The effect of high compared with low dairy consumption on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults: a randomized crossover trial.
ABSTRACT: BACKGROUND:Dairy products contain many nutritious components that may benefit metabolic health. There are indications that glucose metabolism and insulin sensitivity, which are generally disturbed in overweight and obese individuals, may improve by increased dairy intake. This may also affect one's metabolic flexibility. OBJECTIVE:The aim of this study was to investigate the effects of high compared with low dairy intake on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults (aged 45-65 y). METHODS:In this randomized intervention study, subjects consumed a high- and a low-dairy diet [HDD (5-6 dairy portions) and LDD (≤1 dairy portion), respectively] for 6 wk in a crossover design, with a washout period of 4 wk. Dairy portions were 200 g semi-skimmed yoghurt, 30 g reduced-fat (30+) cheese, and 250 mL semiskimmed milk and buttermilk. After 6 wk, a 75-g oral-glucose-tolerance test (13C-labeled) and a subsequent fasting challenge were performed. Metabolic flexibility was studied by determining the respiratory quotient (RQ) using indirect calorimetry. Fasting and postprandial plasma concentrations of glucose and insulin were analyzed. The dual isotope technique enabled calculation of glucose kinetics. RESULTS:The study was completed by 45 overweight men and postmenopausal women [age 58.9 ± 4.3 y, BMI 27.9 ± 1.9 kg/m2 (mean ± SD)]. Fasting RQ and ΔRQ, reflecting metabolic flexibility, did not differ after both diets. Fasting glucose concentrations were similar, whereas fasting insulin concentrations were lower after the LDD (LDD: 8.1 ± 2.8 mU/L; HDD: 8.9 ± 3.3 mU/L; P = 0.024). This resulted in a higher HOMA-IR after the HDD (P = 0.027). Postprandial glucose and insulin responses as well as glucose kinetics were similar after both diets. CONCLUSIONS:The amount of dairy intake during a 6-wk period had a neutral effect on metabolic flexibility or postprandial glucose metabolism in middle-aged overweight subjects. More trials are needed to study the effects of specific dairy types and to differentiate between metabolic subgroups. This trial was registered at trialregister.nl as NTR4899.
Project description:BACKGROUND:Observational studies suggest that high dairy intake is associated with a lower blood pressure (BP). OBJECTIVE:We aimed to investigate the effect of a high-dairy diet (HDD) as compared with a low-dairy diet (LDD) on BP in overweight middle-aged adults. METHODS:Fifty-two overweight men and women were included in a randomized crossover intervention study. Each subject consumed 2 isocaloric diets for 6 wk, an LDD (?1 dairy portion per day) and an HDD (6 or 5 reduced-fat dairy portions for men and women, respectively), with a 4-wk washout period in between the diets during which the subjects consumed their habitual diet. BP was measured at the start and at the end of the intervention diets. The effect of the intervention study was evaluated by 2-sample t tests. Mixed-model analyses were used for adjustment for the potential influence of changes in dietary protein and mineral intake and risk factors for hypertension including body weight and plasma cholesterol. RESULTS:Consumption of an HDD as compared with an LDD resulted in a reduction of both systolic BP (mean ± SD: 4.6 ± 11.2 mm Hg, P < 0.01) and diastolic BP (3.0 ± 6.7 mm Hg, P < 0.01). In further analyses, these reductions appeared dependent on the concomitant increase in calcium intake. CONCLUSIONS:This intervention study shows that an HDD results in a reduction of both systolic and diastolic BP in overweight middle-aged men and women. If the results of our study are reproduced by other studies, advice for high dairy intake may be added to treatment and prevention of high BP. This trial was registered at trialregister.nl as NTR4899.
Project description:Starches of low and high digestibility have different metabolic effects. Here, we examined whether this gives differential metabolic programming when fed in the immediate post-weaning period. Chow-fed mice were time-mated, and their nests were standardized and cross-fostered at postnatal days 1?2. After postnatal week (PW) 3, individually housed female and male offspring were switched to a lowly-digestible (LDD) or highly-digestible starch diet (HDD) for three weeks. All of the mice received the same high-fat diet (HFD) for nine weeks thereafter. Energy and substrate metabolism and carbohydrate fermentation were studied at the end of the HDD/LDD and HFD periods by extended indirect calorimetry. Glucose tolerance (PW 11) and metabolic flexibility (PW14) were analyzed. Directly in response to the LDD versus the HDD, females showed smaller adipocytes with less crown-like structures in gonadal white adipose tissue, while males had a lower fat mass and higher whole body fat oxidation levels. Both LDD-fed females and males showed an enlarged intestinal tract. Although most of the phenotypical differences disappeared in adulthood in both sexes, females exposed to LDD versus HDD in the early post-weaning period showed improved metabolic flexibility in adulthood. Cumulatively, these results suggest that the type of starch introduced after weaning could, at least in females, program later-life health.
Project description:BACKGROUND:Whole-grain intake is associated with lower risk of type 2 diabetes but the mechanisms are unclear. PURPOSE:We tested the hypothesis that a WG diet reduces insulin resistance and improves glucose use in individuals at risk for type 2 diabetes compared with an isocaloric-matched refined-grain diet. METHODS:A double-blind, randomized, controlled, crossover trial of 14 moderately obese adults (Age, 38?±?2?y; BMI, 34.0?±?1.1?kg/m2). Insulin resistance and glucose metabolism was assessed using an oral glucose tolerance test combined with isotopic tracers of [6,6-2H2]-glucose and [U-13C]-glucose, and indirect calorimetry. Peripheral and hepatic insulin resistance was assessed as 1/(rate of disposal/insulin), and endogenous glucose rates of appearance (Ra) iAUC60-240?×?insulin iAUC60-240, respectively. Both diets met ADA nutritional guidelines and contained either whole-grain (50?g per 1000?kcal) or equivalent refined-grain. All food was provided for 8?wk. with an 8-10?wk. washout period between diets. RESULTS:Post-prandial glucose tolerance, peripheral insulin sensitivity, and metabolic flexibility (insulin-stimulated - fasting carbohydrate oxidation) improvements were greater after whole-grain compared to the refined-grain diet (P?<?0.05). Compared to baseline, body fat (~2?kg) and hepatic Ra insulin resistance was reduced by both diets, while fasting glucose and exogenous glucose-meal were unchanged after both interventions. Changes in peripheral insulin resistance and metabolic flexibility correlated with improved glucose tolerance (P?<?0.05). CONCLUSION:Whole-grains reduced diabetes risk and the mechanisms appear to work through reduced post-prandial blood glucose and peripheral insulin resistance that were statistically linked to enhanced metabolic flexibility.
Project description:Milk consumption has decreased in children over the past years. This may play a role in the prevalence of pediatric obesity, because clinical studies have found a beneficial effect of milk consumption for weight management. The objectives of this study were to test whether high-milk consumption leads to greater weight loss and improvements in metabolic risk factors than low milk consumption during a 16-wk healthy eating diet. Overweight children aged 8-10 y were randomized to either high (4 x 236 mL/d) or low (1 x 236 mL/d) milk consumption. Children were provided dietary counseling on healthy eating at baseline and at wk 1, 2, 4, 6, 8, and 12. Serum glucose, insulin, and lipids were measured in fasting children at baseline and wk 8 and 16. An oral glucose tolerance test and body composition assessment by magnetic resonance imaging were conducted at baseline and endpoint. Body weight changes during the 16-wk study not differ between the high-milk (1.3 +/- 0.3 kg) and low-milk (1.1 +/- 0.3 kg) groups. There was no beverage x week interaction on any of the body composition and metabolic variables studied (blood pressure, serum lipids, glucose, and insulin). There was a beverage x week interaction (P = 0.044) on insulin area under the curve showing a trend toward reduced insulin output with a glucose challenge after high-milk consumption (P = 0.062). These data suggest that in overweight children, high-milk consumption in conjunction with a healthy diet does not lead to greater weight loss but may ameliorate insulin action compared with low-milk consumption.
Project description:Starches of low digestibility are associated with improved glucose metabolism. We hypothesise that a lowly digestible-starch diet (LDD) versus a highly digestible-starch diet (HDD) improves the capacity to oxidise starch, and that this is sex-dependent. Mice were fed a LDD or a HDD for 3 weeks directly after weaning. Body weight (BW), body composition (BC), and digestible energy intake (dEI) were determined weekly. At the end of the intervention period, whole-body energy expenditure (EE), respiratory exchange ratio (RER), hydrogen production, and the oxidation of an oral 13C-labelled starch bolus were measured by extended indirect calorimetry. Pancreatic amylase activity and total 13C hepatic enrichment were determined in females immediately before and 4 h after administration of the starch bolus. For both sexes, BW, BC, and basal EE and RER were not affected by the type of starch, but dEI and hydrogen production were increased by the LDD. Only in females, total carbohydrate oxidation and starch-derived glucose oxidation in response to the starch bolus were higher in LDD versus HDD mice; this was not accompanied by differences in amylase activity or hepatic partitioning of the 13C label. These results show that starch digestibility impacts glucose metabolism differently in females versus males.
Project description:Almonds provide a satiating, healthy source of fat and fiber. The postprandial metabolic and satiety response to 2 ounces of nuts or dairy was assessed in 18 overweight/obese women during late pregnancy. Serum glucose, triglycerides, insulin, c-peptide, leptin, ghrelin, and lipoprotein particles were measured prior to and during a 5-h postprandial period following the consumption of an isocaloric breakfast meal with equivalent amounts of fat from either nuts or dairy on two separate mornings. Satiety was assessed by visual analogue scale (VAS) questionnaires and ad libitum food intake at the end of the study. At 33 weeks gestation, the women had gained an average of 7.0 ± 4.4 kg during gestation. Body fat averaged 41.9 ± 5.5% and hemoglobin A1c levels were elevated, (7.2 ± 0.6%). Fasting glucose levels were normal, but hyperinsulinemia was evident. The two test meals did not affect the postprandial metabolic response, but glucose, triglyceride, and ghrelin concentrations changed with time during the postprandial period (p < 0.001, p = 0.0008, p = 0.006). Satiety measures did not differ between the two test meals. Consuming an isocaloric breakfast meal with equivalent amounts of fat from nuts or dairy did not alter postprandial levels of blood lipids, glucose, hormones, or measures of satiety in overweight/obese, pregnant women.
Project description:Previous human studies reported inconsistent effects of dietary protein and branched-chain amino acids (BCAAs) on insulin action and glucose metabolism. Similarly, it is unclear whether saturated fat (SF) intake influences these metabolic variables.The objective of this study was to test the effects of high [30% of energy (%E)] vs. moderate (20%E) intakes of protein (primarily whey) on insulin action and lipid and lipoprotein concentrations in the context of both high (15%E) and low (7%E) SF diets.The study was conducted as a randomized controlled trial in 158 overweight and obese men and women. After a 4-wk baseline diet [55%E carbohydrate, 15%E protein, 30%E fat (7%E SF)], participants were randomly assigned to 4 wk of either the baseline diet or 1 of 4 test diets containing 35%E carbohydrate and either 20%E or 30%E protein and either 7%E or 15%E SF. Frequently sampled i.v. glucose tolerance tests were administered after each dietary period.Other than significantly higher fasting glucose concentrations for high vs. moderate protein intakes with a low-fat diet (difference ± SE: 0.47 ± 0.14 mmol/L; P = 0.001), there were no significant effects of dietary protein or SF on glucose metabolism, plasma insulin, or concentrations of lipids and lipoproteins. Changes in plasma BCAAs across all diets were negatively correlated with changes in the metabolic clearance rate of insulin (? = -0.18, P = 0.03) and positively correlated with changes in the acute insulin response to glucose (? = 0.15, P = 0.05).These findings suggest that short-term intake of BCAAs can influence insulin dynamics. However, in this group of overweight and obese individuals, neither high protein nor SF intake affected insulin sensitivity or plasma concentrations of lipids and lipoproteins. This trial was registered at clinicaltrials.gov as NCT00508937.
Project description:Adolescents consume more sugar-sweetened beverages than do individuals in any other age group, but it is unknown how the type of sugar-sweetened beverage affects metabolic health in this population.The objective was to compare the metabolic health effects of short-term (2-wk) consumption of high-fructose (HF) and high-glucose (HG)-sweetened beverages in adolescents (15-20 y of age).In a counterbalanced, single-blind fashion, 40 male and female adolescents completed two 2-wk trials that included 1) an HF trial in which they consumed 710 mL of a sugar-sweetened beverage/d (equivalent to 50 g fructose/d and 15 g glucose/d) for 2 wk and 2) an HG trial in which they consumed 710 mL of a sugar-sweetened beverage/d (equivalent to 50 g glucose/d and 15 g fructose/d) for 2 wk in addition to their normal ad libitum diet. In addition, the participants maintained similar physical activity levels during each trial. The day after each trial, insulin sensitivity and resistance [assessed via Quantitative Insulin Sensitivity Check Index (QUICKI) and homeostatic model assessment of insulin resistance (HOMA-IR) index] and fasting and postprandial glucose, lactate, lipid, cholesterol, insulin, C-peptide, insulin secretion, and clearance responses to HF or HG mixed meals were assessed.Body weight, QUICKI (whole-body insulin sensitivity), HOMA-IR (hepatic insulin resistance), and fasting lipids, cholesterol, glucose, lactate, and insulin secretion or clearance were not different between trials. Fasting HDL- and HDL?-cholesterol concentrations were ?10-31% greater (P < 0.05) in female adolescents than in male adolescents. Postprandial triacylglycerol, HDL-cholesterol, HDL?-cholesterol, and glucose concentrations were not different between HF and HG trials. The lactate incremental area under the curve was ?3.7-fold greater during the HF trial (P < 0.05), whereas insulin secretion was 19% greater during the HG trial (P < 0.05).Moderate amounts of HF- or HG-sweetened beverages for 2 wk did not have differential effects on fasting or postprandial cholesterol, triacylglycerol, glucose, or hepatic insulin clearance in weight-stable, physically active adolescents.
Project description:Ten-week-old Zucker diabetic fatty (ZDF) rats at an early stage of diabetes embody metabolic characteristics of obese human patients with type 2 diabetes, such as severe insulin and glucose intolerance in muscle and the liver, excessive postprandial excursion of plasma glucose and insulin, and a loss of metabolic flexibility with decreased lipid oxidation. Metabolic flexibility and glucose flux were examined in ZDF rats during fasting and near-normal postprandial insulinemia and glycemia after correcting excessive postprandial hyperglycemia using treatment with a sodium-glucose cotransporter 2 inhibitor (SGLT2-I) for 7 days. Preprandial lipid oxidation was normalized, and with fasting, endogenous glucose production (EGP) increased by 30% and endogenous glucose disposal (E-Rd) decreased by 40%. During a postprandial hyperglycemic-hyperinsulinemic clamp after SGLT2-I treatment, E-Rd increased by normalizing glucose effectiveness to suppress EGP and stimulate hepatic glucose uptake; activation of glucokinase was restored and insulin action was improved, stimulating muscle glucose uptake in association with decreased intracellular triglyceride content. In conclusion, SGLT2-I treatment improves impaired glucose effectiveness in the liver and insulin sensitivity in muscle by eliminating glucotoxicity, which reinstates metabolic flexibility with restored preprandial lipid oxidation and postprandial glucose flux in ZDF rats.
Project description:To examine the effects of Diet (D) and Exercise (E) interventions on cardiovascular fitness, waist circumference, blood lipids, glucose metabolism, inflammation markers, insulin-like growth factor 1 (IGF-1) and blood pressure in overweight and obese lactating women.At 10-14 wk postpartum, 68 Swedish women with a self-reported pre-pregnancy BMI of 25-35 kg/m(2) were randomized to a 12-wk behavior modification treatment with D, E, both or control using a 2×2 factorial design. The goal of D treatment was to reduce body weight by 0.5 kg/wk, accomplished by decreasing energy intake by 500 kcal/d and monitoring weight loss through self-weighing. The goal of E treatment was to perform 4 45-min walks per wk at 60-70% of max heart-rate using a heart-rate monitor. Effects were measured 12 wk and 1 y after randomization. General Linear Modeling was used to study main and interaction effects adjusted for baseline values of dependent variable.There was a significant main effect of the D treatment, decreasing waist circumference (P?=?0.001), total cholesterol (P?=?0.007), LDL-cholesterol (P?=?0.003) and fasting insulin (P?=?0.042), at the end of the 12-wk treatment. The decreased waist circumference (P<0.001) and insulin (P?=?0.024) was sustained and HDL-cholesterol increased (P?=?0.005) at the 1-y follow-up. No effects from the E treatment or any interaction effects were observed.Dietary behavior modification that produced sustained weight loss among overweight and obese lactating women also improved risk factors for cardiovascular disease and type 2 diabetes. This intervention may not only reduce weight-related risks with future pregnancies but also long-term risk for metabolic disease.ClinicalTrials.gov NCT01343238.