Increasing Household Diet Diversity and Food Security in Rural Rwanda Using Small-Scale Nutrition-Sensitive Agriculture: A Community-Engaged Proof-of-Concept Study.

Malnutrition and food insecurity remain high in rural Rwanda, where residents consume a low-diversity diet provided through subsistence farming. Agricultural interventions using kitchen gardens may improve diet diversity in some populations. However, little is known about their efficacy when developed using community-based participatory research in combination with nutrition education focused on the empowerment of women. The objective of this study was to develop and implement a kitchen garden and nutrition education intervention using a community-engaged model and examine its impact on household diet diversity and food security. Using a mixed methods community-level design, we assessed a 16-week intervention implemented in Cyanika, Rwanda. Stratified purposeful sampling was used to select women participants representing 42 households. Household diet diversity scores (HHDS) and hunger scores were calculated at the baseline, post-intervention and one-year follow-up. HDDS increased after intervention from a pre-intervention intake of 2.59 [1.3] food groups/day, to 4.85 [1.6] at four months post-intervention and at one year post-intervention, reaching 5.55 [1.3]. There were no significant changes in household hunger scores. Our results indicate that collaborative community-engaged nutrition-sensitive agricultural interventions can increase household diet diversity; however, future work should explore whether this type of intervention strategy can lead to sustained changes and impact nutritional adequacy in this population.

Observations of parent-adolescent interactions relate to food parenting practices and adolescent disordered eating in adolescents at risk for adult obesity.

Adolescent disordered eating and obesity are interrelated and adversely relate to mental and metabolic health. Parental feeding practices have been associated with adolescent disordered eating and obesity. Yet, observable interactions related to food parenting have not been well characterized. To address this gap, N = 30 adolescents (M ± SD 14 ± 2 year) at risk for adult obesity due to above-average body mass index (BMI ≥70th percentile) or parental obesity (BMI ≥30 kg/m2 ) participated in a video-recorded parent-adolescent task to discuss a food/eating-related disagreement. Interactions were coded for individual/dyadic affect/content using the Interactional Dimensions Coding System. We examined associations of interaction qualities with parent-reported food practices, adolescent disordered eating behaviors/attitudes, and insulin resistance. Reported parenting practices were correlated with multiple interaction qualities (p-values <0.05), with the most consistent correspondence between parent-reported pressure to eat (e.g., pressure to eat more healthy foods) and negative aspects of parent-adolescent interactions. Also, after accounting for adolescent age, sex, and BMI-standard score, parent-adolescent interaction qualities were associated with adolescents' disordered eating and insulin resistance. Specifically, greater adolescent problem-solving related to less adolescent global disordered eating, shape, and weight concern (p-values <0.05); adolescent autonomy related to less weight concern (p = 0.03). Better parent communication skills were associated with less adolescent eating concern (p = 0.04), and observed dyadic mutuality related to adolescents' lower insulin resistance (p = 0.03). Parent-adolescent interaction qualities during food/eating-related disagreements show associations with parent-reported food practices and adolescent disordered eating. This method may offer a tool for measuring the qualities of parent-adolescent food/eating-related interactions. A nuanced understanding of conversations about food/eating may inform family-based intervention in youth at-risk for adult obesity.

Mindfulness-based intervention in adolescents at risk for excess weight gain: 1.5-year follow-up of pilot randomized controlled trial.

BACKGROUND: Mindfulness-based intervention (MBI) may offer a novel means of preventing excess weight gain in adolescents, theoretically by decreasing stress-eating through altering executive functioning (EF) and food-reward sensitivity. METHODS: N = 54 12-17y girls and boys at-risk for excess weight gain (i.e., BMI ≥70th percentile or two biological parents with reported obesity [BMI ≥30 kg/m2]) participated in a 1.5-year follow-up of a pilot randomized controlled trial comparing 6-week/6-session MBI (n = 29) and a health education (HE) control (n = 25). Laboratory stress-eating, food-reward sensitivity, EF, perceived stress, and BMI/adiposity were re-assessed at 1.5-years with validated measures. Changes from baseline to 1.5-year follow-up were explored with ANCOVA, accounting for the respective baseline outcome, age, and sex. RESULTS: Compared to MBI (M = -21, SE = 59), HE had greater increases in stress-eating from baseline to 1.5-years (M = 194, SE = 63, Cohen's d = 0.59, p = .01). There were no other between-condition differences. DISCUSSION: MBI may prevent worsening stress-eating for adolescents at-risk for excess weight gain. The potential for MBI as an intervention for stress-eating and ultimately, weight stabilization warrants testing in an adequately-powered trial.

Associations of adverse childhood experiences with stress physiology and insulin resistance in adolescents at risk for adult obesity.

Adverse childhood experiences (ACEs) heighten the risk for adult obesity and cardiometabolic disease, but physiological factors underlying this connection are not well understood. We determined if ACEs were associated with physiological stress response and insulin resistance in adolescents at risk for adult obesity. Participants were 90 adolescents 12.0-17.5 years (50% female, 30% Hispanic/Latinx), at risk for adult obesity by virtue of above-average body mass index (BMI; kg/m2 ≥ 70th percentile) or parental obesity (BMI ≥ 30 kg/m2 ). ACEs were determined as presence (vs. absence) based upon the Schedule for Affective Disorders and Schizophrenia for School-Aged Children. Physiological stress response was measured as heart rate/blood pressure response to the Trier Social Stress Test. Homeostatic model assessment of insulin resistance was determined from fasting glucose/insulin. Sixty-one percent of adolescents reported positive ACE history. The presence of ACEs predicted greater heart rate (p < .001) and diastolic blood pressure (p = .02) response to stress, controlling for age, sex, race/ethnicity, puberty, and BMI standard score. Systolic blood pressure and insulin resistance did not differ by ACE history (p-values > .08). Findings suggest heightened sympathetic stress response in adolescence could be explanatory in how ACEs increase the risk for later cardiometabolic disease. Future studies should characterize ACEs in relationship to day-to-day variations in adolescents' stress physiology and glucose homeostasis.

The role of mindfulness in associations among depression symptoms, sleep duration, and insulin resistance in adolescents.

Sleep difficulties may be one explanatory factor in the association between depression and insulin resistance; yet, explicit tests of this hypothesis are lacking. We determined if there was an indirect effect of depression symptoms on insulin resistance through sleep duration in adolescents at risk for excess weight gain. We also investigated whether dispositional mindfulness moderated the interconnections among depression, sleep, and insulin resistance. Ninety adolescents (14.2 ± 1.6y; 50% female) at risk for excess weight gain (body mass index [BMI, kg/m2] z score 1.6 ± 0.6) participated in the cross-sectional, baseline phase of a health behaviors study. Depression was assessed with the Center for Epidemiologic Studies-Depression Scale, sleep duration with the Sleep Habits Survey, and mindfulness with the Mindful Attention and Awareness Scale. Homeostatic model assessment of insulin resistance was determined from fasting insulin and glucose. The product-of-coefficients method was used to test the indirect effect of depression on insulin resistance through sleep duration, accounting for age, sex, BMIz, puberty, and socioeconomic status (SES). Dispositional mindfulness was tested as a moderator of the associations among depression, sleep, and insulin resistance. There was a significant indirect effect of depression on insulin resistance through sleep duration, controlling for age, sex, BMIz, puberty, and SES, 95%CI [0.001, 0.05]. Dispositional mindfulness moderated the association between sleep duration and insulin resistance, such that lower sleep duration related to greater insulin resistance only among adolescents with lower mindfulness (p < .001). Short sleep may be one explanatory factor in the depression-insulin resistance connection in adolescents at risk for excess weight gain. Adolescents with poorer mindfulness and short sleep are at highest risk for insulin resistance, whereas higher mindfulness may be protective.

Effects of a mindfulness-induction on subjective and physiological stress response in adolescents at-risk for adult obesity.

BACKGROUND: Mindfulness-training may benefit stress response and stress-eating, yet few studies have experimentally tested these effects in adolescents. In this short communication, we report whether a brief mindfulness-induction affected acute stress response and stress-eating in adolescents at-risk for adult obesity. We explored disordered eating as a moderator. METHOD: Twenty-nine adolescents (age 14 ± 2 y) at-risk for adult obesity participated in a within-subjects, randomized crossover experiment. Following a 10-minute mindfulness or neutral-induction on different days in random order, the Trier Social Stress Test adapted for adolescents was administered, followed by an ad libitum lunch meal. Physiological stress response (heart rate, blood pressure) and subjective stress response (anxiety, mindlessness) were determined with area under the curve with respect to increase. Stress-eating was measured as test meal energy consumed. Global disordered-eating and binge-eating were assessed with the Eating Disorders Examination-Questionnaire. RESULTS: Relative to a neutral-induction, a mindfulness-induction reduced state anxiety response (p = .04). There were significant interactions of induction-type by global disordered-eating (p = .02) and binge-eating (p = .03), such that the mindfulness-induction most reduced anxiety response in adolescents with relatively lower global disordered-eating and those with no binge-eating. Induction-type also interacted with binge-eating in predicting diastolic blood pressure (p = .03). A mindfulness-induction, versus neutral-induction, most reduced diastolic blood pressure response in adolescents with binge-eating. CONCLUSIONS: Brief mindfulness-training may alter some aspects of acute stress response, with variations by disordered-eating. Future research should test alternative mindfulness induction-types (e.g., acceptance/self-compassion) to improve our understanding of how mindfulness-training may benefit adolescents at-risk for adult obesity.

Agricultural Food Production Diversity and Dietary Diversity among Female Small Holder Farmers in a Region of the Ecuadorian Andes Experiencing Nutrition Transition.

Some rural areas of Ecuador, including the Imbabura Province of the Andes Highlands, are experiencing a double burden of malnutrition where micronutrient deficiencies persist at the same time obesity is increasing as many traditional home-grown foods are being replaced with more commercially prepared convenience foods. Thus, the relationships among agricultural food production diversity (FPD), dietary diversity (DD), and household food insecurity (HFI) of the rural small holder farmers need further study. Therefore, we examined these associations in small holder farmers residing in this Province in the Andes Highlands (elevation > 2500 m). Non-pregnant maternal home managers (n = 558, x age = 44.1, SD = 16.5 y) were interviewed regarding the number of different agricultural food crops cultivated and domestic animals raised in their family farm plots. DD was determined using the Minimum Dietary Diversity for Women Score (MDD-W) based on the number of 10 different food groups consumed, and household food insecurity (HFI) was determined using the 8-item Household Food Insecurity Experience Scale. The women reported consuming an average of 53% of their total food from what they cultivated or raised. Women with higher DD [MMD-W score ≥ 5 food groups (79% of total sample)] were on farms that cultivated a greater variety of crops (x = 8.7 vs. 6.7), raised more animals (x = 17.9 vs. 12.7, p < 0.05), and reported lower HFI and significantly higher intakes of energy, protein, iron, zinc, and vitamin A (all p < 0.05). Multiple regression analyses demonstrated that FPD was only modestly related to DD, which together with years of education, per capita family income, and HFI accounted for 26% of DD variance. In rural areas of the Imbabura Province, small holder farmers still rely heavily on consumption of self-cultivated foods, but greater diversity of crops grown in family farm plots is only weakly associated with greater DD and lower HFI among the female caretakers.

Associations of parental feeding practices and food reward responsiveness with adolescent stress-eating.

Rates of adolescent obesity have continued to rise over the past decade. As adolescence is an important time for developing eating habits that endure into adulthood, more information is needed about the potentially modifiable family- and individual-level factors that influence the development of common overeating behaviors such as stress-eating during adolescence. In this study, we conducted secondary data analyses to evaluate how parental feeding practices and adolescents' food reward responsiveness related to adolescents' stress-eating during a laboratory test meal. Participants were 90 healthy adolescents (50% female), 12-17 years of age (M = 14.3, SD = 1.7 years), at risk for excess weight gain (BMI percentile M = 92.7, SD = 7.5). Parental feeding behaviors were assessed with parent-report on the Child Feeding Questionnaire-Adolescent Version. Adolescents' relative reward value of food was measured with a behavioral task. Stress-eating was assessed as total energy intake from a buffet lunch meal after adolescents participated in the Trier Social Stress Test adapted for adolescents. Results revealed that parental concern about their child's weight (t = 2.27, p = .02) and adolescents' relative reward value of food (t = 2.24, p = .03) were related to greater stress-eating, controlling for BMI standard score, age, sex, and general perceived stress. Parental restriction was not related to stress-eating in this sample (p = .21). These findings suggest that parental attitudes about their adolescent's weight and adolescents' own internalized responsiveness to food as a reward may play a role in propensity to engage in overeating in response to stress.

Sodium Glucose Co-Transporter 2 Inhibition Does Not Favorably Modify the Physiological Responses to Dietary Counselling in Diabetes-Free, Sedentary Overweight and Obese Adult Humans.

Sedentary obesity is associated with increased risk of many cardio-metabolic diseases, including type 2 diabetes. Weight loss is therefore a desirable goal for sedentary adults with obesity. Weight loss is also a well-documented side effect of sodium glucose co-transporter 2 (SGLT2) inhibition, a pharmaceutical strategy for diabetes treatment. We hypothesized that, compared with placebo, SGLT2 inhibition as an adjunct to out-patient dietary counselling for weight loss would lead to more favorable modification of body mass and composition, and greater improvement in glucose regulation and lipid profile. Using a randomized, double-blind, repeated measures parallel design, 50 sedentary men and women (body mass index: 33.4 ± 4.7 kg/m2; mean ± SD) were assigned to 12 weeks of dietary counselling, supplemented with daily ingestion of either a placebo or SGLT2 inhibitor (dapagliflozin: up to 10 mg/day). Dietary counselling favorably modified body mass, body fat, glucose regulation, and fasting concentrations of triglyceride and very low-density lipoprotein cholesterol (main effects of counselling: p < 0.05); SGLT2 inhibition did not influence any of these adaptations (counselling × medication interactions: p > 0.05). However, SGLT2 inhibition when combined with dietary counselling led to greater loss of fat-free mass (counselling × medication interaction: p = 0.047) and attenuated the rise in high-density lipoprotein cholesterol (counselling × medication interaction: p = 0.028). In light of these data and the health implications of decreased fat-free mass, we recommend careful consideration before implementing SGLT2 inhibition as an adjunct to dietary counselling for weight loss in sedentary adults with obesity.

Impact of Red Beetroot Juice on Vascular Endothelial Function and Cardiometabolic Responses to a High-Fat Meal in Middle-Aged/Older Adults with Overweight and Obesity: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial.

BACKGROUND: High-fat meal (HFM) consumption may induce transient postprandial atherogenic responses, including impairment of vascular endothelial function, in individuals with overweight/obesity. Red beetroot juice (RBJ) may modulate endothelial function and other measures of cardiometabolic health. OBJECTIVE: This study investigated the impact of acute and chronic RBJ consumption, including nitrate-dependent and -independent effects, on postprandial endothelial function and other cardiometabolic responses to a HFM. METHODS: Fifteen men and postmenopausal women with overweight/obesity were enrolled in this randomized, double-blind, placebo-controlled, 4-period, crossover clinical trial. Following an overnight fast, participants underwent baseline assessment of endothelial function (reactive hyperemia index; RHI) and hemodynamics, and biological sample collection. In random order, participants consumed 70 mL (acute visit) of: 1) RBJ, 2) nitrate-free RBJ (NF-RBJ), 3) placebo + nitrate (PBO + NIT), or 4) placebo (PBO), followed by a HFM. RHI was remeasured 4 h post-HFM, and hemodynamic assessment and biological sample collection were performed 1, 2, and 4 h post-HFM consumption. Participants consumed treatments daily for 4 wk (chronic visit), and assessments were repeated before/after the HFM (without consuming treatments). RESULTS: HFM consumption did not induce significant impairment of postprandial RHI. No significant differences in RHI were detected across treatment groups following acute or chronic exposure, despite increases in circulating nitrate/nitrite (NOx) concentrations in the RBJ and PBO + NIT groups compared with PBO and NF-RBJ (P < 0.0001 for all time points at the acute visit; P < 0.05 for all time points at the chronic visit). Although the HFM led to significant alterations in several secondary outcomes, there were no consistent treatment effects on postprandial cardiometabolic responses. CONCLUSIONS: HFM consumption did not impair postprandial endothelial function in this population, and RBJ exposure did not alter postprandial endothelial function or other outcomes despite increasing NOx concentrations. This trial is registered at clinicaltrials.gov as NCT02949115.

Increasing Energy Flux to Maintain Diet-Induced Weight Loss.

Long-term maintenance of weight loss requires sustained energy balance at the reduced body weight. This could be attained by coupling low total daily energy intake (TDEI) with low total daily energy expenditure (TDEE; low energy flux), or by pairing high TDEI with high TDEE (high energy flux). Within an environment characterized by high energy dense food and a lack of need for movement, it may be particularly difficult for weight-reduced individuals to maintain energy balance in a low flux state. Most of these individuals will increase body mass due to an inability to sustain the necessary level of food restriction. This increase in TDEI may lead to the re-establishment of high energy flux at or near the original body weight. We propose that following weight loss, increasing physical activity can effectively re-establish a state of high energy flux without significant weight regain. Although the effect of extremely high levels of physical activity on TDEE may be constrained by compensatory reductions in non-activity energy expenditure, moderate increases following weight loss may elevate energy flux and encourage physiological adaptations favorable to weight loss maintenance, including better appetite regulation. It may be time to recognize that few individuals are able to re-establish energy balance at a lower body weight without permanent increases in physical activity. Accordingly, there is an urgent need for more research to better understand the role of energy flux in long-term weight maintenance.

Mindfulness-based group intervention in adolescents at-risk for excess weight gain: A randomized controlled pilot study.

OBJECTIVES: To assess feasibility/acceptability of a mindfulness-based approach to excess weight prevention in adolescents at-risk for excess weight gain. To pilot test efficacy of a mindfulness-based intervention for improving food reward sensitivity, stress-eating, executive function (EF), and BMI/adiposity. METHODS: A pilot randomized controlled trial was conducted with 12-17y adolescents at-risk for excess weight gain based on above-average weight (body mass index [BMI]≥70%ile) or parental history of obesity (BMI≥30 kg/m2). Adolescents were randomized to a mindfulness-based (n = 29) or health education control group (n = 25) that met for six weekly one-hour sessions. Feasibility/acceptability were determined from attendance and acceptability survey ratings. At baseline, six-week and six-month follow-up, adolescents' perceived stress was measured with the Perceived Stress Scale, food reward sensitivity with a behavioral task, stress-eating during a laboratory test meal, and EF with the parent-reported Behavior Rating Inventory of Executive Function and NIH Toolbox. At the same intervals, BMI indices and body fat by air displacement plethysmography were assessed in a fasted state. RESULTS: Median session attendance was 6:6 sessions in both conditions; program acceptability ratings were above-average. Compared to health education, adolescents in mindfulness had lower food reward sensitivity at six-months (Cohen's d = 0.64, p = .01). There were no between-condition differences in BMI (mindfulness vs. health educationΔsix-months 95%CI 0.20, 1.52 kg/m2 vs. 0.21, 1.62 kg/m2) or adiposity (-3.64, -0.61% vs. -4.31, -1.04%) changes. CONCLUSIONS: A mindfulness-based group intervention is feasible/acceptable among adolescents at-risk for excess weight. In this pilot sample, mindfulness and health education were equivocal for BMI/adiposity outcomes. Future trials with a larger, adequately-powered sample and longer-term follow-up are necessary to test efficacy of a mindfulness-based intervention for food reward sensitivity, stress-eating, EF, and stabilizing growth trajectories in youth at-risk for adult obesity.

Influence of Sodium Glucose Cotransporter 2 Inhibition on Physiological Adaptation to Endurance Exercise Training.

CONTEXT: The combination of two beneficial antidiabetes interventions, regular exercise and pharmaceuticals, is intuitively appealing. However, metformin, the most commonly prescribed diabetes medication, attenuates the favorable physiological adaptations to exercise; in turn, exercise may impede the action of metformin. OBJECTIVE: We sought to determine the influence of an alternative diabetes treatment, sodium glucose cotransporter 2 (SGLT2) inhibition, on the response to endurance exercise training. DESIGN, PARTICIPANTS, AND INTERVENTION: In a randomized, double-blind, repeated measures parallel design, 30 sedentary overweight and obese men and women were assigned to 12 weeks of supervised endurance exercise training, with daily ingestion of either a placebo or SGLT2 inhibitor (dapagliflozin: ≤10 mg/day). OUTCOME MEASUREMENTS AND RESULTS: Endurance exercise training favorably modified body mass, body composition (dual-energy x-ray absorptiometry), peak oxygen uptake (graded exercise with indirect calorimetry), responses to standardized submaximal exercise (indirect calorimetry, heart rate, and blood lactate), and skeletal muscle (vastus lateralis) citrate synthase activity (main effects of exercise training, all P < 0.05); SGLT2 inhibition did not influence any of these physiological adaptations (exercise training × treatment interaction, all P > 0.05). However, after endurance exercise training, fasting blood glucose was greater with SGLT2 inhibition, and increased insulin sensitivity (oral glucose tolerance test/Matsuda index) was abrogated with SGLT2 inhibition (exercise training × treatment interaction, P < 0.01). CONCLUSION: The efficacy of combining two beneficial antidiabetes interventions, regular endurance exercise and SGLT2 inhibition, was not supported. SGLT2 inhibition blunted endurance exercise training-induced improvements in insulin sensitivity, independent of effects on aerobic fitness or body composition.

Impact of Childhood Malnutrition on Host Defense and Infection.

The global impact of childhood malnutrition is staggering. The synergism between malnutrition and infection contributes substantially to childhood morbidity and mortality. Anthropometric indicators of malnutrition are associated with the increased risk and severity of infections caused by many pathogens, including viruses, bacteria, protozoa, and helminths. Since childhood malnutrition commonly involves the inadequate intake of protein and calories, with superimposed micronutrient deficiencies, the causal factors involved in impaired host defense are usually not defined. This review focuses on literature related to impaired host defense and the risk of infection in primary childhood malnutrition. Particular attention is given to longitudinal and prospective cohort human studies and studies of experimental animal models that address causal, mechanistic relationships between malnutrition and host defense. Protein and micronutrient deficiencies impact the hematopoietic and lymphoid organs and compromise both innate and adaptive immune functions. Malnutrition-related changes in intestinal microbiota contribute to growth faltering and dysregulated inflammation and immune function. Although substantial progress has been made in understanding the malnutrition-infection synergism, critical gaps in our understanding remain. We highlight the need for mechanistic studies that can lead to targeted interventions to improve host defense and reduce the morbidity and mortality of infectious diseases in this vulnerable population.

Attenuating the Biologic Drive for Weight Regain Following Weight Loss: Must What Goes Down Always Go Back Up?

Metabolic adaptations occur with weight loss that result in increased hunger with discordant simultaneous reductions in energy requirements-producing the so-called energy gap in which more energy is desired than is required. The increased hunger is associated with elevation of the orexigenic hormone ghrelin and decrements in anorexigenic hormones. The lower total daily energy expenditure with diet-induced weight loss results from (1) a disproportionately greater decrease in circulating leptin and resting metabolic rate (RMR) than would be predicted based on the decline in body mass, (2) decreased thermic effect of food (TEF), and (3) increased energy efficiency at work intensities characteristic of activities of daily living. These metabolic adaptations can readily promote weight regain. While more experimental research is needed to identify effective strategies to narrow the energy gap and attenuate weight regain, some factors contributing to long-term weight loss maintenance have been identified. Less hunger and greater satiation have been associated with higher intakes of protein and dietary fiber, and lower glycemic load diets. High levels of physical activity are characteristic of most successful weight maintainers. A high energy flux state characterized by high daily energy expenditure and matching energy intake may attenuate the declines in RMR and TEF, and may also result in more accurate regulation of energy intake to match daily energy expenditure.

Ergogenic properties of metformin in simulated high altitude.

Metformin augments glucose/glycogen regulation and may acutely promote fatigue resistance during high-intensity exercise. In hypobaric environments, such as high altitude, the important contribution of carbohydrates to physiological function is accentuated as glucose/glycogen dependence is increased. Because hypoxia/hypobaria decreases insulin sensitivity, replenishing skeletal muscle glycogen in high altitude becomes challenging and subsequent physical performance may be compromised. We hypothesized that in conditions where glycogen repletion was critical to physical outcomes, metformin would attenuate hypoxia-mediated decrements in exercise performance. On three separate randomly ordered occasions, 13 healthy men performed glycogen-depleting exercise and ingested a low-carbohydrate dinner (1200 kcals, <10% carbohydrate). The next morning, in either normoxia or hypoxia (FiO2 =0.15), they ingested a high-carbohydrate breakfast (1225 kcals, 70% carbohydrate). Placebo (719 mg maltodextrin) or metformin (500 mg BID) was consumed 3 days prior to each hypoxia visit. Subjects completed a 12.5 km cycle ergometer time trial 3.5 hours following breakfast. Hypoxia decreased resting and exercise oxyhemoglobin saturation (P<.001). Neither hypoxia nor metformin affected the glucose response to breakfast (P=.977), however, compared with placebo, metformin lowered insulin concentration in hypoxia 45 minutes after breakfast (64.1±6.6 µU/mL vs 48.5±7.8 µU/mL; mean±SE; P<.001). Post-breakfast, pre-exercise vastus lateralis glycogen content increased in normoxia (+33%: P=.025) and in hypoxia with metformin (+81%; P=.006), but not in hypoxia with placebo (+27%; P=.167). Hypoxia decreased time trial performance compared with normoxia (P<.01). This decrement was similar with placebo (+2.6±0.8 minutes) and metformin (+1.6±0.3 minutes). These results indicate that metformin promotes glycogen synthesis but not endurance exercise performance in healthy men exposed to simulated high altitude.

Nutrition and physical activity transitions in the Ecuadorian Andes: Differences among urban and rural-dwelling women.

OBJECTIVES: The nutrition and physical activity transitions, characterized by increased consumption of high energy density foods and more sedentary lifestyles, are associated with increased obesity and hypertension in Ecuador. These transitions have been characterized primarily in urban areas, which may neglect variation in specific rural areas of Ecuador. Therefore we examined the extent of the differences in dietary and activity patterns, obesity prevalence, and blood pressure (BP) in urban and rural-dwelling women in the Ecuadorian central highlands. METHODS: Urban-dwelling women (UW, n = 198, mean age = 44 years) from three areas of a city of 250,000 residents and rural women (RW; n = 202, mean age = 47 years) from three remote communities in the same province (Chimborazo) were randomly selected and surveyed for dietary and activity practices, BP, and anthropometrics. RESULTS: Ninety percent of UW reported obtaining their food primarily from markets while 65% of RW women obtained their food primarily from their own cultivation. Cookies, cakes, candies, ice cream, and French fries were consumed more frequently by UW. RW reported lower consumption of beef, poultry, and chicken, as well as fruits, milk, and white rice. UW compared to RW women spent less time walking and in strenuous work activities. Obesity (BMI > 30 kg/m2 ) (UW = 18.7% vs RW = 9.2%) and hypertension (UW = 15.7%, RW= 3.0%) were more common in UW. Average systolic and diastolic BP was significantly higher in UW. CONCLUSIONS: The nutrition and physical activity transitions appear more evident in urban- compared to rural-dwelling women, and are associated with more obesity and higher BP.

Influence of Nrf2 activators on subcellular skeletal muscle protein and DNA synthesis rates after 6 weeks of milk protein feeding in older adults.

In older adults, chronic oxidative and inflammatory stresses are associated with an impaired increase in skeletal muscle protein synthesis after acute anabolic stimuli. Conjugated linoleic acid (CLA) and Protandim have been shown to activate nuclear factor erythroid-derived 2-like 2 (Nrf2), a transcription factor for the antioxidant response element and anti-inflammatory pathways. This study tested the hypothesis that compared to a placebo control (CON), CLA and Protandim would increase skeletal muscle subcellular protein (myofibrillar, mitochondrial, cytoplasmic) and DNA synthesis in older adults after 6 weeks of milk protein feeding. CLA decreased oxidative stress and skeletal muscle oxidative damage with a trend to increase messenger RNA (mRNA) expression of a Nrf2 target, NAD(P)H dehydrogenase quinone 1 (NQO1). However, CLA did not influence other Nrf2 targets (heme oxygenase-1 (HO-1), glutathione peroxidase 1 (Gpx1)) or protein or DNA synthesis. Conversely, Protandim increased HO-1 protein content but not the mRNA expression of downstream Nrf2 targets, oxidative stress, or skeletal muscle oxidative damage. Rates of myofibrillar protein synthesis were maintained despite lower mitochondrial and cytoplasmic protein syntheses after Protandim versus CON. Similarly, DNA synthesis was non-significantly lower after Protandim compared to CON. After Protandim, the ratio of protein to DNA synthesis tended to be greater in the myofibrillar fraction and maintained in the mitochondrial and cytoplasmic fractions, emphasizing the importance of measuring both protein and DNA synthesis to gain insight into proteostasis. Overall, these data suggest that Protandim may enhance proteostatic mechanisms of skeletal muscle contractile proteins after 6 weeks of milk protein feeding in older adults.

Linking dietary patterns with gut microbial composition and function.

Emerging insights have implicated the gut microbiota as an important factor in the maintenance of human health. Although nutrition research has focused on how direct interactions between dietary components and host systems influence human health, it is becoming increasingly important to consider nutrient effects on the gut microbiome for a more complete picture. Understanding nutrient-host-microbiome interactions promises to reveal novel mechanisms of disease etiology and progression, offers new disease prevention strategies and therapeutic possibilities, and may mandate alternative criteria to evaluate the safety of food ingredients. Here we review the current literature on diet effects on the microbiome and the generation of microbial metabolites of dietary constituents that may influence human health. We conclude with a discussion of the relevance of these studies to nutrition and public health and summarize further research needs required to realize the potential of exploiting diet-microbiota interactions for improved health.