia in the elderly and its development is linked to multifactorial interactions between the environment, genetics, aging and lifestyle. The pathological hallmarks in AD are the accumulation of β-amyloid peptide (Aβ), the hyperphosphorylation of tau protein, neurotoxic events and impaired glucose metabolism. Due to pharmacological limitations and in view of the prevailing glycemic hypometabolism, the ketogenic diet (KD) emerges as a promising non-pharmacological possibility for managing AD, an approach that has already demonstrated efficacy in addressing other disorders, notably epilepsy. The KD consists of a food regimen in which carbohydrate intake is discouraged at the expense of increased lipid consumption, inducing metabolic ketosis whereby the main source of energy becomes ketone bodies instead of glucose. Thus, under these dietary conditions, neuronal death via lack of energy would be decreased, inasmuch as the metabolism of lipids is not impaired in AD. In this way, the clinical picture of patients with AD would potentially improve via the slowing down of symptoms and delaying of the progression of the disease. Hence, this review aims to explore the rationale behind utilizing the KD in AD treatment while emphasizing the metabolic interplay between the KD and the improvement of AD indicators, drawing insights from both preclinical and clinical investigations. Via a comprehensive examination of the studies detailed in this review, it is evident that the KD emerges as a promising alternative for managing AD. Moreover, its efficacy is notably enhanced when dietary composition is modified, thereby opening up innovative avenues for decreasing the progression of AD.

Molecular Mechanisms of Neuroprotection by Ketone Bodies and Ketogenic Diet in Cerebral Ischemia and Neurodegenerative Diseases

Ketone bodies (KBs), such as acetoacetate and β-hydroxybutyrate, serve as crucial alternative energy sources during glucose deficiency. KBs, generated through ketogenesis in the liver, are metabolized into acetyl-CoA in extrahepatic tissues, entering the tricarboxylic acid cycle and electron transport chain for ATP production. Reduced glucose metabolism and mitochondrial dysfunction correlate with increased neuronal death and brain damage during cerebral ischemia and neurodegeneration. Both KBs and the ketogenic diet (KD) demonstrate neuroprotective effects by orchestrating various cellular processes through metabolic and signaling functions. They enhance mitochondrial function, mitigate oxidative stress and apoptosis, and regulate epigenetic and post-translational modifications of histones and non-histone proteins. Additionally, KBs and KD contribute to reducing neuroinflammation and modulating autophagy, neurotransmission systems, and gut microbiome. This review aims to explore the current understanding of the molecular mechanisms underpinning the neuroprotective effects of KBs and KD against brain damage in cerebral ischemia and neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease.

Low-carbohydrate and ketogenic diets: a scoping review of neurological and inflammatory outcomes in human studies and their relevance to chronic pain

Dietary restriction of carbohydrate has been demonstrated to be beneficial for nervous system dysfunction in animal models and may be beneficial for human chronic pain. The purpose of this review is to assess the impact of a low-carbohydrate/ketogenic diet on the adult nervous system function and inflammatory biomarkers to inform nutritional research for chronic pain. An electronic database search was carried out in May 2021. Publications were screened for prospective research with dietary carbohydrate intake <130 g per day and duration of ≥2 weeks. Studies were categorised into those reporting adult neurological outcomes to be extracted for analysis and those reporting other adult research outcomes. Both groups were screened again for reported inflammatory biomarkers. From 1548 studies, there were 847 studies included. Sixty-four reported neurological outcomes with 83% showing improvement. Five hundred and twenty-three studies had a different research focus (metabolic n = 394, sport/performance n = 51, cancer n = 33, general n = 30, neurological with non-neuro outcomes n = 12, or gastrointestinal n = 4). The second screen identified sixty-three studies reporting on inflammatory biomarkers, with 71% reporting a reduction in inflammation. The overall results suggest a favourable outcome on the nervous system and inflammatory biomarkers from a reduction in dietary carbohydrates. Both nervous system sensitisation and inflammation occur in chronic pain, and the results from this review indicate it may be improved by low-carbohydrate nutritional therapy. More clinical trials within this population are required to build on the few human trials that have been done.

Ketogenic therapies in Parkinson's disease, Alzheimer's disease, and mild cognitive impairment: An integrative review

BACKGROUND

Ketogenic therapies have shown benefit for seizure reduction in epilepsy but their impact on other neurologic conditions is less known. In this literature review, the efficacy of ketogenic therapies were assessed in Parkinson's disease (PD), Alzheimer's disease (AD), and mild cognitive impairment (MCI).

METHODS

A literature search was conducted using PubMed, Scopus, and Google Scholar focusing on ketogenic therapies in PD, AD, and MCI.

RESULTS

A total of 2565 records were identified with a total of 15 studies (3 for PD and 12 for MCI/AD) meeting criteria for analysis. The ketogenic diet was used in all the PD studies and did show significant improvement in motor function either through vocal quality, gait, freezing, tremor, and/or balance. A variety of ketogenic therapies were utilized in the MCI and AD groups including a ketogenic diet, low-carbohydrate diet, modified Adkins diet, Mediterranean diet with coconut oil supplementation, a ketogenic diet with a ketogenic medium chain triglyceride (kMCT) supplement, as well as ketogenic supplements including a ketogenic drink with kMCT, oral ketogenic compounds (Axona and AC-1202), and MCT oil or emulsion. The ketogenic diet independently showed a non-significant trend towards improvement in cognition. The Mediterranean diet, modified Adkins diet, and low-carbohydrate diet showed statistically significant improvements in some, although not all, of their cognitive measures. Use of ketogenic supplements, drinks, or compounds showed variable results in the AD and MCI groups. The Axona and AC-1202 compounds showed no significant improvement in cognition at the end of their respective 90-day trials. Most MCT supplements did show cognitive improvements, although only after 6 months of adherence. Adherence to the intervention was problematic in most of the diet studies.

CONCLUSION

Ketogenic therapies have promise in PD, AD, and MCI for symptom improvement although larger studies are needed to support their implementation in clinical practice.

LC-MS/MS method for quantitative profiling of ketone bodies, α-keto acids, lactate, pyruvate and their stable isotopically labelled tracers in human plasma: An analytical panel for clinical metabolic kinetics and interactions

An important area within clinical research is in vivo metabolism of ketone bodies (β-hydroxybutyrate and acetoacetate) and in connection metabolites that may affect their production and/or cellular transport such as the keto-acids from the branched-chain amino acids, lactate and pyruvate. To determine in vivo metabolite turnover, availability of accurate and sensitive methods for analyzing the plasma concentrations of these metabolites and their stable isotopically labeled enrichments is mandatory. Therefore, the present study describes a high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous analysis of ketone bodies, α-keto acids, lactate, pyruvate, and their tracer enrichments in humans using 2 different derivatization techniques with 4-bromo-N-methylbenzylamine and O-benzylhydroxylamine as derivatization reagents, and 1-ethyl-3-dimethylaminopropyl carbodiimide as coupling compound followed by a single LC-MS/MS run. The method was validated for matrix effects, linearity, accuracy, precision, recovery, stability, and enrichment (ratio) analysis of a stable isotopically labelled analytes (tracers) continuously infused in humans divided by the unlabeled endogenous analyte (tracee) that makes it possible to quantify the analyte in vivo synthesis and degradation rates. The applied parallel derivatization procedure yielded good sensitivity for all analytes of interest and their tracers. Despite the double derivatization method, mixing the ethyl acetate portions at the final stage made it possible to simultaneously analyze all compounds in a single LC-MS/MS run. Moreover, the liquid chromatography method was optimized to robustly quantify the keto acids derived from leucine (α-keto-isocaproic acid) and isoleucine (α-keto-β-methylvaleric acid), the compounds with similar chemical structure and identical molecular weights. The presented method is designed and validated for human plasma. However, care should be taken in blood sampling and processing procedures as well as quick freezing and storage at -80 °C due to the instability of especially acetoacetate.

Ketone body β-hydroxybutyrate (BHB) preserves mitochondrial bioenergetics

The ketogenic diet is an emerging therapeutic approach for refractory epilepsy, as well as certain rare and neurodegenerative disorders. The main ketone body, β-hydroxybutyrate (BHB), is the primary energy substrate endogenously produced in a ketogenic diet, however, mechanisms of its therapeutic actions remain unknown. Here, we studied the effects of BHB on mitochondrial energetics, both in non-stimulated conditions and during glutamate-mediated hyperexcitation. We found that glutamate-induced hyperexcitation stimulated mitochondrial respiration in cultured cortical neurons, and that this response was greater in cultures supplemented with BHB than with glucose. BHB enabled a stronger and more sustained maximal uncoupled respiration, indicating that BHB enables neurons to respond more efficiently to increased energy demands such as induced during hyperexcitation. We found that cytosolic Ca2+ was required for BHB-mediated enhancement of mitochondrial function, and that this enhancement was independent of the mitochondrial glutamate-aspartate carrier, Aralar/AGC1. Our results suggest that BHB exerts its protective effects against hyperexcitation by enhancing mitochondrial function through a Ca2+-dependent, but Aralar/AGC1-independent stimulation of mitochondrial respiration.

The proteomic effects of ketone bodies: implications for proteostasis and brain proteinopathies

A growing body of evidence supports the beneficial effects of the ketone bodies (KBs), acetoacetate and β-hydroxybutyrate (BHB), on diverse physiological processes and diseases. Hence, KBs have been suggested as therapeutic tools for neurodegenerative diseases. KBs are an alternative fuel during fasting and starvation as they can be converted to Ac-CoA to produce ATP. A ketogenic diet (KD), enriched in fats and low in carbohydrates, induces KB production in the liver and favors their use in the brain. BHB is the most abundant KB in the circulation; in addition to its role as energy fuel, it exerts many actions that impact the set of proteins in the cell and tissue. BHB can covalently bind to proteins in lysine residues as a new post-translational modification (PTM) named β-hydroxybutyrylation (Kbhb). Kbhb has been identified in many proteins where Kbhb sites can be critical for binding to other proteins or cofactors. Kbhb is mostly found in proteins involved in chromatin structure, DNA repair, regulation of spliceosome, transcription, and oxidative phosphorylation. Histones are the most studied family of proteins with this PTM, and H3K9bhb is the best studied histone mark. Their target genes are mainly related to cell metabolism, chromatin remodeling and the control of circadian rhythms. The role of Kbhb on physiological processes is poorly known, but it might link KB metabolism to cell signaling and genome regulation. BHB also impacts the proteome by influencing proteostasis. This KB can modulate the Unfolded Protein Response (UPR) and autophagy, two processes involved in the maintenance of protein homeostasis through the clearance of accumulated unfolded and damaged proteins. BHB can support proteostasis and regulate the UPR to promote metabolism adaptation in the liver and prevent cell damage in the brain. Also, BHB stimulates autophagy aiding to the degradation of accumulated proteins. Protein aggregation is common to proteinopathies like Alzheimer's (AD) and Parkinson's (PD) diseases, where the KD and BHB treatment have shown favorable effects. In the present review, the current literature supporting the effects of KBs on proteome conformation and proteostasis is discussed, as well as its possible impact on AD and PD.

Ketogenic diet: a potential adjunctive treatment for substance use disorders

Substance use disorders (SUD) can lead to serious health problems, and there is a great interest in developing new treatment methods to alleviate the impact of substance abuse. In recent years, the ketogenic diet (KD) has shown therapeutic benefits as a dietary therapy in a variety of neurological disorders. Recent studies suggest that KD can compensate for the glucose metabolism disorders caused by alcohol use disorder by increasing ketone metabolism, thereby reducing withdrawal symptoms and indicating the therapeutic potential of KD in SUD. Additionally, SUD often accompanies increased sugar intake, involving neural circuits and altered neuroplasticity similar to substance addiction, which may induce cross-sensitization and increased use of other abused substances. Reducing carbohydrate intake through KD may have a positive effect on this. Finally, SUD is often associated with mitochondrial damage, oxidative stress, inflammation, glia dysfunction, and gut microbial disorders, while KD may potentially reverse these abnormalities and serve a therapeutic role. Although there is much indirect evidence that KD has a positive effect on SUD, the small number of relevant studies and the fact that KD leads to side effects such as metabolic abnormalities, increased risk of malnutrition and gastrointestinal symptoms have led to the limitation of KD in the treatment of SUD. Here, we described the organismal disorders caused by SUD and the possible positive effects of KD, aiming to provide potential therapeutic directions for SUD.

Neuroprotective effect of a medium-chain triglyceride ketogenic diet on MPTP-induced Parkinson's disease mice: a combination of transcriptomics and metabolomics in the substantia nigra and fecal microbiome

The ketogenic diet (KD) is a low carbohydrate and high-fat protein diet. It plays a protective role in neurodegenerative diseases by elevating the levels of ketone bodies in blood, regulating central and peripheral metabolism and mitochondrial functions, inhibiting neuroinflammation and oxidative stress, and altering the gut microbiota. However, studies on ketogenic therapy for Parkinson's disease (PD) are still in their infancy. Therefore, we examined the possible protective effect of KD in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model, examined the mouse gut microbiota and its metabolites, and performed transcriptomics and metabolomics on the substantia nigra of mice. Our results showed that a long-term medium-chain triglyceride KD (MCT-KD) significantly reduced MPTP-induced damage to dopaminergic (DA) neurons, exerted antioxidant stress through the PI3K/Akt/Nrf2 pathway, and reversed oxidative stress in DA neurons. The MCT-KD also reduced mitochondrial loss, promoted ATP production, and inhibited the activation of microglia to protect DA neurons in MPTP-induced PD mice. MCT-KD altered the gut microbiota and consequently changed the metabolism of substantia nigra neurons through gut microbiota metabolites. Compared to the MPTP group, MCT-KD increased the abundance of gut microbiota, including Blautia and Romboutsia. MCT-KD also affects purine metabolism in the substantia nigra pars compacta (SNpc) by altering fecal metabolites. This study shows that MCT-KD has multiple protective effects against PD.

Microwave-assisted enzymatic synthesis of geraniol esters in solvent-free systems: optimization of the reaction parameters, purification and characterization of the products, and biocatalyst reuse

Various geraniol esters act as insect pheromones and display pharmacological activities, especially as neuroprotective agents. Therefore, the search for synthetic strategies alternative to traditional chemical synthesis could help designing ecofriendly routes for the preparation of such bioactive compounds. Hence, this work aims at the microwave-assisted enzymatic synthesis of geranyl esters in solvent-free systems. The process variables were optimized for the synthesis of geranyl acetoacetate, achieving 85% conversion after 60 min using a 1:5 substrates molar ratio (ester to geraniol), 80 °C and 8.4% of Lipozyme 435 lipase without removal of the co-produced methanol. On the other hand, a 95% conversion was reached after 30 min using 1:6 substrates molar ratio, 70 °C and 7% lipase in the presence of 5Å molecular sieves for the methanol capture. In addition, the lipase showed good reusability, maintaining the same activity for five reaction cycles. Finally, under the above optimized conditions, other geraniol esters were successfully synthetized such as the geranyl butyrate (98%), geranyl hexanoate (99%), geranyl octanoate (98%), and geranyl (R)-3-hydroxybutyrate (56%). These results demonstrate the microwave-assisted lipase-catalyzed transesterification in a solvent-free system as an excellent and sustainable catalytic methodology to produce geraniol esters.

Regional brain glucose metabolism is differentially affected by ketogenic diet: a human semiquantitative positron emission tomography

PURPOSE

Ketogenic diet (KD) is recommended to avoid intense [18F]FDG myocardial physiologic uptake in PET imaging. Neuroprotective and anti-seizure effects of KD have been suggested, but their mechanisms remain to be elucidated. This [18F]FDG PET study aims to evaluate the effect of KD on glucose brain metabolism.

METHOD

Subjects who underwent KD prior to whole-body and brain [18F]FDG PET between January 2019 and December 2020 in our department for suspected endocarditis were retrospectively included. Myocardial glucose suppression (MGS) on whole-body PET was analyzed. Patients with brain abnormalities were excluded. Thirty-four subjects with MGS (mean age: 61.8 ± 17.2 years) were included in the KD population, and 14 subjects without MGS were considered for a partial KD group (mean age: 62.3 ± 15.1 years). Brain SUVmax was first compared between these two KD groups to determine possible global uptake difference. Semiquantitative voxel-based intergroup analyses were secondarily performed to determine possible inter-regional differences by comparing KD groups with and without MGS, separately, to 27 healthy subjects fasting for at least 6 h (mean age of 62.4 ± 10.9 years), and KD groups between them (p-voxel < 0.001, and p-cluster < 0.05, FWE-corrected).

RESULTS

A 20% lower brain SUVmax was found in subjects under KD with MGS in comparison to those without MGS (Student's t-test, p = 0.02). Whole-brain voxel-based intergroup analysis revealed that patients under KD with and without MGS had relative hypermetabolism of limbic regions including medial temporal cortices and cerebellum lobes and relative hypometabolism of bilateral posterior regions (occipital), without significant difference between them.

CONCLUSION

KD globally reduces brain glucose metabolism but with regional differences, requiring special attention to clinical interpretation. On a pathophysiological perspective, these findings could help understand underlying neurological effects of KD through possible decrease of oxidative stress in posterior regions and functional compensation in the limbic regions.

The Relationship of Ketogenic Diet with Neurodegenerative and Psychiatric Diseases: A Scoping Review from Basic Research to Clinical Practice

BACKGROUND

The ketogenic diet (KD) has become widespread for the therapy of epileptic pathology in childhood and adulthood. In the last few decades, the current re-emergence of its popularity has focused on the treatment of obesity and diabetes mellitus. KD also exerts anti-inflammatory and neuroprotective properties, which could be utilized for the therapy of neurodegenerative and psychiatric disorders.

PURPOSE

This is a thorough, scoping review that aims to summarize and scrutinize the currently available basic research performed in in vitro and in vivo settings, as well as the clinical evidence of the potential beneficial effects of KD against neurodegenerative and psychiatric diseases. This review was conducted to systematically map the research performed in this area as well as identify gaps in knowledge.

METHODS

We thoroughly explored the most accurate scientific web databases, e.g., PubMed, Scopus, Web of Science, and Google Scholar, to obtain the most recent in vitro and in vivo data from animal studies as well as clinical human surveys from the last twenty years, applying effective and characteristic keywords.

RESULTS

Basic research has revealed multiple molecular mechanisms through which KD can exert neuroprotective effects, such as neuroinflammation inhibition, decreased reactive oxygen species (ROS) production, decreased amyloid plaque deposition and microglial activation, protection in dopaminergic neurons, tau hyper-phosphorylation suppression, stimulating mitochondrial biogenesis, enhancing gut microbial diversity, restoration of histone acetylation, and neuron repair promotion. On the other hand, clinical evidence remains scarce. Most existing clinical studies are modest, frequently uncontrolled, and merely assess the short-term impacts of KD. Moreover, several clinical studies had large dropout rates and a considerable lack of compliance assessment, as well as an increased level of heterogeneity in the study design and methodology.

CONCLUSIONS

KD can exert substantial neuroprotective effects via multiple molecular mechanisms in various neurodegenerative and psychiatric pathological states. Large, long-term, randomized, double-blind, controlled clinical trials with a prospective design are strongly recommended to delineate whether KD may attenuate or even treat neurodegenerative and psychiatric disease development, progression, and symptomatology.

α-Tocopherol Protects Lipopolysaccharide-Activated BV2 Microglia

Microglia, the resident macrophage-like population in the central nervous system, play a crucial role in the pathogenesis of many neurodegenerative disorders by triggering an inflammatory response that leads to neuronal death. Neuroprotective compounds to treat or prevent neurodegenerative diseases are a new field of study in modern medicine. Microglia are activated in response to inflammatory stimuli. The pathogenesis of various neurodegenerative diseases is closely related to the constant activation of microglia due to their fundamental role as a mediator of inflammation in the brain environment. α-Tocopherol, also known as vitamin E, is reported to possess potent neuroprotective effects. The goal of this study was to investigate the biological effects of vitamin E on BV2 microglial cells, as a possible neuroprotective and anti-inflammatory agent, following stimulation with lipopolysaccharide (LPS). The results showed that the pre-incubation of microglia with α-tocopherol can guarantee neuroprotective effects during microglial activation induced by LPS. α-Tocopherol preserved the branched morphology typical of microglia in a physiological state. It also reduced the migratory capacity; the production of pro-inflammatory and anti-inflammatory cytokines such as TNF-α and IL-10; and the activation of receptors such as TRL4 and CD40, which modulate the PI3K-Akt signaling pathway. The results of this study require further insights and research, but they present new scenarios for the application of vitamin E as an antioxidant for the purpose of greater neuroprotection in vivo for the prevention of possible neurodegenerative diseases.

The Role of Diet as a Modulator of the Inflammatory Process in the Neurological Diseases

Neurological diseases are recognized as major causes of disability and mortality worldwide. Due to the dynamic progress of diseases such as Alzheimer’s disease (AD), Parkinson’s Disease (PD), Schizophrenia, Depression, and Multiple Sclerosis (MD), scientists are mobilized to look for new and more effective methods of interventions. A growing body of evidence suggests that inflammatory processes and an imbalance in the composition and function of the gut microbiome, which play a critical role in the pathogenesis of various neurological diseases and dietary interventions, such as the Mediterranean diet the DASH diet, or the ketogenic diet can have beneficial effects on their course. The aim of this review was to take a closer look at the role of diet and its ingredients in modulating inflammation associated with the development and/or progression of central nervous system diseases. Presented data shows that consuming a diet abundant in fruits, vegetables, nuts, herbs, spices, and legumes that are sources of anti-inflammatory elements such as omega-3 fatty acids, polyphenols, vitamins, essential minerals, and probiotics while avoiding foods that promote inflammation, create a positive brain environment and is associated with a reduced risk of neurological diseases. Personalized nutritional interventions may constitute a non-invasive and effective strategy in combating neurological disorders.

Ketogenic Diet as a Promising Non-Drug Intervention for Alzheimer’s Disease: Mechanisms and Clinical Implications

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is mainly characterized by cognitive deficits. Although many studies have been devoted to developing disease-modifying therapies, there has been no effective therapy until now. However, dietary interventions may be a potential strategy to treat AD. The ketogenic diet (KD) is a high-fat and low-carbohydrate diet with adequate protein. KD increases the levels of ketone bodies, providing an alternative energy source when there is not sufficient energy supply because of impaired glucose metabolism. Accumulating preclinical and clinical studies have shown that a KD is beneficial to AD. The potential underlying mechanisms include improved mitochondrial function, optimization of gut microbiota composition, and reduced neuroinflammation and oxidative stress. The review provides an update on clinical and preclinical research on the effects of KD or medium-chain triglyceride supplementation on symptoms and pathophysiology in AD. We also detail the potential mechanisms of KD, involving amyloid and tau proteins, neuroinflammation, gut microbiota, oxidative stress, and brain metabolism. We aimed to determine the function of the KD in AD and outline important aspects of the mechanism, providing a reference for the implementation of the KD as a potential therapeutic strategy for AD.

Ketogenic interventions in mild cognitive impairment, Alzheimer's disease, and Parkinson's disease: A systematic review and critical appraisal

Background

There is increasing interest in therapeutic ketosis as a potential therapy for neurodegenerative disorders-in particular, mild cognitive impairment (MCI), Alzheimer's disease (AD), and Parkinson's disease (PD)-following a proof-of-concept study in Parkinson's disease published in 2005.

Methods

To provide an objective assessment of emerging clinical evidence and targeted recommendations for future research, we reviewed clinical trials involving ketogenic interventions in mild cognitive impairment, Alzheimer's disease, and Parkinson's disease reported since 2005. Levels of clinical evidence were systematically reviewed using the American Academy of Neurology criteria for rating therapeutic trials.

Results

10 AD, 3 MCI, and 5 PD therapeutic ketogenic trials were identified. Respective grades of clinical evidence were objectively assessed using the American Academy of Neurology criteria for rating therapeutic trials. We found class "B" evidence (probably effective) for cognitive improvement in subjects with mild cognitive impairment and subjects with mild-to-moderate Alzheimer's disease negative for the apolipoprotein ε4 allele (APOε4-). We found class "U" evidence (unproven) for cognitive stabilization in individuals with mild-to-moderate Alzheimer's disease positive for the apolipoprotein ε4 allele (APOε4+). We found class "C" evidence (possibly effective) for improvement of non-motor features and class "U" evidence (unproven) for motor features in individuals with Parkinson's disease. The number of trials in Parkinson's disease is very small with best evidence that acute supplementation holds promise for improving exercise endurance.

Conclusions

Limitations of the literature to date include the range of ketogenic interventions currently assessed in the literature (i.e., primarily diet or medium-chain triglyceride interventions), with fewer studies using more potent formulations (e.g., exogenous ketone esters). Collectively, the strongest evidence to date exists for cognitive improvement in individuals with mild cognitive impairment and in individuals with mild-to-moderate Alzheimer's disease negative for the apolipoprotein ε4 allele. Larger-scale, pivotal trials are justified in these populations. Further research is required to optimize the utilization of ketogenic interventions in differing clinical contexts and to better characterize the response to therapeutic ketosis in patients who are positive for the apolipoprotein ε4 allele, as modified interventions may be necessary.

The Effects of Dietary Interventions on Brain Aging and Neurological Diseases

Dietary interventions can ameliorate age-related neurological decline. Decades of research of in vitro studies, animal models, and clinical trials support their ability and efficacy to improve behavioral outcomes by inducing biochemical and physiological changes that lead to a more resilient brain. Dietary interventions including calorie restriction, alternate day fasting, time restricted feeding, and fasting mimicking diets not only improve normal brain aging but also slow down, or even reverse, the progression of neurological diseases. In this review, we focus on the effects of intermittent and periodic fasting on improving phenotypic outcomes, such as cognitive and motor-coordination decline, in the normal aging brain through an increase in neurogenesis and synaptic plasticity, and decrease in neuroinflammation, mitochondrial dysfunction, and oxidative stress. We summarize the results of various dietary interventions in animal models of age-related neurological diseases such as Alzheimer's disease, Parkinson's disease, epilepsy, and Multiple Sclerosis and discuss the results of clinical trials that explore the feasibility of dietary interventions in the prevention and treatment of these diseases.

The Role of Ketogenic Diet in the Treatment of Neurological Diseases

Over a hundred years of study on the favourable effect of ketogenic diets in the treatment of epilepsy have contributed to a long-lasting discussion on its potential influence on other neurological diseases. A significant increase in the number of scientific studies in that field has been currently observed. The aim of this paper is a widespread, thorough analysis of the available scientific evidence in respect of the role of the ketogenic diet in the therapy of neurological diseases such as: epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A wide range of the mechanisms of action of the ketogenic diet has been demonstrated in neurological diseases, including, among other effects, its influence on the reduction in inflammatory conditions and the amount of reactive oxygen species (ROS), the restoration of the myelin sheath of the neurons, the formation and regeneration of mitochondria, neuronal metabolism, the provision of an alternative source of energy for neurons (ketone bodies), the reduction in glucose and insulin concentrations, the reduction in amyloid plaques, the induction of autophagy, the alleviation of microglia activation, the reduction in excessive neuronal activation, the modulation of intestinal microbiota, the expression of genes, dopamine production and the increase in glutamine conversion into GABA. The studies discussed (including randomised controlled studies), conducted in neurological patients, have stressed the effectiveness of the ketogenic diet in the treatment of epilepsy and have demonstrated its promising therapeutic potential in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A frequent advantage of the diet was demonstrated over non-ketogenic diets (in the control groups) in the therapy of neurological diseases, with simultaneous safety and feasibility when conducting the nutritional model.

Ketogenic Diet: An Effective Treatment Approach for Neurodegenerative Diseases

This review discusses the effects and mechanisms of a ketogenic diet on neurodegenerative diseases on the basis of available evidence. A ketogenic diet refers to a high-fat, mediumprotein, and low-carbohydrate diet that leads to a metabolic shift to ketosis. This review systematically summarizes the scientific literature supporting this effective treatment approach for neurodegenerative diseases, including effects on mitochondrial function, oxidative stress, neuronal apoptosis, neuroinflammation, and the microbiota-gut-brain axis. It also highlights the clinical evidence for the effects of the ketogenic diet in the treatment of Alzheimer's disease, Parkinson's disease, and motor neuron disease. Finally, it discusses the common adverse effects of ketogenic therapy. Although the complete mechanism of the ketogenic diet in the treatment of neurodegenerative diseases remains to be elucidated, its clinical efficacy has attracted many new followers. The ketogenic diet is a good candidate for adjuvant therapy, but its specific applicability depends on the type and the degree of the disease.

Ketogenic diets and Ketone suplementation: A strategy for therapeutic intervention

Ketogenic diets and orally administered exogenous ketone supplements are strategies to increase serum ketone bodies serving as an alternative energy fuel for high energy demanding tissues, such as the brain, muscles, and the heart. The ketogenic diet is a low-carbohydrate and fat-rich diet, whereas ketone supplements are usually supplied as esters or salts. Nutritional ketosis, defined as serum ketone concentrations of ≥ 0.5 mmol/L, has a fasting-like effect and results in all sorts of metabolic shifts and thereby enhancing the health status. In this review, we thus discuss the different interventions to reach nutritional ketosis, and summarize the effects on heart diseases, epilepsy, mitochondrial diseases, and neurodegenerative disorders. Interest in the proposed therapeutic benefits of nutritional ketosis has been growing the past recent years. The implication of this nutritional intervention is becoming more evident and has shown interesting potential. Mechanistic insights explaining the overall health effects of the ketogenic state, will lead to precision nutrition for the latter diseases.

A Novel Ketone-Supplemented Diet Improves Recognition Memory and Hippocampal Mitochondrial Efficiency in Healthy Adult Mice

Mitochondrial dysfunction and cognitive impairment are common symptoms in many neurologic and psychiatric disorders, as well as nonpathological aging. Ketones have been suggested as therapeutic for their efficacy in epilepsy and other brain pathologies such as Alzheimer's disease and major depressive disorder. However, their effects on cognitive function in healthy individuals is less established. Here, we explored the mitochondrial and performative outcomes of a novel eight-week ketone-supplemented ketogenic (KETO) diet in healthy adult male and female mice. In a novel object recognition test, KETO mice spent more time with the novel, compared to familiar, object, indicating an improvement in recognition memory. High-resolution respirometry on permeabilized hippocampal tissue returned significant reductions in mitochondrial O2 consumption. No changes in ATP production were observed, yielding a significantly higher ATP:O2 ratio, a measure of mitochondrial efficiency. Together, these findings demonstrate the KETO diet improves hippocampal mitochondrial efficiency. They add to a growing body of evidence that suggests ketones and ketogenic diets are neuroprotective and metabolically and cognitively relevant, even in healthy adults. They also suggest that ketogenic lifestyle changes may be effective strategies for protecting against cognitive decline associated with aging and disease.

The Interplay between Gut Microbiota and Parkinson's Disease: Implications on Diagnosis and Treatment

The bidirectional interaction between the gut microbiota (GM) and the Central Nervous System, the so-called gut microbiota brain axis (GMBA), deeply affects brain function and has an important impact on the development of neurodegenerative diseases. In Parkinson’s disease (PD), gastrointestinal symptoms often precede the onset of motor and non-motor manifestations, and alterations in the GM composition accompany disease pathogenesis. Several studies have been conducted to unravel the role of dysbiosis and intestinal permeability in PD onset and progression, but the therapeutic and diagnostic applications of GM modifying approaches remain to be fully elucidated. After a brief introduction on the involvement of GMBA in the disease, we present evidence for GM alterations and leaky gut in PD patients. According to these data, we then review the potential of GM-based signatures to serve as disease biomarkers and we highlight the emerging role of probiotics, prebiotics, antibiotics, dietary interventions, and fecal microbiota transplantation as supportive therapeutic approaches in PD. Finally, we analyze the mutual influence between commonly prescribed PD medications and gut-microbiota, and we offer insights on the involvement also of nasal and oral microbiota in PD pathology, thus providing a comprehensive and up-to-date overview on the role of microbial features in disease diagnosis and treatment.

Propolis induces cardiac metabolism changes in 6-hydroxydopamine animal model: A dietary intervention as a potential cardioprotective approach in Parkinson’s disease

While there is sustained growth of the older population worldwide, ageing is a consistent risk factor for neurodegenerative diseases, such as Parkinson’s-disease (PD). Considered an emblematic movement disorder, PD comprises a miscellany of non-motor symptoms, for which effective management remains an unfulfilled need in clinical practice. Highlighted are the cardiovascular abnormalities, that cause significant burden in PD patients. Evidence suggests that key biological processes underlying PD pathophysiology can be modulated by diet-derived bioactive compounds, such as green propolis, a natural functional food with biological and pharmacological properties. The effects of propolis on cardiac affection associated to PD have received little coverage. In this study, a metabolomics approach and Positron Emission Tomography (PET) imaging were used to assess the metabolic response to diet supplementation with green propolis on heart outcomes of rats with Parkinsonism induced by 6-hydroxydopamine (6-OHDA rats). Untargeted metabolomics approach revealed four cardiac metabolites (2-hydroxybutyric acid, 3-hydroxybutyric acid, monoacylglycerol and alanine) that were significantly modified between animal groups (6-OHDA, 6-OHDA + Propolis and sham). Propolis-induced changes in the level of these cardiac metabolites suggest beneficial effects of diet intervention. From the metabolites affected, functional analysis identified changes in propanoate metabolism (a key carbohydrate metabolism related metabolic pathway), glucose-alanine cycle, protein and fatty acid biosynthesis, energy metabolism, glutathione metabolism and urea cycle. PET imaging detected higher glucose metabolism in the 17 areas of the left ventricle of all rats treated with propolis, substantially contrasting from those rats that did not consume propolis. Our results bring new insights into cardiac metabolic substrates and pathways involved in the mechanisms of the effects of propolis in experimental PD and provide potential novel targets for research in the quest for future therapeutic strategies.

Neuroprotective role of coconut oil for the prevention and treatment of Parkinson's disease: potential mechanisms of action

Neurodegenerative disease (ND) is a clinical condition in which neurons degenerate with a consequent loss of functions in the affected brain region. Parkinson's disease (PD) is the second most progressive ND after Alzheimer's disease (AD), which affects the motor system and is characterized by the loss of dopaminergic neurons from the nigrostriatal pathway in the midbrain, leading to bradykinesia, rigidity, resting tremor, postural instability and non-motor symptoms such as cognitive declines, psychiatric disturbances, autonomic failures, sleep difficulties, and pain syndrome. Coconut oil (CO) is an edible oil obtained from the meat of Cocos nucifera fruit that belongs to the palm family and contains 92% saturated fatty acids. CO has been shown to mediate oxidative stress, neuroinflammation, mitochondrial dysfunction, apoptosis and excitotoxicity-induced effects in PD in various in vitro and in vivo models as a multi-target bioagent. CO intake through diet has also been linked to a decreased incidence of PD in people. During digestion, CO is broken down into smaller molecules, like ketone bodies (KBs). The KBs then penetrate the blood-brain barrier (BBB) and are used as a source of energy its ability to cross BBB made this an important class of natural remedies for the treatment of ND. The current review describes the probable neuroprotective potential pathways of CO in PD, either prophylactic or therapeutic. In addition, we briefly addressed the important pathogenic pathways that might be considered to investigate the possible use of CO in neurodegeneration such as AD and PD.

The effects of a 6-week controlled, hypocaloric ketogenic diet, with and without exogenous ketone salts, on cognitive performance and mood states in overweight and obese adults

Background

Ketogenic diets are a commonly used weight loss method, but little is known how variations in sodium content and ketones influence cognition and mood during the early keto-adaptation period.

Objectives

To investigate the effects of an exogenous ketone salt (KS) as part of a hypocaloric KD on mood and cognitive outcomes in overweight and obese adults. A secondary objective was to evaluate changes in biochemical markers associated with inflammatory and cognitive responses.

Materials and methods

Adults who were overweight or obese participated in a 6-week controlled-feeding intervention comparing hypocaloric diets (∼75% of energy expenditure). KD groups received twice daily ketone salt (KD + KS; n = 12) or a flavor-matched placebo, free of minerals (KD + PL; n = 13). A separate group of age and BMI matched adults were later assigned to an isoenergetic low-fat diet (LFD; n = 12) as comparison to KD. Mood was assessed by shortened Profile of Mood States and Visual Analog Mood Scale surveys. Cognitive function was determined by the Automated Neuropsychological Assessment Metrics mental test battery.

Results

Both KD groups achieved nutritional ketosis. Fasting serum glucose decreased in both KD groups, whereas glucose was unaffected in the LFD. Insulin decreased at week 2 and remained lower in all groups. At week 2, depression scores in the KD + PL group were higher compared to KD + KS. Performance in the math processing and go/no-go cognitive tests were lower for KD + PL and LFD participants, respectively, compared to KD + KS. Serum leptin levels decreased for all groups throughout the study but were higher for KD + KS group at week 6. Serum TNF-α steadily increased for LFD participants, reaching significance at week 6.

Conclusion

During a short-term hypocaloric diet, no indication of a consistent decline in mood or cognitive function were seen in participants following either KD, despite KD + PL being relatively low in sodium. WK2 scores of “anger” and “depression” were higher in the LFD and KD + PL groups, suggesting that KS may attenuate negative mood parameters during the early intervention stages.

Ketones: potential to achieve brain energy rescue and sustain cognitive health during ageing

Alzheimer’s disease (AD) is the most common major neurocognitive disorder of ageing. Although largely ignored until about a decade ago, accumulating evidence suggests that deteriorating brain energy metabolism plays a key role in the development and/or progression of AD-associated cognitive decline. Brain glucose hypometabolism is a well-established biomarker in AD but was mostly assumed to be a consequence of neuronal dysfunction and death. However, its presence in cognitively asymptomatic populations at higher risk of AD strongly suggests that it is actually a pre-symptomatic component in the development of AD. The question then arises as to whether progressive AD-related cognitive decline could be prevented or slowed down by correcting or bypassing this progressive ‘brain energy gap’. In this review, we provide an overview of research on brain glucose and ketone metabolism in AD and its prodromal condition – mild cognitive impairment (MCI) – to provide a clearer basis for proposing keto-therapeutics as a strategy for brain energy rescue in AD. We also discuss studies using ketogenic interventions and their impact on plasma ketone levels, brain energetics and cognitive performance in MCI and AD. Given that exercise has several overlapping metabolic effects with ketones, we propose that in combination these two approaches might be synergistic for brain health during ageing. As cause-and-effect relationships between the different hallmarks of AD are emerging, further research efforts should focus on optimising the efficacy, acceptability and accessibility of keto-therapeutics in AD and populations at risk of AD.

Nutrition and Gut–Brain Pathways Impacting the Onset of Parkinson’s Disease

An emerging body of literature suggests that long-term gut inflammation may be a silent driver of Parkinson’s disease (PD) pathogenesis. Importantly, specific nutritive patterns might improve gut health for PD risk reduction. Here, we review the current literature on the nutritive patterns and inflammatory markers as a predictor for early detection of PD. This knowledge might be used to foster the detection of early nutritive patterns and preclinical biomarkers to potentially alter PD development and progression.

Intermittent Fasting: Potential Utility in the Treatment of Chronic Pain across the Clinical Spectrum

Dietary behavior can have a consequential and wide-ranging influence on human health. Intermittent fasting, which involves intermittent restriction in energy intake, has been shown to have beneficial cellular, physiological, and system-wide effects in animal and human studies. Despite the potential utility in preventing, slowing, and reversing disease processes, the clinical application of intermittent fasting remains limited. The health benefits associated with the simple implementation of a 12 to 16 h fast suggest a promising role in the treatment of chronic pain. A literature review was completed to characterize the physiologic benefits of intermittent fasting and to relate the evidence to the mechanisms underlying chronic pain. Research on different fasting regimens is outlined and an overview of research demonstrating the benefits of intermittent fasting across diverse health conditions is provided. Data on the physiologic effects of intermittent fasting are summarized. The physiology of different pain states is reviewed and the possible implications for intermittent fasting in the treatment of chronic pain through non-invasive management, prehabilitation, and rehabilitation following injury and invasive procedures are presented. Evidence indicates the potential utility of intermittent fasting in the comprehensive management of chronic pain and warrants further investigation.

Cognitive profile of male mice exposed to a Ketogenic Diet

In recent years, nutritional interventions for different psychiatric diseases have gained increasing attention, such as the ketogenic diet (KD). This has led to positive effects in neurological disorders such as Parkinson's disease, addiction, autism or epilepsy. The neurobiological mechanisms through which these effects are induced and the effects in cognition still warrant investigation, and considering that other high-fat diets (HFD) can lead to cognitive disturbances that may affect the results achieved, the main aim of the present work was to evaluate the effects of a KD to determine whether it can induce such cognitive effects. A total of 30 OF1 male mice were employed to establish the behavioral profile of mice fed a KD by testing anxiety behavior (Elevated Plus Maze), locomotor activity (Open Field), learning (Hebb Williams Maze), and memory (Passive Avoidance Test). The results revealed that the KD did not affect locomotor activity, memory or hippocampal-dependent learning, as similar results were obtained with mice on a standard diet, albeit with increased anxiety behavior. We conclude that a KD is a promising nutritional approach to apply in research studies, given that it does not cause cognitive alterations.

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

OBJECTIVE

The 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.

DESIGN

Systematic review of in vivo studies.

METHODS

Studies 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.

RESULTS

Twelve 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.

CONCLUSIONS

Although 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.

Metabolic Strategies in Healthcare: A New Era

Modern healthcare systems are founded on a disease-centric paradigm, which has conferred many notable successes against infectious disorders in the past. However, today's leading causes of death are dominated by non-infectious "lifestyle" disorders, broadly represented by the metabolic syndrome, atherosclerosis, cancer, and neurodegeneration. Our disease-centric paradigm regards these disorders as distinct disease processes, caused and driven by disease targets that must be suppressed or eliminated to clear the disease. By contrast, a health-centric paradigm recognizes the lifestyle disorders as a series of hormonal and metabolic responses to a singular, lifestyle-induced disease of mitochondria dysfunction, a disease target that must be restored to improve health, which may be defined as optimized mitochondria function. Seen from a health-centric perspective, most drugs target a response rather than the disease, whereas metabolic strategies, such as fasting and carbohydrate-restricted diets, aim to restore mitochondria function, mitigating the impetus that underlies and drives the lifestyle disorders. Substantial human evidence indicates either strategy can effectively mitigate the metabolic syndrome. Preliminary evidence also indicates potential benefits in atherosclerosis, cancer, and neurodegeneration. Given the existing evidence, integrating metabolic strategies into modern healthcare systems should be identified as a global health priority.

The Therapeutic Role of Ketogenic Diet in Neurological Disorders

The ketogenic diet (KD) is a high-fat, low-carbohydrate and adequate-protein diet that has gained popularity in recent years in the context of neurological diseases (NDs). The complexity of the pathogenesis of these diseases means that effective forms of treatment are still lacking. Conventional therapy is often associated with increasing tolerance and/or drug resistance. Consequently, more effective therapeutic strategies are being sought to increase the effectiveness of available forms of therapy and improve the quality of life of patients. For the moment, it seems that KD can provide therapeutic benefits in patients with neurological problems by effectively controlling the balance between pro- and antioxidant processes and pro-excitatory and inhibitory neurotransmitters, and modulating inflammation or changing the composition of the gut microbiome. In this review we evaluated the potential therapeutic efficacy of KD in epilepsy, depression, migraine, Alzheimer’s disease and Parkinson’s disease. In our opinion, KD should be considered as an adjuvant therapeutic option for some neurological diseases.

β-Hydroxybutyric acid attenuates heat stress-induced neuroinflammation via inhibiting TLR4/p38 MAPK and NF-κB pathways in the hippocampus

Heat stress causes many pathophysiological responses in the brain, including neuroinflammation and cognitive deficits. β-Hydroxybutyric acid (BHBA) has been shown to have neuroprotective effects against inflammation induced by lipopolysaccharide. The aim of the present study was to evaluate the effects of BHBA on neuroinflammation induced by heat stress, as well as the underlying mechanisms. Mice were pretreated with vehicle, BHBA or minocycline (positive control group) and followed by heat exposure (43°C) for 15 min for 14 days. In mice subjected to heat stress, we found that treatment with BHBA or minocycline significantly decreased the level of serum cortisol, the expressions of heat shock protein 70 (HSP70), and the density of c-Fos⁺ cells in the hippocampus. Surprisingly, the ethological tests revealed that heat stress led to cognitive dysfunctions and could be alleviated by BHBA and minocycline administration. Further investigation showed that BHBA and minocycline significantly attenuated the activation of microglia and astrocyte induced by heat stress. Pro-inflammatory cytokines were attenuated in the hippocampus by BHBA and minocycline treatment. Importantly, compared with the heat stress group, mice in the BHBA treatment group and positive control group experienced a decrease in the expressions of toll-like receptor 4 (TLR4), phospho-p38 (p-p38), and nuclear factor kappa B (NF-κB). Our results elucidated that BHBA inhibits neuroinflammation induced by heat stress by suppressing the activation of microglia and astrocyte, and modulating TLR4/p38 MAPK and NF-κB pathways. This study provides new evidence that BHBA is a potential strategy for protecting animals from heat stress.

Transgenerational effects of androstadienedione and androstenedione at environmentally relevant concentrations in zebrafish (Danio rerio)

Androgens androstadienedione (ADD) and androstenedione (AED) are predominant steroid hormones in surface water, and can disrupt the endocrine system in fish. However, little is known about the transgenerational effects of ADD and AED in fish. In the present study, F0 generation was exposed to ADD and AED from 21 to 144 days post-fertilization (dpf) at nominal concentrations of 5 (L), 50 (M) and 500 (H) ng L^-1, and F1 generation was domesticated in clear water for 144 dpf. The sex ratio, histology and transcription in F0 and F1 generations were examined. In the F0 generation, ADD and AED tended to be estrogenic in zebrafish, resulting in female biased zebrafish populations. In the F1 generation, ADD at the H level caused 63.5% females, while AED at the H level resulted in 78.7% males. In brain, ADD and AED had similar effects on circadian rhythm in the F0 and F1 generations. In the F1 eleutheroembryos, transcriptomic analysis indicated that neuromast hair cell related biological processes (BPs) were overlapped in the ADD and AED groups. Taken together, ADD and AED at environmentally relevant concentrations had transgenerational effects on sex differentiation and transcription in zebrafish.

A Non-Invasive Determination of Ketosis-Induced Elimination of Chronic Daytime Somnolence in a Patient with Late-Stage Dementia (Assessed with Type 3 Diabetes): A Potential Role of Neurogenesis

Background

The study involved a female patient diagnosed with late-stage dementia, with chronic daytime somnolence (CDS) as a prominent symptom.

Objective

To explore whether her dementia resulted from Type 3 diabetes, and whether it could be reversed through ketosis therapy.

Methods

A ketogenic diet (KD) generating low-dose 100 μM Blood Ketone Levels (BKL) enhanced by a brief Ketone Mono Ester (KME) regimen with high-dose 2-4 mM BKLs was used.

Results

Three sets of data describe relief (assessed by % days awake) from CDS: 1) incremental, slow, time-dependent KD plus KME-induced sigmoid curve responses which resulted in partial wakefulness (0-40% in 255 days) and complete wakefulness (40-85% in 50 days); 2) both levels of wakefulness were shown to be permanent; 3) initial permanent relief from CDS with low-dose ketosis from 6.7% to 40% took 87 days. Subsequent low-dose recovery from illness-induced CDS (6.9% to 40%) took 10 days. We deduce that the first restoration involved permanent repair, and the second energized the repaired circuits.

Conclusion

The results suggest a role for ketosis in the elimination of CDS with the permanent functional restoration of the awake neural circuits of the Sleep-Wake cycle. We discuss whether available evidence supports ketosis-induced bioenergetics alone or whether other mechanisms of functional renewal were the basis for the elimination of CDS. Given evidence for permanent repair, two direct links between ketosis and neurogenesis in the adult mammalian brain are discussed: Ketosis-induced 1) brain-derived neurotrophic factor, resulting in neural progenitor/stem cell proliferation, and 2) mitochondrial bioenergetics-induced stem cell biogenesis.

Nutritional Impact on Metabolic Homeostasis and Brain Health

Aging in modern societies is often associated with various diseases including metabolic and neurodegenerative disorders. In recent years, researchers have shown that both dysfunctions are related to each other. Although the relationship is not fully understood, recent evidence indicate that metabolic control plays a determinant role in neural defects onset. Indeed, energy balance dysregulation affects neuroenergetics by altering energy supply and thus neuronal activity. Consistently, different diets to help control body weight, blood glucose or insulin sensitivity are also effective in improving neurodegenerative disorders, dampening symptoms, or decreasing the risk of disease onset. Moreover, adapted nutritional recommendations improve learning, memory, and mood in healthy subjects as well. Interestingly, adjusted carbohydrate content of meals is the most efficient for both brain function and metabolic regulation improvement. Notably, documented neurological disorders impacted by specific diets suggest that the processes involved are inflammation, mitochondrial function and redox balance as well as ATP production. Interestingly, processes involving inflammation, mitochondrial function and redox balance as well as ATP production are also described in brain regulation of energy homeostasis. Therefore, it is likely that changes in brain function induced by diets can affect brain control of energy homeostasis and other brain functions such as memory, anxiety, social behavior, or motor skills. Moreover, a defect in energy supply could participate to the development of neurodegenerative disorders. Among the possible processes involved, the role of ketone bodies metabolism, neurogenesis and synaptic plasticity, oxidative stress and inflammation or epigenetic regulations as well as gut-brain axis and SCFA have been proposed in the literature. Therefore, the goal of this review is to provide hints about how nutritional studies could help to better understand the tight relationship between metabolic balance, brain activity and aging. Altogether, diets that help maintaining a metabolic balance could be key to both maintain energy homeostasis and prevent neurological disorders, thus contributing to promote healthy aging.

Ketogenic diet for human diseases: the underlying mechanisms and potential for clinical implementations

The ketogenic diet (KD) is a high-fat, adequate-protein, and very-low-carbohydrate diet regimen that mimics the metabolism of the fasting state to induce the production of ketone bodies. The KD has long been established as a remarkably successful dietary approach for the treatment of intractable epilepsy and has increasingly garnered research attention rapidly in the past decade, subject to emerging evidence of the promising therapeutic potential of the KD for various diseases, besides epilepsy, from obesity to malignancies. In this review, we summarize the experimental and/or clinical evidence of the efficacy and safety of the KD in different diseases, and discuss the possible mechanisms of action based on recent advances in understanding the influence of the KD at the cellular and molecular levels. We emphasize that the KD may function through multiple mechanisms, which remain to be further elucidated. The challenges and future directions for the clinical implementation of the KD in the treatment of a spectrum of diseases have been discussed. We suggest that, with encouraging evidence of therapeutic effects and increasing insights into the mechanisms of action, randomized controlled trials should be conducted to elucidate a foundation for the clinical use of the KD.

Parkinson's Disease and the Gut: Symptoms, Nutrition, and Microbiota

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, characterized by symptoms of bradykinesia, rigidity, postural instability, and tremor. Recently, there has been a growing focus on the relationship between the gut and the development of PD. Emerging to the forefront, an interesting concept has developed suggesting that the initial pathophysiological changes occur in the gastrointestinal tract before changes are seen within the brain. This review is aimed at highlighting the relationship between PD and the gastrointestinal tract, along with the supporting evidence for this. Firstly, we will focus on the gastrointestinal conditions and symptoms which commonly affects patients, including both upper and lower gastrointestinal issues. Secondly, the impact of nutrition and diet on neurological health and PD physiology, with particular emphasis on commonly consumed items including macronutrients and micronutrients. Finally, variability of the gut microbiome will also be discussed and its link with both the symptoms and signs of PD. The evidence presented in this review highly suggests that the initial pathogenesis in the gut may proceed the development of prodromal PD subtypes, and therefore building on this further could be imperative and lead to earlier diagnosis with new and improved therapeutics.

Kidney plays an important role in ketogenesis induced by risperidone and voluntary exercise in juvenile female rats

The positive role of ketone bodies in the treatment for mental disorders has been demonstrated. Ketogenesis can be triggered by not only exercise and diet but also metabolic disorders. This study aimed to explore the role of risperidone and exercise in ketogenesis. Thirty-two juvenile female Sprague Dawley rats were randomly assigned into four groups: Vehicle-Sedentary, Risperidone (0.9 mg/kg; b.i.d)-Sedentary, Vehicle-Exercise (three hours daily access to running wheels) and Risperidone-Exercise groups for four weeks. Exercise-intervention significantly ameliorated the risperidone-induced increase in white adipose mass, fasting plasma triglyceride and insulin levels. Compared to the vehicle-exercise group, the risperidone-exercise group had significantly higher plasma β-hydroxybutyrate (β-HB) level, which had a positive correlation with plasma non-esterified fatty acid levels. Risperidone-treatment upregulated expression of ketogenic key enzyme, mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase 2 (HMGCS2) in the kidney rather than liver. Exercise-intervention significantly enhanced renal carnitine palmitoyltransferase1A (CPT1A) expression. These results suggested that the kidney plays an important role in ketogenesis associated with risperidone and exercise. Therefore, it is important to monitor the levels of plasma ketone bodies while exercise intervention is utilized to prevent risperidone-induced metabolic disorders in young people.

Sirtuin 3 (SIRT3) Pathways in Age-Related Cardiovascular and Neurodegenerative Diseases

Age-associated cardiovascular and neurodegenerative diseases lead to high morbidity and mortality around the world. Sirtuins are vital enzymes for metabolic adaptation and provide protective effects against a wide spectrum of pathologies. Among sirtuins, mitochondrial sirtuin 3 (SIRT3) is an essential player in preserving the habitual metabolic profile. SIRT3 activity declines as a result of aging-induced changes in cellular metabolism, leading to increased susceptibility to endothelial dysfunction, hypertension, heart failure and neurodegenerative diseases. Stimulating SIRT3 activity via lifestyle, pharmacological or genetic interventions could protect against a plethora of pathologies and could improve health and lifespan. Thus, understanding how SIRT3 operates and how its protective effects could be amplified, will aid in treating age-associated diseases and ultimately, in enhancing the quality of life in elders.