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A plant-based diet in overweight individuals in a 16-week randomized clinical trial: metabolic benefits of plant protein.
Kahleova, H, Fleeman, R, Hlozkova, A, Holubkov, R, Barnard, ND
Nutrition & diabetes. 2018;8(1):58
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Suboptimal nutrition is a major cause of obesity, chronic disease, and premature death across the nation and worldwide. The aim of this study was to explore the effects of plant protein, as part of a plant-based diet, on weight control, body composition, and insulin resistance in overweight individuals. This study is a secondary analysis of data from a 16-week randomized clinical trial. Participants were randomly assigned in a 1:1 ratio to a vegan or a control group. Results indicate that: - the quality and quantity of dietary protein from a plant-based vegan diet are associated with improvements in body composition, body weight, and insulin resistance in overweight individuals. - decreased intake of animal protein and an increased intake of plant protein were associated with a decrease in fat mass. - decreased histidine [amino acid] intake was associated with a decrease in insulin resistance. - decreased intake of the amino acids threonine, leucine, lysine, methionine, and tyrosine were each associated with a decrease in insulin resistance (mainly driven by weight loss). Authors conclude that there is the need for additional research to explore the mechanisms explaining the beneficial role of plant protein and specific amino acids in regulating body weight, body composition, and insulin resistance.
Abstract
BACKGROUND AND OBJECTIVES A plant-based diet is an effective strategy in the treatment of obesity. In this 16-week randomized clinical trial, we tested the effect of a plant-based diet on body composition and insulin resistance. As a part of this trial, we investigated the role of plant protein on these outcomes. SUBJECTS AND METHODS Overweight participants (n = 75) were randomized to follow a plant-based (n = 38) or a control diet (n = 37). Dual X-ray Absorptiometry assessed body composition, Homeostasis Model Assessment (HOMA-IR) assessed insulin resistance, and a linear regression model was used to test the relationship between protein intake, body composition, and insulin resistance. RESULTS The plant-based vegan diet proved to be superior to the control diet in improving body weight, fat mass, and insulin resistance markers. Only the vegan group showed significant reductions in body weight (treatment effect -6.5 [95% CI -8.9 to -4.1] kg; Gxt, p < 0.001), fat mass (treatment effect -4.3 [95% CI -5.4 to -3.2] kg; Gxt, p < 0.001), and HOMA-IR (treatment effect -1.0 [95% CI -1.2 to -0.8]; Gxt, p = 0.004). The decrease in fat mass was associated with an increased intake of plant protein and decreased intake of animal protein (r = -0.30, p = 0.011; and r = +0.39, p = 0.001, respectively). In particular, decreased % leucine intake was associated with a decrease in fat mass (r = +0.40; p < 0.001), in both unadjusted and adjusted models for changes in BMI and energy intake. In addition, decreased % histidine intake was associated with a decrease in insulin resistance (r = +0.38; p = 0.003), also independent of changes in BMI and energy intake. CONCLUSIONS These findings provide evidence that plant protein, as a part of a plant-based diet, and the resulting limitation of leucine and histidine intake are associated with improvements in body composition and reductions in both body weight and insulin resistance.
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Men and women respond differently to rapid weight loss: Metabolic outcomes of a multi-centre intervention study after a low-energy diet in 2500 overweight, individuals with pre-diabetes (PREVIEW).
Christensen, P, Meinert Larsen, T, Westerterp-Plantenga, M, Macdonald, I, Martinez, JA, Handjiev, S, Poppitt, S, Hansen, S, Ritz, C, Astrup, A, et al
Diabetes, obesity & metabolism. 2018;20(12):2840-2851
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Overweight and obesity are major risk factors for developing type 2 diabetes mellitus. Men and women respond differently to weight loss programmes, with men typically losing more weight and more abdominal fat, whilst women lose more subcutaneous fat. The aim of this large multinational study was to compare the effects of weight loss induced by an 8‐week low energy diet on metabolic outcomes in overweight men and women with prediabetes. Study participants followed the Cambridge Weight Plan which is based on four formula meals, with a total of approximately 810kcal, per day, for eight weeks. Small amounts of non-starchy vegetables were allowed, as were psyllium husks in case of digestive problems. Men lost significantly more weight than women, 11.8% versus 10.3%. Insulin resistance improved similarly in men and women, but metabolic syndrome score improved more in men than in women. Men lost more fat than women and generally had more beneficial metabolic changes. Women had higher reductions in fat-free mass, bone mineral content and HDL cholesterol than men, raising the question whether rapid weight loss may have negative longer term effects for women.
Abstract
AIMS: The PREVIEW lifestyle intervention study (ClinicalTrials.gov Identifier: NCT01777893) is, to date, the largest, multinational study concerning prevention of type-2 diabetes. We hypothesized that the initial, fixed low-energy diet (LED) would induce different metabolic outcomes in men vs women. MATERIALS AND METHODS All participants followed a LED (3.4 MJ/810 kcal/daily) for 8 weeks (Cambridge Weight Plan). Participants were recruited from 8 sites in Europe, Australia and New Zealand. Those eligible for inclusion were overweight (BMI ≥ 25 kg/m2 ) individuals with pre-diabetes according to ADA-criteria. Outcomes of interest included changes in insulin resistance, fat mass (FM), fat-free mass (FFM) and metabolic syndrome Z-score. RESULTS In total, 2224 individuals (1504 women, 720 men) attended the baseline visit and 2020 (90.8%) completed the follow-up visit. Following the LED, weight loss was 16% greater in men than in women (11.8% vs 10.3%, respectively) but improvements in insulin resistance were similar. HOMA-IR decreased by 1.50 ± 0.15 in men and by 1.35 ± 0.15 in women (ns). After adjusting for differences in weight loss, men had larger reductions in metabolic syndrome Z-score, C-peptide, FM and heart rate, while women had larger reductions in HDL cholesterol, FFM, hip circumference and pulse pressure. Following the LED, 35% of participants of both genders had reverted to normo-glycaemia. CONCLUSIONS An 8-week LED induced different effects in women than in men. These findings are clinically important and suggest gender-specific changes after weight loss. It is important to investigate whether the greater decreases in FFM, hip circumference and HDL cholesterol in women after rapid weight loss compromise weight loss maintenance and future cardiovascular health.
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The Effects of Extra Virgin Olive Oil on Alanine Aminotransferase, Aspartate Aminotransferase, and Ultrasonographic Indices of Hepatic Steatosis in Nonalcoholic Fatty Liver Disease Patients Undergoing Low Calorie Diet.
Shidfar, F, Bahrololumi, SS, Doaei, S, Mohammadzadeh, A, Gholamalizadeh, M, Mohammadimanesh, A
Canadian journal of gastroenterology & hepatology. 2018;2018:1053710
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Non-alcoholic fatty liver disease (NAFLD) is a risk factor for cardiovascular disease (CVD), which is the most common cause of death. The traditional Mediterranean diet has been shown to reduce the risk of NAFLD and CVD and this protective effect is thought to be in part due to the use of olive oil in this dietary pattern. The aim of this randomised, single-blind study was to evaluate the effect of virgin olive oil as part of a low-calorie diet on markers of NAFLD. 43 overweight or obese patients with NAFLD, characterised by increased liver enzymes (ALT and AST), were randomised to either a low calorie diet with normal fat or a low calorie diet with 20% of total energy intake from olive oil (overall percentage of fat 30% of total energy intake in both groups) for three months. Significant weight loss was observed in both groups, with no significant difference between groups. There was a reduction in liver enzymes in the olive oil group which was significantly greater than in the control group. The severity of liver steatosis (the accumulation of fat in the liver) did not change significantly in either group. The authors concluded that a low calorie diet with virgin olive oil led to slight weight loss and improvements in markers for NAFLD.
Abstract
Background: Coronary artery disease is the most common cause of death in the patients with nonalcoholic fatty liver disease (NAFLD). Studies have shown that there is a strong relation between the increase in the aminotransferase levels and fat accumulation in the liver with cardiovascular complications, independent of all aspects of the metabolic syndrome. This study aimed to examine the effect of virgin olive oil on alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the severity of steatosis in the NAFLD patients undergoing a weight-loss diet. Methods: This clinical trial was carried out on 50 patients with nonalcoholic fatty liver (mean age of 45.91 ± 9.61 years, mean BMI of 29.7 ± 0.58 Kg/m2) and the subjects were randomly assigned to the olive oil group (receiving the equivalent of 20% of their total daily energy requirement from olive oil) or the control group (with normal consumption of oil) for 12 weeks. All the patients received a hypocaloric diet during the study. At the beginning and the end of the study, the serum levels of ALT and AST and liver steatosis were measured. Findings: A significant decrease in the level of ALT enzymes was observed in the control group at the end of the study (P = 0.004). In the olive oil group, both enzymes decreased compared to baseline measurements (P < 0.01). There were significant differences in the ALT and AST levels between the two groups (P < 0.02). The severity of liver steatosis did not change significantly during the study. Conclusion: The consumption of a low calorie diet enriched with olive oil, along with slight weight reduction, reinforces the desired effects of weight loss in improving the levels of the hepatic enzymes.
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A Khorasan Wheat-Based Replacement Diet Improves Risk Profile of Patients With Nonalcoholic Fatty Liver Disease (NAFLD): A Randomized Clinical Trial.
Dinu, M, Whittaker, A, Pagliai, G, Giangrandi, I, Colombini, B, Gori, AM, Fiorillo, C, Becatti, M, Casini, A, Benedettelli, S, et al
Journal of the American College of Nutrition. 2018;37(6):508-514
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Non-alcoholic fatty liver disease (NAFLD) is prevalent, however early intervention with lifestyle modifications such as weight loss, dietary therapy and physical activity may reverse it. Previous studies have shown that the Mediterranean diet, which includes a large proportion of grains, may reduce NAFLD. However no prior studies have assessed grains in isolation on these individuals. This randomised double blind parallel arm study aimed to assess the effects of a replacement diet with ancient khorasan wheat products on patients with NAFLD. 40 people with mild- moderate NAFLD were assigned to either khorasan wheat diet or a modern wheat grain diet for three months. This comparatively small study found that a khorasan wheat based diet improved liver function and inflammation. However regardless of the diet, measures of oxidative stress, which assesses the imbalance of free radicals and antioxidants in the body, was significantly reduced and some individuals were shown to regress from moderate to mild NAFLD. Nutrition practitioners who have clients with mild-moderate NAFLD may recommend a khorasan wheat based diet in the short term to improve biochemical and inflammatory markers and to potentially reverse disease development.
Abstract
OBJECTIVE KAMUT khorasan is an ancient grain with widely acclaimed health benefits. The aim of this study was to investigate the effects of a replacement diet with ancient khorasan wheat products in patients with NAFLD, in comparison to a similar replacement diet with control products made from organic semi-whole-grain modern wheat. METHODS Forty NAFLD patients (12 M/28 F; age 55.2 ± 10.4 years) with mild to moderate liver steatosis were included. The experimental design was a randomized, double-blind, parallel-arm study with 20 participants assigned to consume either KAMUT khorasan or control wheat products (pasta, bread, crackers, biscuits) over a 3-month period. Anthropometric measurements, blood analyses, and ultrasonography examination were performed at both the beginning and end of each dietary intervention. RESULTS After the implementation of a general linear model for repeated measurements adjusted for baseline demographic details, risk factors, and medication, alanine aminotransferase (ALT) was significantly reduced by 12%, aspartate aminotransferase (AST) by 14%, alkaline phosphatase (ALP) by 8%, and cholesterol by 6% only in the khorasan group (p < 0.05 for all). Similarly, significant reductions in circulating proinflammatory tumor necrosis factor-alpha by 50%, interleukin l-receptor antagonist-alpha by 37%, interleukin-8 by 24%, and interferon gamma by 24% were evident only in participants who consumed the khorasan products (p < 0.05 for all). Finally, significant improvements in the liver steatosis grading, Doppler perfusion index values, and reactive oxygen species (ROS) production were evident after consumption of both the khorasan and control products. CONCLUSIONS This study suggests that a short-term replacement diet with ancient KAMUT khorasan products is most effective in reducing metabolic risk factors and ameliorating the liver profile in patients with NAFLD.
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Effect of intermittent vs. daily calorie restriction on changes in weight and patient-reported outcomes in people with multiple sclerosis.
Fitzgerald, KC, Vizthum, D, Henry-Barron, B, Schweitzer, A, Cassard, SD, Kossoff, E, Hartman, AL, Kapogiannis, D, Sullivan, P, Baer, DJ, et al
Multiple sclerosis and related disorders. 2018;23:33-39
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Multiple sclerosis (MS) is a disease of the central nervous system. Dietary modification is emerging as a safe intervention to potentially modify disease course. The main aim of this study was to assess the safety and feasibility of an intermittent fasting diet in people with MS. Secondary outcomes explored the effects of calorie restriction (CR) diets on body weight and anthropometric characteristics as well as on patient-reported outcomes including fatigue, sleep and mood. The study is a pilot randomised controlled feeding study of three different types of diets. Each participant (n=36) was randomized to 1 of 3 diets: a control diet (placebo), a daily CR diet and intermittent CR diet. Results indicate that daily CR diet was associated with marginally greater weight loss than the intermittent CR diet. Both CR diets were associated with trends toward improvements in cardiometabolic outcomes. Furthermore, CR diets were associated with in improvements in emotional well-being. Authors conclude that CR and weight loss represent interventions for clinically relevant symptoms due to MS, such as emotional well-being, without adding meaningful risks or adverse outcomes.
Abstract
An intermittent fasting or calorie restriction diet has favorable effects in the mouse forms of multiple sclerosis (MS) and may provide additional anti-inflammatory and neuroprotective advantages beyond benefits obtained from weight loss alone. We conducted a pilot randomized controlled feeding study in 36 people with MS to assess safety and feasibility of different types of calorie restriction (CR) diets and assess their effects on weight and patient reported outcomes in people with MS. Patients were randomized to receive 1 of 3 diets for 8 weeks: daily CR diet (22% daily reduction in energy needs), intermittent CR diet (75% reduction in energy needs, 2 days/week; 0% reduction, 5 days/week), or a weight-stable diet (0% reduction in energy needs, 7 days/week). Of the 36 patients enrolled, 31 (86%) completed the trial; no significant adverse events occurred. Participants randomized to CR diets lost a median 3.4 kg (interquartile range [IQR]: -2.4, -4.0). Changes in weight did not differ significantly by type of CR diet, although participants randomized to daily CR tended to have greater weight loss (daily CR: -3.6 kg [IQR: -3.0, -4.1] vs. intermittent CR: -3.0 kg [IQR: -1.95, -4.1]; P = 0.15). Adherence to study diets differed significantly between intermittent CR vs. daily CR, with lesser adherence observed for intermittent CR (P = 0.002). Randomization to either CR diet was associated with significant improvements in emotional well-being/depression scores relative to control, with an average 8-week increase of 1.69 points (95% CI: 0.72, 2.66). CR diets are a safe/feasible way to achieve weight loss in people with MS and may be associated with improved emotional health.
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Effects of 3-week total meal replacement vs. typical food-based diet on human brain functional magnetic resonance imaging food-cue reactivity and functional connectivity in people with obesity.
Kahathuduwa, CN, Davis, T, O'Boyle, M, Boyd, LA, Chin, SH, Paniukov, D, Binks, M
Appetite. 2018;120:431-441
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Weight loss diets that use total meal replacement shakes have been shown to reduce food cravings compared to typical reduced-calorie diets. The mechanism for this is unclear. This study examined the effects of a 3-week 1120 kcal per day meal replacement diet compared to a reduced calorie diet on activity in areas of the brain associated with food cravings. Thirty-two obese adults participated in the study. Before and after the study, the participants were given magnetic resonance imaging (MRI) scans to measure activity in different areas of the brain. They were also questioned on food cravings and weighed. The group following the meal replacement diet experienced a significant weight loss of 4.87 kg, a reduction in body fat of 2.19 kg and reduced their overall food cravings. The reduced calorie diet group also experienced significant weight loss and a reduction in body fat (2.37kg and 1.64kg, respectively) but less than the meal replacement group. The meal replacement group experienced reduced cravings compared to the reduced calorie diet group. MRI scans suggested that this was due to changes in activity in the food reward related regions in several areas of the brain, resulting in an increase in executive control. The authors concluded that meal replacement diets may increase executive control within the brain, leading to a reduction in food cravings and weight loss.
Abstract
OBJECTIVES Calorie restriction via total meal replacement (TMR) results in greater reduction of food cravings compared to reduced-calorie typical diet (TD). Direct evidence of the impact of these interventions on human brain fMRI food-cue reactivity (fMRI-FCR) and functional connectivity is absent. We examined the effects of a 3-week 1120 kcal/d TMR intervention as compared to an iso-caloric TD intervention using an fMRI-FCR paradigm. METHODS Thirty-two male and female subjects with obesity (19-60 years; 30-39.9 kg/m2) participated in a randomized two-group repeated measures dietary intervention study consisting of 1120 kcal/d from either 1) TMR (shakes), 2) TD (portion control). Pre-intervention and following the 3-week diet fMRI-FCR, functional connectivity, food cravings (Food Craving Inventory) and weight were considered. RESULTS Compared to TD, TMR showed increased fMRI-FCR of the bilateral dorsolateral prefrontal (dlPFC), orbitofrontal, anterior cingulate, primary motor and left insular cortices and bilateral nucleus accumbens regions in the post-intervention state relative to the pre-intervention state. Compared to TD, TMR was also associated with negative modulation of fMRI-FCR of the nucleus accumbens, orbitofrontal cortex and amygdala by dlPFC. Reduced body weight (4.87 kg, P < 0.001), body fat (2.19 kg, P = 0.004) and overall food cravings (0.41, P = 0.047) were seen in the TMR group. In the TD group reduced body weight (2.37 kg, P = 0.004) and body fat (1.64 kg, P = 0.002) were noted. Weight loss was significantly greater in TMR versus TD (2.50 kg, P = 0.007). CONCLUSIONS Greater weight loss and reduced cravings, coupled with stronger activations and potential negative modulation of the food reward related regions by the dlPFC during exposure to visual food cues is consistent with increased executive control in TMR vs. TD.
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Effects of Providing High-Fat versus High-Carbohydrate Meals on Daily and Postprandial Physical Activity and Glucose Patterns: a Randomised Controlled Trial.
Parr, EB, Devlin, BL, Callahan, MJ, Radford, BE, Blankenship, JM, Dunstan, DW, Hawley, JA
Nutrients. 2018;10(5)
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The timing of habitual meal consumption and composition is known to be an important factor in health status, particularly for blood glucose regulation. The aim of this randomised crossover study was to assess the effects of altering meal timing and diet composition on postprandial glucose and physical activity levels. Eight overweight or obese men with a sedentary lifestyle completed two 12-day measurement periods including a 7-day habitual period followed by a 5-day experimental period, with an 8-day washout period. The two conditions tested were a high-fat, low carbohydrate diet (HFD) and a high-carbohydrate, low-fat diet (HCD) and participants were instructed to consume meals at standardised times throughout both conditions. Body composition, oxygen consumption and blood glucose were measured at baseline and between each experimental condition. This trial found the provision of meals did not alter overall activity patterns or postprandial activity patterns. The authors observed increased sedentary activity across the day, and identify evening time as an important target for sedentary time to be minimised. Based on these results, the authors suggest that future dietary interventions consider habitual meal consumption and composition to best replicate real-world behaviours.
Abstract
We determined the effects of altering meal timing and diet composition on temporal glucose homeostasis and physical activity measures. Eight sedentary, overweight/obese men (mean ± SD, age: 36 ± 4 years; BMI: 29.8 ± 1.8 kg/m²) completed two × 12-day (12-d) measurement periods, including a 7-d habitual period, and then 5 d of each diet (high-fat diet [HFD]: 67:15:18% fat:carbohydrate:protein versus high-carbohydrate diet [HCD]: 67:15:18% carbohydrate:fat:protein) of three meals/d at ±30 min of 0800 h, 1230 h, and 1800 h, in a randomised order with an 8-d washout. Energy intake (EI), the timing of meal consumption, blood glucose regulation (continuous glucose monitor system (CGMS)), and activity patterns (accelerometer and inclinometer) were assessed across each 12-d period. Meal provision did not alter the patterns of reduced physical activity, and increased sedentary behaviour following dinner, compared with following breakfast and lunch. The HCD increased peak (+1.6 mmol/L, p < 0.001), mean (+0.5 mmol/L, p = 0.001), and total area under the curve (+670 mmol/L/min, p = 0.001), as well as 3-h postprandial meal glucose concentrations (all p < 0.001) compared with the HFD. In overweight/obese males, the provision of meals did not alter physical activity patterns, but did affect glycaemic control. Greater emphasis on meal timing and composition is required in diet and/or behaviour intervention studies to ensure relevance to real-world behaviours.
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Carbohydrate restriction with postmeal walking effectively mitigates postprandial hyperglycemia and improves endothelial function in type 2 diabetes.
Francois, ME, Myette-Cote, E, Bammert, TD, Durrer, C, Neudorf, H, DeSouza, CA, Little, JP
American journal of physiology. Heart and circulatory physiology. 2018;314(1):H105-H113
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Prevention of cardiovascular disease in individuals with type 2 diabetes (T2D) is a major treatment goal. Within this, diet and exercise remain the cornerstone lifestyle therapies. The aim of this study was to examine the effects of 4 days of a low-carbohydrate diet, with or without daily post-meal walking, on vascular health in individuals with T2D. The study recruited sixteen individuals with physician-diagnosed T2D to complete 3 short-term controlled intervention periods in a randomised crossover design. Results indicate that attenuating postprandial hyperglycaemia (a very high rise in blood sugar following a meal) by restricting carbohydrates and post-meal walking can improve vascular health in individuals with T2D. Authors conclude that carbohydrate restriction and post-meal exercise may represent an effective strategy to mitigate the negative effects of postprandial hyperglycaemia and reduce cardiovascular disease risk in individuals with T2D.
Abstract
Postprandial hyperglycemia has deleterious effects on endothelial function. Restricting carbohydrate intake and postmeal walking have each been shown to reduce postprandial hyperglycemia, but their combination and subsequent effects on endothelial function have not been investigated. Here, we sought to examine the effect of blunting postprandial hyperglycemia by following a low-carbohydrate diet, with or without postmeal walking exercise, on markers of vascular health in type 2 diabetes (T2D). In a randomized crossover design, individuals with T2D ( n = 11) completed three 4-day controlled diet interventions consisting of 1) low-carbohydrate diet alone (LC), 2) low-carbohydrate diet with 15-min postmeal walks (LC + Ex), and 3) low-fat control diet (CON). Fasting blood samples and brachial artery flow-mediated dilation (%FMD) were measured before and after each intervention. Total circulating microparticles (MPs), endothelial MPs, platelet MPs, monocyte-platelet aggregates, and adhesion molecules were assessed as biomarkers of vascular health. There was a significant condition × time interaction for %FMD ( P = 0.01), with post hoc tests revealing improved %FMD after LC + Ex (+0.8 ± 1.0%, P = 0.02), with no change after LC or CON. Endothelial MPs were significantly reduced with the LC diet by ~45% (from 99 ± 60 to 44 ± 31 MPs/μl, P = 0.02), with no change after LC + Ex or CON (interaction: P = 0.04). Total MPs were lower (main effect time: P = 0.02), whereas monocyte-platelet aggregates were higher (main effect time: P < 0.01) after all interventions. Plasma adhesion molecules and C-reactive protein were unaltered. Attenuating postprandial hyperglycemic excursions using a low-carbohydrate diet combined with postmeal walking appears to be an effective strategy to improve endothelial function in individuals with T2D. NEW & NOTEWORTHY Carbohydrate restriction and postmeal walking lower postprandial hyperglycemia in individuals with type 2 diabetes. Here, we show that the combination significantly improved endothelial function and that carbohydrate restriction alone reduced circulating endothelial microparticles in individuals with type 2 diabetes. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/low-carb-diet-and-exercise-improve-endothelial-health/ .
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Effect of Vitamin D Supplementation on Obesity-Induced Insulin Resistance: A Double-Blind, Randomized, Placebo-Controlled Trial.
Cefalo, CMA, Conte, C, Sorice, GP, Moffa, S, Sun, VA, Cinti, F, Salomone, E, Muscogiuri, G, Brocchi, AAG, Pontecorvi, A, et al
Obesity (Silver Spring, Md.). 2018;26(4):651-657
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Vitamin D concentration has been inversely associated with impaired glucose regulation, insulin resistance and risk of metabolic dysfunction. The aim of the study was to evaluate whether Vitamin D supplementation could improve insulin sensitivity in patients with a high risk of diabetes. The study is a randomised, double-blind, placebo-controlled trial. The participants with obesity were supplemented with Vitamin D or placebo on top of a hypocaloric diet. Results indicate that Vitamin D supplementation combined with weight loss is linked with a significant improvement in insulin sensitivity in vitamin D deficient participants with obesity.
Abstract
OBJECTIVE The aim was to investigate whether vitamin D supplementation, combined with a hypocaloric diet, could have an independent effect on insulin sensitivity in subjects with both overweight and hypovitaminosis D. Changes from baseline in anthropometric parameters, body composition, glucose tolerance, and insulin secretion were considered as secondary outcomes. METHODS Eighteen volunteers who were nondiabetic and vitamin D deficient and had BMI > 25 kg/m2 were randomized (1:1) in a double-blind manner to a hypocaloric diet + either oral cholecalciferol at 25,000 IU/wk or placebo for 3 months. Hyperinsulinemic-euglycemic clamp to measure insulin sensitivity was performed at baseline and after intervention. RESULTS Body weight in both groups decreased significantly (-7.5% in the vitamin D group and -10% in the placebo group; P < 0.05 for both), with no between-group differences. Serum 25-hydroxyvitamin D levels in the vitamin D group increased considerably (from 36.7 ± 13.2 nmol/L to 74.8 ± 18.7 nmol/L; P < 0.001). Insulin sensitivity in the vitamin D group improved (from 4.6 ± 2.0 to 6.9 ± 3.3 mg·kg-1 ·min-1 ; P < 0.001), whereas no changes were observed in the placebo group (from 4.9 ± 1.1 to 5.1 ± 0.3 mg·kg-1 ·min-1 ; P = 0.84). CONCLUSIONS Cholecalciferol supplementation, combined with a weight loss program, significantly improves insulin sensitivity in healthy subjects with obesity and might represent a personalized approach for insulin-resistant subjects with obesity.
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The Effect of a High-Dose Vitamin B Multivitamin Supplement on the Relationship between Brain Metabolism and Blood Biomarkers of Oxidative Stress: A Randomized Control Trial.
Ford, TC, Downey, LA, Simpson, T, McPhee, G, Oliver, C, Stough, C
Nutrients. 2018;10(12)
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A diet rich in vitamins and micronutrients, particularly B vitamins, is essential for body and brain functionality. B vitamin supplementation has been found to reduce depression, enhance mood, lessen anxiety and improve cognition. New neuroimaging techniques have shed light on the relationship between blood and neural biomarkers, connecting diet quality and brain function. The aim of this randomised, placebo-controlled, double-blind trial was to investigate the effect of 6-month high-dose B-vitamin supplementation on neural and blood biomarkers of metabolism in 32 healthy adults. Participants were randomised to consume either B-vitamin supplementation or placebo pills twice a day for six months and underwent blood tests and brain imaging before and after supplementation. This study found supplementation effectively increased vitamin B6 and B12 levels and reduced homocysteine with no changes in folate as compared with placebo. Supplementation promoted neural metabolic pathways and reduced oxidative stress and inflammation. Based on these findings, the authors conclude B-group vitamins are important for maintaining brain health in healthy adults and may play a role in prevention and alleviation of neural disease and disability.
Abstract
A diet rich in B-group vitamins is essential for optimal body and brain function, and insufficient amounts of such vitamins have been associated with higher levels of neural inflammation and oxidative stress, as marked by increased blood plasma homocysteine. Neural biomarkers of oxidative stress quantified through proton magnetic spectroscopy (1H-MRS) are not well understood, and the relationship between such neural and blood biomarkers is seldom studied. The current study addresses this gap by investigating the direct effect of 6-month high-dose B-group vitamin supplementation on neural and blood biomarkers of metabolism. Using a randomized, double-blind, placebo-controlled design, 32 healthy adults (20 female, 12 male) aged 30⁻65 years underwent blood tests (vitamin B6, vitamin B12, folate, and homocysteine levels) and 1H-MRS of the posterior cingulate cortex (PCC) and dorsolateral prefrontal cortex (DLPFC) before and after supplementation. Results confirmed the supplement was effective in increasing vitamin B6 and vitamin B12 levels and reducing homocysteine, whereas there was no change in folate levels. There were significant relationships between vitamin B6 and N-acetylaspartate (NAA), choline, and creatine, as well as between vitamin B12 and creatine (ps < 0.05), whereas NAA in the PCC increased, albeit not significantly (p > 0.05). Together these data provide preliminary evidence for the efficacy of high-dose B-group supplementation in reducing oxidative stress and inflammation through increasing oxidative metabolism. It may also promote myelination, cellular metabolism, and energy storage.