Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence from Animal and Human Studies

A 3-Week Ketogenic Diet Increases Skeletal Muscle Insulin Sensitivity in Individuals With Obesity: A Randomized Controlled Crossover Trial

A ketogenic diet (KD) can induce weight loss and improve glycemic regulation, potentially reducing the risk of type 2 diabetes development. To elucidate the underlying mechanisms behind these beneficial effects of a KD, we investigated the impact of a KD on organ-specific insulin sensitivity (IS) in skeletal muscle, liver, and adipose tissue. We hypothesized that a KD would increase IS in skeletal muscle. The study included 11 individuals with obesity who underwent a randomized, crossover trial with two 3-week interventions: 1) a KD and 2) a standard diet. Skeletal muscle IS was quantified as the increase in glucose disposal during a hyperinsulinemic-euglycemic clamp (HEC). Hepatic IS and adipose tissue IS were quantified as the relative suppression of endogenous glucose production (EGP) and the relative suppression of palmitate flux during the HEC. The KD led to a 2.2-kg weight loss and increased insulin-stimulated glucose disposal, whereas the relative suppression of EGP during the HEC was similar. In addition, the KD decreased insulin-mediated suppression of lipolysis. In conclusion, a KD increased skeletal muscle IS in individuals with obesity.

ARTICLE HIGHLIGHTS

The ketogenic diet does not improve cardiac function and blunts glucose oxidation in ischaemic heart failure

AIMS

Cardiac energy metabolism is perturbed in ischaemic heart failure and is characterized by a shift from mitochondrial oxidative metabolism to glycolysis. Notably, the failing heart relies more on ketones for energy than a healthy heart, an adaptive mechanism that improves the energy-starved status of the failing heart. However, whether this can be implemented therapeutically remains unknown. Therefore, our aim was to determine if increasing ketone delivery to the heart via a ketogenic diet can improve the outcomes of heart failure.

METHODS AND RESULTS

C57BL/6J male mice underwent either a sham surgery or permanent left anterior descending coronary artery ligation surgery to induce heart failure. After 2 weeks, mice were then treated with either a control diet or a ketogenic diet for 3 weeks. Transthoracic echocardiography was then carried out to assess in vivo cardiac function and structure. Finally, isolated working hearts from these mice were perfused with appropriately 3H or 14C labelled glucose (5 mM), palmitate (0.8 mM), and β-hydroxybutyrate (β-OHB) (0.6 mM) to assess mitochondrial oxidative metabolism and glycolysis. Mice with heart failure exhibited a 56% drop in ejection fraction, which was not improved with a ketogenic diet feeding. Interestingly, mice fed a ketogenic diet had marked decreases in cardiac glucose oxidation rates. Despite increasing blood ketone levels, cardiac ketone oxidation rates did not increase, probably due to a decreased expression of key ketone oxidation enzymes. Furthermore, in mice on the ketogenic diet, no increase in overall cardiac energy production was observed, and instead, there was a shift to an increased reliance on fatty acid oxidation as a source of cardiac energy production. This resulted in a decrease in cardiac efficiency in heart failure mice fed a ketogenic diet.

CONCLUSION

We conclude that the ketogenic diet does not improve heart function in failing hearts, due to ketogenic diet-induced excessive fatty acid oxidation in the ischaemic heart and a decrease in insulin-stimulated glucose oxidation.

Protein acylations induced by a ketogenic diet demonstrate diverse patterns depending on organs and differ between histones and global proteins

An essential ketone body, β-hydroxybutyrate (BOHB), plays various roles in physiological regulations via protein acylations such as lysine acetylation and β-hydroxybutyrylation. Here, to understand how BOHB systemically regulates acylations from an overarching perspective, we administered a ketogenic diet to mice to increase BOHB concentration and examined acylations. We found that global acetylation and β-hydroxybutyrylation dramatically increase in various organs except for the brains, where the increase was much smaller than in the other organs. Interestingly, we observe no increase in histone acetylation in the organs where significant global protein acetylation occurs despite a substantial rise in histone β-hydroxybutyrylation. Finally, we compared the transcriptome data of the mice's liver after the ketogenic diet to the public databases, showing that upregulated genes are enriched in those related to histone β-hydroxybutyrylation in starvation. Our data indicate that a ketogenic diet induces diverse patterns of acylations depending on organs and protein localizations, suggesting that different mechanisms regulate acylations and that the ketogenic diet is associated with starvation in terms of protein modifications.

Palm oil as part of a high-fat diet: advances and challenges, or possible risks of pathology?

Nutritional status disorders have the most significant impact on the development of cardiovascular and oncologic diseases; therefore, the interest in the study of palm oil as among the leading components of nutrition has been increasing. The data examined in this review were sourced from the Scopus, SCIE (Web of Science), PubMed and PubMed Central, MEDLINE, CAPlus/SciFinder, and Embase databases; experts in the field; bibliographies; and abstracts from review analyses from the past 15 years. This review summarizes recent research data focusing on the quantitative and qualitative composition of nutrition of modern humans; concepts of the relationship between high-fat diets and disorders of insulin functioning and transport and metabolism of fatty acids; analyses of data regarding the palmitic acid (16:0) to oleic acid (18:1) ratio; and the effect of diet based on palm oil consumption on cardiovascular risk factors and lipid and lipoprotein levels. Several studies suggest a potential vector contributing to the transmission of maternal, high-fat-diet-induced, addictive-like behaviors and obesogenic phenotypes across generations. The relationship between cholesterol accumulation in lysosomes that may lead to lysosome dysfunction and inhibition of the autophagy process is analyzed, as is the progression of inflammatory diseases, atherosclerosis, nonalcoholic liver inflammation, and obesity with associated complications. Data are discussed from analyses of differences between rodent models and human population studies in the investigated different effects of palm oil consumption as a high-fat diet component. A conclusion is reached that the results cannot be generalized in human population studies because no similar effects were observed. Although there are numerous published reports, more studies are necessary to elucidate the complex regulatory mechanisms in digestive and nutrition processes, because there are great differences in lipoprotein profiles between rodents and humans, which makes it difficult to reproduce the pathology of many diseases caused by different types of the high-fat diet.

Ketogenic Diet Intervention on Metabolic and Psychiatric Health in Bipolar and Schizophrenia: A Pilot Trial

The ketogenic diet (KD, also known as metabolic therapy) has been successful in the treatment of obesity, type 2 diabetes, and epilepsy. More recently, this treatment has shown promise in the treatment of psychiatric illness. We conducted a 4-month pilot study to investigate the effects of a KD on individuals with schizophrenia or bipolar disorder with existing metabolic abnormalities. Twenty-three participants were enrolled in a single-arm trial. Results showcased improvements in metabolic health, with no participants meeting metabolic syndrome criteria by study conclusion. Adherent individuals experienced significant reduction in weight (12 %), BMI (12 %), waist circumference (13 %), and visceral adipose tissue (36 %). Observed biomarker enhancements in this population include a 27 % decrease in HOMA-IR, and a 25 % drop in triglyceride levels. In psychiatric measurements, participants with schizophrenia showed a 32 % reduction in Brief Psychiatric Rating Scale scores. Overall Clinical Global Impression (CGI) severity improved by an average of 31 %, and the proportion of participants that started with elevated symptomatology improved at least 1-point on CGI (79 %). Psychiatric outcomes across the cohort encompassed increased life satisfaction (17 %) and enhanced sleep quality (19 %). This pilot trial underscores the potential advantages of adjunctive ketogenic dietary treatment in individuals grappling with serious mental illness.

Influence of dietary patterns in the pathophysiology of Huntington's Disease: A literature review

Huntington's disease (HD), a rare autosomal dominant neurodegenerative disease, causes the gradual deterioration of neurons in the basal ganglia, specifically in the striatum. HD displays a wide range of symptoms, from motor disturbances such as chorea, dystonia, and bradykinesia to more debilitating symptoms such as cognitive decline, behavioral abnormalities, and psychiatric disturbances. Current research suggests the potential use of dietary interventions as viable strategies for slowing the progression of HD. Most notably, the Mediterranean, vegan, carnivore, paleo, and ketogenic diets have gained attention due to their hypothesized impact on neuroprotection and symptomatic modulation in various neurodegenerative disorders. Despite substantial nutritional differences among these diets, they share a fundamental premise-that dietary factors have an influential impact in modifying pertinent biological pathways linked to neurodegeneration. Understanding the intricate interactions between these dietary regimens and HD pathogenesis could open avenues for personalized interventions tailored to the individual's specific needs and genetic background. Ultimately, elucidating the multifaceted effects of these diets on HD offers a promising framework for developing comprehensive therapeutic approaches that integrate dietary strategies with conventional treatments.

Daily olive oil intake is feasible to reduce trigeminal neuralgia facial pain: A pilot study

Extra virgin olive oil (EVOO) is thought to contribute to neuroprotection and, thus, may influence pain symptoms experienced by adults with demyelination-related trigeminal neuralgia (TN). This study aimed to determine the feasibility of daily intake of EVOO and its potential to alleviate facial pain of TN. Adults, self-reporting as female and affected by TN, were enrolled in a 16-week nonblinded, parallel study. After a 4-week baseline, participants were randomized to 60 mL/day EVOO or control (usual diet and no supplemental EVOO) for 12 weeks. Participants completed a daily questionnaire on pain intensity and compliance, the Penn Facial Pain Scale weekly, the 36-Item Short Form Survey monthly, and dietary assessment during baseline and intervention. Participants (n = 52; 53.3 ± 12.9 years) were recruited nationally; 42 completed the study. The EVOO group, with 90% intake compliance, showed significant decreases in the Penn Facial Pain Scale items of interference with general function, interference with orofacial function, and severity of pain from baseline, whereas the control group showed no improvements. EVOO benefit, compared with control, trended for the interference with orofacial function (P = .05). The 36-Item Short Form Survey items of role limitations resulting from emotional problems and role limitations from physical health favored EVOO. The EVOO group significantly improved their Healthy Eating Index 2015 component scores of fatty acids (primarily from increased oleic acid), sodium, and refined grains. EVOO intake of 60 mL/day was feasible for participants experiencing TN and may mitigate pain and improve quality of life. This trial was registered at clinicaltrials.gov (NCT05032573).

The Ketone Bridge Between the Heart and the Bladder: How Fast Should We Go?

Metabolic syndrome (MS) is associated with both cardiovascular and bladder dysfunction. Insulin resistance (IR) and central obesity, in particular, are the main risk factors. In these patients, vicious pathological cycles exacerbate abnormal carbohydrate metabolism and sustain an inflammatory state, with serious implications for both the heart and bladder. Ketone bodies serve as an alternative energy source in this context. They are considered a "super-fuel" because they generate adenosine triphosphate with less oxygen consumption per molecule, thus enhancing metabolic efficiency. Ketone bodies have a positive impact on all components of MS. They aid in weight loss and glycemic control, lower blood pressure, improve lipid profiles, and enhance endothelial function. Additionally, they possess direct anti-inflammatory, antioxidant, and vasodilatory properties. A shared key player in dysfunction of both the heart and bladder dysfunction is the formation of the NLRP3 inflammasome, which ketone bodies inhibit. Interventions that elevate ketone body levels-such as fasting, a ketogenic diet, ketone supplements, and sodium-glucose cotransporter 2 inhibitors-have been shown to directly affect cardiovascular outcomes and improve lower urinary tract symptoms derived from MS. This review explores the pathophysiological basis of the benefits of ketone bodies in cardiac and bladder dysfunction.

The changes of cardiac energy metabolism with sodium-glucose transporter 2 inhibitor therapy

Background/aims

To investigate the specific effects of s odium-glucose transporter 2 inhibitor (SGLT2i) on cardiac energy metabolism.

Methods

A systematic literature search was conducted in eight databases. The retrieved studies were screened according to the inclusion and exclusion criteria, and relevant information was extracted according to the purpose of the study. Two researchers independently screened the studies, extracted information, and assessed article quality.

Results

The results of the 34 included studies (including 10 clinical and 24 animal studies) showed that SGLT2i inhibited cardiac glucose uptake and glycolysis, but promoted fatty acid (FA) metabolism in most disease states. SGLT2i upregulated ketone metabolism, improved the structure and functions of myocardial mitochondria, alleviated oxidative stress of cardiomyocytes in all literatures. SGLT2i increased cardiac glucose oxidation in diabetes mellitus (DM) and cardiac FA metabolism in heart failure (HF). However, the regulatory effects of SGLT2i on cardiac FA metabolism in DM and cardiac glucose oxidation in HF varied with disease types, stages, and intervention duration of SGLT2i.

Conclusion

SGLT2i improved the efficiency of cardiac energy production by regulating FA, glucose and ketone metabolism, improving mitochondria structure and functions, and decreasing oxidative stress of cardiomyocytes under pathological conditions. Thus, SGLT2i is deemed to exert a benign regulatory effect on cardiac metabolic disorders in various diseases.

Systematic review registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023484295).

Glucose restriction induces AMPK-SIRT1-mediated circadian clock gene Per expression and delays NSCLC progression

The rhythmic expression of the circadian clock is intimately linked to the health status of the body. Disturbed circadian clock rhythms might lead to a wide range of metabolic diseases and even cancers. Our previous study showed that glucose restriction was able to inhibit non-small cell lung cancer (NSCLC). In the current study, we found that glucose restriction enhanced apoptosis and cell growth delay in NSCLC cells. In addition, we used GEPIA database analysis to derive different effects of each circadian clock gene on lung cancer tissue. Among these circadian clock genes, Per (Period) is lowly expressed in cancer tissues and highly expressed in normal tissues. Moreover, the higher expression of Per in cancer patients has a better prognostic significance. Furthermore, we revealed that glucose restriction induced the expression of the circadian clock gene Per in NSCLC cells by upregulating SIRT1 (Sirtuin1) via activation of the energy response factor AMPK (AMP-activated protein kinase). Changes in Per expression following upregulation or downregulation of AMPK were consistent with AMPK expression. Additionally, a low-carbohydrate ketogenic diet significantly delayed tumor progression in a xenograft tumor model of severe combined immunodeficiency (SCID) mice. Meanwhile, the ketogenic diet increased the expression of AMPK, SIRT1 and Per in vivo. Besides, the ketogenic diet was found to restore the normal rhythmic level of Per by Zeitgeber Time (ZT) experiments. Taken these together, these results indicated a novel mechanism that glucose restriction induces AMPK-SIRT1 mediated circadian clock gene Per expression and delays NSCLC progression, which provided more evidence for glucose restriction as an adjuvant clinical therapeutic strategy in NSCLC.

Regulatory effects of ketogenic diet on the inflammatory response in obese Saudi women

Objective

In recent years, the use of a ketogenic diet (KD) against obesity has gained popularity in KSA. This study was designed to determine the impact of KD on anthropometric indices and on the abnormal regulation of inflammatory activities in obese Saudi women. Moreover, we investigated the potential of beta-hydroxybutyrate (BHB) supplementation on the inhibition of pro-inflammatory activities.

Methods

We enrolled 31 Saudi women (aged, 35.3 ± 8.4 years) with an average BMI of 33.96 ± 4.44 kg/m² underwent an 8-week KD (8KD) from January to March 2021. Changes in anthropometric measurements were collected at baseline and after 4-8 weeks of intervention. Compliance with the dietary regimen was monitored weekly by plasma BHB level.

Results

Twenty-nine females commenced the diets and 23 completed the study (a 79% completion rate). In comparison to pre-intervention, the 8KD resulted in a significant increase in the levels of plasma BHB (P < 0.001) throughout the duration of the trial. This was accompanied by a significant reduction in weight loss (7.7 kg ± 11.3; P < 0.001), BMI, waist circumference (P < 0.001), and levels of the inflammatory cytokine IL-1β (P < 0.001).

Conclusions

An 8-week KD was found to be useful in producing a positive impact on anthropometric indices, biochemical and inflammatory processes. This study indicated that the intake of a KD by obese Saudi women induced the release of BHB in the blood without stimulation of an overall starvation response. This may be useful to alleviate the severity of chronic inflammatory disorders associated with obesity.

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.

Intravenous and oral whole body ketone dosimetry, biodistribution, metabolite correction and kinetics studied by (R)-[1-11C]β-hydroxybutyrate ([11C]OHB) PET in healthy humans

BACKGROUND

Ketones are increasingly recognized as an important and possibly oxygen sparing source of energy in vital organs such as the heart, the brain and the kidneys. Drug treatments, dietary regimens and oral ketone drinks designed to deliver ketones for organ and tissue energy production have therefore gained popularity. However, whether ingested ketones are taken up by various extra-cerebral tissues and to what extent is still largely unexplored. It was therefore the aim of this study to use positron emission tomography (PET) to explore the whole body dosimetry, biodistribution and kinetics of the ketone tracer (R)-[1-¹¹C]β-hydroxybutyrate ([¹¹C]OHB). Six healthy subjects (3 women and 3 men) underwent dynamic PET studies after both intravenous (90 min) and oral (120 min) administration of [¹¹C]OHB. Dosimetry estimates of [¹¹C]OHB was calculated using OLINDA/EXM software, biodistribution was assessed visually and [¹¹C]OHB tissue kinetics were obtained using an arterial input function and tissue time-activity curves.

RESULTS

Radiation dosimetry yielded effective doses of 3.28 [Formula: see text]Sv/MBq (intravenous administration) and 12.51 [Formula: see text]Sv/MBq (oral administration). Intravenous administration of [¹¹C]OHB resulted in avid radiotracer uptake in the heart, liver, and kidneys, whereas lesser uptake was observed in the salivary glands, pancreas, skeletal muscle and red marrow. Only minimal uptake was noted in the brain. Oral ingestion of the tracer resulted in rapid radiotracer appearance in the blood and radiotracer uptake in the heart, liver and kidneys. In general, [¹¹C]OHB tissue kinetics after intravenous administration were best described by a reversible 2-tissue compartmental model.

CONCLUSION

The PET radiotracer [¹¹C]OHB shows promising potential in providing imaging data on ketone uptake in various physiologically relevant tissues. As a result, it may serve as a safe and non-invasive imaging tool for exploring ketone metabolism in organs and tissues of both patients and healthy individuals. Trial registration Clinical trials, NCT0523812, Registered February 10th 2022, https://clinicaltrials.gov/ct2/show/NCT05232812?cond=NCT05232812&draw=2&rank=1 .

Cardiovascular Remodeling Post-Ischemia: Herbs, Diet, and Drug Interventions

Cardiovascular disease (CVD) is a serious health burden with increasing prevalence, and CVD continues to be the principal global source of illness and mortality. For several disorders, including CVD, the use of dietary and medicinal herbs instead of pharmaceutical drugs continues to be an alternate therapy strategy. Despite the prevalent use of synthetic pharmaceutical medications, there is currently an unprecedented push for the use of diet and herbal preparations in contemporary medical systems. This urge is fueled by a number of factors, the two most important being the common perception that they are safe and more cost-effective than modern pharmaceutical medicines. However, there is a lack of research focused on novel treatment targets that combine all these strategies-pharmaceuticals, diet, and herbs. In this review, we looked at the reported effects of pharmaceutical drugs and diet, as well as medicinal herbs, and propose a combination of these approaches to target independent pathways that could synergistically be efficacious in treating cardiovascular disease.

Diets, Gut Microbiota and Metabolites

The gut microbiota refers to the gross collection of microorganisms, estimated trillions of them, which reside within the gut and play crucial roles in the absorption and digestion of dietary nutrients. In the past decades, the new generation 'omics' (metagenomics, transcriptomics, proteomics, and metabolomics) technologies made it possible to precisely identify microbiota and metabolites and describe their variability between individuals, populations and even different time points within the same subjects. With massive efforts made, it is now generally accepted that the gut microbiota is a dynamically changing population, whose composition is influenced by the hosts' health conditions and lifestyles. Diet is one of the major contributors to shaping the gut microbiota. The components in the diets vary in different countries, religions, and populations. Some special diets have been adopted by people for hundreds of years aiming for better health, while the underlying mechanisms remain largely unknown. Recent studies based on volunteers or diet-treated animals demonstrated that diets can greatly and rapidly change the gut microbiota. The unique pattern of the nutrients from the diets and their metabolites produced by the gut microbiota has been linked with the occurrence of diseases, including obesity, diabetes, nonalcoholic fatty liver disease, cardiovascular disease, neural diseases, and more. This review will summarize the recent progress and current understanding of the effects of different dietary patterns on the composition of gut microbiota, bacterial metabolites, and their effects on the host's metabolism.

Ketogenic Diet and Ketone Bodies as Clinical Support for the Treatment of SARS-CoV-2-Review of the Evidence

One of the proposed nutritional therapies to support drug therapy in COVID-19 is the use of a ketogenic diet (KD) or ketone bodies. In this review, we summarized the evidence from tissue, animal, and human models and looked at the mechanisms of action of KD/ketone bodies against COVID-19. KD/ketone bodies were shown to be effective at the stage of virus entry into the host cell. The use of β-hydroxybutyrate (BHB), by preventing the metabolic reprogramming associated with COVID-19 infection and improving mitochondrial function, reduced glycolysis in CD4+ lymphocytes and improved respiratory chain function, and could provide an alternative carbon source for oxidative phosphorylation (OXPHOS). Through multiple mechanisms, the use of KD/ketone bodies supported the host immune response. In animal models, KD resulted in protection against weight loss and hypoxemia, faster recovery, reduced lung injury, and resulted in better survival of young mice. In humans, KD increased survival, reduced the need for hospitalization for COVID-19, and showed a protective role against metabolic abnormalities after COVID-19. It appears that the use of KD and ketone bodies may be considered as a clinical nutritional intervention to assist in the treatment of COVID-19, despite the fact that numerous studies indicate that SARS-CoV-2 infection alone may induce ketoacidosis. However, the use of such an intervention requires strong scientific validation.

Ketogenic Diet in Children and Adolescents: the Effects on Growth and Nutritional Status

The ketogenic diet is known to be a possible adjuvant treatment in several medical conditions, such as in patients with severe or drug-resistant forms of epilepsy. Its use has recently been increasing among adolescents and young adults due to its supposed weight-loss effect, mediated by lipolysis and lowered insulin levels. However, there are still no precise indications on the possible use of ketogenic diets in pediatric age for weight loss. This approach has also recently been proposed for other types of disorder such as inherited metabolic disorders, Prader-Willi syndrome, and some specific types of cancers. Due to its unbalanced ratio of lipids, carbohydrates and proteins, a clinical evaluation of possible side effects with a strict evaluation of growth and nutritional status is essential in all patients following a long-term restrictive diet such as the ketogenic one. The prophylactic use of micronutrients supplementation should be considered before starting any ketogenic diet. Lastly, while there is sufficient literature on possible short-term side effects of ketogenic diets, their possible long-term impact on growth and nutritional status is not yet fully understood, especially when started in pediatric age.

Food, gut barrier dysfunction, and related diseases: A new target for future individualized disease prevention and management

Dysfunction of gut barrier is known as "leaky gut" or increased intestinal permeability. Numerous recent scientific evidences showed the association between gut dysfunction and multiple gastrointestinal tract (GI) and non-GI diseases. Research also demonstrated that food plays a crucial role to cause or remedy gut dysfunction related to diseases. We reviewed recent articles from electronic databases, mainly PubMed. The data were based on animal models, cell models, and human research in vivo and in vitro models. In this comprehensive review, our aim focused on the relationship between dietary factors, intestinal permeability dysfunction, and related diseases. This review synthesizes currently available literature and is discussed in three parts: (a) the mechanism of gut barrier and function, (b) food and dietary supplements that may promote gut health, and food or medication that may alter gut function, and (c) a table that organizes the synthesized information by general mechanisms for diseases related to leaky gut/intestinal permeability and associated dietary influences. With future research, dietary intervention could be a new target for individualized disease prevention and management.

The hypocholesterolemic effect of methanolic extract of Bassia muricata l. on hypercholesterolemic rats

Hypercholesterolemia is correlated with cardiovascular diseases. The search for effective alternatives for lipid-lowering drugs is continuous. We investigated the hypocholesterolemic activity of Bassia muricata methanolic extract (BMME) in a model of hyperlipidemia. B. muricata was extracted with methanol. Male rats were randomly divided into six groups: normal control group (G1) was fed normal diet, negative control group (G2) was fed high cholesterol and fat diet (HCFD), positive control group (G3) was fed HCFD and treated with atorvastatin (20 mg/kg), a fourth, fifth and sixth groups (G4, G5, and G6) were fed HCFD and treated with 10, 30 and 100 mg/Kg of BMME, respectively. All rat groups received, for 4 weeks, the appropriate daily dose after initial two weeks of feeding normal diet or HCFD. Body weight, lipid profile, serum glucose, liver enzymes were measured weekly. HCFD caused an increased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and glucose, decreased triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C), and blunted the normal gain of body weight. BMME doses restored the normal gain of body weight, caused significant decrease in serum TC, LDL-C, and increased HDL-C when compared to G2. 10 mg/kg and 30 mg/kg of BMME failed to induce any change in alkaline phosphatase whereas 100 mg/Kg of BMME caused a significant increase in alanine transaminase. 10 mg/kg and 30 mg/kg of BMME significantly decreased serum glucose whereas 100 mg/kg BMME significantly increased it. BMME had significant hypocholesterolemic effect and 100 mg/kg BMME increased alanine transaminase, TG and glucose in rats.

Graphical abstract

The Role of Ketone Bodies in Various Animal Models of Kidney Disease

The kidney is a vital organ that carries out significant metabolic functions in our body. Due to the complexity of its role, the kidney is also susceptible to many disease conditions, such as acute kidney injury (AKI) and chronic kidney disease (CKD). Despite the prevalence and our increased understanding of the pathophysiology of both AKI and CKD as well as the transition of AKI to CKD, no well-established therapeutics have been applied clinically to these conditions, rendering an urgent need for a novel potential therapeutic target to be developed. In this article, we reviewed the function of ketone bodies in some common kidney conditions, such as drug-induced nephrotoxicity, ischemia and reperfusion injury, fibrosis development, diabetic kidney disease, kidney aging, hypertension, and CKD progression. All the selected studies reviewed were performed in animal models by primarily utilizing rodents, which also provide invaluable sources for future clinical applications. Ketone bodies have shown significant renal protective properties via attenuation of oxidative stress, increased expression of anti-inflammatory proteins, gene regulation, and a reduction of apoptosis of renal cells. A physiological level of ketone bodies could be achieved by fasting, a ketogenic diet, and an exogenous ketone supplement. Finally, the limitations of the long-term ketogenic diet were also discussed.

Acute Insulin Secretory Effects of a Classic Ketogenic Meal in Healthy Subjects: A Randomized Cross-Over Study

The classic ketogenic diet (KD) is a high-fat, low-carbohydrate diet that mimics a starvation state with sufficient caloric intake to sustain growth and development. KD is an established treatment for several diseases, and it is currently evaluated in the management of insulin-resistant states, although insulin secretion after a classic ketogenic meal has never been investigated. We measured the insulin secretion to a ketogenic meal in 12 healthy subjects (50% females, age range 19-31 years, BMI range 19.7-24.7 kg/m²) after cross-over administrations of a Mediterranean meal and a ketogenic meal both satisfying ~40% of an individual's total energy requirement, in random order and separated by a 7-day washout period. Venous blood was sampled at baseline and at 10, 20, 30, 45, 60, 90, 120, and 180 min to measure glucose, insulin, and C-peptide concentrations. Insulin secretion was calculated from C-peptide deconvolution and normalized to the estimated body surface area. Glucose, insulin concentrations, and insulin secretory rate were markedly reduced after the ketogenic meal with respect to the Mediterranean meal: glucose AUC in the first OGTT hour -643 mg × dL^-1 × min^-1, 95% CI -1134, -152, p = 0.015; total insulin concentration -44,943 pmol/L, 95% CI -59,181, -3706, p < 0.001; peak rate of insulin secretion -535 pmol × min^-1 × m^-2, 95% CI -763, -308, p < 0.001. We have shown that a ketogenic meal is disposed of with only a minimal insulin secretory response compared to a Mediterranean meal. This finding may be of interest to patients with insulin resistance and or insulin secretory defects.

Effects of the ketogenic diet on bone health: A systematic review

OBJECTIVE

To carry out a systematic review of published studies to evaluate the relationship between different type of ketogenic diet (KD) and bone health as supported by the scientific literature.

METHODS

The study involved all articles that assessed the relationship between the use of KD for the treatment of overweight or obesity and bone health. The quality assessment was evaluated with using the Cambridge Quality Checklists. The search strategy included the following combination of Medical Subjects Headings terms and keywords: "osteoporosis", "bone health, "bone function", "bone mineral density", and "ketogenic diet".

RESULTS

Seven trials were identified and reviewed. No significant changes in bone mass density (BMD) were observed after KD. The results showed no significant effect on bone resorption by measuring urinary N-telopeptide levels, on bone formation by measuring bone-specific alkaline phosphatase, or alterations in overall bone turnover in patients who followed KD. Only in female subject after a 10% weight loss, bone resorption increases while new bone synthesis decreases, but without increasing the risk of osteoporosis. Finally, patients on KD lost significantly more weight than controls, associated with an increase in serum vitamin D levels and a reduction in plasma parathyroid hormone (PTH) levels.

CONCLUSION

No human studies have currently been conducted with adequate and powerful experimental designs to definitively understand the impact of KD therapy on bone health.

Ketogenic Diet and Inflammation: Implications for Mood and Anxiety Disorders

The ketogenic diet, known as a low-carbohydrate, high-protein, and high-fat diet, drastically restrains the major source of energy for the body, forcing it to burn all excess fat through a process called ketosis-the breaking down of fat into ketone bodies. First suggested as a medical treatment for children suffering from epilepsy, this diet has gained increased popularity as a rapid weight loss strategy. Over the past few years, there have been numerous studies suggesting that the ketogenic diet may provide therapeutic effects for several psychiatric conditions such as mood- and anxiety-related disorders. However, despite significant progress in research, the mechanisms underlying its therapeutic effects remain largely unexplored and are yet to be fully elucidated. This chapter provides an in-depth overview of preclinical and clinical evidence supporting the use of a ketogenic diet in the management of mood and anxiety disorders and discusses its relationship with inflammatory processes and potential mechanisms of actions for its therapeutic effects.

Ketogenic diet modulates cardiac metabolic dysregulation in streptozocin-induced diabetic rats

The ketogenic diet (KD) might improve cardiac function in diabetic cardiomyopathy, but the mechanisms remain unclear. This study investigated the effects of KD on myocardial fatty acid (FA), glucose, and ketone metabolism in diabetic cardiomyopathy. Echocardiograms, biochemistry, and micro-positron emission tomography were performed to evaluate cardiac function and glucose uptake in control rats and streptozotocin-induced diabetes mellitus (DM) rats with normal diet (ND) or KD for 6 weeks. Histopathology, adenosine triphosphate measurement, and Western blot were performed in the ventricular myocytes to analyze fibrosis, FA, ketone body, and glucose utilization. The ND-fed DM rats exhibited impaired left ventricular systolic function and increased chamber dilatation, whereas control and KD-fed DM rats did not. The KD reduced myocardial fibrosis and apoptosis in the DM rats. Myocardial glucose uptake in the micro-positron emission tomography was similar between ND-fed DM rats and KD-fed DM rats and was substantially lower than the control rats. Compared with the control rats,  ND-fed DM rats had increased phosphorylation of acetyl CoA carboxylase and higher expressions of CD-36, carnitine palmitoyltransferase-1β, tumor necrosis factor-α, interleukin-1β, interleukin6, PERK, and e-IF2α as well as more myocardial fibrosis and apoptosis (assessed by Bcl-2, BAX, and caspase-3 expression); these increases were attenuated in the KD-fed DM rats. Moreover, ND-fed DM rats had significantly lower myocardial adenosine triphosphate, BHB, and OXCT1 levels than the control and KD-fed DM rats. The KD may improve the condition of diabetic cardiomyopathy by suppressing FA metabolism, increasing ketone utilization, and decreasing endoplasmic reticulum stress and inflammation.

Low carbohydrate ketogenic diets reduce cardiovascular risk factor levels in obese or overweight patients with T2DM: A meta-analysis of randomized controlled trials

Background

The purpose of this meta-analysis was to explore the effects of low-carbohydrate ketogenic diets on cardiovascular risk factors in overweight or obese patients. However, there are limited literature data about effects of low-carbohydrate ketogenic diets on cardiovascular risk factors in obese or overweight patients.

Methods

We systematically searched PubMed, EMBASE, Web of Science, OVID, and Cochrane Library databases (last updated in September 2022) for randomized controlled trials (RCTs) which recruited overweight or obesity patients on ketogenic diets in order to control cardiovascular risk factors (blood glucose, weight, and lipids). The overall effect size for continuous variables was expressed as a weighted standardized mean difference (SMD) with a confidence interval of 95%. Considering type 2 diabetes mellitus (T2DM) status at baseline, subgroup analyses were performed when appropriate, based on T2DM comorbidity among patients. The effect model was selected according to heterogeneity.

Results

We finally selected 21 studies. Low carbohydrate ketogenic diets exerted a greater impact on cardiovascular risk factors in obese/ overweight patients with T2DM when compared with those on non-ketogenic diets, with lower fasting plasma glucose (FPG) (SMD, -0.75; P < 0.001) and hemoglobin A1c (HbA1c) (SMD, -0.53; P < 0.001) levels identified. Low-carbohydrate ketogenic diets significantly reduced body mass index (BMI) (SMD, -2.27; P = 0.032), weight (SMD, -6.72; P < 0.001), and waist circumference (SMD, -4.45; P = 0.003) in obese/ overweight patients with T2DM. Also, ketogenic diets improved lipid profiles in these patients; triglyceride (TG) (SMD, -0.32; P = 0.013) levels were lowered and high density lipoprotein (HDL) showed an upward trend with the P-value close to statistically significant level (SMD, -0.32; P = 0.052). In general, irrespective of diabetic status at baseline, ketogenic diets were more effective in reducing TG (SMD, -0.2; P = 0.02) and increasing HDL (SMD, 0.11; P = 0.03) levels when compared with non-ketogenic diets.

Conclusions

Low-carbohydrate ketogenic diets effectively improved cardiovascular risk factors (blood glucose, weight, and lipids) in obese/ overweight patients, especially those with T2DM when compared with non-ketogenic diets.

Low-Carbohydrate High-Fat Diet: A SWOC Analysis

Insulin resistance (IR) plays a role in the pathogenesis of many diseases, such as type 2 diabetes mellitus, cardiovascular disease, non-alcoholic fatty liver disease, obesity, and neurodegenerative diseases, including Alzheimer's disease. The ketogenic diet (KD) is a low-carbohydrate/high-fat diet that arose in the 1920s as an effective treatment for seizure control. Since then, the KD has been studied as a therapeutic approach for various IR-related disorders with successful results. To date, the use of the KD is still debatable regarding its safety. Some studies have acknowledged its usefulness, while others do not recommend its long-term implementation. In this review, we applied a SWOC (Strengths, Weaknesses, Opportunities, and Challenges) analysis that revealed the positive, constructive strengths of the KD, its potential complications, different conditions that can make used for it, and the challenges faced by both physicians and subjects throughout a KD. This SWOC analysis showed that the KD works on the pathophysiological mechanism of IR-related disorders such as chronic inflammation, oxidative stress and mitochondrial stress. Furthermore, the implementation of the KD as a potential adjuvant therapy for many diseases, including cancer, neurodegenerative disorders, polycystic ovary syndrome, and pain management was proven. On the other hand, the short and long-term possible undesirable KD-related effects, including nutritional deficiencies, growth retardation and nephrolithiasis, should be considered and strictly monitored. Conclusively, this review provides a context for decision-makers, physicians, researchers, and the general population to focus on this dietary intervention in preventing and treating diseases. Moreover, it draws the attention of scientists and physicians towards the opportunities and challenges associated with the KD that requires attention before KD initiation.

The janus face of ketone bodies in hypertension

Hypertension is the most important risk factor for the development of terminal cardiovascular diseases, such as heart failure, chronic kidney disease, and atherosclerosis. Lifestyle interventions to lower blood pressure are generally desirable prior to initiating pharmaceutical drug treatments, which may have undesirable side effects. Ketogenic interventions are popular but the scientific literature supporting their efficacy is specific to certain interventions and outcomes in animal models and patient populations. For example, although caloric restriction has its own inherent difficulties (e.g. it requires high levels of motivation and adherence is difficult), it has unequivocally been associated with lowering blood pressure in hypertensive patients. On the other hand, the antihypertensive efficacy of ketogenic diets is inconclusive, and this is surprising, given that these diets have been largely helpful in mitigating metabolic syndrome and promoting longevity. It is possible that side effects associated with ketogenic diets (e.g. dyslipidemia) aggravate the hypertensive phenotype. However, given the recent data from our group, and others, reporting that the most abundant ketone body, β-hydroxybutyrate, can have positive effects on endothelial and vascular health, there is hope that ketone bodies can be harnessed as a therapeutic strategy to combat hypertension. Therefore, we conclude this review with a summary of the type and efficacy of ketone supplements. We propose that ketone supplements warrant investigation as low-dose antihypertensive therapy that decreases total peripheral resistance with minimal adverse side effects.

Disturbed Cardiac Metabolism Triggers Atrial Arrhythmogenesis in Diabetes Mellitus: Energy Substrate Alternate as a Potential Therapeutic Intervention

Atrial fibrillation (AF) is the most common type of sustained arrhythmia in diabetes mellitus (DM). Its morbidity and mortality rates are high, and its prevalence will increase as the population ages. Despite expanding knowledge on the pathophysiological mechanisms of AF, current pharmacological interventions remain unsatisfactory; therefore, novel findings on the underlying mechanism are required. A growing body of evidence suggests that an altered energy metabolism is closely related to atrial arrhythmogenesis, and this finding engenders novel insights into the pathogenesis of the pathophysiology of AF. In this review, we provide comprehensive information on the mechanistic insights into the cardiac energy metabolic changes, altered substrate oxidation rates, and mitochondrial dysfunctions involved in atrial arrhythmogenesis, and suggest a promising advanced new therapeutic approach to treat patients with AF.

Dietary Risk Factors and Eating Behaviors in Peripheral Arterial Disease (PAD)

Dietary risk factors play a fundamental role in the prevention and progression of atherosclerosis and PAD (Peripheral Arterial Disease). The impact of nutrition, however, defined as the process of taking in food and using it for growth, metabolism and repair, remains undefined with regard to PAD. This article describes the interplay between nutrition and the development/progression of PAD. We reviewed 688 articles, including key articles, narrative and systematic reviews, meta-analyses and clinical studies. We analyzed the interaction between nutrition and PAD predictors, and subsequently created four descriptive tables to summarize the relationship between PAD, dietary risk factors and outcomes. We comprehensively reviewed the role of well-studied diets (Mediterranean, vegetarian/vegan, low-carbohydrate ketogenic and intermittent fasting diet) and prevalent eating behaviors (emotional and binge eating, night eating and sleeping disorders, anorexia, bulimia, skipping meals, home cooking and fast/ultra-processed food consumption) on the traditional risk factors of PAD. Moreover, we analyzed the interplay between PAD and nutritional status, nutrients, dietary patterns and eating habits. Dietary patterns and eating disorders affect the development and progression of PAD, as well as its disabling complications including major adverse cardiovascular events (MACE) and major adverse limb events (MALE). Nutrition and dietary risk factor modification are important targets to reduce the risk of PAD as well as the subsequent development of MACE and MALE.

A technology assisted precision ketogenic diet intervention for cardio-renal-metabolic health in overweight or obese adults: Protocol for a randomized controlled trial

BACKGROUND

The obesity epidemic is a public health concern, as it is associated with a variety of chronic conditions. The ketogenic diet has drawn much scientific and public attention. However, implementation is challenging and its effect on cardio-renal-metabolic health is inconclusive. This study will assess the feasibility, acceptability, and preliminary efficacy of a technology-assisted ketogenic diet on cardio-renal-metabolic health.

METHODS

This is a single center, 6-month, stratified, randomized controlled trial. A total of 60 overweight/obese adults (18+ years old) will be enrolled, including 20 without type 2 diabetes (T2D) and without chronic kidney disease (CKD); 20 with T2D, but without CKD; and 20 with early-stage CKD. Participants will be stratified based on health conditions and randomized into a ketogenic diet (n = 30) or a low-fat diet group (n = 30). Health education involving diet and physical activity will be delivered both digitally and in-person. Mobile and connected health technologies will be used to track lifestyle behaviors and health indicators, as well as provide weekly feedback. The primary outcome (weight) and the secondary outcomes (e.g., blood pressure, glycemic control, renal health) will be assessed with traditional measurements and metabolomics.

DISCUSSION

Mobile and connected health technologies provide new opportunities to improve chronic condition management, health education attendance, planned lifestyle changes and engagement, and health outcomes. The advancement of bioinformatics technology offers the possibility to profile and analyze omics data which may advance our understanding of the underlying mechanisms of intervention effects on health outcomes at the molecular level for personalized and precision lifestyle interventions.

Citrate Synthase Insufficiency Leads to Specific Metabolic Adaptations in the Heart and Skeletal Muscles Upon Low-Carbohydrate Diet Feeding in Mice

A decrease in TCA cycle activity may lead to impaired nutrition metabolism and cellular energy shortage. Herein, we aimed to characterize the detailed metabolic changes that compensate for energy shortages in energy-consuming organs (heart and skeletal muscles) in mice with knockout of citrate synthase (CS), an important enzyme in the TCA cycle. CS hetero knockout (CS +/−) mice and wild-type mice were fed a low-carbohydrate ketogenic diet (LCKD) or high-fat, high-carbohydrate diet (HFHCD) to induce metabolic changes. Body weight, blood serum parameters, metabolic gene expression, and adenosine triphosphate (ATP) levels were measured in the heart and skeletal muscles. Glycogen content, anabolic and catabolic biomarkers, and morphological changes were also assessed in the skeletal muscles. After diet feeding, there were no differences observed in the body weight and blood serum parameters between wild-type and CS +/− mice. The cardiac expression of genes related to the utilization of fatty acids, monocarboxylates, and branched amino acids increased in LCKD-fed CS +/− mice. In contrast, no significant differences in gene expression were observed in the muscles of LCKD-fed mice or the heart and muscles of HFHCD-fed mice. ATP levels decreased only in the skeletal muscles of LCKD-fed CS +/− mice. Additionally, the decrease in glycogen content, suppression of p70 S6 kinase, and presence of type I fiber atrophy were observed in the muscles of LCKD-fed CS +/− mice. These results suggest that the energy-consuming organs with CS insufficiency may undergo tissue-specific adaption to compensate for energy shortages when the carbohydrate supply is limited.

Keto is Trending: Implications for Body Weight and Lipid Management

PURPOSE OF REVIEW

Very-low-carbohydrate (VLC) and ketogenic diets (KDs) have been used for weight loss and more recently in patients with insulin resistance and type 2 diabetes. The impact of VLC and KDs on lipids/lipoproteins is a concern. The purpose of this review is to discuss the impact of KDs on body weight and lipids/lipoproteins.

RECENT FINDINGS

VLC/KDs contribute to greater weight loss in the short term (< 6 months) compared to higher carbohydrate diets, but there is typically no difference between the diets by 12 months. Triglyceride and high-density lipoprotein cholesterol levels generally improve, but there is a variable response in low-density lipoprotein cholesterol levels, with some individuals experiencing a dramatic increase, particularly those with latent genetic dyslipidemias. Healthcare professionals should educate patients on the risks and benefits of following VLC/KDs and encourage the consumption of carbohydrate-rich foods associated with positive health outcomes.

Ketogenic Diets and Hepatocellular Carcinoma

The ketogenic diet (KD) is a low-carbohydrate, high-fat diet regarded as a potential intervention for cancers owing to its effects on tumor metabolism and behavior. Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer, and its management is worth investigating because of the high fatality rate. Additionally, as the liver is the glucose and lipid metabolism center where ketone bodies are produced, the application of KD to combat HCC is promising. Prior studies have reported that KD could reduce the energy supply and affect the proliferation and differentiation of cancer cells by lowering the blood glucose and insulin levels. Furthermore, KD can increase the expression of hydroxymethylglutaryl-CoA synthase 2 (HMGCS2) in hepatocytes and regulate lipid metabolism to inhibit the progression of HCC. In addition, β-hydroxybutyrate can induce histone hyperacetylation and reduce the expression of inflammatory factors to alleviate damage to hepatocytes. However, there are few relevant studies at present, and the specific effects and safety of KD on HCC warrant further research. Optimizing the composition of KD and combining it with other therapies to enhance its anti-cancer effects warrant further exploration.

The effectiveness of diet intervention in improving the metabolism of overweight and obese women: a systematic review and meta-analysis

OBJECTIVES

Dietary therapy may improve glucose and lipid metabolism function in women. However, there is no systematic review to investigate the association between metabolic effects and different dietary interventions in obese women. The main purpose of this study is to summarize the current literature and investigate whether different dietary interventions have an effect on glucose and metabolic indicators of overweight or obese women.

METHODS

We conducted a scoping review of randomized controlled trial (RCT) studies from 1991 to 2022 by adopting a systematic review and meta-analysis. The database includes Google Scholar, PubMed, Embase and Web of Science. Literature screening, data extraction, and quality assessment were independently completed by 2 researchers. Meta-analysis was performed with RevMan.

RESULTS

Twelve articles were extracted and the meta-analysis results showed that the mean difference of metabolic indexes of obese women before and after dietary intervention, including fasting glucose, fasting insulin, HOMA-IR (Homeostasis model assessment-insulin resistance), TG (triglyceride), TC (total cholesterol), LDL-C (low-density lipoprotein cholesterol), HDL-C (high-density lipoprotein cholesterol) are -0.13 [-0.15, -0.10], -2.41 [-3.44, -1.38], -0.13 [-0.15, -0.10], -21.71 [-24.19, -19.22], -21.71 [-24.19, -19.22], -13.29 [-17.86, -8.72], 3.31 [2.22, 4.40], respectively.

CONCLUSIONS

Different dietary interventions benefit glucose and lipid metabolism of overweight or obese women. Further study is needed to determine which specific dietary effects have the greatest effect on improving metabolic indicators.

Fish Oil Enriched n-3 Polyunsaturated Fatty Acids Improve Ketogenic Low-Carbohydrate/High-Fat Diet-Caused Dyslipidemia, Excessive Fat Accumulation, and Weight Control in Rats

Low-carbohydrate and high-fat diets have been used for body weight (BW) control, but their adverse effects on lipid profiles have raised concern. Fish oil (FO), rich in omega-3 polyunsaturated fatty acids, has profound effects on lipid metabolism. We hypothesized that FO supplementation might improve the lipid metabolic disturbance elicited by low-carbohydrate and high-fat diets. Male SD rats were randomized into normal control diet (NC), high-fat diet (HF), and low-carbohydrate/high-fat diet (LC) groups in experiment 1, and NC, LC, LC + 5% FO (5CF), and LC + 10% FO diet (10CF) groups in experiment 2. The experimental duration was 11 weeks. In the LC group, a ketotic state was induced, and food intake was decreased; however, it did not result in BW loss compared to either the HF or NC groups. In the 5CF group, rats lost significant BW. Dyslipidemia, perirenal and epididymal fat accumulation, hepatic steatosis, and increases in triglyceride and plasma leptin levels were observed in the LC group but were attenuated by FO supplementation. These findings suggest that a ketogenic low-carbohydrate/high-fat diet with no favorable effect on body weight causes visceral and liver lipid accumulation. FO supplementation not only aids in body weight control but also improves lipid metabolism in low-carbohydrate/high-fat diet-fed rats.

Ketogenic Diet and Cardiac Substrate Metabolism

The ketogenic diet (KD) entails a high intake of fat, moderate intake of protein, and a very limited intake of carbohydrates. Ketogenic dieting has been proposed as an effective intervention for type 2 diabetes and obesity since glycemic control is improved and sustained weight loss can be achieved. Interestingly, hyperketonemia is also associated with beneficial cardiovascular effects, possibly caused by improved cardiac energetics and reduced oxygen use. Therefore, the KD has the potential to both treat and prevent cardiovascular disease. However, the KD has some adverse effects that could counteract the beneficial cardiovascular properties. Of these, hyperlipidemia with elevation of triglycerides and LDL cholesterol levels are the most important. In addition, poor diet adherence and lack of knowledge regarding long-term effects may also reduce the broader applicability of the KD. The objective of this narrative review is to provide insights into the KD and its effects on myocardial ketone body utilization and, consequently, cardiovascular health.

KMT2A: Umbrella Gene for Multiple Diseases

KMT2A (Lysine methyltransferase 2A) is a member of the epigenetic machinery, encoding a lysine methyltransferase responsible for the transcriptional activation through lysine 4 of histone 3 (H3K4) methylation. KMT2A has a crucial role in gene expression, thus it is associated to pathological conditions when found mutated. KMT2A germinal mutations are associated to Wiedemann–Steiner syndrome and also in patients with initial clinical diagnosis of several other chromatinopathies (i.e., Coffin–Siris syndromes, Kabuki syndrome, Cornelia De Lange syndrome, Rubinstein–Taybi syndrome), sharing an overlapping phenotype. On the other hand, KMT2A somatic mutations have been reported in several tumors, mainly blood malignancies. Due to its evolutionary conservation, the role of KMT2A in embryonic development, hematopoiesis and neurodevelopment has been explored in different animal models, and in recent decades, epigenetic treatments for disorders linked to KMT2A dysfunction have been extensively investigated. To note, pharmaceutical compounds acting on tumors characterized by KMT2A mutations have been formulated, and even nutritional interventions for chromatinopathies have become the object of study due to the role of microbiota in epigenetic regulation.

The effect of a low carbohydrate ketogenic diet with or without exercise on postpartum weight retention, metabolic profile and physical activity performance in postpartum mice

OBJECTIVE

the present study examined the effect of the isocaloric low-carbohydrate ketogenic diet (LCKD) with or without exercise training for 6 weeks on postpartum weight retention (PPWR), body composition, metabolic profile and physical activity performance in postpartum mice.

METHODS

postpartum mice were assigned to 4 groups (n=8/group) as follows: (1) those on a control diet without aerobic exercise (CN); (2) those on a control diet with aerobic exercise (CN+EX), (3); those on a LCKD without aerobic exercise (LCKD); (4) those on a LCKD with aerobic exercise (LCKD+EX). CN+EX and LCKD+EX mice performed 6 weeks of exercise training on a treadmill. After the 6-week intervention, physical activity performance was determined.

RESULTS

postpartum mice in all groups experienced progressive reductions in body weight over the study period. The LCKD group had the smallest reduction in PPWR (p<0.05). The LCKD group had significantly higher total cholesterol, low-density lipoprotein cholesterol and lactate dehydrogenase levels, and liver lipid concentrations with a worsened glucose tolerance, compared to the CN group (p<0.05). The LCKD group showed significant reductions in physical activity performance, whilst the LCKD+EX group showed significantly improvement in endurance performance, and paralleled the concomitant elevation in blood ketone levels.

CONCLUSIONS

6-week LCKD feeding on its own was less effective for reducing PPWR, and more detrimental to postpartum metabolic outcomes and physical activity performance of the postpartum mice. The feasibility of a LCKD with or without exercise during the postpartum period as a strategy for managing PPWR and improving postpartum metabolic profiles should be carefully considered.

Severe Hypertriglyceridemia-Induced Necrotizing Pancreatitis Associated With Ketogenic Diet in a Well-Controlled Patient With Type 2 Diabetes Mellitus

The ketogenic diet (keto diet) has become an increasingly popular approach for both weight loss and as an alternative diet for type 2 diabetes mellitus (T2DM). Owing to the nature of the keto diet, patients are at risk of developing hypertriglyceridemia (HTG) due to the high amount of triglycerides consumed by individuals during the initiation of this diet. Acute pancreatitis can result from HTG. We present a case of a 19-year-old African American male with well-controlled T2DM and no history of HTG who developed severe necrotizing HTG-induced pancreatitis after an unsupervised three-month trial of the keto diet.

The Effect of Ketogenic Diet on Inflammatory Arthritis and Cardiovascular Health in Rheumatic Conditions: A Mini Review

The principle of ketogenic diet (KD) is restriction of carbohydrates to a maximum of 5-10% of the total daily caloric intake, aiming at shifting body metabolism toward ketone bodies. Different studies suggested promising results of KD to help patients to lose weight, to reduce insulin requirements in diabetes, to supplement cancer protocols, to treat neurological conditions and to optimize control of metabolic and cardiovascular diseases. However, literature about the anti-inflammatory properties of KD in rheumatic diseases is still limited. The beneficial effects of weight loss in patients with inflammatory arthritis can be explained by biomechanical and biochemical factors. Obesity is associated with macrophage activation and production of pro-inflammatory cytokines including TNF-α, IL-1b, and IL-6. The clinical effect of KD may be primarily attributed to improvement of insulin sensitivity. Insulin resistance is associated with an increase of TNF-α, IL-1α, IL-1β, IL-6, and leptin. Moreover, reduction of body's adipose tissue and weight loss account for part of the anti-inflammatory effects and for the impact of KD on cardiovascular health. In rheumatoid arthritis, fasting was shown to be effective in reducing disease symptoms, possibly through the production of β-hydroxybutyrate (BHB), the main ketone body. BHB may exert inhibitory effects also on IL-17 and intermittent fasting improved the clinical manifestations of psoriatic arthritis. In ankylosing spondylitis, current literature doesn't allow to draw conclusion about the effects of KD. Future prospective studies will be needed to elucidate the potential beneficial effects of KD on specific domains and clinical outcomes in patients with inflammatory arthritis.

Nonalcoholic fatty liver disease, circulating ketone bodies and all-cause mortality in a general population-based cohort

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent, paralleling the obesity epidemic. Ketone bodies are produced in the liver, but it is currently uncertain whether circulating ketone bodies are increased in the context of NAFLD. We investigated the association between NAFLD and circulating ketone bodies and determined the extent to which NAFLD and circulating ketone bodies are associated with all-cause mortality.

METHODS

Plasma ketone bodies were measured by nuclear magnetic resonance spectroscopy in participants of the general population-based PREVEND study. A fatty liver index (FLI) ≥60 was regarded as a proxy of NAFLD. Associations of an elevated FLI and ketone bodies with all-cause mortality were investigated using Cox regression analyses.

RESULTS

The study included 6,297 participants aged 54 ± 12 years, of whom 1,970 (31%) had elevated FLI. Participants with elevated FLI had higher total ketone bodies (194 [153-259] vs 170 [133-243] µmol/L; P < .001) than participants without elevated FLI. During 7.9 [7.8-8.9] years of follow-up, 387 (6%) participants died. An elevated FLI was independently associated with an increased risk of mortality (HR: 1.34 [1.06-1.70]; P = .02). Higher total ketone bodies were also associated with an increased mortality risk (HR per doubling: 1.29 [1.12-1.49]; P < .001). Mediation analysis suggested that the association of elevated FLI with all-cause mortality was in part mediated by ketone bodies (proportion mediated: 10%, P < .001).

CONCLUSION

Circulating ketone bodies were increased in participants with suspected NAFLD. Both suspected NAFLD and higher circulating ketone bodies are associated with an increased risk of all-cause mortality.

Effects of a Low-Carbohydrate High-Fat Diet Combined with High-Intensity Interval Training on Body Composition and Maximal Oxygen Uptake: A Systematic Review and Meta-Analysis

The low-carbohydrate high-fat (LCHF) diet has recently been subject to attention on account of its reported influences on body composition and physical performance. However, the combined effect of LCHF with high-intensity interval training (HIIT) is unclear. A systematic review and meta-analysis were conducted to explore the effect of the LCHF diet combined with HIIT on human body composition (i.e., body weight (BM), body mass index (BMI), fat mass (FM), body fat percentage (BFP), fat-free mass (FFM)) and maximal oxygen uptake (VO_2max). Online libraries (PubMed, Web of Science, EMBASE, Cochrane Library, EBSCO, CNKI, Wan Fang) were used to search initial studies until July 2021, from which 10 out of 2440 studies were included. WMD served as the effect size with a confidence interval value of 95%. The results of meta-analysis showed a significant reduction in BM (WMD = −5.299; 95% CI: −7.223, −3.376, p = 0.000), BMI (WMD = −1.150; 95% CI: −2.225, −0.075, p = 0.036), BFP (WMD = −2.787; 95% CI: −4.738, −0.835, p = 0.005) and a significant increase in VO_2max (WMD = 3.311; 95% CI: 1.705, 4.918, p = 0.000), while FM (WMD = −2.221; 95% CI: −4.582, 0.139, p = 0.065) and FFM (WMD = 0.487; 95% CI: −3.512, 4.469, p = 0.814) remained unchanged. In conclusion, the LCHF diet combined with HIIT can reduce weight and fat effectively. This combination is sufficient to prevent muscle mass loss during LCHF, and further enhance VO_2max. Further research might be required to clarify the effect of other types of exercise on body composition and physical performance during LCHF.

Ketone Ester D-β-Hydroxybutyrate-(R)-1,3 Butanediol Prevents Decline in Cardiac Function in Type 2 Diabetic Mice

Background

Heart failure is responsible for approximately 65% of deaths in patients with type 2 diabetes mellitus. However, existing therapeutics for type 2 diabetes mellitus have limited success on the prevention of diabetic cardiomyopathy. The aim of this study was to determine whether moderate elevation in D‐β‐hydroxybutyrate improves cardiac function in animals with type 2 diabetes mellitus.

Methods and Results

Type 2 diabetic (db/db) and their corresponding wild‐type mice were fed a control diet or a diet where carbohydrates were equicalorically replaced by D‐β‐hydroxybutyrate‐(R)‐1,3 butanediol monoester (ketone ester [KE]). After 4 weeks, echocardiography demonstrated that a KE diet improved systolic and diastolic function in db/db mice. A KE diet increased expression of mitochondrial succinyl‐CoA:3‐oxoacid‐CoA transferase and restored decreased expression of mitochondrial β‐hydroxybutyrate dehydrogenase, key enzymes in cardiac ketone metabolism. A KE diet significantly enhanced both basal and ADP‐mediated oxygen consumption in cardiac mitochondria from both wild‐type and db/db animals; however, it did not result in the increased mitochondrial respiratory control ratio. Additionally, db/db mice on a KE diet had increased resistance to oxidative and redox stress, with evidence of restoration of decreased expression of thioredoxin and glutathione peroxidase 4 and less permeability transition pore activity in mitochondria. Mitochondrial biogenesis, quality control, and elimination of dysfunctional mitochondria via mitophagy were significantly increased in cardiomyocytes from db/db mice on a KE diet. The increase in mitophagy was correlated with restoration of mitofusin 2 expression, which contributed to improved coupling between cytosolic E3 ubiquitin ligase translocation into mitochondria and microtubule‐associated protein 1 light chain 3–mediated autophagosome formation.

Conclusions

Moderate elevation in circulating D‐β‐hydroxybutyrate levels via KE supplementation enhances mitochondrial biogenesis, quality control, and oxygen consumption and increases resistance to oxidative/redox stress and mPTP opening, thus resulting in improvement of cardiac function in animals with type 2 diabetes mellitus.

Sodium-Glucose Co-transporter 2 Inhibitor-Associated Euglycemic Diabetic Ketoacidosis After Bariatric Surgery: A Case and Literature Review

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce cardiovascular, kidney, and overall mortality. SGLT2i are also associated with a rare adverse event, euglycemic diabetic ketoacidosis (EDKA). This report describes a case of EDKA one day after bariatric surgery in a 51-year-old female with type 2 diabetes mellitus managed with the SGLT2i, canagliflozin. She was following a ketogenic diet for three weeks prior to surgery. The patient made a steady recovery with rapid anion gap closure followed by prolonged non-anion gap metabolic acidosis. Her medical record was tagged with a life-threatening reaction to SGLT2i. The risk of EDKA from SGLT2i may be increased by a low carbohydrate diet or postoperative status. Our case was complicated by hypokalemia, exemplifying the need for aggressive electrolyte management. Further guidance is needed to manage risk factors provoking EDKA and the use of SGLT2i therapy after an episode of EDKA.

Effects of Combining a Ketogenic Diet with Resistance Training on Body Composition, Strength, and Mechanical Power in Trained Individuals: A Narrative Review

Ketogenic diets (KD) have gained popularity in recent years among strength-trained individuals. The present review summarizes current evidence—with a particular focus on randomized controlled trials—on the effects of KD on body composition and muscle performance (strength and power output) in strength-trained individuals. Although long-term studies (>12 weeks) are lacking, growing evidence supports the effectiveness of an ad libitum and energy-balanced KD for reducing total body and fat mass, at least in the short term. However, no or negligible benefits on body composition have been observed when comparing hypocaloric KD with conventional diets resulting in the same energy deficit. Moreover, some studies suggest that KD might impair resistance training-induced muscle hypertrophy, sometimes with concomitant decrements in muscle performance, at least when expressed in absolute units and not relative to total body mass (e.g., one-repetition maximum). KD might therefore be a beneficial strategy for promoting fat loss, although it might not be a recommendable option to gain muscle mass and strength/power. More research is needed on the adoption of strategies for avoiding the potentially detrimental effect of KD on muscle mass and strength/power (e.g., increasing protein intake, reintroduction of carbohydrates before competition). In summary, evidence is as yet scarce to support a major beneficial effect of KD on body composition or performance in strength-trained individuals. Furthermore, the long-term effectiveness and safety of this type of diet remains to be determined.

Efficacy of Ketogenic Diets on Type 2 Diabetes: a Systematic Review

To assess the pleiotropic effects of ketogenic diets (KD) on glucose control, changes in medication, and weight loss in individuals with type 2 diabetes, and to evaluate its practical feasibility RECENT FINDINGS: KD results in improved HbA1c already after 3 weeks, and the effect seems to persist for at least 1 year. This is associated with a reduction in glucose-lowering medications. The weight loss observed after a short time period seems to be maintained with a long-term diet. Adequate support (supportive psychological counseling, enhancing positive affectivity, reinforcing mindful eating) is necessary to achieve a benefit and to assure adherence. Despite the documented decrease in HbA1, a definitive causal effect of KD remains to be proven. KD should be performed under strict medical supervision. Future research should clarify how compliance can be maximized and how ketosis can be optimally monitored.

[Obesity, inflammation and COVID-19: preventive interest of ketogenic diet?]

Obesity is considered a pandemic responsible for millions of deaths worldwide for many years. At the end of 2019, the Coronavirus disease 2019 (COVID-19) appeared, causing the death of more than a million people in less than a year. Numerous studies suggest that obesity could be defined as key to the onset of severe forms of this emerging disease. Indeed, SARS-CoV2 infects the host by binding to ACE2 receptors present on the surface of the cells and causes excessive secretion of pro-inflammatory cytokines including IL-1, IL-6 and TNF-α, which lead to developing acute respiratory distress syndrome (ARDS). It therefore seems essential to make up effective preventive strategies to protect this part of the population from the risk of developing a severe form of COVID-19. The ketogenic diet, which is low in sugars and high in fat, has interesting properties, both in the fight against obesity but also against severe infections. This article focuses on the latest scientific advances that make it possible to consider the ketogenic diet as a preventive strategy that simultaneously reduces the development of obesity while strengthening the immune system, two key actions in the fight against SARS-CoV2 infections and severe forms of COVID-19.

Slow but Steady-The Responsiveness of Sympathoadrenal System to a Hypoglycemic Challenge in Ketogenic Diet-Fed Rats

The sympathoadrenal counterregulatory response to hypoglycemia is critical for individuals with type 1 diabetes due to impaired ability to produce glucagon. Ketogenic diets (KD) are an increasingly popular diabetes management tool; however, the effects of KD on the sympathoadrenal response are largely unknown. Here, we determined the effects of KD-induced ketosis on the sympathoadrenal response to a single insulin-induced hypoglycemic challenge. We investigated how a 3 week KD feeding regimen affected the main components of the sympathoadrenal counterregulatory response: adrenal sympathetic nerve activity (ASNA), adrenal gland activity, plasma epinephrine, and brainstem glucose-responsive C1 neuronal activation in anesthetized, nondiabetic male Sprague-Dawley rats. Rats on KD had similar blood glucose (BG) levels and elevated ketone body β-hydroxybutyrate (BHB) levels compared to the control Chow diet group. All KD rats responded to hypoglycemia with a robust increase in ASNA, which was initiated at significantly lower BG levels compared to Chow-fed rats. The delay in hypoglycemia-induced ASNA increase was concurrent with rapid disappearance of BHB from cerebral and peripheral circulation. Adrenal gland activity paralleled epinephrine and ASNA response. Overall, KD-induced ketosis was associated with initiation of the sympathoadrenal response at lower blood glucose levels; however, the magnitude of the response was not diminished.

Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks

Very-low-carbohydrate ketogenic diets have been long been used to reduce seizure frequency and more recently have been promoted for a variety of health conditions, including obesity, diabetes, and liver disease. Ketogenic diets may provide short-term improvement and aid in symptom management for some chronic diseases. Such diets affect diet quality, typically increasing intake of foods linked to chronic disease risk and decreasing intake of foods found to be protective in epidemiological studies. This review examines the effects of ketogenic diets on common chronic diseases, as well as their impact on diet quality and possible risks associated with their use. Given often-temporary improvements, unfavorable effects on dietary intake, and inadequate data demonstrating long-term safety, for most individuals, the risks of ketogenic diets may outweigh the benefits.