Circadian rhythms, gut microbiota, and diet: Possible implications for health

Microbial metabolites as engines of behavioral variation across animals

The microbiome, especially that present in the gut, has emerged as a key modulator of animal behavior. However, the extent of its influence across species and behavioral repertoires, as well as the underlying mechanisms, remains poorly understood. Increasing evidence suggests that microbial metabolites play an important role in driving behavioral variation. In this review, we synthesize findings from vertebrates to invertebrates, spanning both model and non-model organisms, to define key groups of microbial-derived metabolites involved in modulating seven distinct behaviors: nutrition, olfaction, circadian rhythms, reproduction, locomotion, aggression, and social interactions. We discuss how these microbial metabolites interact with host chemosensory systems, neurotransmitter signaling, and epigenetic modifications to shape behavior. Additionally, we highlight critical gaps in mechanistic understanding, including the need to map additional host receptors and signaling pathways, as well as the untapped potential of microbial biosynthetic gene clusters as sources for novel bioactive compounds. Advancing these areas will enhance understanding of the microbiome's role in behavioral modulation and open new avenues for microbiome-based interventions for behavioral disorders.

Interactions between Gut Microbiota, Host Circadian Rhythms, and Metabolic Diseases

The circadian rhythm arises endogenously from genetically encoded molecular clocks, wherein the components collaborate to induce cyclic fluctuations, occurring approximately every 24 h. The rhythms synchronize biological processes with regular and predictable environmental patterns to guarantee the host metabolism and energy homeostasis function and well-being. Disruptions to circadian rhythms are widely associated with metabolic disorders. Notably, microbial rhythms are influenced by both the host's intrinsic circadian clock and external rhythmic factors (i.e., light-dark cycle, diet patterns, and diet composition), which affect the structure of microbial communities and metabolic functions. Moreover, microbiota and the metabolites also reciprocally influence host rhythms, potentially impacting host metabolic function. This review aimed to explore the bidirectional interactions between the circadian clock, factors influencing host-microbial circadian rhythms, and the effects on lipid metabolism and energy homeostasis.

Nutritional profile of the diet according to circadian clock genes in the European Prospective Investigation into Cancer and Nutrition (EPIC) chronodiet study

BACKGROUND & AIMS

Circadian rhythms seem to impact both dietary intake and metabolism, depending on the individual's chronotype. We aimed to explore whether the nutritional composition of meals throughout the day is influenced by genetics linked to the circadian clock and chronotype within the "European Prospective Investigation into Cancer and Nutrition (EPIC) chronodiet" study.

METHODS

The study population comprised 3,183 subjects with information on diet and twelve genetic variants of six genes (PER1, PER2, PER3, CRY1, NR1D1, CLOCK). The associations between the variants with chrononutrition variables (macronutrients and serving sizes of each meal) were evaluated using linear regression, considering an additive genetic model, and adjusting for sex, age and center, among others. The β coefficients, 95 % confidence intervals (CI), and p-values corrected for multiple comparisons were estimated. A genetic risk score (GRS) that was associated to the evening/late chronotype as well as overweight/obesity in a previous study, the chronotype-GRS, was tested for its association with chrononutrition variables.

RESULTS

The nutritional profile of the diet differed according to the individual's chronotype, with evening/late chronotypes exhibiting an unbalanced intake during breakfast and dinner compared to the intermediate and early chronotypes (e.g., percentage of fats consumed at breakfast relative to the total fat intake: 13 % and 9 %, respectively). However, significant differences were not encountered by the chronotype-GRS. In multivariate analyses, individual associations between the genetic variants and the nutrients revealed some nominal associations (e.g., rs1801260 and rs2070062 with carbohydrates at breakfast: β = -0.06 to 0.08). Higher scorings of the chronotype-GRS were inversely associated with the intake of proteins and carbohydrates (β = -0.46 and -0.41; nominal p-value<0.006; corrected = 0.25) during breakfast. Also, there was an inverse association between the chronotype-GRS and the breakfast's portion size (β = -0.3; nominal p-value = 0.03; corrected = 0.1).

CONCLUSIONS

Genetic susceptibility to an evening-like chronotype prone to overweight/obesity seems to be associated with a smaller serving size during breakfast, with lower protein and carbohydrate content.

The diverse roles of the circadian clock in cancer

A growing part of the human population is affected by circadian misalignment caused by deregulated sleep, increased nighttime light exposure and erratic eating patterns. Thus, circadian rhythms are a key research area, with compelling links to cancer. Here, we review the circadian regulation of critical cellular processes, including immunity, metabolism, cell cycle control and DNA repair, under physiological homeostasis and in cancer. We discuss the divergent evidence indicating tissue-specific roles of the circadian clock in different cancer types and the potential link between circadian misalignment and early-onset cancers. Finally, we outline how understanding the circadian clock can improve cancer prevention and chronomedicine-based therapies.

Gut microbiota and the tryptophan-kynurenine pathway in anxiety: new insights and treatment strategies

Anxiety disorders are mental health disorders characterized by long-lasting fear, worry, nervousness, and alterations in gut microbiota (GM). The GM is a vital modulator of brain function through the gut-brain axis, which acts as the neural pathway between the central and peripheral nervous systems. Dysbiosis of GM plays an essential role in anxiety development because of alterations in the vagus nerve, increased intestinal permeability, and altered breakdown of tryptophan (TRP). The Kynurenine (KYN) pathway plays a crucial role in the pathogenesis of anxiety disorders, primarily through its neuroprotective (KYNA) and neurotoxic (QUIN) metabolites. Higher ratios of KYNA/QUIN result in neuroprotection, whereas higher KYN/TRP ratios indicate increased QUIN production causing neuroinflammation. Studies on germ-free models exhibit higher plasma TRP levels, which interrupt the metabolic balance of TRP-derived compounds, thus causing brain impairment. A key issue in anxiety disorders is the dysregulation of GM, which disrupts TRP metabolism and neuroinflammatory pathways, however, remains poorly understood. Hence, the proper understanding of these mechanisms is crucial for future therapeutic advancements. Here, we highlight the significance of the TRP-KYN pathway and the potential of modulating KYN pathway enzymes, such as kynurenine aminotransferases (KATs), to adjust KYNA levels and restore neurotransmitter balance. It further discusses new therapeutic methods with a particular focus on probiotics that may restore GM and modulate TRP metabolism. Advancing our understanding of the intricate relationship between GM and anxiety disorders may facilitate novel, microbiota-targeted interventions. This ultimately contributes to precision medicine approaches in mental health care, thereby enhancing treatment efficacy and patient outcomes.

The impact of the timing of pasta intake on sleep quality and health outcomes: a protocol for a randomized controlled trial

BACKGROUND

Pasta is a fundamental component of the Mediterranean diet and a key source of carbohydrates. Despite its nutritional benefits, misconceptions persist regarding its potential to promote weight gain, particularly when consumed at dinner. While no evidence supports this concern, emerging chrononutritional research suggests that evening carbohydrate intake may positively influence sleep quality by promoting serotonin production. This study aims to assess, for the first time, whether pasta consumption (lunch vs. dinner) affects sleep quality, circadian rhythms, cardiometabolic health, and gut microbiota composition in healthy, normal-weight adults.

METHODS

A 7-month randomized, open-label, cross-over trial will enroll 70 participants, assigned to two isocaloric, Mediterranean-style diets differing only in pasta consumption timing. Each phase will last 3 months, separated by a 1-month wash-out period. At the beginning and end of each phase, participants will wear an actigraph for 7 days and provide saliva, blood, and stool samples. Additional assessments include body composition analysis, indirect calorimetry, and food and lifestyle diaries. The primary outcome will be changes in sleep quality from baseline. Secondary outcomes include anthropometric measurements, body composition, metabolic rate, biochemical and hormonal markers, inflammatory and oxidative stress markers, gut microbiota composition, and short-chain fatty acid production. The study has been approved by the Tuscany Regional Ethics Committee of the Azienda Ospedaliera Universitaria (AOU)-Careggi, Florence.

DISCUSSION

This study will provide experimental data on how the timing of pasta consumption affects sleep quality and a range of health outcomes, contributing to the debate on the optimal timing of carbohydrate intake.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06185634. Registered on 07/01/2024.

Diet-microbiome interactions in cancer

Diet impacts cancer in diverse manners. Multiple nutritional effects on tumors are mediated by dietary modulation of commensals, residing in mucosal surfaces and possibly also within the tumor microenvironment. Mechanistically understanding such diet-microbiome-host interactions may enable to develop precision nutritional interventions impacting cancer development, dissemination, and treatment responses. However, data-driven nutritional strategies integrating diet-microbiome interactions are infrequently incorporated into cancer prevention and treatment schemes. Herein, we discuss how dietary composition affects cancer-related processes through alterations exerted by specific nutrients and complex foods on the microbiome. We highlight how dietary timing, including time-restricted feeding, impacts microbial function in modulating cancer and its therapy. We review existing and experimental nutritional approaches aimed at enhancing microbiome-mediated cancer treatment responsiveness while minimizing adverse effects, and address challenges and prospects in integrating diet-microbiome interactions into precision oncology. Collectively, mechanistically understanding diet-microbiome-host interactomes may enable to achieve a personalized and microbiome-informed optimization of nutritional cancer interventions.

Photobiomodulation and the oral-gut microbiome axis: therapeutic potential and challenges

This Perspective article explores the challenges associated with the direct application of photobiomodulation (PBM) to the gut and presents a novel hypothesis for indirect gut health modulation through oral microbiome alteration. Given the difficulties in delivering PBM effectively to deep gastrointestinal tissues, an alternative approach involves targeting the oral microbiome, which has a demonstrated relationship with the gut microbiome. Research indicates that PBM applied to the oral cavity could selectively alter microbial composition. This alteration may, via the oral-gut microbiome axis, indirectly impact gut health. This hypothesis, supported by preliminary studies, suggests that oral PBM could offer a promising non-invasive strategy for managing gut-related disorders. Furthermore, there may be a link between the oral microbiome and brain diseases. Given the proximity to the brain, PBM-induced changes in the oral microbiota could indirectly help prevent neurological disorders. However, further investigation is necessary to comprehensively elucidate the underlying mechanisms and therapeutic implications of this approach.

Gut microbiota and their metabolites in the immune response of rheumatoid arthritis: Therapeutic potential and future directions

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent joint inflammation, damage, and loss of function. In recent years, the role of gut microbiota and its metabolites in immune regulation has attracted increasing attention. The gut microbiota influences the host immune system's homeostasis through various mechanisms, regulating the differentiation, function, and immune tolerance of immune cells. Dysbiosis of the gut microbiota in RA patients is closely associated with abnormal activation of immune cells and excessive secretion of inflammatory cytokines. Metabolites produced by the gut microbiota, such as short-chain fatty acids (SCFAs), tryptophan metabolites, bile acids, and amino acid metabolites, play a critical role in immune responses, regulating the functions of immune cells like T cells, B cells, and macrophages, and inhibiting the release of pro-inflammatory cytokines. Restoring the balance of the gut microbiota and optimizing the production of metabolic products may become a new strategy for RA treatment. This review discusses the role of gut microbiota and its metabolites in the immune response of RA, exploring how they influence the immunopathological process of RA through the regulation of immune cells and key immune factors. It also provides a theoretical basis for future therapeutic strategies based on gut microbiota modulation.

Chronotype and Cancer: Emerging Relation Between Chrononutrition and Oncology from Human Studies

Fasting-feeding timing is a crucial pattern implicated in the regulation of daily circadian rhythms. The interplay between sleep and meal timing underscores the importance of maintaining circadian alignment in order to avoid creating a metabolic environment conducive to carcinogenesis following the molecular and systemic disruption of metabolic performance and immune function. The chronicity of such a condition may support the initiation and progression of cancer through a variety of mechanisms, including increased oxidative stress, immune suppression, and the activation of proliferative signaling pathways. This review aims to summarize current evidence from human studies and provide an overview of the potential mechanisms underscoring the role of chrononutrition (including time-restricted eating) on cancer risk. Current evidence shows that the morning chronotype, suggesting an alignment between physiological circadian rhythms and eating timing, is associated with a lower risk of cancer. Also, early time-restricted eating and prolonged nighttime fasting were also associated with a lower risk of cancer. The current evidence suggests that the chronotype influences cancer risk through cell cycle regulation, the modulation of metabolic pathways and inflammation, and gut microbiota fluctuations. In conclusion, although there are no clear guidelines on this matter, emerging evidence supports the hypothesis that the role of time-related eating (i.e., time/calorie-restricted feeding and intermittent/periodic fasting) could potentially lead to a reduced risk of cancer.

Sleep deprivation-induced shifts in gut microbiota: Implications for neurological disorders

Sleep deprivation is a prevalent issue in contemporary society, with significant ramifications for both physical and mental well-being. Emerging scientific evidence illuminates its intricate interplay with the gut-brain axis, a vital determinant of neurological function. Disruptions in sleep patterns disturb the delicate equilibrium of the gut microbiota, resulting in dysbiosis characterized by alterations in microbial composition and function. This dysbiosis contributes to the exacerbation of neurological disorders such as depression, anxiety, and cognitive decline through multifaceted mechanisms, including heightened neuroinflammation, disturbances in neurotransmitter signalling, and compromised integrity of the gut barrier. In response to these challenges, there is a burgeoning interest in therapeutic interventions aimed at restoring gut microbial balance and alleviating neurological symptoms precipitated by sleep deprivation. Probiotics, dietary modifications, and behavioural strategies represent promising avenues for modulating the gut microbiota and mitigating the adverse effects of sleep disturbances on neurological health. Moreover, the advent of personalized interventions guided by advanced omics technologies holds considerable potential for tailoring treatments to individualized needs and optimizing therapeutic outcomes. Interdisciplinary collaboration and concerted research efforts are imperative for elucidating the underlying mechanisms linking sleep, gut microbiota, and neurological function. Longitudinal studies, translational research endeavours, and advancements in technology are pivotal for unravelling the complex interplay between these intricate systems.

The role of circadian rhythm regulator PERs in oxidative stress, immunity, and cancer development

The complex interaction between circadian rhythms and physiological functions is essential for maintaining human health. At the heart of this interaction lies the PERIOD proteins (PERs), pivotal to the circadian clock, influencing the timing of physiological and behavioral processes and impacting oxidative stress, immune functionality, and tumorigenesis. PER1 orchestrates the cooperation of the enzyme GPX1, modulating mitochondrial dynamics in sync with daily rhythms and oxidative stress, thus regulating the mechanisms managing energy substrates. PERs in innate immune cells modulate the temporal patterns of NF-κB and TNF-α activities, as well as the response to LPS-induced toxic shock, initiating inflammatory responses that escalate into chronic inflammatory conditions. Crucially, PERs modulate cancer cell behaviors including proliferation, apoptosis, and migration by influencing the levels of cell cycle proteins and stimulating the expression of oncogenes c-Myc and MDM2. PER2/3, as antagonists in cancer stem cell biology, play important roles in differentiating cancer stem cells and in maintaining their stemness. Importantly, the expression of Pers serve as a significant factor for early cancer diagnosis and prognosis. This review delves into the link between circadian rhythm regulator PERs, disruptions in circadian rhythm, and oncogenesis. We examine the evidence that highlights how dysfunctions in PERs activities initiate cancer development, aid tumor growth, and modify cancer cell metabolism through pathways involved in oxidative stress and immune system. Comprehending these connections opens new pathways for the development of circadian rhythm-based therapeutic strategies, with the aims of boosting immune responses and enhancing cancer treatments.

Depression and Accelerated Aging: The Eveningness Chronotype and Low Adherence to the Mediterranean Diet Are Associated with Depressive Symptoms in Older Subjects

BACKGROUND AND OBJECTIVES

Depression often results in premature aging, which increases the risk of other chronic diseases, but very few studies have analyzed the association between epigenetic biomarkers of aging and depressive symptoms. Similarly, limited research has examined the joint effects of adherence to the Mediterranean diet (MedDiet) and chronotype on depressive symptoms, accounting for sex differences. Therefore, these are the objectives of our investigation in a Mediterranean population at high cardiovascular risk.

METHODS

We analyzed 465 older subjects (aged 55-75) with metabolic syndrome and assessed depressive symptoms by the Beck Depression Inventory (BDI-II). MedDiet adherence was measured with the 17-item MedDiet score, and chronotype with the Morningness-Eveningness Questionnaire (MEQ). Blood DNA methylation was analyzed, and epigenomic biomarkers of age acceleration were determined. We focused on the Dunedin Pace of Aging Computed from the Epigenome (DunedinPACE). We fitted multivariable models with interaction terms.

RESULTS

Prevalence of depression was statistically higher in women (p < 0.001). MedDiet adherence was strongly and inversely associated with depressive symptoms in the whole population (p < 0.01), while the MEQ score was inversely associated (p < 0.05). In the joint analysis, both MedDiet adherence and chronotype remained statistically associated with the BDI-II score (p < 0.05), showing additive effects. No interaction effects were observed. In women, a higher score in depressive symptoms was significantly associated with faster age acceleration (measured with the DunedinPACE biomarker). This association remained significant even after adjustment for MedDiet adherence and chronotype.

CONCLUSIONS

In older subjects with metabolic syndrome, the eveningness chronotype was associated with greater depressive symptoms, but a higher adherence to the MedDiet could potentially counteract the chronotype risk with additive effects. Women showed stronger associations, and importantly, we reported for the first time in this population that depressive symptoms were associated with accelerated aging.

Effectiveness of the SYNCHRONIZE + Brief Intervention in Improving Mediterranean Diet Adherence, Nutritional Quality and Intake Pattern in Persons with Fibromyalgia and Chronic Fatigue Syndrome

BACKGROUND

Multidisciplinary lifestyle interventions are being researched to treat fibromyalgia. However, the impact of nutrition as a key treatment component is little studied. This study aimed to evaluate the effectiveness of the SYNCHRONIZE + lifestyle multidisciplinary intervention in improving adherence to the Mediterranean diet, nutrition quality and dietary intake pattern in persons with fibromyalgia and chronic fatigue syndrome.

METHODS

A pragmatic randomized clinical trial was conducted in primary care. Data were collected using the 17-item energy-restricted Mediterranean Adherence Screener (er-MEDAS), the food frequency questionnaire (sFFQ) and the 24 h recall questionnaire (24 HR), in addition to chrono-nutritional, anthropometric, and body composition data, at baseline and 3-, 6-, and 12- month follow-up visits, and statistically analyzed.

RESULTS

A total of 158 participants were evaluated. Results showed the effectiveness of the intervention in improving adherence to the Mediterranean diet. The adherence depended on the group-time interaction being positive and significant at 3 and 6 months post-intervention in the INT group and on the participant age and educational level. Specifically, the intake of legumes, fruits, vegetables, nuts and blue fish was increased, while the intake of sweets and pastries, butter and cream and red and processed meat was reduced. Furthermore, the intake of chips and candies was also reduced, and the consumption of fermented food (yogurts, cheese, kefir) increased. Thus, general diet quality improved. Interestingly, the intake of key nutrients such as protein and iron increased. Furthermore, the number of night eaters was decreased significantly. Muscle mass index was also improved in the intervention group. These results were maintained in the medium to long term.

CONCLUSION

SYNCHRONIZE + is a brief, low-cost, multidisciplinary intervention effective in improving adherence to the Mediterranean diet and improving nutritional and dietary intake patterns in persons with fibromyalgia and chronic fatigue syndrome. Further evaluation of the effect on quality of life and symptoms is needed.

Interaction Between Early Meals (Big-Breakfast Diet), Clock Gene mRNA Expression, and Gut Microbiome to Regulate Weight Loss and Glucose Metabolism in Obesity and Type 2 Diabetes

The circadian clock gene system plays a pivotal role in coordinating the daily rhythms of most metabolic processes. It is synchronized with the light-dark cycle and the eating-fasting schedule. Notably, the interaction between meal timing and circadian clock genes (CGs) allows for optimizing metabolic processes at specific times of the day. Breakfast has a powerful resetting effect on the CG network. A misaligned meal pattern, such as skipping breakfast, can lead to a discordance between meal timing and the endogenous CGs, and is associated with obesity and T2D. Conversely, concentrating most calories and carbohydrates (CH) in the early hours of the day upregulates metabolic CG expression, thus promoting improved weight loss and glycemic control. Recently, it was revealed that microorganisms in the gastrointestinal tract, known as the gut microbiome (GM), and its derived metabolites display daily oscillation, and play a critical role in energy and glucose metabolism. The timing of meal intake coordinates the oscillation of GM and GM-derived metabolites, which in turn influences CG expression, playing a crucial role in the metabolic response to food intake. An imbalance in the gut microbiota (dysbiosis) can also reciprocally disrupt CG rhythms. Evidence suggests that misaligned meal timing may cause such disruptions and can lead to obesity and hyperglycemia. This manuscript focuses on the reciprocal interaction between meal timing, GM oscillation, and circadian CG rhythms. It will also review studies demonstrating how aligning meal timing with the circadian clock can reset and synchronize CG rhythms and GM oscillations. This synchronization can facilitate weight loss and improve glycemic control in obesity and those with T2D.

Health-promoting worms? Prospects and pitfalls of helminth therapy

In this manuscript, we explore the potential therapeutic use of helminths. After analyzing helminths' role in connection with human health from the perspective of their symbiotic and evolutionary relationship, we critically examine some studies on their therapeutic applications. In doing so, we focus on some prominent mechanisms of action and potential benefits, but also on the exaggerations and theoretical and methodological difficulties of such proposals. We conclude that further studies are needed to fully explore the potential benefits of this perspective, and we encourage the scientific community in doing so.

The Microbiota-Gut-Brain Axis and Neurological Disorders: A Comprehensive Review

Microbes have inhabited the earth for hundreds of millions of years longer than humans. The microbiota-gut-brain axis (MGBA) represents a bidirectional communication pathway. These communications occur between the central nervous system (CNS), the enteric nervous system (ENS), and the emotional and cognitive centres of the brain. The field of research on the gut-brain axis has grown significantly during the past two decades. Signalling occurs between the gut microbiota and the brain through the neural, endocrine, immune, and humoral pathways. A substantial body of evidence indicates that the MGBA plays a pivotal role in various neurological diseases. These include Alzheimer's disease (AD), autism spectrum disorder (ASD), Rett syndrome, attention deficit hyperactivity disorder (ADHD), non-Alzheimer's neurodegeneration and dementias, fronto-temporal lobe dementia (FTLD), Wilson-Konovalov disease (WD), multisystem atrophy (MSA), Huntington's chorea (HC), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), temporal lobe epilepsy (TLE), depression, and schizophrenia (SCZ). Furthermore, the bidirectional correlation between therapeutics and the gut-brain axis will be discussed. Conversely, the mood of delivery, exercise, psychotropic agents, stress, and neurologic drugs can influence the MGBA. By understanding the MGBA, it may be possible to facilitate research into microbial-based interventions and therapeutic strategies for neurological diseases.

Exploring gut microbiota and metabolite alterations in patients with thyroid-associated ophthalmopathy using high-throughput sequencing and untargeted metabolomics

Introduction

Thyroid-associated ophthalmopathy (TAO) is an autoimmune-driven orbital inflammatory disease. Despite research efforts, its exact pathogenesis remains unclear. This study aimed to characterize the intestinal flora and metabolic changes in patients with TAO to identify the flora and metabolites associated with disease development.

Methods

Thirty patients with TAO and 29 healthy controls were included in the study. The intestinal flora and metabolites were analyzed using high-throughput sequencing of the 16S rRNA gene and non-targeted metabolomics technology, respectively. Fresh fecal samples were collected from both populations for analysis.

Results

Reduced gut richness and diversity were observed in patients with TAO. Compared to healthy controls, significant differences in relative abundance were observed in patients with TAO at the order level Clostridiales, family level Staphylococcaceae, genus level Staphylococcus, Fournierella, Eubacterium siraeum, CAG-56, Ruminococcus gnavus, Intestinibacter, Actinomyces, and Erysipelotrichaceae UCG-003 (logFC>1 and P<0.05). Veillonella and Megamonas were closely associated with clinical symptoms in patients with TAO. Among the 184 significantly different metabolites, 63 were upregulated, and 121 were downregulated in patients with TAO compared to healthy controls. The biosynthesis of unsaturated fatty acids was the significantly enriched metabolic pathway. Correlation analysis revealed Actinomyces was positively correlated with NAGlySer 15:0/16:0, FAHFA 3:0/20:0, and Lignoceric Acid, while Ruminococcus gnavu was positively correlated with Cer 18:0;2O/16:0; (3OH) and ST 24:1;O4/18:2.

Conclusion

Specific intestinal flora and metabolites are closely associated with TAO development. Further investigation into the functional associations between these flora and metabolites will enhance our understanding of TAO pathogenesis.

The Role of Gut Microbiome in Sleep Quality and Health: Dietary Strategies for Microbiota Support

Dietary components, including dietary fiber, unsaturated fatty acids, and polyphenols, along with meal timing and spacing, significantly affect the microbiota's capacity to produce various metabolites essential for quality sleep and overall health. This review explores the role of gut microbiota in regulating sleep through various metabolites such as short-chain fatty acids, tryptophan, serotonin, melatonin, and gamma-aminobutyric acid. A balanced diet rich in plant-based foods enhances the production of these sleep-regulating metabolites, potentially benefiting overall health. This review aims to investigate how dietary habits affect gut microbiota composition, the metabolites it produces, and the subsequent impact on sleep quality and related health conditions.

Unraveling the gut-brain connection: The association of microbiota-linked structural brain biomarkers with behavior and mental health

AIM

The gut microbiota can influence human behavior. However, due to the massive multiple-testing problem, research into the relationship between microbiome ecosystems and the human brain faces drawbacks. This problem arises when attempting to correlate thousands of gut bacteria with thousands of brain voxels.

METHODS

We performed brain magnetic resonance imaging (MRI) scans on 133 participants and applied machine-learning algorithms (Ridge regressions) combined with permutation tests. Using this approach, we were able to correlate specific gut bacterial families with brain MRI signals, circumventing the difficulties of massive multiple testing while considering sex, age, and body mass index as confounding factors.

RESULTS

The relative abundance (RA) of the Selenomonadaceae, Clostridiaceae, and Veillonellaceae families in the gut was associated with altered cerebellar, visual, and frontal T2-mapping and diffusion tensor imaging measures. Conversely, decreased relative abundance of the Eubacteriaceae family was also linked to T2-mapping values in the cerebellum. Significantly, the brain regions associated with the gut microbiome were also correlated with depressive symptoms and attentional deficits.

CONCLUSIONS

Our analytical strategy offers a promising approach for identifying potential brain biomarkers influenced by gut microbiota. By gathering a deeper understanding of the microbiota-brain connection, we can gain insights into the underlying mechanisms and potentially develop targeted interventions to mitigate the detrimental effects of dysbiosis on brain function and mental health.

Effect of gut microbiome on serotonin metabolism: a personalized treatment approach

Several factors including diet, exercise, and medications influence the makeup of the resilient but adaptable gut microbiome. Bacteria in the gut have a significant role in the homeostasis of the neurotransmitter serotonin, also known as 5-hydroxytryptamine, involved in mood and behavior. The goal of the current work is to review the effect of the gut microbiome on serotonin metabolism, and how it can potentially contribute to the development of a personalized treatment approach for depression and anxiety. Bacterial strains provide innovative therapeutic targets that can be used for disorders, such as depression, that involve dysregulation of serotonin. Advances in bacterial genomic sequencing have increased the accessibility and affordability of microbiome testing, which unlocks a new targeted pathway to modulate serotonin metabolism by targeting the gut-brain axis. Microbiome testing can facilitate the recommendation of strain-specific probiotic supplements based on patient-specific microbial profiles. Several studies have shown that supplementation with probiotics containing specific species of bacteria, such as Bifidobacterium and Lactobacillus, can improve symptoms of depression. Further research is needed to improve the process and interpretation of microbiome testing and how to successfully incorporate testing results into guiding clinical decision-making. This targeted approach centered around the gut-brain axis can provide a novel way to personalize therapy for mental health disorders.

Association between circadian syndrome and chronic diarrhea: a cross-sectional study of NHANES 2005-2010 data

Background

Circadian rhythms are reported to influence physiological processes in the gastrointestinal system, but associations between circadian syndrome (Circs) and chronic diarrhea (CD) remain unclear. Here, we explored such relationships to provide new insights into CD management.

Methods

We conducted a cross-sectional retrospective analysis using the National Health and Nutrition Examination Survey (NHANES) data between 2005 and 2010. Univariate and multivariable logistic regression analyses were performed on weighted data to explore associations between Circs and CD.

Results

Results were presented using forest plots, odds ratios (ORs), and 95% confidence intervals (CIs). Data with p-values < 0.05 were considered statistically significant. In total, 5,661 US participants, of which 412 had CD (weighted percentage = 6.20%), were enrolled. In univariate logistic regression analyses, participants with Circs had a significantly higher risk of CD (OR = 1.51, 95% CI: 1.15-1.99). After adjusting for covariates, model 2 (OR = 1.40, 95% CI: 1.03-1.90) and model 3 (OR = 1.42, 95% CI: 1.01-2.00) data were consistent with model 1 data. Additionally, the number of Circs components was positively associated with CD in all three models. Subgroup analyses revealed an association between CD and Circs in participants who had high blood pressure (OR = 2.46, 95% CI: 1.48-4.11, p < 0.001).

Conclusion

In this cross-sectional study, we found that Circs is positively associated with the risk of CD in US adults, especially in those with high blood pressure. This association may provide new management strategies for CD.

Neuroinflammation and Schizophrenia: New Therapeutic Strategies through Psychobiotics, Nanotechnology, and Artificial Intelligence (AI)

The prevalence of schizophrenia, affecting approximately 1% of the global population, underscores the urgency for innovative therapeutic strategies. Recent insights into the role of neuroinflammation, the gut-brain axis, and the microbiota in schizophrenia pathogenesis have paved the way for the exploration of psychobiotics as a novel treatment avenue. These interventions, targeting the gut microbiome, offer a promising approach to ameliorating psychiatric symptoms. Furthermore, advancements in artificial intelligence and nanotechnology are set to revolutionize psychobiotic development and application, promising to enhance their production, precision, and effectiveness. This interdisciplinary approach heralds a new era in schizophrenia management, potentially transforming patient outcomes and offering a beacon of hope for those afflicted by this complex disorder.

Circadian Syndrome Is Associated with Dietary Patterns among Middle-Older Americans: The Health and Retirement Study

Population aging is a global demographic characteristic of the 21st century, and healthy eating is a core component of healthy aging. However, limited evidence is available among older adults for associations between diet quality and circadian syndrome (CircS). Thus, this study examined associations between dietary patterns and CircS among a representative sample of middle-older adults in the US. The sample comprised middle-older adults enrolled in the 2016 core wave of the Health and Retirement Study (HRS) and one of its sub-studies, the 2013 Health Care and Nutrition Study (HCNS). A food frequency questionnaire was used to quantify habitual food intake and identify dietary patterns using a factor analysis. CircS was defined based on the existence of ≥4 components of metabolic syndrome and indicators of sleep disorders and depression. A total of 4253 middle-older adults with a mean age (SD) of 65.4 (10.0) years were included in the study. The prevalence of CircS was 35.9%. Comparing extreme quartiles of the "Prudent Pattern", the odds ratio (95% CI) for CircS was 0.72 (0.55-0.94), and it was 1.47 (1.10-1.95) for the "Western Pattern". The "Western Pattern" was positively associated while the "Prudent Pattern" was inversely associated with the odds of CircS among middle-older adults.

Effects of a chronotype-adapted diet on weight loss, cardiometabolic health, and gut microbiota: study protocol for a randomized controlled trial

BACKGROUND

Obesity and its associated health complications have become a global public health concern, necessitating innovative approaches to weight management. One emerging area of research focuses on the influence of chronotype, an individual's preferred timing for daily activities, on eating habits, weight regulation, and metabolic health. Recent observational studies suggest that the misalignment between an individual's chronotype and external cues, such as meal timing, may contribute to metabolic dysregulation and obesity, but evidence from intervention studies is still limited. This study protocol describes a randomized controlled trial designed to explore the effects of a chronotype-adapted diet, compared with a diet with a conventional calorie distribution, on weight loss, cardiometabolic health, and gut microbiota composition.

METHODS

A total of 150 overweight/obese adults will be recruited for this 4-month parallel-group, randomized, two-arm, open-label, superiority trial with 1:1 allocation ratio. Participants will be randomly assigned to either the intervention group or the control group. The intervention group will receive a low-calorie chronotype-adapted diet with a calorie distribution adapted to the individual chronotype (morning or evening), optimizing meal timing according to their peak metabolic periods. The control group will follow a standardized low-calorie healthy eating plan without considering chronotype. Both diets will have equivalent daily calorie content, adjusted according to gender and starting weight. Anthropometric measurements, body composition, blood, and fecal samples will be obtained from each participant at the beginning and the end of the study. The primary outcome is weight change from baseline. Secondary outcomes are changes from baseline in body mass index (BMI), fat mass, lipid and glycemic profile, fecal microbiota profile, and short-chain fatty acids (SCFAs).

DISCUSSION

The results of this randomized controlled trial have the potential to advance our understanding of the complex interactions between chronotype, diet, body weight, and health outcomes. By providing evidence for personalized dietary interventions based on individuals' circadian preferences, this research could offer insights into personalized nutrition strategies. Such knowledge could guide the development of innovative dietary interventions to optimize the prevention and management of overweight and obesity, while also improving the risk profile of these individuals.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05941871. Registered on 18 May 2023.

Accelerometer-based sleep metrics and gut microbiota during adolescence: Association findings from a Brazilian population-based birth cohort

BACKGROUND

Sleep and gut microbiota are emerging putative risk factors for several physical, mental, and cognitive conditions. Sleep deprivation has been shown to be linked with unhealthy microbiome environments in animal studies. However, in humans, the results are mixed. Epidemiological studies evaluating the effect of accelerometer-based sleep measures on gut microbiome are scarce. This study aims to explore the relationship between sleep duration and efficiency with the gut microbiota in adolescence.

METHODS

A subsample of 352 participants from the 2004 Pelotas (Brazil) Birth Cohort Study with sleep and fecal microbiota data available were included in the study. Sleep duration and sleep efficiency were obtained from actigraphy information at 11 years old whereas microbiota information from fecal samples was collected at 12 years. The fecal microbiota was analyzed via Illumina MiSeq (16S rRNA V3-V4 region) and the UNOISE pipeline. Alpha was assessed in QIIME2. Association measures for sleep variables and microbial α-diversity, and bacterial relative abundance were assessed through generalized models (linear and logistic regression), adjusting for maternal and child variables confounders.

RESULTS

Adjusted models showed that sleep duration was positively associated with Simpson index of α-diversity (β = 0.003; CI95 %: 0.00004; 0.01). Both sleep duration (OR = 0.43; CI95 % 0.25; 0.74) and efficiency (OR = 0.55; CI95 % 0.38; 0.78) were associated with lower Bacteroidetes abundance.

CONCLUSION

Our results suggest that sleep duration and efficiency are linked to gut microbiota diversity and composition even with 1-2 years gap from exposure to outcome. The findings support the role of sleep in the gut-brain axis as well as provide insights on how to improve microbiota health.

Nutrition and Chronobiology as Key Components of Multidisciplinary Therapeutic Interventions for Fibromyalgia and Associated Chronic Fatigue Syndrome: A Narrative and Critical Review

Fibromyalgia (FM) is often accompanied by chronic fatigue syndrome (CFS). It is a poorly understood disorder that mainly affects women and leads to chronic pain, fatigue, and insomnia, among other symptoms, which decrease quality of life. Due to the inefficiency of current pharmacological treatments, increasing interest is being directed towards non-pharmacological multicomponent therapies. However, nutrition and chronobiology are often overlooked when developing multicomponent therapies. This narrative and critical review explore the relevance of nutritional and chronobiological strategies in the therapeutic management of FM and the often-associated CFS. Reviewed literature offers scientific evidence for the association of dietary habits, nutrient levels, body composition, gut microbiota imbalance, chronobiological alterations, and their interrelation with the development and severity of symptoms. This review highlights the key role of nutrition and chronobiology as relevant and indispensable components in a multidisciplinary approach to FM and CFS.

[The interactions along the microbiota-gut-brain axis in the regulation of circadian rhythms, sleep mechanisms and disorders]

The bidirectional relationship between cerebral structures and the gastrointestinal tract involving the microbiota embraces the scientific concept of the microbiota-gut-brain axis. The gut microbiome plays an important role in many physiological and biochemical processes of the human body, in the immune response and maintenance of homeostasis, as well as in the regulation of circadian rhythms. There is a relationship between the higher prevalence of a number of neurological disorders, sleep disorders and changes in the intestinal microbiota, which actualizes the study of the complex mechanisms of such correlation for the development of new treatment and prevention strategies. Environmental factors associated with excessive light exposure can aggravate the gut dysbiosis of intestinal microflora, and as a result, lead to sleep disturbances. This review examines the integrative mechanisms of sleep regulation associated with the gut microbiota (the role of neurotransmitters, short-chain fatty acids, unconjugated bile acids, bacterial cell wall components, cytokines). Taking into account the influence of gut dysbiosis as a risk factor in the development of various diseases, the authors systematize key aspects and modern scientific data on the importance of microflora balance to ensure optimal interaction along the microbiota-gut-brain axis in the context of the regulatory role of the sleep-wake cycle and its disorders.

Mediterranean diet and chronotype: Data from Italian adults and systematic review of observational studies

Scientific evidence suggests a relation between dietary factors and sleep. Several studies show that higher adherence to the Mediterranean diet is associated with better sleep quality, but the relation with chronotype has been only recently explored. The aim of this study was to better understand the relation between chronotype and Mediterranean diet adherence. For this purpose, an analysis of 1936 adults (age 18-90 y) living in Italy was performed to investigate the association between chronotype (assessed with a short form of the morningness-eveningness questionnaire) and adherence to the Mediterranean diet (assessed through a 110-item food frequency questionnaire and the Medi-Lite literature-based Mediterranean adherence score). A multivariate logistic regression analysis was conducted to calculate odds ratios (OR) and 95 % confidence intervals (CIs) describing the association between chronotypes and high adherence to the Mediterranean diet (>14 points). Moreover, a systematic review of other observational studies published so far was performed. Individuals reporting having intermediate (n = 614) and evening (n = 173) chronotypes were less likely to have high adherence to the Mediterranean diet compared to morning chronotype (OR = 0.28, 95 % CI: 0.18, 0.42 and OR = 0.08, 95 % CI: 0.03, 0.27, respectively). When the analysis was conducted in subgroups of age, the results were similar in mid-age (>50 y) participants (for intermediate and evening chronotypes, OR = 0.21, 95 % CI: 0.10, 0.43 and OR = 0.92, 95 % CI: 0.01, 0.69, respectively) while the association with high adherence to the Mediterranean diet of evening compared to morning chronotype lost significance in older (>60 y) participants (for intermediate and evening chronotypes, OR = 0.27, 95 % CI: 0.09, 0.82 and OR = 0.22, 95 % CI: 0.02, 1.92, respectively). Out of 10 studies (date range of publication 2020-2022) included in the systematic review, there was a general consistence of findings showing higher adherence to the Mediterranean diet among morning chronotypes, although few studies reported null results. In conclusion, current evidence suggests that an intermediate and evening chronotype could be associated with lower adherence to a Mediterranean diet, but the association could be modified by other factors when considering older individuals.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism-A Narrative Review

Achieving synchronization between the central and peripheral body clocks is essential for ensuring optimal metabolic function. Meal timing is an emerging field of research that investigates the influence of eating patterns on our circadian rhythm, metabolism, and overall health. This narrative review examines the relationship between meal timing, circadian rhythm, clock genes, circadian hormones, and metabolic function. It analyzes the existing literature and experimental data to explore the connection between mealtime, circadian rhythms, and metabolic processes. The available evidence highlights the importance of aligning mealtime with the body's natural rhythms to promote metabolic health and prevent metabolic disorders. Specifically, studies show that consuming meals later in the day is associated with an elevated prevalence of metabolic disorders, while early time-restricted eating, such as having an early breakfast and an earlier dinner, improves levels of glucose in the blood and substrate oxidation. Circadian hormones, including cortisol and melatonin, interact with mealtimes and play vital roles in regulating metabolic processes. Cortisol, aligned with dawn in diurnal mammals, activates energy reserves, stimulates appetite, influences clock gene expression, and synchronizes peripheral clocks. Consuming meals during periods of elevated melatonin levels, specifically during the circadian night, has been correlated with potential implications for glucose tolerance. Understanding the mechanisms of central and peripheral clock synchronization, including genetics, interactions with chronotype, sleep duration, and hormonal changes, provides valuable insights for optimizing dietary strategies and timing. This knowledge contributes to improved overall health and well-being by aligning mealtime with the body's natural circadian rhythm.