12-h Fast Research Articles

PSXIV-3 3-Nitrooxypropanol Dosages to Reduce Methane Emission By Feedlot Beef Cattle

Abstract Our objective was to evaluate the effects of 3-nitrooxypropanol (3-NOP, Bovaer, DSM Nutritional Products) at different levels in feedlot beef cattle diets on productive performance, biological efficiency, and methane (CH4) emissions. Thirty Nellore bulls (iBW, 407 ± 6 kg) were randomly assigned to three treatments with ten replicates (animal) per treatment. The animals were fed a high-concentrate feedlot diet for 87 days, according to the three treatments: 1) 0, Control (no addition of 3-NOP); 2) Bovaer75 (75 mg/kg DM of 3-NOP), 3) Bovaer100 (100 mg/kg DM of 3-NOP,). Gas emissions (CH4 and H2) were evaluated individually using the GreenFeed unit (C-Lock, USA), while the variables of dry matter intake (DMI) were evaluated using digital feeders (Intergado System, Brazil). Body weights of yearling bulls were recorded after 16-h fasting at the beginning and end of the experiment. Data were submitted to be analyzed using PROC MIXED from SAS 9.4, evaluated by orthogonal contrasts, with a significance level of 5%. Initial BW was used as a covariate when significant to adjust the statistic model. No differences on DMI (kg/d and %BW, P = 0.323) were observed between control animals and those fed with Bovaer. Animals fed with Bovaer75 had greater ADG than control and Bovaer100, (1.73 vs. 1.63 and 1.60 kg/d; P = 0.038 and P = 0.025, respectively) and better biological efficiency than control (⁓127.0 vs 135.3 kg DMI/15 kg carcass produced, P < 0.023). A similar result was observed for carcass gain, in which animals supplemented with Bovaer 75 had greater gains than the control. Animals fed 75 and 100 mg/kg DM of Bovaer emitted respectively 33.7% and 42.7% less methane per se (g/d, P < 0.01) compared with control, and additionally produced more hydrogen (P < 0.01) vs control. There were significant reductions in the measured methane yield in relation to DMI (CH4: DMI, P < 0.01) and methane intensity (CH4/ADG, P < 0.01) for animals fed the two levels of Bovaer, in comparison with the control, as well as a significant difference in the reduction of CH4 in relation to the biological efficiency for the animals fed with Bovaer (P < 0.01). We conclude that feeding Bovaer consistently reduces methane emission from feedlot cattle, in which the reduction intensity increased over the dosages evaluated in the current study.

343 Combination of Feed Additives to Reduce Methane Emissions and Increase Performance By Feedlot Cattle

Abstract Our objective was to evaluate the effects of 3-Nitrooxypropanol (3-NOP) associated with different feed additives on performance, carcass characteristics and enteric methane (CH4) emissions. Twenty-seven Nellore bulls (initial BW, 410 ± 6 kg) were randomly allocated to three treatments with nine replicates per treatment (animal as experimental unit). The animals were fed a high-concentrate feedlot diet (R:C, 10:90) for 102 days, according with the following three treatments: 1) Control (CTRL): Sodium Monensin (26 mg/kg DM); 2) BOV: Control + 3-NOP (Bovaer;100 mg/kg DM); 3) BOVPERF (Bovaer Performance pack): Control + 3-NOP (100 mg/kg DM) + Essential oils (Crina Ruminants, 100 mg/kg DM) + 25-OH-Vitamin D3 (Hy-D, 0.10 mg/kg DM) + carbo-amino-phospho-chelate of chromium and zinc (0.4 and 60 mg/kg of DM, respectively). The gases emissions (CH4 and H2) and DMI variables were assessed individually, by using the GreenFeed and Intergado electronic system placed in the feedlot pen, respectively. The BW of Yearling bulls were recorded at the beginning and final of the experiment after 16-h fasting (Table). Data were analyzed by ANOVA using the PROC MIXED of SAS 9.4, in which means comparison were evaluated by Tukey test at P < 0.05. Feeding BOVPERF increased DM intake during adaptation period (P = 0.04), and over the total period (P < 0.01) compared with control with no difference on feed efficiency (P =0.61). There was no difference (P > 0.05) on DMI between CTRL and BOV. Animals fed BOVPERF had greater HCW (+13 kg, P = 0.04) and greater carcass ADG (+120 g/d, P = 0.04) compared with CTRL. Animals fed BOV and BOVPERF emitted 39% less CH4 (P < 0.01) and produced 292% more H2 (P < 0.01) compared with CTRL. In addition, there were significant reductions in methane intensity, as measured by the ratios CH4/kg DM (-42%; P < 0.01), and CH4/kg carcass ADG (-41.13%; P < 0.01) for animals fed with BOV and BOVPERF compared with CTRL. We conclude that feeding Bovaer performance pack reduces methane emissions and increases carcass production in feedlot beef cattle.

272 The Effect of Increasing Standardized Ileal Digestible Methionine Intake on Whole-Body Nitrogen Retention and Plasma Amino Acids, Homocysteine, and Glutathione of Gilts in Late Gestation

Abstract Gestating gilts (n = 70; 166 ± 13 kg initial body weight at d 31 of gestation) were used to determine the dietary standardized ileal digestible (SID) Methionine (Met) content required to optimize whole-body nitrogen (N) retention versus the appearance of biomolecules derived via Met metabolism. On d 102 of gestation, gilts were randomly assigned to one of seven dietary treatments that provided between 50 and 150% of estimated SID Met requirements for late gestation gilts (0.10 to 0.30% SID Met). All other indispensable amino acids were supplied at least 20% above estimated requirements (NRC, 2012). A N balance (total urine collection and fecal grab sampling) was conducted for each gilt between days 109 and 112 of gestation, blood samples were collected on day 109 after a 24-h fasting period for analyses of plasma amino acids, homocysteine (Hcys), and reduced glutathione (GSH). Contrast statements were used to determine linear and quadratic effects of dietary SID Met levels. Linear and quadratic broken-line and polynomial quadratic models were used to determine the optimum level of SID Met for whole-body N retention and plasma concentrations of Hcys and GSH. Whole-body N retention increased with increasing dietary Met (linear and quadratic; P < 0.001; Table 1). Plasma concentrations of Hcys increased with increasing dietary Met (linear; P < 0.05). Glutathione tended to decrease and then increase at dietary SID Met greater than 0.20% (quadratic; P = 0.061; Table 2). Plasma glutamine increased with increasing dietary SID Met (linear; P < 0.01). Histidine increased then decreased at dietary SID Met greater than 0.20% (quadratic; P < 0.05), other amino acids were not influenced by dietary treatment. Linear and quadratic broken-line models described a lower breaking point for whole-body N retention, plasma Hcys, and plasma GSH compared with the quadratic polynomial model (0.154% and 0.155% vs. 0.226%, 0.185% and 0.188% vs. 0.328%, and 0.114% and 0.124% vs. 0.224% SID Met, respectively). The Bayesian information criterion (BIC) indicated that the quadratic polynomial model best fit the data versus the linear and quadratic broken-line models for plasma GSH (BIC 317.9 vs. 320.3 and 322.6, respectively; Graphic 1). However, the fits were similar among models for whole-body N retention (BIC 385.2 vs. 384.6 and 386.9, respectively; Graphic 2) and Hcys (BIC 465.5 vs. 465.6 and 467.9, respectively; Graphic 3). Based on the best fit (quadratic polynomial) model 0.226% SID Met is required to optimize whole-body N retention for late gestation gilts which is greater than that recommended by the NRC (2012; 0.20% SID Met). It appears that gilts have further capacity for Met transmethylation since the plasma Hcys breakpoint occurred at a greater dietary SID Met level than for whole-body N retention, though the impact on transsulfuration and remethylation pathways cannot be discounted. Therefore, greater feeding levels of SID Met might be required to maximize both protein and non-protein utilization of Met.

The impact of food stimuli and fasting on cognitive control in task switching.

Previous research demonstrated motivation-control interactions in task switching. However, motivational effects on switch costs have been mostly examined using monetary rewards. Here, we investigated whether stimulus material linked to food and fasting affect control processes in task switching. We predicted that switching to the task comprising food stimuli would be facilitated, which should result in lower switch costs for this task, and that these effects would be stronger with higher motivational salience of the food stimuli, i.e. in hungry individuals and/or individuals with restrictive eating. Participants switched between categorising food items as sweet or savoury and digits as odd or even in two task-switching paradigms: an alternating runs and a voluntary task switching. Hunger was induced by 14h fasting in the experimental compared to the control group. Results showed lower switch costs for the motivational-affective food task in both task-switching paradigms and in both groups. Switch costs for the neutral digit task were significantly higher in the fasting group compared to the control group in alternating runs task switching only. Individual differences in restrictive eating were related negatively but not significantly to the size of the switch costs. All in all, the results demonstrate an impact of motivational-affective stimuli on cognitive control in task switching and suggest a potential modulatory role of motivational states, though the findings need to be replicated.

Chromium propionate in turkeys: effects on insulin sensitivity

The objective of this study was to evaluate the effects of dietary chromium (Cr), as Cr propionate (Cr Prop), on measures of insulin sensitivity in turkeys. Plasma glucose and nonesterified fatty acid (NEFA), and liver glycogen concentrations were used as indicators of insulin sensitivity. One-day-old Nicholas Large White female poults (n=336) were randomly assigned to dietary treatments consisting of 0 (control), 0.2, 0.4, or 0.6 mg supplemental Cr/kg diet. Each treatment consisted of 12 replicate cages with 7 turkeys per cage. Final BW were taken on d 34, and on d 35 two birds from each cage were sampled for plasma glucose and NEFA, and liver glycogen determination at the initiation (fed state) and termination (fasted state) of a 24-h fast. Following a 24-h fast, 2 turkeys per cage were refed (refed state) their treatment diet for 4 h, and then harvested. Feed/gain and ADG did not differ between control and Cr-supplemented turkeys over the 34-d study, but feed intake tended (P=0.071) to be greater for controls than turkeys receiving 0.4 mg Cr/kg diet. Fed turkeys had greater plasma glucose (P=0.002) and liver glycogen (P=0.001) concentrations, and lower (P=0.001) NEFA concentrations than fasted birds. Turkeys refed after fasting had greater (P=0.001) plasma glucose and liver glycogen concentrations, and lower (P=0.001) plasma NEFA levels than fed turkeys. Liver glycogen and plasma NEFA concentrations did not differ among control and Cr-supplemented birds in the fed, fasted, or refed state. Plasma glucose concentrations were not affected by treatment in fed or fasted turkeys. Turkeys supplemented with 0.2 or 0.4 mg Cr/kg and refed after fasting had lower (quadratic, P=0.038) plasma glucose concentrations than controls. Plasma glucose concentrations in refed birds did not differ among Cr-supplemented turkeys. The lower plasma glucose concentration in Cr-supplemented turkeys following refeeding is consistent with Cr enhancing insulin sensitivity.

Functional and molecular profiling of fasted piglets reveals decreased energy metabolic function and cell proliferation in the small intestine.

The small intestine requires energy to exert its important role in nutrient uptake and barrier function. Pigs are an important source of food and a model for humans. Young piglets and infants can suffer from periods of insufficient food intake. Whether this functionally affects the small intestinal epithelial cell (IEC) metabolic capacity and how this may be associated with an increased vulnerability to intestinal disease is unknown. We therefore performed a 48-h fasting intervention in young piglets. After feeding a standard weaning diet for 2 wk, 6-wk-old piglets (n = 16/group) were fasted for 48 h, and midjejunal IECs were collected upon euthanasia. Functional metabolism of isolated IECs was analyzed with the Seahorse XF analyzer and gene expression was assessed using RNA-sequencing. Fasting decreased the mitochondrial and glycolytic function of the IECs by 50% and 45%, respectively (P < 0.0001), signifying that overall metabolic function was decreased. The RNA-sequencing results corroborated our functional metabolic measurements, showing that particularly pathways related to mitochondrial energy production were decreased. Besides oxidative metabolic pathways, decreased cell-cycle progression pathways were most regulated in the fasted piglets, which were confirmed by 43% reduction of Ki67-stained cells (P < 0.05). Finally, the expression of barrier function genes was reduced upon fasting. In conclusion, we found that the decreased IEC energy metabolic function in response to fasting is supported by a decreased gene expression of mitochondrial pathways and is likely linked to the observed decreased intestinal cell proliferation and barrier function, providing insight into the vulnerability of piglets, and infants, to decreased food intake.NEW & NOTEWORTHY Fasting is identified as one of the underlying causes potentiating diarrhea development, both in piglets and humans. With this study, we demonstrate that fasting decreases the metabolism of intestinal epithelial cells, on a functional and transcriptional level. Transcriptional and histological data also show decreased intestinal cell proliferation. As such, fasting-induced intestinal energy shortage could contribute to intestinal dysfunction upon fasting.

Nutrient sensing: LEAP2 concentration in response to fasting, glucose, lactate, and β-hydroxybutyrate in healthy young males

BackgroundThe appetite-suppressing potential of liver-expressed antimicrobial peptide 2 (LEAP2), and its antagonistic effects on the hunger-inducing hormone ghrelin have attracted scientific interest. It is unclear how LEAP2 is influenced by fasting and how it responds to specific nutrients. ObjectivesThe purpose of this investigation was to assess whether LEAP2 concentration 1) decreases after fasting, 2) increases postprandially, and 3) is regulated by nutrient sensing in the splanchnic bed. MethodsPlasma LEAP2 concentration was measured in blood samples from 5 clinical cross-over trials, following 1) 36 h of fasting (n = 8), 2) 10 h of fasting (n = 37, baseline data pooled from 4 of the clinical trials), 3) Oral and intravenous glucose administration (n = 11), 4) Oral and intravenous Na-lactate administration (n = 10), and 5) Oral and intravenous Na-β-hydroxybutyrate (BHB) administration (n = 8). All 5 trials included healthy males. ResultsCompared with a 10-h fasting period, the median LEAP2 concentration was 38% lower following 36 h of fasting (P < 0.001). Oral administration of glucose elevated, whereas intravenous glucose administration lowered LEAP2 concentration (intervention x time, P = 0.001), resulting in a mean difference of 9 ng/mL (95% confidence interval [CI]: 1, 17) after 120 min. Oral lactate increased, and intravenous lactate decreased LEAP2 (intervention x time, P = 0.007), with a mean difference between interventions of 10 ng/mL (95% CI: 6, 15) after 120 min. In contrast, oral and intravenous administration of BHB reduced the LEAP2 concentration (main effect of time, P < 0.001). ConclusionsOur investigations show that LEAP2 concentration was lower after a 36-h fast than an overnight fast and that oral delivery of glucose and lactate elevated LEAP2 concentration compared with intravenous administration, whereas LEAP2 concentrations decreased with both oral and intravenous BHB. This indicates that the LEAP2 concentration is sensitive to intestinal exposure to specific substrates, highlighting the need for future studies exploring the relationship between nutrients and LEAP2.This trial was registered at clinicaltrials.gov as NCT01840098, NCT03204877, NCT04299815, NCT03935841, and NCT01705782.

The impact of prolonged fasting on 24h energy metabolism and its 24h rhythmicity in healthy, lean males: A randomized cross-over trial

Human energy expenditure and substrate oxidation are under circadian control and food intake is a time cue for the human biological clock, leading to 24h feeding-fasting cycles in energy and substrate metabolism. In recent years, (intermittent) fasting protocols have also become popular to improve metabolic health. Here, we aimed to investigate the impact of food intake on the 24h patterns of energy metabolism as well as to provide data on the timeline of changes in energy metabolism that occur upon an extended period of fasting. In a randomized, cross-over design, twelve healthy males underwent a 60h fast which was compared to a 60h fed condition. In the fed condition meals were provided at energy balance throughout the study. Conditions were separated by a two week period of habitual diet. Volunteers resided in a respiration chamber for the entire 60h to measure energy expenditure and substrate oxidation hour by hour. Volunteers performed a standardized activity protocol while in the chamber. Blood samples were drawn after 12, 36 and 60h. Immediately following the breakfast meal (in the fed condition), fat oxidation became higher in the fasted condition compared to the fed condition and remained elevated throughout the study period. The initial rapid increase in fat oxidation corresponded with a decline in the hepatokine activin A (r=-0.86, p=0.001). The contribution of fat oxidation to total energy expenditure gradually increased with extended abstinence from food, peaking after 51h of fasting at 160mg/min. Carbohydrate oxidation stabilized at a low level during the second day of fasting and averaged around 60mg/min with only modest elevations in response to physical activity. Although 24h energy expenditure was significantly lower with prolonged fasting (11.0±0.4 vs 9.8±0.2 and 10.9±0.3 vs 10.3±0.3MJ in fed vs fasting, day 2 and 3 respectively, p<0.01), the 24h fluctuations in energy expenditure were comparable between the fasted and fed condition. The fluctuations in substrate oxidation were, however, significantly (p<0.001 for both carbohydrate and fat oxidation) altered in the fasted state, favouring fat oxidation. Energy expenditure displays a day-night rhythm, which is independent of food intake. In contrast, the day-night rhythm of both carbohydrate and fat oxidation is mainly driven by food intake. Upon extended fasting, the absolute rate of fat oxidation rapidly increases and keeps increasing during a 60h fast, whereas carbohydrate oxidation becomes progressively diminished. www.trialregister.nl NTR 2042.

Metabolic effects of an oral carbohydrate–whey protein supplement after fasting in volunteers: A randomized controlled crossover trial

ObjectiveOral supplements containing carbohydrates (CHOs) can be used to reduce preoperative fasting time. The aim of this study was to investigate the early metabolic and acute phase responses to a clear, oral supplement containing CHO and whey protein (WP) in young, healthy volunteers during a fasting-induced organic response. MethodsIn this controlled crossover clinical trial, volunteers were randomized into groups after a 12-h fast: the CHO+WP group consumed 200 mL CHO enriched with WP (n = 30); the CHO group members consumed 200 mL water plus maltodextrin (n = 30), and the Fast group was fasted only (n = 30). Blood samples were collected after fasting and 3 h after ingestion of the supplement. The samples were analyzed for glucose, glycated hemoglobin, insulin, C-reactive protein, β-hydroxybutyrate, triacylglycerols, albumin, chlorine, and sodium. After 7 d, the groups were inverted, so all volunteers entered the three groups. ResultsThe nutritional intervention did not change the biochemical parameters related to the acute phase response or insulin resistance; however, there was a statistically significant reduction (P < 0.001) in serum β-hydroxybutyrate in the CHO+WP group (0.05 ± 0.08 mmol/L) compared with the other two groups (Fast group: 0.11 ± 0.08 mmol/L; CHO group: 0.09 ± 0.13 mmol/L). ConclusionsAfter overnight fasting, the oral supplement containing CHO and WP decreased ketosis. These findings may help select the most efficient oral supplement to be given 2 to 3 h before elective surgeries.

Effect of Home-based Aerobic Exercise on Leukocyte TERT Gene Expression Without Altering DNA Oxidative Damage in Postmenopausal Women

Objectives: In middle-aged women, the postmenopausal period is associated with increased oxidative, inflammatory, and psychological stress. We intend to investigate the effect of home-based aerobic exercise (HAE) on serum levels of 8-hydroxy-2’-deoxyguanosine (8-C) and the expression of telomerase reverse transcriptase (TERT) in leukocytes of postmenopausal women. Methods: A total of 20 sedentary postmenopausal women who had at least 12 months passed since their last menstruation participated in the study voluntarily. Their Mean±SD age, height, weight, and body mass index (BMI) were respectively 52.4±3.8 years, 161.4±3.7 cm, 74.4±6.8 kg, and 28.6±3.4 kg/m2 . They were randomly divided into two groups: Home-based aerobic exercise (HAE, n=10) and inactive control (CON, n=10). HAE group undertook 4 weeks of home-based aerobic exercise (4 d/wk, intensity: 70%-80% maximal heart rate) with online supervision. Participants’ weight and fasting blood samples (12-h fasting state) were measured and taken before and 48 hours after the intervention. TERT expression in blood leukocytes and serum levels of 8-OHDG were assessed by real-time PCR and ELISA methods, respectively. The collected data were analyzed using mixed (2×2) repeated measure ANOVA and independent samples t-test in SPSS software. A significance level of P&lt;0.05 was considered for all tests. Results: The findings showed that 4 weeks of HAE increased TERT expression significantly compared to the CON (ES=0.40, P&lt;0.05). Although 8-OHDG serum level in the HAE group increased following training compared to pre-training (P&lt;0.05), no significant difference was observed between the CON and HAE groups (P&gt;0.05). Also, the interaction effect on 8-OHDG was not significant (ES=0.11, P&gt;0.05). In addition, after 4 weeks of HAE, body weight and BMI significantly decreased in the training group compared to the control (P&lt;0.05). Discussion: According to these findings, HEA effectively reduces telomere erosion and improves weight control in postmenopausal women.

Intermittent fasting and changes in clinical risk scores: Secondary analysis of a randomized controlled trial

BackgroundIntermittent fasting may increase longevity and lower cardiometabolic risk. This study evaluated whether fasting modifies clinical risk scores for mortality [i.e., Intermountain Mortality Risk Score (IMRS)] or chronic diseases [e.g., Pooled Cohort Risk Equations (PCRE), Intermountain Chronic Disease score (ICHRON)]. Methods and resultsSubjects (N = 71) completing the WONDERFUL trial were aged 21–70 years, had ≥1 metabolic syndrome criteria, elevated cholesterol, and no anti-diabetes medications, statins, or chronic diseases. The intermittent fasting arm underwent 24-h water-only fasting twice-per-week for 4 weeks and once-per-week for 22 weeks (26 weeks total). Analyses examined the IMRS change score at 26 weeks vs. baseline between intermittent fasting (n = 38) and ad libitum controls (n = 33), and change scores for PCRE, ICHRON, HOMA-IR, and a metabolic syndrome score (MSS). Age averaged 49 years; 65% were female. Intermittent fasting increased IMRS (0.78 ± 2.14 vs. controls: −0.61 ± 2.56; p = 0.010) but interacted with baseline IMRS (p-interaction = 0.010) to reduce HOMA-IR (but not MSS) more in subjects with higher baseline IMRS (median HOMA-IR change: fasters, −0.95; controls, +0.05) vs. lower baseline IMRS (−0.29 vs. −0.32, respectively). Intermittent fasting reduced ICHRON (−0.92 ± 2.96 vs. 0.58 ± 3.07; p = 0.035) and tended to reduce PCRE (−0.20 ± 0.22 vs. −0.14 ± 0.21; p = 0.054). ConclusionsIntermittent fasting increased 1-year IMRS mortality risk, but decreased 10-year chronic disease risk (PCRE and ICHRON). It also reduced HOMA-IR more in subjects with higher baseline IMRS. Increased IMRS suggests fasting may elevate short-term mortality risk as a central trigger for myriad physiological responses that elicit long-term health improvements. Increased IMRS may also reveal short-term fasting-induced safety concerns.

Influence of acute fasting on pain tolerance in healthy subjects: a randomised crossover study.

Although chronic pain and obesity are global health crises with substantial healthcare costs, little is known about the relationship between pain perception and eating behaviours. Food consumption has been reported to provide an analgesic effect by the release of neurotransmitters modulating the pain network. However, whether short-term (acute) fasting affects pain perception remains unclear. This study aimed to investigate the effect of acute fasting on pain perception and whether attention and mood changes drove the observed changes. The cold pressor test (CPT) was used to investigate the pain tolerance of 25 healthy participants in both non-fasting and 12-h fasting sessions. They were randomised to either session with a crossover to the other after at least 24 h, with the experimenter blinded to the sessions. The pain tolerance was measured using a Stroop task in both attentive and distracted states. The Profile of Mood States (POMS) questionnaire was used to capture the mood, and a 10-point hunger scale was used to measure hunger. Mixed-effects models were used to investigate the influence of fasting and distraction on pain perception, accounting for the repeated measures. Fasting reduced CPT pain tolerance, with fasting participants twice as likely to withdraw their hands early (hazard ratio = 2.4, 95% CI: 1.3-4.5). Though men tolerated CPT pain longer than women, there was no evidence that men responded to fasting differently than women (p = 0.9). In addition, no evidence supporting that fasting affected attention or mood was found. Nonetheless, it increased hunger scores by 2.7 points on a 10-point scale (95% CI: 1.2-4.2) and decreased blood glucose concentration levels by 0.51 mmol/L (95% CI: 0.19-0.84). Acute fasting reduces pain tolerance in the healthy participants, and this effect is independent of gender and attention or mood changes.

A single 36-h water-only fast vastly remodels the plasma lipidome.

Prolonged fasting, characterized by restricting caloric intake for 24 h or more, has garnered attention as a nutritional approach to improve lifespan and support healthy aging. Previous research from our group showed that a single bout of 36-h water-only fasting in humans resulted in a distinct metabolomic signature in plasma and increased levels of bioactive metabolites, which improved macrophage function and lifespan in C. elegans. This secondary outcome analysis aimed to investigate changes in the plasma lipidome associated with prolonged fasting and explore any potential links with markers of cardiometabolic health and aging. We conducted a controlled pilot study with 20 male and female participants (mean age, 27.5 ± 4.4 years; mean BMI, 24.3 ± 3.1 kg/m2) in four metabolic states: (1) overnight fasted (baseline), (2) 2-h postprandial fed state (fed), (3) 36-h fasted state (fasted), and (4) 2-h postprandial refed state 12 h after the 36-h fast (refed). Plasma lipidomic profiles were analyzed using liquid chromatography and electrospray ionization mass spectrometry. Several lipid classes, including lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylethanolamine, and triacylglycerol were significantly reduced in the 36-h fasted state, while free fatty acids, ceramides, and sphingomyelin were significantly increased compared to overnight fast and fed states (P < 0.05). After correction for multiple testing, 245 out of 832 lipid species were significantly altered in the fasted state compared to baseline (P < 0.05). Random forest models revealed that several lipid species, such as LPE(18:1), LPC(18:2), and FFA(20:1) were important features in discriminating the fasted state from both the overnight fasted and postprandial state. Our findings indicate that prolonged fasting vastly remodels the plasma lipidome and markedly alters the concentrations of several lipid species, which may be sensitive biomarkers of prolonged fasting. These changes in lipid metabolism during prolonged fasting have important implications for the management of cardiometabolic health and healthy aging, and warrant further exploration and validation in larger cohorts and different population groups.

Short-term fasting affects biomarkers of creatine metabolism in healthy men and women

We studied the effects of 24-h fasting on serum levels of guanidinoacetic acid (GAA), creatine, and creatinine in 24 non-vegetarian healthy adults. Blood was taken before and following an intervention, with levels corrected for fasting-induced changes in plasma volume. Food abstention induced a significant decrease in serum GAA by 39.5% (p < 0.001), while creatinine levels increased by 14.7% (p < 0.01); the concentration of creatine remains unchanged. The reduction in GAA during fasting may indicate an increased demand for creatine production for this energy-demanding condition and/or potential kidney dysfunction which requires further exploration.

Not so fast: Paradoxically increased variability in the glucose tolerance test due to food withdrawal in continuous glucose-monitored mice

ObjectiveThis study was performed to determine the effect of fasting on reproducibility of the glucose tolerance test. Due to individual variation in animal feeding behaviors, fasting animals prior to metabolic and behavioral experiments is widely held to reduce inter-subject variation in glucose and metabolic parameters of preclinical rodent models. Reducing variability is especially important for studies where initial metabolite levels can influence the magnitude of experimental interventions, but fasting also imposes stress that may distort the variables of interest. One such intervention is the glucose tolerance test (GTT) which measures the maximum response and recovery following a bolus of exogenous glucose. We sought to investigate how fasting affects the response of individual mice to a GTT. MethodsUsing simultaneous continuous glucose monitoring (CGM) and indirect calorimetry, we quantified blood glucose, physical activity, body temperature, metabolic rates, and food consumption levels on a minute-to-minute basis in adult male mice for 4 weeks. We tested the effects of a 4-h or 18-h fast on the GTT to examine the effect of food withdrawal in light or dark photoperiods. Studies were also performed with 4-h fasting in additional mice without implanted CGM probes. ResultsContrary to our expectations, a 4-h fast during the light photoperiod promotes a paradoxical increase in inter-animal variation in metabolic rate, physical activity, body temperature, glycemia, and glucose tolerance. This hyperglycemic and hyper-metabolic phenotype promotes increased corticosterone levels and is consistent with a behavioral stress response to food deprivation, even in well-fed mice. We find that mice undergoing an 18-h fast entered torpor, a hibernation-like state. In addition to low body temperature and metabolic rate, torpor is also associated with glucose levels 56 mg/dl lower than those seen in mice with ad libitum access to food. Moreover, the time spent in torpor affects the response to a GTT. ConclusionOur results suggest fasting mice before glucose tolerance testing, and perhaps other experiments, can have the opposite of the intended effect where fasting can increase, rather than decrease, experimental variability.

Effects of alternate-day fasting and time-restricted feeding in obese middle-aged female rats

ObjectivesObesity is a multifactorial condition associated with metabolic alterations that can be aggravated during female aging. Calorie restriction via intermittent fasting (IF) diets may reduce body weight and therefore have the potential to decrease obesity and associated comorbidities, such as insulin resistance. This study investigated the effects of two IF protocols, alternate-day fasting (ADF) and time-restricted feeding (TRF) in middle-aged obese female rats. MethodsWistar rats (age 15 mo) were fed with standard chow or high-fat diet for 8 wk and then separated into the following groups (n = 5–8 each) for another 8 wk: control (received standard chow), obese (received high-fat diet), obese + ADF (24-h fasting protocol), and obese + TRF (14 h daily). ResultsAt the end of the study, both IF protocols were able to reduce body weight and body mass index compared with the obese group. However, no changes were observed in adiposity and glucose homeostasis. We also found an increase in total leukocytes, lymphocytes, and monocytes in the TRF group and a higher number of platelets in the ADF group. Blood lipid profiles, including triglycerides and high-density lipoprotein, as well as liver stress responses, such as heat shock protein 70 and malondialdehyde, were not changed by IF. ConclusionsAlthough ADF and TRF protocols resulted in a reduction of body weight and body mass index, these dietary interventions did not promote health benefits, such as reducing blood lipid profile, adiposity, and insulin resistance. In addition, ADF and TRF increased inflammatory biomarkers, which may increase the risk of obesity-associated comorbidities.

Licochalcone A promotes renewal of intestinal mucosa through modulating uc.173

Ethnopharmacological relevanceLicorice can nourish Pi (spleen) and thereby strengthening the digestive system according to the theory of traditional Chinese medicine. Licorice has been generally used in the compound prescription to treat intestinal inflammatory disease. Licochalcone A (Lico A) is one of the characteristic molecules from licorice. T-UCRs, which are transcribed from ultraconserved regions, are a new class of long noncoding RNAs related to the renewal of intestinal epithelial renewal. Aim of the studyThis study aimed to investigate the effect and the uc.173-related mechanism of Lico A on intestinal epithelial renewal. Materials and methodsIE-6 and Caco-2 cells were used to evaluate the effect of Lico A on apoptosis, proliferation, and migration of IECs. The intestinal organoid was used to investigate ex vivo effect and mechanism of Lico A promoting intestinal organoid development. C57BL/6J mice (both normal and uc.173-deficient ones) were used to examine the in vivo effect of Lico A on the renewal of intestinal mucosa. ResultsThe expression of three T-UCRs related to the intestinal mucosa renewal was altered in Lico A-treated IECs. Lico A promoted the proliferation and inhibited the apoptosis of IECs through uc.173/miR-195 pathway. The development of intestinal organoids and the renewal of intestinal mucosa of mice subjected to the 48-h FAST were all promoted by the treatment of Lico A. Moreover, the growth arrest of uc.173-deficient intestinal organoids and the atrophy of intestinal mucosa in uc.173-deficient mice could be rescued by the Lico A administration. ConclusionResults in this paper suggest that targeting T-UCRs may be the novel therapeutic approach for the promotion of epithelial regeneration, and through stimulating the regeneration of intestinal mucosa, Lico A may become a new therapeutic agent for the maintenance of intestinal epithelial integrity.

Novel approach using [18F]FTHA-PET and de novo synthesized VLDL for assessment of FFA metabolism in a rat model of diet induced NAFLD

The worldwide prevalence of Non-alcoholic Fatty Liver Disease (NAFLD) raises concerns about associated risk factors, such as obesity and type 2 Diabetes Mellitus, for leading causes of disability and death. Besides Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS), functional imaging with Positron Emission Tomography (PET) could contribute to a deeper understanding of the pathophysiology of NAFLD. Here we describe a novel approach using the PET tracer [18F]FTHA, which is an analog of long-chain free fatty acids (FFA) and is taken up by tissues to enter mitochondria or to be incorporated into complex lipids for further export as very-low-density lipoprotein (VLDL). Male Sprague Dawley rats, after 6 weeks on a high-fat diet (HFD), were used as a model of diet induced NAFLD, while a standard diet (SD) served as a control group. Liver fat was estimated by MR spectroscopy at a 9.4T system for phenotyping. To measure hepatic FFA uptake, rats underwent 60min dynamic [18F]FTHA-PET scans after unrestricted access to food (HFD: n=6; SD: n=6) or overnight (≤16h) fasting (HFD: n=6; SD: n=5). FFA removal was assessed from incorporated 18F-residual in de novo synthesized VLDL out of plasma. MRS of the liver confirmed the presence of NAFLD (>5.6% fat). Under non-fasting conditions, hepatic [18F]FTHA uptake was significantly increased in NAFLD: SUVmean (p=0.03) within [0; 60] min interval, SUVmean (p=0.01) and SUVmax (p=0.03) within [30; 60] min interval. SUVs for hepatic uptake under fasting conditions were not significantly different between the groups. Analysis of FFA removal demonstrated elevated values of 18F-residue in the VLDL plasma fraction of the healthy group compared to the NAFLD (p=0.0569). Our novel approach for assessing FFA metabolism using [18F]FTHA demonstrated differences in the hepatic FFA uptake and FFA incorporation into VLDL between healthy and NAFLD rats. [18F]FTHA-PET could be used to study metabolic disturbances involved in the progression of NAFLD.

Establishment of a reference interval for 12-hour fasted serum gastrin concentration in adult dogs.

Adherence to traditional 24-h fasting periods for serum gastrin concentration in dogs can be challenging and may delay the institution of therapies for suspected hypergastrinemia. Peer-reviewed publications regarding serum gastrin reference intervals (RI) are lacking. Hypercalcemia is associated with hypergastrinemia in people; limited data exist in dogs. The objective of the study was to generate a RI for a 12-h fasted serum gastrin concentration in dogs and to investigate whether correlations exist with age, weight, sex, and total calcium concentration. Fifty-five healthy adult dogs (>1 year of age). The screening included: medical history, physical examination, CBC (15 dogs), and serum chemistry (55 dogs). Gastrin was measured via a commercial radioimmunoassay. The RI for 12-h fasted serum gastrin concentration was calculated according to the recommendations of the American Society for Veterinary Clinical Pathology. Additionally, data were evaluated for correlation with selected variables. The RI for serum gastrin following a 12-h fasting period was 15.1-78.9 ng/L with 90% confidence intervals for the lower and upper limits of 14.0-22.9 and 68.3-83.0 ng/L, respectively. A generalized linear model did not detect significant relationships between gastrin and age (P = 0.48), sex (P = 0.30), weight (P = 0.93), or total calcium concentration (P = 0.84). A 12-h fasted serum gastrin concentration RI has been established. Given the limited range of serum calcium concentrations in our healthy study population, additional investigations are needed to determine the effects of hypercalcemia on serum gastrin concentrations in dogs and for any potential clinical consequences thereof.

Prospective External Validation of an Algorithm Predicting Hourly Basal Insulin Infusion Rates from Characteristics of Patients with Type 1 Diabetes Treated with Insulin Pumps.

We previously published an algorithm predicting 24 h basal insulin infusion profiles in insulin pump-treated subjects with type 1 diabetes profiles from six subject characteristics. This algorithm was to be externally validated in an independent environment and patient population. Thirty-two patients with pump-treated type diabetes were switched to their individually algorithm-derived basal insulin infusion profile, and the appropriateness of fasting glycemic control was scrutinized by means of a supervised 24 h fast. Primary endpoint was appropriate fasting glycemic control according to pre-defined criteria in at least 80% of the cohort. In 24 out of 32 patients switching to the algorithm-derived basal insulin infusion rate and undergoing a 24-h fasting period, appropriate glycemic control was achieved (=75%, lower than the pre-defined threshold of 80%), two patients discontinued the fast due to hyperglycemia, and six finished the fasting period, however, with inappropriate fasting glycemic control (entirely due to hyperglycemic episodes). There were no obvious differences in baseline characteristics between those with appropriate vs. inappropriate fasting glycemic control on the basal insulin infusion rate provided by the algorithm. In conclusion, when testing fasting glycemic control with an algorithm-derived individual basal insulin infusion profile during a 24 h fasting period in a cohort unrelated in terms of the hospital environment and catchment area, the success rate was lower than a pre-defined threshold for concluding utility of this algorithm. Therefore, applying this algorithm in order to initiate or optimize basal insulin infusion profiles in type 1 diabetes cannot be generally recommended.