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Effects of Low-Carbohydrate versus Mediterranean Diets on Weight Loss, Glucose Metabolism, Insulin Kinetics and β-Cell Function in Morbidly Obese Individuals.
Tricò, D, Moriconi, D, Berta, R, Baldi, S, Quinones-Galvan, A, Guiducci, L, Taddei, S, Mari, A, Nannipieri, M
Nutrients. 2021;13(4)
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Both low-carbohydrate and Mediterranean style diets are used to prevent lifestyle associated diseases such as obesity and type 2 diabetes. However, which diet is more effective is unclear. The aim of this randomised control trial of 36 morbidly obese individuals was to compare the effectiveness of Mediterranean diets and low-carbohydrate diets to improve metabolic measures such as blood sugar levels, pre-diabetes, and the body’s ability to use sugar. The results showed that in the short-term both diets were equally effective at improving biochemical dysfunctions that contribute to type 2 diabetes. The low-carbohydrate diet did result in higher weight loss than the Mediterranean diet. Studies on long-term effects are warranted. It was concluded that a low-carbohydrate diet is in the short-term a feasible alternative to the Mediterranean diet for improved weight loss and biological contributors to type 2 diabetes. This study could be used by healthcare professionals to understand that the Mediterranean diet and low-carbohydrate diet are both effective in the short-term for improvements to contributors to type 2 diabetes, however the low-carbohydrate diet may be superior if weight loss is required.
Abstract
Low-calorie Mediterranean-style or low-carbohydrate dietary regimens are widely used nutritional strategies against obesity and associated metabolic diseases, including type 2 diabetes. The aim of this study was to compare the effectiveness of a balanced Mediterranean diet with a low-carbohydrate diet on weight loss and glucose homeostasis in morbidly obese individuals at high risk to develop diabetes. Insulin secretion, insulin clearance, and different β-cell function components were estimated by modeling plasma glucose, insulin and C-peptide profiles during 75-g oral glucose tolerance tests (OGTTs) performed at baseline and after 4 weeks of each dietary intervention. The average weight loss was 5%, being 58% greater in the low-carbohydrate-group than Mediterranean-group. Fasting plasma glucose and glucose tolerance were not affected by the diets. The two dietary regimens proved similarly effective in improving insulin resistance and fasting hyperinsulinemia, while enhancing endogenous insulin clearance and β-cell glucose sensitivity. In summary, we demonstrated that a low-carbohydrate diet is a successful short-term approach for weight loss in morbidly obese patients and a feasible alternative to the Mediterranean diet for its glucometabolic benefits, including improvements in insulin resistance, insulin clearance and β-cell function. Further studies are needed to compare the long-term efficacy and safety of the two diets.
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Gastric emptying of solutions containing the natural sweetener erythritol and effects on gut hormone secretion in humans: A pilot dose-ranging study.
Wölnerhanssen, BK, Drewe, J, Verbeure, W, le Roux, CW, Dellatorre-Teixeira, L, Rehfeld, JF, Holst, JJ, Hartmann, B, Tack, J, Peterli, R, et al
Diabetes, obesity & metabolism. 2021;23(6):1311-1321
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In recent years, erythritol, a non-calorie sweetener, has gained popularity due to the rise in obesity and Type 2 diabetes worldwide. The purpose of this randomised, placebo-controlled, double-blind, cross-over trial was to assess the effects of erythritol on the release of gut hormones, speed of gastric emptying, and the release of glucagon, motilin, and glucose-dependent insulinotropic polypeptide after erythritol administration. Erythritol in doses of ten, twenty-five, and fifty grams was well tolerated by the participants. The administration of erythritol induced a statistically significant dose-dependent stimulation of gut hormones such as plasma cholecystokinin, active glucagon‐like peptide‐1 and peptide tyrosine. Compared to the placebo, participants had slower gastric emptying with erythritol. Erythritol had no effect on the levels of motilin, glucose-dependent insulinotropic polypeptide, blood glucose, insulin, glucagon, blood lipids, or uric acid. Erythritol should be evaluated in larger, robust studies to determine whether it improves glycaemic control. However, healthcare professionals can use the results of this study to understand the potential uses of erythritol in the management of obesity and type 2 diabetes.
Abstract
AIM: To determine whether a dose-dependent effect in the stimulation of gut hormone release (plasma cholecystokinin [CCK], active glucagon-like peptide-1 [aGLP-1] and peptide tyrosine tyrosine [PYY]) is found for the natural sweetener erythritol. MATERIALS AND METHODS Twelve healthy, lean volunteers received solutions with 10, 25 or 50 g erythritol, or tap water enriched with 13 C-sodium acetate on four study days via a nasogastric tube in this randomized (active treatments), placebo-controlled, double-blind, cross-over trial. Blood samples and breath samples (13 C-sodium acetate method for measurement of gastric emptying [GE]) were taken at regular intervals, and sensations of appetite and gastrointestinal symptoms were rated. RESULTS We found (a) a dose-dependent stimulation of CCK, aGLP-1 and PYY, and slowing of GE, (b) no effect on blood glucose, insulin, motilin, glucagon or glucose-dependent insulinotropic polypeptide, (c) no effect on blood lipids and uric acid, and (d) no abdominal pain, nausea or vomiting. CONCLUSIONS Solutions with 10 and 50 g of erythritol stimulated gut hormone release. Emptying of erythritol-containing solutions from the stomach was slower compared with placebo. There was no effect on plasma glucose, insulin, glucagon, blood lipids or uric acid. All doses were well tolerated.
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The Weight Optimization Revamping Lifestyle using the Dietary Guidelines (WORLD) Study: Sustained Weight Loss Over 12 Months.
Psota, TL, Tindall, AM, Lohse, B, Miller, PE, Petersen, KS, Kris-Etherton, PM
Obesity (Silver Spring, Md.). 2020;28(7):1235-1244
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Effective long-term weight loss strategies to reduce the risk of death and diseases associated with being obese or overweight are required, as restrictive programmes are difficult to sustain, and weight loss may be heavily influenced by behavioural factors. This randomised control trial of 101 premenopausal women with obesity or overweight aimed to compare a lower-fat and moderate-fat diets, both with nutrition education for 12 months. The results showed that both treatment groups lost weight. Both groups consumed the same amount of fat but increased their diet quality. Diet quality and greater attendance at nutritional education sessions were associated with greater weight loss. Cholesterol was significantly lower in both groups, but blood pressure remained unchanged. Interestingly there were a large number of women who did not complete the trial. It was concluded that irrespective of the amount of fat consumed, nutrition education can help to achieve sustained weight loss, improve diet quality and decrease heart disease risk for at least 12 months. This study could be used by healthcare professionals to understand that recommending fat-based targets for weight loss may be ineffective and the importance of emotional and behavioural support for individuals on a weight loss regime to improve their risk for heart disease.
Abstract
OBJECTIVE This study aimed to compare two energy-restricted, nutrient-dense diets at the upper or lower ends of the dietary fat recommendation range (lower fat [20% energy from fat] versus moderate fat [35%]) on weight loss using behavioral theory-based nutrition education. METHODS A total of 101 premenopausal women with overweight or obesity were randomized to an energy-restricted lower-fat or moderate-fat diet for 1 year. Interventions included 28 behavioral theory-based nutrition education sessions plus weekly exercise sessions. RESULTS Both treatment groups experienced weight loss (-5.0 kg for lower fat and -4.3 kg for moderate fat; P < 0.0001), but there was no difference in weight loss or fat intake between groups. Total and low-density lipoprotein cholesterol decreased (-3. 4 mg/dL and -3.8 mg/dL; P < 0.05), and high-density lipoprotein cholesterol increased (1.9 mg/dL; P < 0.05) in both groups at 12 months. Diet quality, assessed by the Healthy Eating Index, increased significantly at 4 months versus baseline (70.8 [0.9] vs. 77.8 [1.0]) and was maintained through 12 months. Higher Healthy Eating Index scores were associated with greater weight loss at 4 months (r = -0.2; P < 0.05). CONCLUSIONS In the context of a well-resourced, free-living weight-loss intervention, total fat intake did not change; however, theory-based nutrition education underpinned by food-based recommendations resulted in caloric deficits, improvements in diet quality, and weight loss that was sustained for 1 year.
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Combined aerobic exercise and high-intensity respiratory muscle training in patients surgically treated for non-small cell lung cancer: a pilot randomized clinical trial.
Messaggi-Sartor, M, Marco, E, Martínez-Téllez, E, Rodriguez-Fuster, A, Palomares, C, Chiarella, S, Muniesa, JM, Orozco-Levi, M, Barreiro, E, Güell, MR
European journal of physical and rehabilitation medicine. 2019;55(1):113-122
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Lung cancer treatment initiates a deconditioning storm that further reduces the capacity to deliver and utilize oxygen and metabolic substrates during exercise, contributing to poor cardiorespiratory fitness. The main aim of this study was to assess the impact of aerobic exercise with inspiratory and expiratory muscle training on cardiovascular fitness and respiratory muscle dysfunction in non-small cell lung cancer patients. The study is a two-centre, prospective, single-blind, pilot randomized controlled trial. The eligible patients were randomly assigned to the exercise (n=16) or control groups (n=21). Study results showed strong improvement in respiratory muscle strength and exercise capacity following high-intensity inspiratory and expiratory muscle training. Authors conclude that structured and supervised exercise interventions should be recommended to patients with lung cancer.
Abstract
BACKGROUND Lung resection surgery further decreases exercise capacity and negatively affects respiratory muscle function in patients with non-small cell lung cancer (NSCLC). The best design for exercise interventions in these patients has not been determined yet. AIM: To assess the impact of aerobic exercise and high-intensity respiratory muscle training on patient outcomes following lung cancer resection surgery. DESIGN Prospective, single-blind, pilot randomized controlled trial. SETTING Outpatient cardiopulmonary rehabilitation unit of two university hospitals. POPULATION Thirty-seven patients with NSCLC after tumor resection. METHODS Patients were randomly assigned to exercise training or usual post-operative care. The training program consisted of aerobic exercises and high-intensity respiratory muscle training (24 supervised sessions, 3 per week, 8 weeks). Primary outcome was exercise capacity assessed with peak oxygen uptake (VO2peak) during cardiopulmonary exercise test. Secondary outcomes included changes in respiratory muscle strength, levels of serum insulin growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3), and quality of life assessed with the European Organization for Research and Treatment of Cancer (EORTC QLQ-C30) questionnaire. RESULTS The 8-week training program was associated with significant improvement in VO2peak (2.13 mL/Kg/min [95%CI 0.06 to 4.20]), maximal inspiratory and expiratory pressures (18.96 cmH2O [95% CI 2.7 to 24.1] and 18.58 cmH2O [95% CI 4.0 to 33.1], respectively) and IGFBP-3 (0.61 µg/mL [%95 CI 0.1 to 1.12]). No significant differences were observed in the EORTC QLQ-C30. CONCLUSIONS An 8-week exercise program consisting of aerobic exercise and high-intensity respiratory muscle training improved exercise capacity, respiratory muscle strength, and serum IGFBP-3 levels in NSCLC patients after lung resection. There was no impact on the other outcomes assessed. CLINICAL REHABILITATION IMPACT A combination of aerobic exercise and respiratory muscle training could be included in the rehabilitation program of deconditioned patients with NSCLC after lung resection surgery.
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Effects of Mediterranean Diet and Physical Activity on Pulmonary Function: A Cross-Sectional Analysis in the ILERVAS Project.
Gutiérrez-Carrasquilla, L, Sánchez, E, Hernández, M, Polanco, D, Salas-Salvadó, J, Betriu, À, Gaeta, AM, Carmona, P, Purroy, F, Pamplona, R, et al
Nutrients. 2019;11(2)
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The Mediterranean diet is characterised by an abundant consumption of extra-virgin olive oil, fruits, vegetables, nuts, and legumes, a moderate consumption of fish and seafood, poultry, fermented dairy products, and red wine with meals, and low intakes of sweetened beverages, red meat and ready meals. The aim of the study was to evaluate the association between adherence to a Mediterranean diet and physical activity on pulmonary function in a large middle-aged population at low-to-moderate cardiovascular risk. The study is an ongoing study that between 2015 and 2017 enrolled a total of 3020 subjects – women aged between 50 to 70 years and men aged between 45 to 65 years – with the presence of at least one cardiovascular risk factor. Results indicate that a low adherence to the Mediterranean diet was linked with impaired breathing patterns and higher prevalence of abnormal lung function when compared to participants with a higher adherence to this dietary pattern. Additionally, vigorous physical activity was accompanied by better results in lung function than that observed in inactive subjects. The study provides initial clinical evidence about the independent and deleterious effect of both low adherence to the Mediterranean diet and low physical activity practice on lung function in participants without known pulmonary disease.
Abstract
A few studies showed that both adherence to Mediterranean diet (MedDiet) and physical activity practice have a positive impact on pulmonary function in subjects with lung disease. These associations are not well studied in subjects free from lung disease. In a cross-sectional study conducted in 3020 middle-aged subjects free of lung disease, adherence to the MedDiet using the Mediterranean Diet Adherence Screener, and physical activity practice using the International Physical Activity Questionnaire short form were recorded. Respiratory function was assessed using forced spirometry and the results were evaluated according to the Global initiative for Chronic Obstructive Lung Disease. Logistic regression models were used to analyze the associations between adherence to the MedDiet and physical activity practice with the presence of ventilatory defects. Participants with a high adherence to MedDiet, in comparison to those with low adherence, had both higher forced vital capacity (FVC; 100 (87⁻109) vs. 94 (82⁻105) % of predicted, p = 0.003) and forced expired volume in the first second (FEV1; 100 (89⁻112) vs. 93 (80⁻107) % of predicted, p < 0.001). According to their degree of physical activity, those subjects with a high adherence also had both higher FVC (100 (88⁻107) vs. 94 (83⁻105) % of predicted, p = 0.027) and FEV1 (100 (89⁻110) vs. 95 (84⁻108) % of predicted, p = 0.047) in comparison with those with low adherence. The multivariable logistic regression models showed a significant and independent association between both low adherence to MedDiet and low physical activity practice, and the presence of altered pulmonary patterns, with differences between men and women. However, no joint effect between adherence to MedDiet and physical activity practice on respiratory function values was observed. Low adherence to MedDiet and low physical activity practice were independently associated with pulmonary impairment. Therefore, the lung mechanics seem to benefit from heart-healthy lifestyle behaviors.
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Effects of n-3 fatty acids and exercise on oxidative stress parameters in type 2 diabetic: a randomized clinical trial.
Fayh, APT, Borges, K, Cunha, GS, Krause, M, Rocha, R, de Bittencourt, PIH, Moreira, JCF, Friedman, R, da Silva Rossato, J, Fernandes, JR, et al
Journal of the International Society of Sports Nutrition. 2018;15:18
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An elevated blood glucose level is one of the key metabolic abnormalities associated with complications in type 2 diabetes. Literature shows that individuals with type 2 diabetes have higher inflammatory levels than those with normal blood glucose tolerance. The aim of this study was to examine if omega-3 polyunsaturated fatty acid (PUFA) supplementation can reduce the inflammatory response associated with high-intensity exercise in type 2 diabetic individuals. This was a randomised, double-blind controlled study, which recruited 30 type 2 diabetic men and women aged between 30 and 60 years. Results indicate that after 8 weeks, omega-3 PUFA supplementation diminished the concentration of the total reactive antioxidant potential and triglyceride levels after high intensity exercise, however did not reduce the inflammatory response.
Abstract
BACKGROUND The relationship between diabetes and oxidative stress has been previously reported. Exercise represents a useful non-pharmacological strategy for the treatment in type 2 diabetic (T2DM) patients, but high intensity exercise can induce a transient inflammatory state and increase oxidative stress. Nutritional strategies that may contribute to the reduction of oxidative stress induced by acute exercise are necessary. The aim of this study was to examine if n-3 PUFA supplementation intervention can attenuate the inflammatory response and oxidative stress associated with high intensity exercise in this population. As a primary outcome, lipoperoxidation measurements (TBARS and F2-isoprostanes) were selected. METHODS Thirty T2DM patients, without chronic complications, were randomly allocated into two groups: placebo (gelatin capsules) or n-3 PUFA (capsules containing 180 mg of eicosapentaenoic acid and 120 mg of docosahexaenoic acid). Blood samples were collected fasting before and after 8 weeks supplementation. In the beginning and at the end of protocol, an acute exercise was performed (treadmill), and new blood samples were collected before and immediately after the exercise for measurements of oxidative stress and high-sensitivity C-reactive protein (hs-CRP). RESULTS After the supplementation period, a decrease in triglycerides levels was observed only in n-3 PUFA supplementation group (mean difference and 95% CI of 0.002 (0.000-0.004), p = 0.005). Supplementation also significantly reduced TRAP levels after exercise (mean difference and 95% CI to 9641 (- 20,068-39,351) for - 33,884 (- 56,976 - -10,793), p = 0.004, Cohen's d effect size = 1.12), but no significant difference was observed in n-3 PUFA supplementation group in lipoperoxidation parameters as TBARS (mean difference and 95% CI to - 3.8 (- 10-2.4) for - 2.9 (- 1.6-7.4) or F2-isoprostanes (mean difference and 95% CI -0.05 (- 0.19-0.10) for - 0.02 (- 0.19-0.16), p > 0.05 for both. CONCLUSION PUFA n-3 supplementation reduced triglycerides as well as TRAP levels after exercise, without a significant effect on inflammatory and oxidative stress markers.This study is registered at ClinicalTrials.gov with the registration number of NCT03182712.
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Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males.
Moro, T, Tinsley, G, Bianco, A, Marcolin, G, Pacelli, QF, Battaglia, G, Palma, A, Gentil, P, Neri, M, Paoli, A
Journal of translational medicine. 2016;14(1):290
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Time-restricted feeding (TRF) allows subjects to consume ad libitum energy intake within a defined window of time, which means a fasting window of 12–21 h per day is employed. The aim of the present study was to investigate the effects of an isoenergetic TRF protocol on body composition, athletic performance, and metabolic factors during resistance training in healthy resistance trained males. The study enrolled thirty-four resistance-trained males. The participants were randomly assigned to a TRF group (n = 17) or standard diet group (n = 17). Training was standardized for both groups. Results indicate that after 8 weeks, a significant decrease in fat mass was observed in the TRF group, while fat-free mass was maintained in both groups. The same trend was observed for arm and thigh muscle cross-sectional area. Leg press maximal strength increased significantly, but no difference was present between treatments. Authors conclude that TRF can maintain muscle mass, reducing body fat, and reducing inflammation markers and anabolic hormones. This kind of regimen could be adopted by athletes during maintenance phases of training in which the goal is to maintain muscle mass while reducing fat mass.
Abstract
BACKGROUND Intermittent fasting (IF) is an increasingly popular dietary approach used for weight loss and overall health. While there is an increasing body of evidence demonstrating beneficial effects of IF on blood lipids and other health outcomes in the overweight and obese, limited data are available about the effect of IF in athletes. Thus, the present study sought to investigate the effects of a modified IF protocol (i.e. time-restricted feeding) during resistance training in healthy resistance-trained males. METHODS Thirty-four resistance-trained males were randomly assigned to time-restricted feeding (TRF) or normal diet group (ND). TRF subjects consumed 100 % of their energy needs in an 8-h period of time each day, with their caloric intake divided into three meals consumed at 1 p.m., 4 p.m., and 8 p.m. The remaining 16 h per 24-h period made up the fasting period. Subjects in the ND group consumed 100 % of their energy needs divided into three meals consumed at 8 a.m., 1 p.m., and 8 p.m. Groups were matched for kilocalories consumed and macronutrient distribution (TRF 2826 ± 412.3 kcal/day, carbohydrates 53.2 ± 1.4 %, fat 24.7 ± 3.1 %, protein 22.1 ± 2.6 %, ND 3007 ± 444.7 kcal/day, carbohydrates 54.7 ± 2.2 %, fat 23.9 ± 3.5 %, protein 21.4 ± 1.8). Subjects were tested before and after 8 weeks of the assigned diet and standardized resistance training program. Fat mass and fat-free mass were assessed by dual-energy x-ray absorptiometry and muscle area of the thigh and arm were measured using an anthropometric system. Total and free testosterone, insulin-like growth factor 1, blood glucose, insulin, adiponectin, leptin, triiodothyronine, thyroid stimulating hormone, interleukin-6, interleukin-1β, tumor necrosis factor α, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured. Bench press and leg press maximal strength, resting energy expenditure, and respiratory ratio were also tested. RESULTS After 8 weeks, the 2 Way ANOVA (Time * Diet interaction) showed a decrease in fat mass in TRF compared to ND (p = 0.0448), while fat-free mass, muscle area of the arm and thigh, and maximal strength were maintained in both groups. Testosterone and insulin-like growth factor 1 decreased significantly in TRF, with no changes in ND (p = 0.0476; p = 0.0397). Adiponectin increased (p = 0.0000) in TRF while total leptin decreased (p = 0.0001), although not when adjusted for fat mass. Triiodothyronine decreased in TRF, but no significant changes were detected in thyroid-stimulating hormone, total cholesterol, high-density lipoprotein, low-density lipoprotein, or triglycerides. Resting energy expenditure was unchanged, but a significant decrease in respiratory ratio was observed in the TRF group. CONCLUSIONS Our results suggest that an intermittent fasting program in which all calories are consumed in an 8-h window each day, in conjunction with resistance training, could improve some health-related biomarkers, decrease fat mass, and maintain muscle mass in resistance-trained males.
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Feasibility outcomes of a presurgical randomized controlled trial exploring the impact of caloric restriction and increased physical activity versus a wait-list control on tumor characteristics and circulating biomarkers in men electing prostatectomy for prostate cancer.
Demark-Wahnefried, W, Nix, JW, Hunter, GR, Rais-Bahrami, S, Desmond, RA, Chacko, B, Morrow, CD, Azrad, M, Frugé, AD, Tsuruta, Y, et al
BMC cancer. 2016;16:61
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There is a strong body of evidence associating obesity and increased risk for more aggressive and progressive cancer. This paper aims to assess the feasibility of a presurgical diet and exercise weight loss intervention in men with newly-diagnosed prostate cancer who elected for prostatectomy. It also aims to explore the intervention’s effects on tumour proliferation rates and other biomarkers. The 3-weeks randomised controlled study included 40 overweight or obese men newly-diagnosed with prostate cancer. Participants in experimental arm were assigned to a healthy energy-restricted diet versus wait-list control arm. All feasibility endpoints were achieved with accrual completed within 2 years, retention of 85%, adherence of 95% and no adverse events. Biologic outcomes were not included in this paper, as biological testing was still ongoing. Authors concluded that this study’s methods and data on feasibility could provide useful framework for the design of future trials. They also highlighted the importance of presurgical trials as a feasible and safe means to assess the impacts of diet and exercise on tumour tissue.
Abstract
BACKGROUND Obesity is associated with tumor aggressiveness and disease-specific mortality for more than 15 defined malignancies, including prostate cancer. Preclinical studies suggest that weight loss from caloric restriction and increased physical activity may suppress hormonal, energy-sensing, and inflammatory factors that drive neoplastic progression; however, exact mechanisms are yet to be determined, and experiments in humans are limited. METHODS We conducted a randomized controlled trial among 40 overweight or obese, newly-diagnosed prostate cancer patients who elected prostatectomy to explore feasibility of a presurgical weight loss intervention that promoted a weight loss of roughly one kg. week(-1) via caloric restriction and physical activity, as well as to assess effects on tumor biology and circulating biomarkers. Measures of feasibility (accrual, retention, adherence, and safety) were primary endpoints. Exploratory aims were directed at the intervention's effect on tumor proliferation (Ki-67) and other tumor markers (activated caspase-3, insulin and androgen receptors, VEGF, TNFβ, NFκB, and 4E-BP1), circulating biomarkers (PSA, insulin, glucose, VEGF, TNFβ, leptin, SHBG, and testosterone), lymphocytic gene expression of corresponding factors and cellular bioenergetics in neutrophils, and effects on the gut microbiome. Consenting patients were randomized in a 1:1 ratio to either: 1) weight loss via a healthful, guidelines-based diet and exercise regimen; or 2) a wait-list control. While biological testing is currently ongoing, this paper details our methods and feasibility outcomes. RESULTS The accrual target was met after screening 101 cases (enrollment rate: 39.6%). Other outcomes included a retention rate of 85%, excellent adherence (95%), and no serious reported adverse events. No significant differences by age, race, or weight status were noted between enrollees vs. non-enrollees. The most common reasons for non-participation were "too busy" (30%), medical exclusions (21%), and "distance" (16%). CONCLUSIONS Presurgical trials offer a means to study the impact of diet and exercise interventions directly on tumor tissue, and other host factors that are feasible and safe, though modifications are needed to conduct trials within an abbreviated period of time and via distance medicine-based approaches. Pre-surgical trials are critical to elucidate the impact of lifestyle interventions on specific mechanisms that mediate carcinogenesis and which can be used subsequently as therapeutic targets. TRIAL REGISTRATION NCT01886677.
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Three 15-min bouts of moderate postmeal walking significantly improves 24-h glycemic control in older people at risk for impaired glucose tolerance.
DiPietro, L, Gribok, A, Stevens, MS, Hamm, LF, Rumpler, W
Diabetes care. 2013;36(10):3262-8
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The insulin response is known to decline with age, which puts older people at risk of hyperglycaemia after eating. Insulin and exercise stimulate the uptake of glucose into skeletal muscle so exercise could aid insulin in age-related impaired glucose tolerance (IGT). This small randomised controlled trial (RCT) used a multiple crossover design to compare the effect of exercise timing and frequency on glycaemia control in older people. The ten trial subjects were at risk of impaired glucose tolerance (IGT), but were otherwise healthy with an average age of sixty-nine years old. Subjects were housed in whole room calorimeters, fed three standardised meals a day and glucose levels were monitored. Subjects were randomly assigned to walk on a treadmill for either fifteen minutes after each of the three meals, or walk for forty-five minutes either at mid-morning or mid-afternoon. It was found that that both the morning walk and the post-meal walking decreased 24 hour glucose concentration, whilst the afternoon walk had little impact. Post-meal walking was effective at lowering glucose levels after each meal including dinner, where the other exercise protocols were not. The author concluded that the timing of the exercise may be as important, if not more, than volume. Short (15 minute) bouts of post-meal walking could be manageable for older people and appears to be an effective way of controlling post eating hyperglycaemia.
Abstract
OBJECTIVE The purpose of this study was to compare the effectiveness of three 15-min bouts of postmeal walking with 45 min of sustained walking on 24-h glycemic control in older persons at risk for glucose intolerance. RESEARCH DESIGN AND METHODS Inactive older (≥60 years of age) participants (N=10) were recruited from the community and were nonsmoking, with a BMI<35 kg/m2 and a fasting blood glucose concentration between 105 and 125 mg dL(-1). Participants completed three randomly ordered exercise protocols spaced 4 weeks apart. Each protocol comprised a 48-h stay in a whole-room calorimeter, with the first day serving as the control day. On the second day, participants engaged in either 1) postmeal walking for 15 min or 45 min of sustained walking performed at 2) 10:30 a.m. or 3) 4:30 p.m. All walking was on a treadmill at an absolute intensity of 3 METs. Interstitial glucose concentrations were determined over 48 h with a continuous glucose monitor. Substrate utilization was measured continuously by respiratory exchange (VCO2/VO2). RESULTS Both sustained morning walking (127±23 vs. 118±14 mg dL(-1)) and postmeal walking (129±24 vs. 116±13 mg dL(-1)) significantly improved 24-h glycemic control relative to the control day (P<0.05). Moreover, postmeal walking was significantly (P<0.01) more effective than 45 min of sustained morning or afternoon walking in lowering 3-h postdinner glucose between the control and experimental day. CONCLUSIONS Short, intermittent bouts of postmeal walking appear to be an effective way to control postprandial hyperglycemia in older people.
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Effect of the artificial sweetener, sucralose, on gastric emptying and incretin hormone release in healthy subjects.
Ma, J, Bellon, M, Wishart, JM, Young, R, Blackshaw, LA, Jones, KL, Horowitz, M, Rayner, CK
American journal of physiology. Gastrointestinal and liver physiology. 2009;296(4):G735-9
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Artificial sweeteners have been used to replace carbohydrate in the management of diabetes and obesity. Sucralose is a noncaloric sweetener derived from sucrose and is ∼600 times sweeter. The aims of this study were to evaluate the incretin [metabolic hormone], insulin, and glycaemic responses to sucralose administration and to determine whether this artificial sweetener is capable of generating feedback in the small intestine that slows gastric emptying in healthy humans. This study studied seven healthy subjects whose average age was 24 years. Each subject attended the Discipline of Medicine at the Royal Adelaide Hospital on four occasions (after 14hr overnight fast), each separated by 3–7 days. Women were studied in the follicular phase of the menstrual cycle. Results indicate that fasting blood glucose concentrations and plasma incretin and insulin concentrations did not differ between the four study days. Authors conclude that artificial sweeteners may have no therapeutic benefit in the dietary management of diabetes, other than as a substitute for carbohydrate.
Abstract
The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), play an important role in glucose homeostasis in both health and diabetes. In mice, sucralose, an artificial sweetener, stimulates GLP-1 release via sweet taste receptors on enteroendocrine cells. We studied blood glucose, plasma levels of insulin, GLP-1, and GIP, and gastric emptying (by a breath test) in 7 healthy humans after intragastric infusions of 1) 50 g sucrose in water to a total volume of 500 ml (approximately 290 mosmol/l), 2) 80 mg sucralose in 500 ml normal saline (approximately 300 mosmol/l, 0.4 mM sucralose), 3) 800 mg sucralose in 500 ml normal saline (approximately 300 mosmol/l, 4 mM sucralose), and 4) 500 ml normal saline (approximately 300 mosmol/l), all labeled with 150 mg 13C-acetate. Blood glucose increased only in response to sucrose (P<0.05). GLP-1, GIP, and insulin also increased after sucrose (P=0.0001) but not after either load of sucralose or saline. Gastric emptying of sucrose was slower than that of saline (t50: 87.4+/-4.1 min vs. 74.7+/-3.2 min, P<0.005), whereas there were no differences in t50 between sucralose 0.4 mM (73.7+/-3.1 min) or 4 mM (76.7+/-3.1 min) and saline. We conclude that sucralose, delivered by intragastric infusion, does not stimulate insulin, GLP-1, or GIP release or slow gastric emptying in healthy humans.