Effect of 2 years of calorie restriction on liver biomarkers: results from the CALERIE phase 2 randomized controlled trial.

PURPOSE: Calorie restriction (CR) is an effective treatment for obesity-related liver and metabolic disease. However, CR studies in individuals without obesity are needed to see if CR could delay disease onset. Liver biomarkers indicate hepatic health and are linked to cardiometabolic disease. Our aim was to examine the effects of a 2-year CR intervention on liver biomarkers in healthy individuals without obesity. METHODS: The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) study was a 2-year randomized controlled trial. Overall, 218 participants (body mass index: 25.1 ± 1.7 kg/m2) were enrolled into a control group (n = 75) that ate ad libitum (AL), or a CR group (n = 143) that aimed to decrease energy intake by 25%. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), and bilirubin were measured during the trial. RESULTS: At month 24, relative to the AL group, ALP (- 7 ± 1 IU/L; P < 0.01) and GGT (- 0.11 ± 0.04 log IU/L; P = 0.02) decreased and bilirubin increased (0.21 ± 0.06 log mg/dL; P < 0.01) in the CR group; no between-group differences in ALT (- 1 ± 1 IU/L; P > 0.99) or AST (2 ± 2 IU/L; P = 0.68) were revealed. However, sex-by-treatment-by-time interactions (P < 0.01) were observed, with CR (vs. control) inducing reduced ALT and GGT and increased AST in men only (P ≤ 0.02). CONCLUSIONS: In metabolically healthy individuals without obesity, 2 years of CR improves several liver biomarkers, with potentially greater improvements in men. These data suggest that sustained CR may improve long-term liver and metabolic disease risk in healthy adults. TRIAL REGISTRATION: Clinicaltrials.gov (NCT00427193). Registered January 2007.

Simultaneous Pharmacokinetic Analysis of Nitrate and its Reduced Metabolite, Nitrite, Following Ingestion of Inorganic Nitrate in a Mixed Patient Population.

PURPOSE: The pharmacokinetic properties of plasma NO3- and its reduced metabolite, NO2-, have been separately described, but there has been no reported attempt to simultaneously model their pharmacokinetics following NO3- ingestion. This report describes development of such a model from retrospective analyses of concentrations largely obtained from primary endpoint efficacy trials. METHODS: Linear and non-linear mixed effects analyses were used to statistically define concentration dependency on time, dose, as well as patient and study variables, and to integrate NO3- and NO2- concentrations from studies conducted at different times, locations, patient groups, and several studies in which sample range was limited to a few hours. Published pharmacokinetic studies for both substances were used to supplement model development. RESULTS: A population pharmacokinetic model relating NO3- and NO2- concentrations was developed. The model incorporated endogenous levels of the two entities, and determined these were not influenced by exogenous NO3- delivery. Covariate analysis revealed intersubject variability in NO3- exposure was partially described by body weight differences influencing volume of distribution. The model was applied to visualize exposure versus response (muscle contraction performance) in individual patients. CONCLUSIONS: Extension of the present first-generation model, to ultimately optimize NO3- dose versus pharmacological effects, is warranted.

Change in self-efficacy, eating behaviors and food cravings during two years of calorie restriction in humans without obesity.

Calorie restriction (CR) enhances longevity in humans who are normal weight, overweight and obese. While dietary regimens can change self-efficacy, eating behaviors, and food cravings in individuals with obesity, the responses of these measures to prolonged CR in individuals who are exclusively not obese is unknown. The aim of this analysis was to test the effects of a two-year CR intervention on self-efficacy and eating attitudes and behaviors in humans without obesity by analyzing data from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE 2) study. Participants (n = 218, BMI range = 21.3-29.0 kg/m2) were randomized to a 25% CR group or an ad libitum (AL) group. Eating attitudes and behaviors and self-efficacy were assessed using validated questionnaires at baseline, month 12, and month 24. Dietary restraint and self-efficacy increased in the CR compared to the AL group (ES ≥ 0.32). Increased self-efficacy was negatively related to weight change (ρ < -0.24). In the CR group, males showed a reduction in cravings for carbohydrates and fats at month 24, whereas females did not. The CR group showed elevations in state hunger, which were transient, and disinhibited eating (ES ≥ 0.37). In individuals without obesity, dietary restraint and self-efficacy could be important in promoting long-term CR for individuals looking to use CR as a tool to improve longevity.

The Promise of Selecting Individuals from the Extremes of Exposure in the Analysis of Gene-Physical Activity Interactions.

BACKGROUND: Dichotomization using the lower quartile as cutoff is commonly used for harmonizing heterogeneous physical activity (PA) measures across studies. However, this may create misclassification and hinder discovery of new loci. OBJECTIVES: This study aimed to evaluate the performance of selecting individuals from the extremes of the exposure (SIEE) as an alternative approach to reduce such misclassification. METHOD: For systolic and diastolic blood pressure in the Framingham Heart Study, we performed a genome-wide association study with gene-PA interaction analysis using three PA variables derived by SIEE and two other dichotomization approaches. We compared number of loci detected and overlap with loci found using a quantitative PA variable. In addition, we performed simulation studies to assess bias, false discovery rates (FDR), and power under synergistic/antagonistic genetic effects in exposure groups and in the presence/absence of measurement error. RESULTS: In the empirical analysis, SIEE's performance was neither the best nor the worst. In most simulation scenarios, SIEE was consistently outperformed in terms of FDR and power. Particularly, in a scenario characterized by antagonistic effects and measurement error, SIEE had the least bias and highest power. CONCLUSION: SIEE's promise appears limited to detecting loci with antagonistic effects. Further studies are needed to evaluate SIEE's full advantage.

Ezetimibe Increases Endogenous Cholesterol Excretion in Humans.

OBJECTIVE: Ezetimibe improves cardiovascular outcomes when added to optimum statin treatment. It lowers low-density lipoprotein cholesterol and percent intestinal cholesterol absorption, but the exact cardioprotective mechanism is unknown. We tested the hypothesis that the dominant effect of ezetimibe is to increase the reverse transport of cholesterol from rapidly mixing endogenous cholesterol pool into the stool. APPROACH AND RESULTS: In a randomized, placebo-controlled, double-blind parallel trial in 24 healthy subjects with low-density lipoprotein cholesterol 100 to 200 mg/dL, we measured cholesterol metabolism before and after a 6-week treatment period with ezetimibe 10 mg/d or placebo. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d7 in a lipid emulsion and dietary cholesterol with cholesterol-d5 and sitostanol-d4 solubilized in oil. Plasma and stool samples collected during a cholesterol- and phytosterol-controlled metabolic kitchen diet were analyzed by mass spectrometry. Ezetimibe reduced intestinal cholesterol absorption efficiency 30±4.3% (SE, P<0.0001) and low-density lipoprotein cholesterol 19.8±1.9% (P=0.0001). Body cholesterol pool size was unchanged, but fecal endogenous cholesterol excretion increased 66.6±12.2% (P<0.0001) and percent cholesterol excretion from body pools into the stool increased 74.7±14.3% (P<0.0001), whereas plasma cholesterol turnover rose 26.2±3.6% (P=0.0096). Fecal bile acids were unchanged. CONCLUSIONS: Ezetimibe increased the efficiency of reverse cholesterol transport from rapidly mixing plasma and tissue pools into the stool. Further work is needed to examine the potential relation of reverse cholesterol transport and whole body cholesterol metabolism to coronary events and the treatment of atherosclerosis. CLINICAL TRIALS REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603758.

Endogenous Cholesterol Excretion Is Negatively Associated With Carotid Intima-Media Thickness in Humans.

OBJECTIVE: Epidemiological studies strongly suggest that lipid factors independent of low-density lipoprotein cholesterol contribute significantly to cardiovascular disease risk. Because circulating lipoproteins comprise only a small fraction of total body cholesterol, the mobilization and excretion of cholesterol from plasma and tissue pools may be an important determinant of cardiovascular disease risk. Our hypothesis is that fecal excretion of endogenous cholesterol is protective against atherosclerosis. APPROACH AND RESULTS: Cholesterol metabolism and carotid intima-media thickness were quantitated in 86 nondiabetic adults. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d7 solubilized in a lipid emulsion and dietary cholesterol by cholesterol-d5 and the nonabsorbable stool marker sitostanol-d4. Plasma and stool samples were collected while subjects consumed a cholesterol- and phytosterol-controlled metabolic kitchen diet and were analyzed by mass spectrometry. Carotid intima-media thickness was negatively correlated with fecal excretion of endogenous cholesterol (r=-0.426; P<0.0001), total cholesterol (r=-0.472; P≤0.0001), and daily percent excretion of cholesterol from the rapidly mixing cholesterol pool (r=-0.343; P=0.0012) and was positively correlated with percent cholesterol absorption (r=+0.279; P=0.0092). In a linear regression model controlling for age, sex, systolic blood pressure, hemoglobin A1c, low-density lipoprotein, high-density lipoprotein cholesterol, and statin drug use, fecal excretion of endogenous cholesterol remained significant (P=0.0008). CONCLUSIONS: Excretion of endogenous cholesterol is strongly, independently, and negatively associated with carotid intima-media thickness. The reverse cholesterol transport pathway comprising the intestine and the rapidly mixing plasma, and tissue cholesterol pool could be an unrecognized determinant of cardiovascular disease risk not reflected in circulating lipoproteins. Further work is needed to relate measures of reverse cholesterol transport to atherosclerotic disease. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603758.

Sex differences in FITNESSGRAM® health risk based on aerobic capacity and body composition among urban public elementary school children.

Children residing in urban, low-resource neighborhoods may be at increased risk for poor aerobic fitness and obesity. The objective of this collaborative project with an urban public school district was to quantify the combination of poor aerobic capacity and high percent body fat using FITNESSGRAM® Healthy Fitness Zone (HFZ) standards among urban, predominantly Black, public elementary school boys and girls. Measurements of aerobic capacity with the 20-m Progressive Aerobic Cardiovascular Endurance Run (PACER) test and body composition by bioelectrical impedance analysis were completed on 1,775 fourth and fifth grade students in 45 public elementary schools in St. Louis, Missouri during three school years (2012-2015). Our findings reveal that a higher proportion of girls than boys failed to meet the HFZ for aerobic capacity (70.1% vs. 42.3%), percent body fat (53.0% vs. 29.9%), and the combination of aerobic capacity and percent body fat (44.4% vs. 21.8%, all P<0.001). These results highlight the importance of addressing modifiable, lifestyle-related health risks among urban minority children, particularly girls.

BMI-for-age graphs with severe obesity percentile curves: tools for plotting cross-sectional and longitudinal youth BMI data.

BACKGROUND: Severe obesity is an important and distinct weight status classification that is associated with disease risk and is increasing in prevalence among youth. The ability to graphically present population weight status data, ranging from underweight through severe obesity class 3, is novel and applicable to epidemiologic research, intervention studies, case reports, and clinical care. METHODS: The aim was to create body mass index (BMI) graphing tools to generate sex-specific BMI-for-age graphs that include severe obesity percentile curves. We used the Centers for Disease Control and Prevention youth reference data sets and weight status criteria to generate the percentile curves. The statistical software environments SAS and R were used to create two different graphing options. RESULTS: This article provides graphing tools for creating sex-specific BMI-for-age graphs for males and females ages 2 to <20 years. The novel aspects of these graphing tools are an expanded BMI range to accommodate BMI values ˃35 kg/m2, inclusion of percentile curves for severe obesity classes 2 and 3, the ability to plot individual data for thousands of children and adolescents on a single graph, and the ability to generate cross-sectional and longitudinal graphs. CONCLUSIONS: These new BMI graphing tools will enable investigators, public health professionals, and clinicians to view and present youth weight status data in novel and meaningful ways.

Preparation of intravenous cholesterol tracer using current good manufacturing practices.

Studies of human reverse cholesterol transport require intravenous infusion of cholesterol tracers. Because insoluble lipids may pose risk and because it is desirable to have consistent doses of defined composition available over many months, we investigated the manufacture of cholesterol tracer under current good manufacturing practice (CGMP) conditions appropriate for phase 1 investigation. Cholesterol tracer was prepared by sterile admixture of unlabeled cholesterol or cholesterol-d7 in ethanol with 20% Intralipid(®). The resulting material was filtered through a 1.2 micron particulate filter, stored at 4°C, and tested at time 0, 1.5, 3, 6, and 9 months for sterility, pyrogenicity, autoxidation, and particle size and aggregation. The limiting factor for stability was a rise in thiobarbituric acid-reacting substances of 9.6-fold over 9 months (P < 0.01). The emulsion was stable with the Z-average intensity-weighted mean droplet diameter remaining at 60 nm over 23 months. The zeta potential (a measure of negative surface charge protecting from aggregation) was unchanged at -36.2. Rapid cholesterol pool size was 25.3 ± 1.3 g. Intravenous cholesterol tracer was stable at 4°C for 9 months postproduction. CGMP manufacturing methods can be achieved in the academic setting and need to be considered for critical components of future metabolic studies.

Energy expenditure and activity among Hadza hunter-gatherers.

OBJECTIVES: Studies of total energy expenditure, (TEE; kcal/day) among traditional populations have challenged current models relating habitual physical activity to daily energy requirements. Here, we examine the relationship between physical activity and TEE among traditional Hadza hunter-gatherers living in northern Tanzania. METHODS: Hadza adults were studied at two camps, with minimal intervention so as to monitor energy expenditure and activity during normal daily life. We measured daily walking distance and walking speed using wearable GPS units for 41 adults. For a subset of 30 adults, we measured TEE using doubly labeled water, three indices of work load (foraging return rate, maternal status, and number of dependent children), and urinary biomarkers of metabolic activity and stress (8-hydroxydeoxyguanosine, cortisol, and testosterone). RESULTS: Fat-free mass was the single strongest predictor of TEE among Hadza adults (r(2) = 0.66, P < 0.001). Hadza men used greater daily walking distances and faster walking speeds compared with that of Hadza women, but neither sex nor any measure of physical activity or work load were correlated with TEE in analyses controlling for fat-free mass. Compared with developed, industrial populations, Hadza adults had similar TEE but elevated levels of metabolic stress as measured by 8-hydroxydeoxyguanosine. CONCLUSION: Our results indicate that daily physical activity may not predict TEE within traditional hunter-gatherer populations like the Hadza. Instead, adults with high levels of habitual physical activity may adapt by reducing energy allocation to other physiological activity.

Breakfast intake among adults with type 2 diabetes: influence on daily energy intake.

OBJECTIVE: To assess the association between breakfast energy and total daily energy intake among individuals with type 2 diabetes. DESIGN: Cross-sectional study. Daily energy intake was computed from a 24 h dietary recall. Multiple regression models were used to estimate the association between daily energy intake (dependent variable) and quartiles of energy intake at breakfast (independent variable), expressed in either absolute or relative (percentage of total daily energy intake) terms. Orthogonal polynomial contrasts were used to test for linear and quadratic trends. Models were controlled for sex, age, race/ethnicity, BMI, physical activity and smoking. In addition, we used separate multiple regression models to test the effect of quartiles of absolute and relative breakfast energy on energy intake at lunch, dinner and snacks. SETTING: The 1999-2004 National Health and Nutrition Examination Survey (NHANES). SUBJECTS: Participants aged ≥30 years with self-reported history of diabetes (n 1146). RESULTS: Daily energy intake increased as absolute breakfast energy intake increased (linear trend, P<0·0001; quadratic trend, P=0·02), but decreased as relative breakfast energy intake increased (linear trend, P<0·0001). In addition, while higher quartiles of absolute breakfast intake had no associations with energy intake at subsequent meals, higher quartiles of relative breakfast intake were associated with lower energy intake during all subsequent meals and snacks (P<0·05). CONCLUSIONS: Consuming a breakfast that provided less energy or comprised a greater proportion of daily energy intake was associated with lower total daily energy intake in adults with type 2 diabetes.

Influence of physical education on moderate-to-vigorous physical activity of urban public school children in St. Louis, Missouri, 2011-2014.

We quantified the moderate-to-vigorous physical activity (MVPA, heart rate ≥140 bpm) of urban public elementary school children on school days with and schooldays without physical education (PE) class by using continuous heart rate monitoring. The heart rate of 81 students (93.8% black) in grades 3 and 5 was recorded in 15-second intervals. On the basis of 575 school-day observations (mean 7.1 days/student), students accumulated 44.4 (standard deviation [SD], 34.4) minutes of MVPA on days with PE and 30.6 (SD, 29.9) MVPA minutes on days without PE (P < .001). School policies should promote daily PE to help children in under-resourced areas achieve the recommended 60 minutes per day of MVPA.

Natural Dietary Phytosterols.

Most clinical phytosterol studies are performed by adding purified supplements to smaller phytosterol amounts present in the natural diet. However, natural dietary phytosterols themselves may also have important effects on cholesterol metabolism. Epidemiological work using food frequency questionnaires to estimate dietary intake suggest that extremes of normal consumption may be associated with 3-14% changes in LDL cholesterol. Standardized food databases do not have enough phytosterol values to allow calculation of phytosterol intake for individuals outside of specialized studies. Natural diets contain phytosterol amounts ranging from less than 60 mg/2000 kcal to over 500 mg/2000 kcal. Physiological studies in which whole body cholesterol metabolism is investigated show large effects of natural dietary phytosterols on cholesterol absorption efficiency, cholesterol biosynthesis and cholesterol excretion which exceed the magnitude of changes in LDL cholesterol. The dual effects of natural phytosterols on both LDL-C and whole body cholesterol metabolism need to be considered in relating them to potential protection from coronary heart disease risk.

The doubly labeled water method produces highly reproducible longitudinal results in nutrition studies.

The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reproducibility of the DLW method using 2 protocols developed and implemented in a multicenter clinical trial-the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE). To document the longitudinal reproducibility of the DLW method, 2 protocols, 1 based on repeated analysis of dose dilutions over the course of the clinical trial (dose-dilution protocol) and 1 based on repeated but blinded analysis of randomly selected DLW studies (test-retest protocol), were carried out. The dose-dilution protocol showed that the theoretical fractional turnover rates for (2)H and (18)O and the difference between the 2 fractional turnover rates were reproducible to within 1% and 5%, respectively, over 4.5 y. The Bland-Altman pair-wise comparisons of the results generated from 50 test-retest DLW studies showed that the fractional turnover rates and isotope dilution spaces for (2)H and (18)O, and total energy expenditure, were highly reproducible over 2.4 y. Our results show that the DLW method is reproducible in longitudinal studies and confirm the validity of this method to measure energy expenditure, define energy intake prescriptions, and monitor adherence and body composition changes over the period of 2.5-4.4 y. The 2 protocols can be adopted by other laboratories to document the longitudinal reproducibility of their measurements to ensure the long-term outcomes of interest are meaningful biologically. This trial was registered at clinicaltrials.gov as NCT00427193.

Macronutrient intake as a mediator with FTO to increase body mass index.

BACKGROUND: The fat mass and obesity-associated (FTO) single nucleotide polymorphisms (SNPs; rs1421085, rs17817449, rs9939609, rs8050136) and macronutrient intake (carbohydrate, protein, fat, total calories) are associated with body mass index (BMI). However, the mechanism for this relationship has not been fully elucidated. OBJECTIVE: This study examined whether macronutrient intake mediates the association between FTO SNPs and BMI. DESIGN: Baseline cross-sectional data from the Atherosclerosis Risk in Communities (ARIC) study of whites (n = 10,176) and African Americans (n = 3641) aged 45 to 64 years were analyzed. RESULTS: In linear regression models with BMI as the dependent variable, FTO SNPs were significantly associated with higher BMI after adjusting for covariates. The addition of energy-adjusted macronutrients attenuated the FTO effect estimates, indicating partial mediation. In whites, ß ranged from 0.40 (95% confidence interval [CI], 0.20, 0.60) for rs17817449 heterozygous carriers to 0.93 (95% CI, 0.64, 122) for rs8050136 homozygous carriers; for African Americans rs17817449 homozygous carriers ß was 0.65 (95% CI, 0.03, 1.27). In models with macronutrient intake as the dependent variable, all FTO SNPs were associated with higher protein intake for homozygous carriers after adjusting for BMI and other covariates. Among whites, ß ranged from 1.44 (95% CI, 0.51, 2.37) for rs8050136 to 1.73 (95% CI, 0.85, 2.61) for rs17817449; among African American rs8050136 homozygous carriers ß was 2.46 (95% CI, 0.77, 4.14). In mediation analysis, in whites only, FTO high-risk alleles were associated with higher BMI partly through their small effects on carbohydrate and protein intake. CONCLUSIONS: These findings suggest that in adults, the relationship between FTO variants and BMI is not primarily through mediation of food intake.

Dietary Sodium and Potassium Patterns in Adults with Food Insecurity in the Context of Hypertension Risk.

Background: Food insecurity (FIS), characterized by the lack of consistent access to nutritious food, is associated with hypertension and adverse health outcomes. Despite evidence of a higher prevalence of hypertension (HTN) in patients living with FIS, there is limited data exploring the underlying mechanism. Methods: We conducted a cross-sectional analysis of 17,015 adults aged 18-65 years, using dietary recall data from the National Health and Nutrition Examination Survey (2011-2018). Univariate and multivariable analyses were used to examine the association between FIS, HTN, and dietary sodium and potassium levels. Results: Individuals reporting FIS had a significantly lower mean intake of potassium (2.5±0.03 gm) compared to those in food-secure households (2.74±0.02 gm). No significant difference was found in the mean dietary sodium intake based on food security status. Non-Hispanic Black participants showed a high prevalence of HTN and FIS. While Non-Hispanic White and Hispanic participants had a high prevalence of FIS, it did not appear to influence their risk of HTN. Conclusions: Adults with FIS and HTN were more likely to report a lower dietary potassium intake. Increasing access to healthy foods, particularly potassium-rich foods, for individuals facing FIS, may contribute to reducing the HTN prevalence and improving cardiovascular outcomes.

Adipokines and adiposity among postmenopausal women of the Multi-Ethnic Study of Atherosclerosis.

OBJECTIVE: We investigated whether the associations of serum adiponectin, leptin, and resistin with adiposity differ with menopausal age. METHODS: In this cross-sectional study, we included 751 postmenopausal women from the Multi-Ethnic Study of Atherosclerosis (MESA) who reported their menopausal age (<45, 45-49, 50-54 and ≥55 y) and had anthropometrics, serum adipokines, and abdominal computed tomography measures of visceral and subcutaneous adipose tissue (VAT and SAT) obtained at MESA exam 2 or 3. Linear regression models were used for analysis. RESULTS: The mean ± SD age was 65.1 ± 9.0 years for all participants. The median (interquartile range) values for serum adiponectin, leptin and resistin, VAT, and SAT were 21.9 (14.8-31.7) ng/L, 24.3 (12.5-42.4) pg/L, 15.3 (11.8-19.5) pg/L, 183.9 (130.8-251.1) cm2, and 103.7 (65.6-151.5) cm2, respectively. The mean ± SD values for body mass index, waist circumference, and waist-to-hip ratio were 28.3 ± 5.81 kg/m2, 96.6 ± 15.9 cm, and 0.91 ± 0.078, respectively. Adiponectin was inversely associated with all adiposity measures, with similar patterns across menopausal age categories. Leptin was positively associated with all adiposity measures, and the strength of associations varied across menopausal age categories for body mass index, waist circumference, and SAT (Pinteraction ≤ 0.01 for all). The associations of resistin with adiposity measures were mostly nonsignificant except in the 45- to 49-year menopausal age category. CONCLUSIONS: Menopausal age category had no influence on the association of serum adiponectin with adiposity. The association of serum leptin and resistin differed according to menopausal age category for generalized adiposity but was inconsistent for measures of abdominal adiposity.

Blunted brachial blood flow velocity response to acute mental stress in PTSD females.

Post-traumatic stress disorder (PTSD) is associated with increased cardiovascular disease (CVD) risk. Compared with males, females are twice as likely to develop PTSD after trauma exposure, and cardiovascular reactivity to stress is a known risk factor for CVD. We aimed to examine hemodynamic responses to acute mental stress in trauma-exposed females with and without a clinical diagnosis of PTSD. We hypothesized that females with PTSD would have higher heart rate (HR), blood pressure (BP), and lower blood flow velocity (BFV) responsiveness compared with controls. We enrolled 21 females with PTSD and 21 trauma-exposed controls. We continuously measured HR using a three-lead electrocardiogram, BP using finger plethysmography, and brachial BFV using Doppler ultrasound. All variables were recorded during 10 min of supine rest, 5 min of mental arithmetic, and 5 min of recovery. Females with PTSD were older, and had higher BMI and higher resting diastolic BP. Accordingly, age, BMI, and diastolic BP were covariates for all repeated measures analyses. Females with PTSD had a blunted brachial BFV response to mental stress (time × group, p = 0.005) compared with controls, suggesting greater vasoconstriction. HR and BP responses were comparable. In conclusion, our results suggest early impairment of vascular function in premenopausal females with PTSD.

Calorie restriction reduces biomarkers of cellular senescence in humans.

Calorie restriction (CR) with adequate nutrient intake is a potential geroprotective intervention. To advance this concept in humans, we tested the hypothesis that moderate CR in healthy young-to-middle-aged individuals would reduce circulating biomarkers of cellular senescence, a fundamental mechanism of aging and aging-related conditions. Using plasma specimens from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE™) phase 2 study, we found that CR significantly reduced the concentrations of several senescence biomarkers at 12 and 24 months compared to an ad libitum diet. Using machine learning, changes in biomarker concentrations emerged as important predictors of the change in HOMA-IR and insulin sensitivity index at 12 and 24 months, and the change in resting metabolic rate residual at 12 months. Finally, using adipose tissue RNA-sequencing data from a subset of participants, we observed a significant reduction in a senescence-focused gene set in response to CR at both 12 and 24 months compared to baseline. Our results advance the understanding of the effects of CR in humans and further support a link between cellular senescence and metabolic health.

Effect of long-term caloric restriction on telomere length in healthy adults: CALERIE™ 2 trial analysis.

Caloric restriction (CR) modifies lifespan and aging biology in animal models. The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE™) 2 trial tested translation of these findings to humans. CALERIE™ randomized healthy, nonobese men and premenopausal women (age 21-50y; BMI 22.0-27.9 kg/m2), to 25% CR or ad-libitum (AL) control (2:1) for 2 years. Prior analyses of CALERIE™ participants' blood chemistries, immunology, and epigenetic data suggest the 2-year CR intervention slowed biological aging. Here, we extend these analyses to test effects of CR on telomere length (TL) attrition. TL was quantified in blood samples collected at baseline, 12-, and 24-months by quantitative PCR (absolute TL; aTL) and a published DNA-methylation algorithm (DNAmTL). Intent-to-treat analysis found no significant differences in TL attrition across the first year, although there were trends toward increased attrition in the CR group for both aTL and DNAmTL measurements. When accounting for adherence heterogeneity with an Effect-of-Treatment-on-the-Treated analysis, greater CR dose was associated with increased DNAmTL attrition during the baseline to 12-month weight-loss period. By contrast, both CR group status and increased CR were associated with reduced aTL attrition over the month 12 to month 24 weight maintenance period. No differences were observed when considering TL change across the study duration from baseline to 24-months, leaving it unclear whether CR-related effects reflect long-term detriments to telomere fidelity, a hormesis-like adaptation to decreased energy availability, or measurement error and insufficient statistical power. Unraveling these trends will be a focus of future CALERIE™ analyses and trials.