Effects of Calorie Restriction on Health Span and Insulin Resistance: Classic Calorie Restriction Diet vs. Ketosis-Inducing Diet

Effects of Calorie Restriction on Preserving Male Fertility Particularly in a State of Obesity

PURPOSE OF REVIEW

Highlight the importance of exploring nutritional interventions that could be applied as alternative or supplementary therapeutic strategies to enhance men's fertility.

RECENT FINDINGS

Lifestyle choices have prompted extensive discussions regarding its implications and applications as a complementary therapy. The growing concern over the decline in sperm quality underscores the urgency of investigating these alternative interventions. Calorie restriction (CR) has emerged as a promising strategy to improve male fertility. The efficacy of CR depends on factors like age, ethnicity and genetics. Clinical studies, such as CALERIE, have shown an improvement in serum testosterone level and sexual drive in men with or without obesity. Additionally, CR has been shown to positively impact sperm count and motility; however, its effects on sperm morphology and DNA fragmentation remain less clear, and the literature has shown discrepancies, mainly due to the nature of technically dependent assessment tools. The review advocates a personalized approach to CR, considering individual health profiles to maximize its benefits. It underscores the need for routine, accessible diagnostic techniques in male reproductive health. It suggests that future research should focus on personalized dietary interventions to improve male fertility and overall well-being in individuals with or without obesity and unravel CR's immediate and lasting effects on semen parameters in men without obesity.

Dietary Insulin Index (DII) and Dietary Insulin load (DIL) and Caveolin gene variant interaction on cardiometabolic risk factors among overweight and obese women: a cross-sectional study

BACKGROUND AND OBJECTIVE

Studies have shown that Caveolin gene polymorphisms (CAV-1) are involved in chronic diseases, such as metabolic syndrome. Moreover, the dietary insulin index (DII) and dietary insulin load (DIL) have been shown to potentially elicit favorable effects on cardiovascular disease (CVD) risk. Therefore, this study sought to investigate the effect of DII DIL and CAV-1 interaction on CVD risk factors.

METHODS

This cross-sectional study consisted of 333 overweight and obese women aged 18-48 years. Dietary intakes, DII, and DIL were evaluated using the 147-item food frequency questionnaire (FFQ). Serum profiles were measured by standard protocols. The CAV-1 rs 3,807,992 and anthropometric data were measured by the PCR-RFLP method and bioelectrical impedance analysis (BIA), respectively. Participants were also divided into three groups based on DII, DIL score, and rs3807992 genotype.

RESULTS

This comparative cross-sectional study was conducted on 333 women classified as overweight or obese. Participants with A allele for the caveolin genotype and higher DII score showed significant interactions with high-density lipoprotein (HDL) (P for AA = 0.006 and P for AG = 0.019) and CRI-I (P for AA < 0.001 and P for AG = 0.024). In participants with AA genotype and greater DII score, interactions were observed in weight, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, CRI-II, fat-free mass (FFM), and skeletal muscle mass (SMM) (P < 0.079). Those with higher DIL scores and AA genotype had higher weight (P = 0.033), FFM (P = 0.022), and SMM (P = 0.024). In addition, DIL interactions for waist/hip ratio (WHR), waist circumference (WC), triglyceride (TG), CRI-I, and body fat mass (BFM) among individuals with AA genotype, while an HDL interaction was observed in individuals with AG and AA (P < 0.066).

CONCLUSION

The findings of the present study indicate that people who carry the caveolin rs3807992 (A) allele and have greater DII and DIL scores are at higher risk for several cardiovascular disease and metabolic syndrome biomarkers. These results highlight that diet, gene variants, and their interaction, should be considered in the risk evaluation of developing CVD.

TorS - Reframing a rational for type 2 diabetes treatment

The mammalian target of rapamycin complex 1 syndrome (Tors), paradigm implies an exhaustive cohesive disease entity driven by a hyperactive mTORC1, and which includes obesity, type 2 diabetic hyperglycemia, diabetic dyslipidemia, diabetic cardiomyopathy, diabetic nephropathy, diabetic peripheral neuropathy, hypertension, atherosclerotic cardiovascular disease, non-alcoholic fatty liver disease, some cancers, neurodegeneration, polycystic ovary syndrome, psoriasis and other. The TorS paradigm may account for the efficacy of standard-of-care treatments of type 2 diabetes (T2D) in alleviating the glycaemic and non-glycaemic diseases of TorS in T2D and non-T2D patients. The TorS paradigm may generate novel treatments for TorS diseases.

Effect of dietary restriction on health span in Caenorhabditis elegans: A systematic review

Dietary restriction (DR) interventions have demonstrated their efficacy in extending lifespan; however, the association between lifespan extension and health span remains unclear. This article aims to analyze the relationship between DR-induced lifespan and health span in Caenorhabditis elegans (C. elegans), a widely used animal model in lifespan studies. By examining various parameters such as lipofuscin accumulation (an aging marker) and locomotor and feeding capacities (indicators of muscle degradation rate), we have compiled papers that investigate and report on these DR-induced effects.The majority of the papers reviewed consistently demonstrate that DR improves both lifespan and health span in C. elegans. Worms subjected to DR exhibit slower lipofuscin accumulation compared to those fed ad libitum, indicating a reduction in age-related cellular damage. Additionally, DR-treated worms display a higher locomotion capacity, suggesting a slower rate of muscle degradation. However, it is worth noting that there are some discrepancies among the papers regarding feeding capacity. These contradictions can be attributed to the different methods employed to initiate DR. While many approaches slow muscle degeneration and enhance pumping rates through adaptation to limited food sources, other methods, such as using eat-2 mutant worms or interventions that mimic the effects of eat-2, reduce feeding capacity and consequently restrict food intake. In conclusion, the findings suggest a strong correlation between DR-induced longevity and the extension of health span in C. elegans, as evidenced by improvements in various health span parameters. DR interventions not only extend lifespan but also mitigate age-related markers and preserve locomotor capacity. Although conflicting results are observed regarding feeding capacity, the overall evidence supports the notion that DR promotes healthier aging in this animal model.

Obesity control and liver health in breast cancer: Normalized hepatic elasticity after ketogenic diet

Most socially significant diseases, including breast cancer, are undeniably linked to obesity. Recently, a positive relationship between excessive weight and increased risk of breast cancer poor outcomes has been proved. Liver integrity is an essential point during chemotherapy. Consequently, a hepatic safe therapeutic approach for managing obesity in patients with breast cancer should be initiated. Our study aimed to assess the impact of the ketogenic diet on body mass index (BMI) and to evaluate its safety on liver function in female patients with breast cancer. The study comprised 520 women with ductal breast cancer who underwent a 60-day modified ketogenic diet. BMI, prothrombin time (PT), activated partial thromboplastin clotting time (aPTT), aspartate aminotransferase to platelet ratio index (APRI), and ultrasound liver elasticity was evaluated before and after the diet. The results showed a significant decrease in BMI and an improvement in ultrasound liver elasticity in all the participants after completing the diet. Before the KD, the participants' median BMI was 35.0 kg/m2, and after the 60-day diet, the median BMI was reduced to 30.0 kg/m2. No significant liver parameter changes were found after the diet. In conclusion, we can safely promote the keto diet amongst individuals with an increased chance of developing breast cancer for a better disease prevention.

The Beneficial and Adverse Effects of Autophagic Response to Caloric Restriction and Fasting

Each cell is equipped with a conserved housekeeping mechanism, known as autophagy, to recycle exhausted materials and dispose of injured organelles via lysosomal degradation. Autophagy is an early-stage cellular response to stress stimuli in both physiological and pathological situations. It is thought that the promotion of autophagy flux prevents host cells from subsequent injuries by removing damaged organelles and misfolded proteins. As a correlate, the modulation of autophagy is suggested as a therapeutic approach in diverse pathological conditions. Accumulated evidence suggests that intermittent fasting or calorie restriction can lead to the induction of adaptive autophagy and increase longevity of eukaryotic cells. However, prolonged calorie restriction with excessive autophagy response is harmful and can stimulate a type II autophagic cell death. Despite the existence of a close relationship between calorie deprivation and autophagic response in different cell types, the precise molecular mechanisms associated with this phenomenon remain unclear. Here, we aimed to highlight the possible effects of prolonged and short-term calorie restriction on autophagic response and cell homeostasis.

Dynamics of glucose concentration during the initiation of ketogenic diet treatment in children with refractory epilepsy: Results of continuous glucose monitoring

OBJECTIVE

The ketogenic diet (KD) is a diet low in carbohydrates and rich in fats which has long been used to treat refractory epilepsy. The metabolic changes related to the KD may increase the risk of hypoglycemia, especially during the first days. The study focused on the impact of KD initiation on glycemia in non-diabetic patients with refractory epilepsy.

METHODS

The subjects were 10 pediatric patients (6 boys, mean age 6.1 ± 2.4 years), treated for intractable epilepsy. Blinded continuous glucose monitoring system (CGM) Dexcom G4 was used. Patients started on their regular diet in the first 36 hours of monitoring, followed by an increase in lipids intake and a gradual reduction of carbohydrates (relations 1:1; 2:1; 3:1; 3.5:1). We analyzed changes in glycemia during fat: nonfat ratio changes using a generalized linear model.

RESULTS

The mean monitored time per person was 6 days, 10 hours and 44 minutes. The mean ± SD glycemia for the regular diet was 4.84 ± 0.20 mmol/L, for the carbohydrates/fat ratio of 1:1 it was 4.03 ± 0.16, for the ratio of 2:1 it was 3.57 ± 0.10, for the ratio 3:1 it was 3.39 ± 0.13 and for the final ratio of 3.5:1 it was 2.79 ± 0.06 mmol/L (P < 0.001). The portions of time spent in glycemia ≤3.5 mmol/L (≤2.5 mmol/L respectively) were: on the normal diet 0.88% (0.31%) of the monitored period, during 1:1 KD ratio 1.92% (0.95%), during 2:1 ratio 3.18% (1.02%), and during 3:1 and 3.5:1 ratios 13.64% (2.36%) of the monitored time (P < 0.05).

SIGNIFICANCE

Continuous glucose monitoring system shows the dynamic of glucose concentration in ketogenic diet treatment initiation. It may be a useful tool to control the effects of this diet on glucose metabolism, especially in hypoglycemia detection.

A low-calorie diet raises β-aminoisobutyric acid in relation to glucose regulation and leptin independent of exercise in women with obesity

Introduction: β-aminoisobutyric acid (BAIBA) is a suggested cytokine secreted from skeletal muscles that regulates insulin sensitivity, pancreatic function, and fat oxidation. However, no studies to date have examined if a low-calorie diet (LCD) or LCD + with interval exercise (LCD + INT) differentially raises BAIBA. The purpose was to examine if LCD or LCD + INT raises circulating BAIBA in relation to cardiometabolic health. Methods: For this, twenty-three women with obesity were randomized to either 2-weeks of LCD (n = 12, 48.4 ± 2.5 y, 37.84 ± 1.5 kg/m2; ∼1200 kcal/day) or LCD + INT (n = 11, 47.6 ± 4.3 y, 37.9 ± 2.3 kg/m2; ∼60 min/d of INT alternating 3 min of 90% and 50% HRpeak), with matched energy availability. Fasting BAIBA and adipokines along with glucose, insulin, C-peptide, and FFA after every 30 min up to 120 min were obtained during a 75 g OGTT to estimate total area under the curve (tAUC), insulin sensitivity (SIIS), pancreatic function [disposition index (DI)], and hepatic insulin clearance (HIC). Fuel use (indirect calorimetry) was tested at 0, 60, and 120 min of the OGTT along with fitness (VO2peak) and body composition (BodPod). Results: Both treatments lowered body weight (p < 0.001) and leptin (p < 0.001) but raised BAIBA (p = 0.007) and insulin sensitivity (p = 0.02). LCD + INT increased VO2peak (p = 0.02) and REE tAUC120min (p = 0.02) while LCD and LCD + INT decreased carbohydrate oxidation (CHOox) tAUC120min (p < 0.001). Increased BAIBA associated with reduced weight (r = -0.67, p < 0.001), leptin (r = -0.66, p = 0.001), CHOox tAUC120min (r = -0.44, p = 0.03) and DImuscle120min (r = -0.45, p = 0.03), but elevated HIC120min (r = 0.47, p = 0.02). Discussion: Concluding, LCD and LCD + INT increased BAIBA in relation to reduced body weight and pancreatic function in women with obesity. This suggests energy deficit is a key factor regulating circulating BAIBA.

mTORC1 syndrome (TorS): unified paradigm for diabetes/metabolic syndrome

'Glucolipotoxicity' and 'insulin resistance' are claimed to drive type 2 diabetes (T2D) and the non-glycemic diseases of the metabolic syndrome (MetS) (obesity, dyslipidemia, hypertension). In line with that, glycemic and/or insulin control are considered to be primary goal in treating T2D/MetS. However, recent standard-of-care (SOC) treatments of T2D, initially designed to control T2D hyperglycemia, appear now to alleviate the cardio-renal and non-glycemic diseases of T2D/MetS independently of glucose lowering and insulin resistance, and in non-T2D patients altogether, calling for an alternative unifying pathophysiology/treatment paradigm for T2D/MetS. This opinion article proposes to replace the current 'glucolipotoxic/insulin-resistance' paradigm of T2D/MetS with an 'mammalian target of rapamycin complex 1 (mTORC1) syndrome' (TorS) paradigm, implying an exhaustive cohesive disease entity driven by an upstream hyperactive mTORC1, and which includes diabetic hyperglycemia, diabetic dyslipidemia, hypertension, diabetic macrovascular and microvascular disease, non-alcoholic fatty liver disease, some cancers, neurodegeneration, polycystic ovary syndrome (PCOS), psoriasis, and others. The TorS paradigm may account for the insulin-resistant glycemic context of TorS, combined with response to insulin of the non-glycemic diseases of TorS. The TorS paradigm may account for the efficacy of current antidiabetic SOC treatments in diabetic and nondiabetic patients. Most importantly, the TorS paradigm may generate novel treatments for TorS.

Association of triglyceride-glucose index and its 6-year change with risk of hypertension: A prospective cohort study

BACKGROUND AND AIM

We aimed to investigate the association of triglyceride-glucose (TyG) index and its dynamic change with risk of hypertension in rural Chinese and, further, to explore whether the TyG index mediates the obesity-related hypertension.

METHODS AND RESULTS

A prospective cohort study, including 10,309 subjects without hypertension at baseline, was conducted in 2007-2008 and followed up in 2013-2014. TyG index was calculated as Ln[fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. Logistic regression model was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs). Mediation analysis was performed to examine the contribution of the TyG index to the association of obesity-hypertension incidence. During a median follow-up of 6 years, 2073 subjects developed hypertension. In multivariate logistic model adjusted for age, sex, alcohol drinking, smoking, physical activity and education, monthly income, family history of hypertension, TC, and HDL-C, the risk of hypertension was 1.14 (1.07-1.22) for per-SD increase in TyG. After additional controlling for obesity, this association was nonsignificant (1.06, 0.99-1.13) and (1.05, 0.99-1.13) for BMI and WC, respectively. Increasing trends were found for hypertension incidence as the TyG change increased, with or without adjustment for obesity (all P_trend < 0.05). With per-SD increment in TyG change, the risks of hypertension incidence were 1.14 (1.07-1.22) for absolute TyG change, and 1.15 (1.08-1.22) for relative TyG change in multivariate logistic model; the results were significant after further adjustment for BMI or WC, respectively. The TyG index partially mediated the obesity-incident hypertension association: 6.84% for BMI and 6.68% for WC, respectively.

CONCLUSIONS

Elevated TyG index and its dynamic change were positively associated with risk of incident hypertension in rural Chinese population, and the TyG index may play a partially mediating role in obesity-related incident hypertension.

Effect of Two-Only-Meal Frequency and Exercise on HbA1C Outcomes, Weight, and Anti-Diabetic Medication in Type 2 Diabetes in a Popular Lifestyle Change Campaign in Maharashtra, Compared to Conventional Clinical Management: A Quasi-Experimental Multicenter Study in Maharashtra

Background

Rising prevalence and poor outcomes make the twin challenges of diabetes epidemiology. This study evaluates effect of 2-only-daily-meals with exercise (2-OMEX) for its effect on HbA1c, oral hypoglycaemic agents (OHA) usage, body-weight among type-2-diabetes (T2DM) subjects, compared with conventional management.

Material and Methods

A quasi-experimental, multicentre study in 2-OMEX arm, and HbA1c by HPLC method. HbA1c and body-weight changes were analyzed by 'Difference in Difference' (DID) method. Meal frequency, exercise, energy intakes were based on recall. The required sample size was 20X2 for 1.1 difference in HbA1c with 95% CL and 80% power.

Results

Socio-demographic and risk profile of analysed and omitted subjects were similar. Studied arms were also similar in baseline features. The results in 2-OMEX and conventional arm are: complete records analyzed 201 and 120. Mean (sd) values as follows: observation days 234 and 236, age 52.03(8.84) and 52.45(9.48) years (P=0.6977), diabetes duration 4.6(3.05) and 4.9(2.97) years, BMI 27.28(5.27), 26.90(3.74) (P = 0.1859), baseline HbA1c gm% 7.46(1.52) and 7.55(1.58), end-line proportion of subjects attaining HbA1c ≤6.5gm% was 35.3% and 19.2% (P=0.002), bodyweight loss 2.57% and 1.26%. OHA count 1.6 (1.23) and 2.7(1.06), (P=0.0003). In 2-OMEX arm log-normal HbA1c declined significantly by 0.94 (95%CI: 1.60 to - 0.56, p=0.0333), weight loss difference 0.96 kg, and statistically not significant (P=0.595). Two subjects in 2-OMEX arm showed partial remission. Mean baseline Kcal intakes in 2-OMEX arm, were 1200.4(F) and 1437.3(M) were significantly higher than conventional arm (F) and 1430 (M).

Conclusion

The 2-OMEX showed a sizeable and significant reduction in HbA1c and OHA use, in 7-months, with moderate intakes, compared to the conventional arm, possibly attributable to fewer insulin surges. More studies are required for its impact and pathways.

Calorie restriction remodels gut microbiota and suppresses tumorigenesis of colorectal cancer in mice

Colorectal cancer (CRC) is one of the most common cancers worldwide and the consumption of a high-calorie diet is one of its risk factors. Calorie restriction (CR) slows tumor growth in a variety of cancers, including colorectal cancer; however, the mechanism behind this remains unknown. In the present study, CR effectively reduced the tumor volume and weight in a xenograft BALB/c male nude mouse model. In addition, tumor immunohistochemistry revealed that the CR group had significantly higher expression of Bax (P<0.001) and significantly lower levels of Bcl2 (P<0.0001) and Ki67 (P<0.001) compared with control group. Furthermore, data from 16S ribosomal (r)RNA sequencing implied that CR was able to reprogram the microbiota structure, characterized by increased Lactobacillus constituent ratio (P<0.05), with amelioration of microbial dysbiosis caused by CRC. Further receiver operating characteristic curves demonstrated that the bacteria Bacteroides [area under the curve (AUC)=0.800], Lactobacillus (AUC=0.760) and Roseburia (AUC=0.720) served key roles in suppression of CRC in the mouse model. The functional prediction of intestinal flora indicated 'cyanoamino acid metabolism' (P<0.01), 'replication initiation protein REP (rolling circle plasmid replication)' (P<0.01), 'tRNA G10 N-methylase Trm11' (P<0.01) and 'uncharacterized protein with cyclophilin fold, contains DUF369 domain' (P<0.05) were downregulated in CR group. These findings implied that CR suppressed CRC in mice and altered the gut microbiota.

Dietary Plant Protein Intake Can Reduce Maternal Insulin Resistance during Pregnancy

Evidence suggests that the source of dietary protein may have an impact on insulin resistance, but no studies have explored it in pregnant populations. In this study, we combined a population study and an animal experiment to explore this effect. The population study was conducted with data from NHANES. Multiple linear regression was used to observe the association of protein intake with outcomes, including fasting glucose (GLU), insulin (INS), and HOMA-IR. In the animal experiment, 36 pregnant SD rats in three groups were orally administered 100% animal protein, 50% animal protein and 50% plant protein, or 100% plant protein, respectively. The intervention continued throughout the whole pregnancy. On day 19.5, maternal plasma was collected after overnight fasting, and metabolomics was performed using UPLC-MS. We found plant protein intake was negatively correlated with INS and HOMA-IR in the whole population. During the third trimester, a similar correlation was also observed. The animal experiment also presented the same result. In metabolomic analysis, changes in various metabolites and related pathways including FoxO and mTOR signaling pathways were observed. In conclusion, we found a negative association between dietary plant protein intake and maternal insulin resistance during pregnancy. Changes in some active substances and related metabolic pathways may play an important role.

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.

Epigenome Modulation Induced by Ketogenic Diets

Ketogenic diets (KD) are dietary strategies low in carbohydrates, normal in protein, and high, normal, or reduced in fat with or without (Very Low-Calories Ketogenic Diet, VLCKD) a reduced caloric intake. KDs have been shown to be useful in the treatment of obesity, metabolic diseases and related disorders, neurological diseases, and various pathological conditions such as cancer, nonalcoholic liver disease, and chronic pain. Several studies have investigated the intracellular metabolic pathways that contribute to the beneficial effects of these diets. Although epigenetic changes are among the most important determinants of an organism’s ability to adapt to environmental changes, data on the epigenetic changes associated with these dietary pathways are still limited. This review provides an overview of the major epigenetic changes associated with KDs.

Addition of grapes to both a standard and a high-fat Western pattern diet modifies hepatic and urinary metabolite profiles in the mouse

The benefits of fruit and vegetable dietary consumption are largely defined in epidemiological terms. Relatively little is known about the discrete effects on metabolic pathways elicited by individual dietary fruits and vegetables. To address this, grape powder was added to both a standard and a high-fat Western pattern diet given to 10-week-old female C57BL/6J mice for a period of 91 days, whereupon 24 h urines were collected and the mice euthanized after a 12 h fast for the collection of liver tissue. Alterations in hepatic and urinary metabolite patterns were determined by gas chromatography-mass spectrometry-based metabolomics. Urinary excretion of the gut microbiota metabolites 4-hydroxyphenylacetic acid, 5-hydroxyindole, glyceric acid, gluconic acid and myo-inositol was attenuated when grape was added to the standard diet but the gut microbiota metabolites gluconic acid, scyllo-inositol, mannitol, xylitol, 5-hydroxyindole and 2-deoxyribonic acid were increased in urine when grape was added to the high-fat diet. Increased hepatic ascorbic acid and 5-oxoproline levels indicated the anti-oxidant effect of grape powder on the liver. Pathway enrichment analysis demonstrated that for both standard and high-fat diets, grape addition significantly upregulated the malate-aspartate shuttle indicating enhanced hepatic utilization of glucose via cytosolic glycolysis for mitochondrial ATP production. It is concluded that a grape diet reprogrammes gut microbiota metabolism, attenuates the hepatic oxidative stress of a high-fat diet and increases the efficiency of glucose utilization by the liver for energy production.

Circadian Synchrony: Sleep, Nutrition, and Physical Activity

The circadian clock in mammals regulates the sleep/wake cycle and many associated behavioral and physiological processes. The cellular clock mechanism involves a transcriptional negative feedback loop that gives rise to circadian rhythms in gene expression with an approximately 24-h periodicity. To maintain system robustness, clocks throughout the body must be synchronized and their functions coordinated. In mammals, the master clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is entrained to the light/dark cycle through photic signal transduction and subsequent induction of core clock gene expression. The SCN in turn relays the time-of-day information to clocks in peripheral tissues. While the SCN is highly responsive to photic cues, peripheral clocks are more sensitive to non-photic resetting cues such as nutrients, body temperature, and neuroendocrine hormones. For example, feeding/fasting and physical activity can entrain peripheral clocks through signaling pathways and subsequent regulation of core clock genes and proteins. As such, timing of food intake and physical activity matters. In an ideal world, the sleep/wake and feeding/fasting cycles are synchronized to the light/dark cycle. However, asynchronous environmental cues, such as those experienced by shift workers and frequent travelers, often lead to misalignment between the master and peripheral clocks. Emerging evidence suggests that the resulting circadian disruption is associated with various diseases and chronic conditions that cause further circadian desynchrony and accelerate disease progression. In this review, we discuss how sleep, nutrition, and physical activity synchronize circadian clocks and how chronomedicine may offer novel strategies for disease intervention.

Circadian Synchrony: Sleep, Nutrition, and Physical Activity

The circadian clock in mammals regulates the sleep/wake cycle and many associated behavioral and physiological processes. The cellular clock mechanism involves a transcriptional negative feedback loop that gives rise to circadian rhythms in gene expression with an approximately 24-h periodicity. To maintain system robustness, clocks throughout the body must be synchronized and their functions coordinated. In mammals, the master clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is entrained to the light/dark cycle through photic signal transduction and subsequent induction of core clock gene expression. The SCN in turn relays the time-of-day information to clocks in peripheral tissues. While the SCN is highly responsive to photic cues, peripheral clocks are more sensitive to non-photic resetting cues such as nutrients, body temperature, and neuroendocrine hormones. For example, feeding/fasting and physical activity can entrain peripheral clocks through signaling pathways and subsequent regulation of core clock genes and proteins. As such, timing of food intake and physical activity matters. In an ideal world, the sleep/wake and feeding/fasting cycles are synchronized to the light/dark cycle. However, asynchronous environmental cues, such as those experienced by shift workers and frequent travelers, often lead to misalignment between the master and peripheral clocks. Emerging evidence suggests that the resulting circadian disruption is associated with various diseases and chronic conditions that cause further circadian desynchrony and accelerate disease progression. In this review, we discuss how sleep, nutrition, and physical activity synchronize circadian clocks and how chronomedicine may offer novel strategies for disease intervention.

Prediabetes: how pathophysiology drives potential intervention on a subclinical disease with feared clinical consequences

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder whose rising incidence suggests the epidemic proportions of the disease. Impaired Fasting Glucose (IFG) and Impaired Glucose Tolerance (IGT) - alone or combined - represent two intermediate metabolic condition between Normal Glucose Tolerance (NGT) and overt T2DM. Several studies have demonstrated that insulin resistance and beta-cell impairment can be identified even in normoglycemic prediabetic individuals. Worsening of these two conditions may lead to progression of IGT and/or IFG status to overt diabetes. Starting from these assumptions, it seems logical to suppose that interventions aimed at improving metabolic conditions, even in prediabetes, could represent an effective target to halt transition from IGT/IFG to manifest T2DM. Starting from pathophysiological knowledge, in this review we evaluate two possible interventions (lifestyle modifications and pharmacological agents) eligible as prediabetes therapy since they have been demonstrated to improve insulin resistance and beta-cell impairment. Detecting high-risk people and treating them could represent an effective strategy to slow down progression to overt diabetes, normalize glucose tolerance, and even prevent micro- and macrovascular complications.