Dataset Information

A whole-grain diet reduces peripheral insulin resistance and improves glucose kinetics in obese adults: A randomized-controlled trial.

ABSTRACT:

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 (R_a) iAUC_60-240 × insulin iAUC_60-240, 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 R_a 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.

SUBMITTER: Malin SK

PROVIDER: S-EPMC5930046 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Publications

A whole-grain diet reduces peripheral insulin resistance and improves glucose kinetics in obese adults: A randomized-controlled trial.

Malin Steven K SK Kullman Emily L EL Scelsi Amanda R AR Haus Jacob M JM Filion Julianne J Pagadala Mangesh R MR Godin Jean-Philippe JP Kochhar Sunil S Ross Alastair B AB Kirwan John P JP

Metabolism: clinical and experimental 20180103

<h4>Background</h4>Whole-grain intake is associated with lower risk of type 2 diabetes but the mechanisms are unclear.<h4>Purpose</h4>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.<h4>Methods</h4>A double-blind, randomized, controlled, crossover trial of 14 moderately obese adults (Age, 38 ± 2 y; BMI, 34.0 ± 1.1 kg/m<sup>2</sup>). Insulin resistance and ...[more]

PMID: 29305946

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Project description:BackgroundIncreased dietary whole-grain intake may protect against cardiovascular disease (CVD).ObjectiveThe objective was to evaluate the efficacy of whole grains compared with refined grains on body composition, hypertension, and related mediators of CVD in overweight and obese adults.MethodsWe conducted a double-blind, randomized, controlled crossover trial in 40 overweight or obese men and women aged <50 y with no known history of CVD. Complete whole-grain and refined-grain diets were provided for two 8-wk periods, with a 10-wk washout between diets. Macronutrient composition was matched, except for the inclusion of either whole grains or refined grains (50 g/1000 kcal in each diet). Measurements included blood pressure, body composition, blood lipids and adiponectin, and markers of inflammation and glycemia.ResultsThirty-three participants (6 men and 27 women) completed the trial [mean ± SD age: 39 ± 7 y; mean ± SD body mass index (in kg/m2): 33.1 ± 4.3]. Decreases in diastolic blood pressure were -5.8 mm Hg (95% CI: -7.7, -4.0 mm Hg) after the whole-grain diet and -1.6 mm Hg (95% CI: -4.4, 1.3 mm Hg) after the control diet (between effect, P = 0.01). Decreases in plasma adiponectin were -0.1 (95% CI: -0.9, 0.7) after the whole-grain diet and -1.4 (95% CI: -2.6, -0.3) after the control diet (between effect, P = 0.05). Decreases in diastolic blood pressure correlated with the circulating adiponectin concentration (r = 0.35, P = 0.04). Substantial reductions in body weight, fat loss, systolic blood pressure, total cholesterol, and LDL cholesterol were observed during both diet periods, with no relevant difference between them.ConclusionsThe improvement in diastolic blood pressure was >3-fold greater in overweight and obese adults when they consumed a whole-grain compared with a refined-grain diet. Because diastolic blood pressure predicts mortality in adults aged <50 y, increased whole-grain intake may provide a functional approach to control hypertension. This may benefit patients at risk of vascular-related morbidity and mortality. This trial was registered at clinicaltrials.gov as NCT01411540.

Project description:Abstract Objectives We investigated the effect of consuming a whole-grain diet on whole-body protein metabolism compared to a macronutrient-matched refined-grain diet in adults with overweight/obesity using labelled amino acids (ClinicalTrials.gov Identifier: NCT01411540). Methods We conducted a randomized, controlled crossover trial in 14 adults with overweight/obesity (age: 40 ± 7 yrs, BMI: 33 ± 5 kg/m2) in which isocaloric, macronutrient-matched whole-grain (WG) and refined-grain (RG) diets were fully provided for two 8-week periods (with a 10-week washout period). Diets differed only in the inclusion of whole grains (50 g/1000 kcal). Body composition was measured via DEXA. Whole-body protein kinetics were assessed before and after each diet in the fasted state (13C-Leucine, primed, constant infusion) and over 24 hours (15N-Glycine, bolus). Protein kinetics were normalized to fat-free mass (FFM). Results Both diets resulted in mild weight loss (WG: −2.0 ± 2.5 kg; RG: −2.9 ± 3.3 kg; both P = 0.01 compared to baseline). Fasted-state leucine kinetics revealed greater protein synthesis (WG: 205 ± 61 µmol/kgFFM/hr; RG: 178 ± 36 µmol/kgFFM/hr; P = 0.04) and protein breakdown (WG: 235 ± 68 µmol/kgFFM/hr; RG: 203 ± 40 µmol/kgFFM/hr, P = 0.03) on a WG vs RG diet. This resulted in a more negative fasted-state net balance on a WG diet (WG: −30 ± 8 µmol/kg/hr; RG: −25 ± 6 µmol/kg/hr, P = 0.02). In contrast, 24-hour whole-body protein turnover measured by the end-product method (15N-Glycine), revealed greater protein synthesis (WG: 316 ± 135 mg protein/kgFFM/hr; RG: 250 ± 94 mg protein/kgFFM/hr) with no difference in protein breakdown, yielding a more positive 24-hr net balance on a WG diet (WG: 31 ± 21 mg protein/kgFFM/hr; RG: 10 ± 34 mg protein/kgFFM/hr). Conclusions A whole-grain diet increases whole-body leucine flux and results in a greater 24-hr net protein balance in adults with overweight/obesity compared to a refined-grain diet. This trial suggests whole-grains have an independent effect on protein metabolism and may benefit adults with overweight/obesity. Funding Sources This research was supported by the NIH (UL1 RR024989, T32DK007319 (JPK); T32AT004094 (JTM – trainee)) and an investigator-initiated grant from Nestle (JPK). Nestle Product Technology Center and Cereal Partners Worldwide provided the study meals and foods.

Dataset Information

A whole-grain diet reduces peripheral insulin resistance and improves glucose kinetics in obese adults: A randomized-controlled trial.

Background

Purpose

Methods

Results

Conclusion

Publications

A whole-grain diet reduces peripheral insulin resistance and improves glucose kinetics in obese adults: A randomized-controlled trial.

Similar Datasets

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