Effects Of Whole-grain Intake Research Articles

Effects of whole grain intake on glucagon-like peptide 1 and glucose-dependent insulinotropic peptide: a systematic review and meta-analysis.

Whole grain intake may control help glycemia and reduce food intake by affecting the secretion of glucagon-like peptide1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). This systematic review and meta-analysis aimed to assess the postprandial and long-term effects of whole grains on GLP-1 and GIP levels. PubMed, Web of Science, and Scopus online databases were searched systematically to identify relevant randomized clinical trials (RCTs) published up to April 2021. RCTs that evaluated the effects of whole grains, compared with refined grains, on the postprandial area under the curve (AUC) value, the postprandial serum concentration of incretins from 0 to 180 minutes, or the fasting level of incretins after at least 14 days of intervention were included. Nineteen studies were included in the meta-analysis. The results showed that acute intake of whole grains could not significantly change the AUC value of GLP-1 or GIP. However, the AUC value of GIP was reduced more significantly in (1) unhealthy participants (standard mean difference [SMD] -1.08; 95%CI, -2.07 to -0.10; I2 = 75.9%) compared with healthy participants, and (2) those with a baseline fasting blood glucose of ≥99 mg/dL (SMD -0.71; 95%CI, -1.30 to -0.11; I2 = 74.4%) compared with those with a baseline value of < 99 mg/dL. On the other hand, the results of time-response evaluation during 0 to 180 minutes after the intake of test meals showed that serum concentrations of GIP decreased significantly from 0 to 30 minutes (coefficient = -44.72; P = 0.005), but increased from 60 to 180 minutes (coefficient = 27.03; P = 0.005). However, long-term studies found no significant effects of whole grains on fasting concentrations of GLP-1 or GIP. Whole grain intake did not affect postprandial levels of GLP-1 but enhanced postprandial levels of GIP from 60 to 180 minutes. Further high-quality trials are required to assess the long-term effects of whole grain intake on serum levels of incretins. PROSPERO registration no. CRD42021256695.

Effects of whole grain intake on glycemic control: A meta-analysis of randomized controlled trials.

Although mounting evidence has suggested an inverse association between the intake of whole grains and glycemic control, findings from randomized controlled trials are still conflicting. The current study was carried out to evaluate the effect of medium/long-term whole grain intake on glycemic control in metabolic syndrome and healthy populations. A literature search was carried out to identify qualified studies up to July 2021. The effects of whole grain consumption on glycemic control were calculated using a fixed effects model. Subgroup analysis was used to study whether grouping factors were important influencing factors of heterogeneity between research results. A total of 32 randomized controlled trials with 2,060 participants were included in the analyses. Whole grain consumption showed a significant inverse regulatory effect on fasting glucose concentration, but no significant effect was found for other glycemic measures, such as fasting insulin, homeostatic model assessment for insulin resistance, glycated hemoglobin and 2-h glucose, in the pooled analysis. Through subgroup analyses, a significant decrease in fasting glucose concentration was observed for studies with a higher whole grain dose, with participants of normal glycemia, and with mixed types of whole grain. Medium-/long-term whole grain intake reduced the fasting glucose concentration compared with similar refined foods. Appropriate intervention dose and accurate population selection might be the key links for whole grain consumption to exert its glycemic control effect.

Effects of Whole Grain Intake, Compared to Refined Grain, on Glycemia and Insulinemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract Objectives Epidemiological study results suggest that whole grain (WG) consumption is associated with a reduced risk of type 2 diabetes; however, the potential mechanism behind this observation is unclear. WG intake may lower postprandial glycemia and insulinemia and improve insulin sensitivity, thereby contributing to a reduced risk of type 2 diabetes. The objective of this systematic review and meta-analysis was to evaluate the impact of WG on postprandial glycemia and insulinemia and markers of glycemic control and insulin sensitivity/resistance. Methods A systematic review and meta-analysis was conducted on randomized controlled trials (RCTs) evaluating the effect of WG intake, compared to refined grain (RG) intake, on postprandial glycemia and insulinemia area under the curve and markers of glycemic control and insulin sensitivity/resistance in adults. A search of PubMed and Scopus yielded 80 relevant RCTs. Pooled estimates were expressed as standardized mean differences (SMD) between the WG intervention and RG control group. Results WG intake resulted in a significant reduction of postprandial glycemia (SMD: −0.46, 95% CI: −0.59, −0.33, P &amp;lt; 0.001) and insulinemia (SMD: −0.29, 95% CI: −0.39, −0.20, P &amp;lt; 0.001), compared to RG intake. There were no significant effects of WG on fasting glucose, fasting insulin, or homeostatic model assessment of insulin resistance (HOMA-IR); however, there was a marginally significant benefit of WG intake for glycated hemoglobin (HbA1c) (P = 0.050). Conclusions Compared to RG foods, WG foods improve postprandial glycemia and insulinemia which may partially explain the association of WG intake and reduced risk of type 2 diabetes. However, WG intake did not impact long-term markers of glycemic and insulinemic control, except for a marginally significant effect on HbA1c. While short term improvements in glycemic response may be beneficial, more investigations are needed to determine if these lead to long-term benefits in reducing the risk of type 2 diabetes. PROSPERO Registration: CRD42020180069 Funding Sources This research was funded by General Mills, Inc.

Whole grain intake favorably affects blood glucose and serum triacylglycerols in overweight and obese children: A randomized controlled crossover clinical trial

ObjectivesThe aim of this study was to determine the effects of whole grain consumption on the metabolic profiles of overweight or obese children. MethodsThis was a randomized crossover clinical trial with 44 overweight or obese girls. After a 2-wk run-in period, girls were randomly assigned to either intervention or control groups. Participants in the intervention group were asked to obtain 50% of their grain servings from whole grain foods each day for 6 wk. Those in the control group were asked not to consume any of these foods. A 4-wk washout period was applied following which participants were crossed over to the alternate arm. Fasting blood samples were taken before and after each phase of study. ResultsMean (± SD) age and body mass index was 11.2 ± 1.49 y and 23.5 ± 2.5 kg/m2, respectively. Mean whole grain intake in intervention and control groups throughout the study was 26.5 and 3.7 g/d, respectively (P = 0.01). Whole grain consumption resulted in lower concentrations of plasma glucose (changes from baseline in intervention group: –0.10 versus 0.21 mmol/L in control group, P = 0.01), serum triacylglycerols (changes from baseline in intervention group: –0.18 versus 0.08 mmol/L in control group, P = 0.01) and higher concentrations of serum high-density lipoprotein cholesterol (changes from baseline in intervention group: 0.16 versus –0.14 mmol/L in control group, P = 0.05) after 6 wk of intervention. No effects of whole grain intake on serum concentrations of total- and low-density lipoprotein cholesterol or on blood pressure were found. ConclusionThis study provided evidence supporting the beneficial effects of whole grain foods on serum concentrations of glucose, triacylglycerols and high-density lipoprotein cholesterol in overweight children.

The effects of whole grain intake on anthropometric measures in overweight and obese children: a crossover randomised clinical trial.

Whole-grain foods have been reported to affect body weight and satiety. However, we are aware of no study in this regard among children. The present study aimed to determine the effects of whole grain consumption on anthropometric measures in overweight or obese children. In this randomised crossover clinical trial, forty-four overweight or obese girls participated. After a 2-week run-in period, subjects were randomly assigned to either intervention (n 44) or non-intervention (n 44) groups. Subjects in the intervention group were given a list of whole-grain foods and were asked to obtain half of their grain servings from these foods each day for 6 weeks. Individuals in the non-intervention group were asked not to consume any of these foods. A 4-week washout period was applied. Then, participants were crossed over to the alternate arm. The measurements were done before and after each phase. Mean age, weight and BMI of participants were 11·2 (sd 1·49) years, 51·2 (sd 10·2) kg and 23·5 (sd 2·5) kg/m2, respectively. Despite the slight reduction in weight and BMI, there were no significant differences in changes in these anthropometric measures. We found a significant effect of whole grain intake on waist circumference (-2·7 v. 0·3 cm, P = 0·04). No significant changes in hip circumference were observed. Changes in the prevalence of overweight, obesity and abdominal obesity were not significantly different. This study indicated a beneficial effect of whole-grain foods on waist circumference in overweight children; however, these foods did not influence weight and BMI.

Whole grain intake and cancer: A review of the literature

There has been little research concerning the health effects of whole grain intake in humans. We have synthesized 15 american and European case-control and prospective studies of whole grain intake. Most subjects were middle aged or older. The studies employed disparate dietary methods, and the foods referred to and quantities eaten are ill defined. Nevertheless there is a striking consistency in reduced risk for colorectal and gastric cancers associated with intake of whole grain, also found in isolated studies of endometrial cancer and coronary heart disease. Because reduced risk was not associated with refined grain intake, these findings do not appear to be confounded by participant confusion concerning refined vs. whole grains. The independence of these findings from reduced risk associated with fruit and vegetable intake is not established. There should be further research to establish whether whole grain intake is protective against chronic disease.