Determination of the glycaemic index of foods: interlaboratory study

The Effect of Adding Protein to a Carbohydrate Meal on Postprandial Glucose and Insulin Responses: A Systematic Review and Meta-Analysis of Acute Controlled Feeding Trials

BACKGROUND

Protein influences acute postprandial glucose and insulin responses, but the effects of dose, protein type, and health status are unknown.

OBJECTIVES

We aimed to determine the acute effect of adding protein to carbohydrate on postprandial responses and identify effect modifiers.

METHODS

We searched MEDLINE, EMBASE, and Cochrane databases through 30 July, 2023 for acute, crossover trials comparing acute postprandial responses elicited by carbohydrate-containing test meals with and without added protein in adults without diabetes or with type 2 (T2DM) or type 1 (T1DM) diabetes mellitus. Group data were pooled separately using generic inverse variance with random-effects models and expressed as the ratio of means with 95% confidence interval. Risk of bias and certainty of evidence (Grading of Recommendations Assessment, Development, and Evaluation) were assessed.

RESULTS

In 154 trial comparisons of animal, dairy, and plant proteins (without diabetes, n = 22, 67, 32, respectively; T2DM, n = 14, 16, 3, respectively), each gram protein per gram available carbohydrate (g/g) reduced the glucose area under the curve (AUC) less in adults with T2DM than in those without diabetes (-10% compared with -50%, P < 0.05) but increased the insulin AUC similarly (+76% compared with +56%). In subjects without diabetes, each g/g of dairy and plant protein reduced glucose AUC by 52% and 55%, respectively, and increased the insulin AUC by 64% and 45%, respectively (all P < 0.05). Animal proteins significantly reduced the glucose AUC by 31% and increased the insulin AUC by 37% (pooled effects) but without a significant dose-response. In adults with T2DM, animal protein reduced the glucose AUC by 13% and increased the insulin AUC by 105%, with no significant dose-response. Dairy protein reduced the glucose AUC by 18% (no dose-response), but each g/g increased the insulin AUC by 34% (P < 0.05). In adults with T1DM, protein increased the glucose AUC by 40% (P < 0.05, n = 5). Data source (reported AUC compared with calculated AUC) and study methodology quality significantly modified some outcomes and contributed to high between-study heterogeneity.

CONCLUSIONS

In people without diabetes, adding dairy or plant protein to a carbohydrate-containing meal elicits physiologically significant reductions in glucose AUC and increases insulin AUC. Animal protein may slightly reduce the glucose AUC and may increase the insulin AUC. In people with T2DM, protein may not have such large and consistent effects. Further research is needed to determine if the effects of protein differ by health status and protein source. This study was registered at PROSPERO as CRD42022322090.

Dietary glycemic index and glycemic load predict longitudinal change in glycemic and cardio-metabolic biomarkers among old diabetic adults living in a resource-poor country

This study aims to investigate longitudinal associations between the dietary glycemic index (GI) and glycemic load (GL) and changes in glycemic and cardio-metabolic outcomes. A 28-month retrospective cohort study included 110 Vietnamese diabetic patients, collecting their dietary GI and GL values along with blood biochemical data from baseline 24-h dietary recall and medical records. Latent class growth modelling identified three distinct HbA1c trajectories during the follow-up period, with 51% of patients achieving good glycemic control. The adjusted linear mixed-effect model showed that 1 unit increase in logarithms in dietary GL was associated with a 0.14% increase in the log-HbA1c. Among poorly controlled diabetic patients, baseline GL values were positively correlated with increases in HbA1c; GI showed effects on changes in fasting plasma glucose and the triglyceride-glucose (TyG) index. No significant association was observed in patients with good glycemic control.

Savory Cracker Development for Blood Glucose Control and Management: Glycogen Storage Diseases

The blood glucose response of savory slow energy-release crackers (GLY-HYP) were evaluated in volunteers carrying glycogen storage diseases (GSDs), Types I (Ia) and IV. The crackers have been shown previously to provide a "flat" slow glucose response in healthy volunteers, for up to 4 h. On average for the mixed-sex volunteer group aged 53 to 70 for Type I, the blood glucose concentration increased from baseline to a maximum of 9.5 mmol/L at 60 min and remained above baseline for up to 210 min; overall, above 5 mmol/L for 4 h. In common with healthy individuals, a relatively flat blood glucose response was recorded. For Type IV, mixed-sex patients aged between 55 and 72, the blood glucose concentration reached maximum of 10.2 mmol/L at 45 min and then stayed above baseline for 150 min. Again, overall, above 5 mmol/L for 4 h. Altogether, these data indicate that these crackers would provide a valuable contribution to the nutritional needs of people of different age groups with GSDs (Clinical Registration Number: HRC10032021).

Determination of glycaemic response to the consumption of two specialised formulas for glycaemic control

To assess the glycaemic response after ingestion of two specialised oral and enteral nutrition formulas for glycaemic control. The participants were sixteen healthy volunteers, aged 21-49 years, with normal glucose tolerance. The volunteers attended the tests fasting for 10 h, for 5 weeks, and consumed the reference food - glucose solution - for 3 weeks, and the two formulas DiamaxO and DiamaxIG in the following weeks, in amounts equivalent to 25 g of available carbohydrates. During the period of 120 min, seven blood samples were taken through capillary blood sampling to determine the glycaemic response. The glycaemic index (GI) was calculated according to the trapezoidal rule, ignoring areas below the fasting line. The glycaemic load (GL) was determined by the formula GL = ((GI(glucose = reference) × 'g' of available carbohydrate per serving]/100. The formulas showed low GI and GL. GI = 37·8 and GL = 6·6 for DiamaxO and GI = 21·5 and GL = 3·5 for DiamaxIG. The peak of the glycaemic response occurred 30 min after ingestion, with a marked difference in blood glucose between the Diamax products in relation to glucose. Differences were also significant at times 15, 45, 60 and 90 min in relation to glucose (ANOVA with post hoc Bonferroni, P < 0·005), but not between the two products. However, the AUC and the GI of DiamaxIG are significantly smaller than that of the DiamaxO second t test (P = 0·0059). The glycaemic response to the products is quite reduced, presenting a curve with a little accentuated shape, without high peak, especially in the modified product.

The importance of molecular weight in determining the minimum dose of oat β-glucan required to reduce the glycaemic response in healthy subjects without diabetes: a systematic review and meta-regression analysis

To determine the minimum amount of oat β-glucan (OBG) required to reduce glycaemic responses (MinDose), we conducted a systematic review and meta-regression analysis of acute, crossover, single-meal feeding trials that examined the effects of adding OBG or oat bran to a carbohydrate-containing test-meal versus a control test-meal containing an equivalent amount of available-carbohydrate (avCHO) from the same or similar source. Medline, Embase, and Cochrane Library were searched up to 18 August 2021. The primary outcome was glucose incremental-area-under-the-curve (iAUC). Secondary outcomes included insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two independent reviewers extracted data. Results were expressed as ratio-of-means (RoM) with 95% confidence intervals (CIs). Linear associations were assessed by random effects meta-regression. MinDose was defined as the dose at which the upper 95% CI of the regression line cut the line of no effect (i.e., RoM = 1). Fifty-nine comparisons (n = 340) were included; 57 in healthy subjects without diabetes and two in subjects with diabetes; 24 high-MW (>1000 kg/mol), 22 medium-MW (300-1,000 kg/mol), and 13 low-MW (<300 kg/mol). In healthy subjects without diabetes the associations between OBG dose and glucose iAUC and iPeak were linear (non-linear p value >0.05). MinDoses for glucose iAUC for high-MW, medium-MW and low-MW OBG, respectively, were estimated to be 0.2 g, 2.2 g and 3.2 g per 30 g avCHO; MinDoses for glucose iPeak were less than those for iAUC. Insufficient data were available to assess MinDose for insulin, however, there was no evidence of a disproportionate increase in insulin. More high-quality trials are needed to establish MinDose in individuals with diabetes.

Comparison of Glycemic Response to Carbohydrate Meals without or with a Plant-Based Formula of Kidney Bean Extract, White Mulberry Leaf Extract, and Green Coffee Extract in Individuals with Abdominal Obesity

Due to the rising prevalence of obesity and type 2 diabetes, a strategy that can positively influence diet quality in a simple way is being explored, since a low glycemic index (GI) diet is advised in the dietoprophylaxis and diet therapy of diabetes. Methods: Twenty-three women with abdominal obesity participated in the study. The postprandial glycemic response and glycemic index were determined after three carbohydrate meals (noodle soup, white rice, strawberry sorbet) without or with the addition of a plant-base supplement (extracts of kidney bean, white mulberry leaf, and green coffee) with a potentially hypoglycemic effect. For two products (instant noodle soup and white rice), the addition of the plant supplement resulted in a reduction in glicemic iAUC values (respectively, by: 17.1%, p = 0.005 and 5.3%; p = 0.03; 40.6%, p = 0.004 and 5.3%, p = 0.019). However, this effect was not observed for strawberry sorbet. The blood glucose concentrations 30 min after the consumption of instant noodle soup and white rice with the plant-based formula addition significantly affected the GI value of tested meals (p = 0.0086, r = 0.53; p = 0.0096, r = 0.53), which may indicate the effect of this plant supplement on enterohormone and/or insulin secretion. Conclusion: A formula containing kidney bean, white mulberry leaves, and green coffee extracts may therefore be a notable factor in lowering postprandial glycemia and the GI of carbohydrate foods. However, further research is needed to determine for which food groups and meals its use may be most effective.

In Vitro Digestive Analysis of Digestible and Resistant Starch Fractions, with Concurrent Glycemic Index Determination, in Whole Grain Wheat Products Minimally Processed for Reduced Glycaemic Impact

Eight wheat products differing in texture (porridge vs. bread), grain fineness (fine, kibbled, intact), and cooking (raw vs. cooked), with pre-measured glycaemic indexes (GI), were analysed by in vitro amylolytic digestion to determine effects of processing to reduce GI on quantities of starch fractions differing in digestibility. The accuracy and precision of the in vitro analysis was assessed from its ability to concurrently predict clinical GI. In porridges, kernel intactness and lack of cooking reduced GI while increasing Type 1 (inaccessible) and Type 2 (ungelatinised) resistant starch. Porridge in vitro GI values (GI_iv), calculated from the area under in vitro digestion curves minus estimated blood glucose disposal, were: raw fine, 26.3; raw kibbled, 12.6; cooked fine, 63.9; cooked kibbled, 44.1; and correlated closely with clinical GI values (R² = 0.97). In bread, the negative association of kernel intactness and resistant starch with GI was seen in vitro but not in vivo. Bread GI_iv values were: roller milled flour, 67.4; stoneground flour 61.1; kibbled grain, 53.0; kibbled + intact kernel, 49.5; but correlation with clinical values was low (R² = 0.47), and variability in the clinical results was high (clinical CV = 72.5%, in vitro CV = 3.7%). Low glycaemic potency of wheat by minimal processing was achieved by maintaining particle size, avoiding hydrothermal treatment, avoiding crushing and using a food matrix requiring little chewing for ingestion. Use of in vitro digestive analysis for high precision measurement of starch fractions with potential secondary health benefits was validated by accurate concurrent prediction of the glycaemic index but needed to account for effects of chewing.

Effects of high-amylose maize starch on the glycemic index of Chinese steamed buns (CSB)

The incorporation of resistant starch (RS) in food has gained importance to be a good replacement for digestible carbohydrate. This study examined the effect of compositing RS (high-amylose maize starch (HM)) as wheat flour substitute (30%) in Chinese steamed bun (CSB) formulation on postprandial glycemic response in healthy human subject. In this single-blind and cross-over experimental trial, a total of 15 female participants (mean age = 31.5 ± 3.9) were randomly assigned to receive CSB containing 30% HM (HM30) or control CSB (without HM) with their blood glucose were recorded throughout the test. The blood glucose concentrations recorded for HM30 were significantly lower than control CSB at 15 min (6.03 vs. 7.04 mmol/L, p = 0.041), 30 min (6.93 vs. 7.76 mmol/L, p = 0.021), 45 min (6.21 vs. 7.55 mmol/L, p = 0.032), 60 min (5.68 vs. 6.26 mmol/L, p = 0.038), and 90 min (5.08 vs. 5.73 mmol/L, p = 0.022). The 2-h postprandial glucose was significantly lower in HM30 (iAUC = 105.2 mmol x min/L) than the control (186.1 mmol x min/L). The low GI property of HM30 (GI = 39.11 ± 5.6) did not cause sudden rapid increase in blood glucose concentration as observed in medium-GI control CSB (GI = 69.18 ± 9.8). This study suggests that adding 30g of HM decreased the glycemic index of CSB in healthy female adult.

Effects of Spaghetti Differing in Soluble Fiber and Protein Content on Glycemic Responses in Humans: A Randomized Clinical Trial in Healthy Subjects

This randomized, single blind, cross-over study investigated the glycemic responses to three spaghetti No 7 types differing in dietary protein and soluble fiber content. Fourteen clinically and metabolically healthy, fasting individuals (25 ± 1 years; ten women; BMI 23 ± 1 kg/m²) received isoglucidic test meals (50 g available carbohydrate) and 50 g glucose reference, in random order. GI was calculated using the FAO/WHO method. Capillary blood glucose and salivary insulin samples were collected at 0, 15, 30, 45, 60, and 120 min. Subjective appetite ratings (hunger, fullness, and desire to eat) were assessed by visual analogue scales (VAS, 100 mm) at baseline and 120 min. All three spaghetti types (regular, whole wheat, and high soluble fiber–low carbohydrates) provided low GI values (33, 38, and 41, respectively, on glucose scale) and lower peak glucose values compared to glucose or white bread. No differences were observed between spaghetti No 7 types for fasting glucose, fasting and post-test-meal insulin concentrations, blood pressure (systolic and diastolic), and subjective appetite. Conclusions: all spaghetti No 7 types, regardless of soluble fiber and/or protein content, attenuated postprandial glycemic response, which may offer advantages to glycemic control.

Neither low salivary amylase activity, cooling cooked white rice, nor single nucleotide polymorphisms in starch-digesting enzymes reduce glycemic index or starch digestibility: a randomized, crossover trial in healthy adults

BACKGROUND

It was suggested that low salivary-amylase activity (SAA) and cooling or stir-frying cooked starch decreases its digestibility and glycemic index.

OBJECTIVE

We determined the effects of SAA, cooling, and single-nucleotide polymorphisms (SNPs) in the salivary amylase (AMY1), pancreatic amylase (AMY2A, AMY2B), maltase-glucoamylase (MGAM), and sucrase-isomaltase (SI) genes on starch digestibility and glycemic index of cooked polished rice.

METHODS

Healthy subjects [pilot, n = 12; main, n = 20 with low-SAA (<50 U/mL), and n = 20 with high-SAA (>105 U/mL)] consumed test meals containing 25 g (pilot) or 50 g (main) available carbohydrate at a contract research organization using open-label (pilot) or assessor-blinded (main), randomized, crossover, Latin-square designs (trial registration: NCT03667963). Pilot-trial test meals were dextrose, freshly cooked polished rice, cooked rice cooled overnight, stir-fried hot rice, or stir-fried cold rice. Main-trial test meals were dextrose, dextrose plus 10 g lactulose, plain hot rice, or plain cold rice. In both trials, blood glucose was measured fasting and at intervals over 2 h. In the main trial, breath hydrogen was measured fasting and hourly for 6 h to estimate in vivo starch digestibility. Data were analyzed by repeated-measures ANOVA for the main effects of temperature and stir-frying (pilot trial) or the main effects of SAA and temperature (main trial) and their interactions. Effects of 24 single nucleotide polymorphisms (SNPs) were assessed separately. Means were considered to be equivalent if the 95% CI of the differences were within ±20% of the comparator mean for glucose response/glycemic index or ±7% for digestibility.

RESULTS

Pilot: neither temperature nor stir-frying significantly affected glucose incremental AUC (primary endpoint, n = 12). Main: mean ± SEM glycemic index (primary endpoint, n = 40) was equivalent for low-SAA compared with high-SAA (73 ± 3 vs. 75 ± 4) and cold rice compared with hot rice (75 ± 3 vs. 70 ± 3). Estimated starch digestibility (n = 39) was equivalent for low-SAA compared with high-SAA (95% ± 1% vs. 92% ± 1%) and hot rice compared with cold rice (94% ± 1% vs. 93% ± 1%). No meaningful associations were observed between genotypes and starch digestibility or glycemic index for any of the SNPs.

CONCLUSIONS

The results do not support the hypotheses that low-SAA, cooling, and common genetic variations in starch-digesting enzymes affect the glycemic index or in vivo carbohydrate digestibility of cooked polished rice. This trial was registered at clinicaltrials.gov as NCT03667963.

Glycemic Index Values of Pasta Products: An Overview

Durum wheat pasta is considered a low-glycemic index (GI) food. In recent years, the interest in developing enriched pasta has increased. Since both the formulation and processing technologies may affect the GI, this study aimed to investigate the GI values of pasta products (pp) reported in the literature until 2020. GI values of pp analyzed following the ISO guidelines were included in this survey. A total of 95 pp were identified and, according to their formulation, classified into 10 categories (n, mean GI): category n 1: 100% refined wheat (35, 55); category n 2: 100% whole wheat (6, 52); category n 3: other cereal-based products (8, 52); category n 4: containing egg (5, 52); category n 5: gluten free (11, 60); category n 6: containing legumes (9, 46); category n 7: noodles and vermicelli (9, 56); category n 8: containing vegetable or algae (6, 51); category n 9: containing other ingredients (5, 37); category n 10: stuffed (1, 58). Overall, pasta is confirmed to be a medium–low-GI food, even if a high variability among or within each category emerged. The formulation of enriched pp able to elicit a controlled glycemic response could represent a strategy to improve the nutritional value of pasta.

Toward an Evidence-Based Definition and Classification of Carbohydrate Food Quality: An Expert Panel Report

Carbohydrate-containing crops provide the bulk of dietary energy worldwide. In addition to their various carbohydrate forms (sugars, starches, fibers) and ratios, these foods may also contain varying amounts and combinations of proteins, fats, vitamins, minerals, phytochemicals, prebiotics, and anti-nutritional factors that may impact diet quality and health. Currently, there is no standardized or unified way to assess the quality of carbohydrate foods for the overall purpose of improving diet quality and health outcomes, creating an urgent need for the development of metrics and tools to better define and classify high-quality carbohydrate foods. The present report is based on a series of expert panel meetings and a scoping review of the literature focused on carbohydrate quality indicators and metrics produced over the last 10 years. The report outlines various approaches to assessing food quality, and proposes next steps and principles for developing improved metrics for assessing carbohydrate food quality. The expert panel concluded that a composite metric based on nutrient profiling methods featuring inputs such as carbohydrate–fiber–sugar ratios, micronutrients, and/or food group classification could provide useful and informative measures for guiding researchers, policymakers, industry, and consumers towards a better understanding of carbohydrate food quality and overall healthier diets. The identification of higher quality carbohydrate foods could improve evidence-based public health policies and programming—such as the 2025–2030 Dietary Guidelines for Americans.

A Systematic Review and Meta-Analysis of the Potential of Millets for Managing and Reducing the Risk of Developing Diabetes Mellitus

Millets (including sorghum) are known to be highly nutritious besides having a low carbon footprint and the ability to survive in high temperatures with minimal water. Millets are widely recognised as having a low Glycaemic Index (GI) helping to manage diabetes. This systematic review and meta-analyzes across the different types of millets and different forms of processing/cooking collated all evidences. Of the 65 studies that were collected globally, 39 studies with 111 observations were used to analyze GI outcomes and 56 studies were used to analyze fasting, post-prandial glucose level, insulin index and HbA1c outcomes in a meta-analysis. It is evident from the descriptive statistics that the mean GI of millets is 52.7 ± 10.3, which is about 36% lower than in typical staples of milled rice (71.7 ± 14.4) and refined wheat (74.2 ± 14.9). The descriptive, meta and regression analyses revealed that Job's tears, fonio, foxtail, barnyard, and teff were the millets with low mean GI (<55) that are more effective (35-79%) in reducing dietary GI than the control samples. Millets with intermediate GI (55-69) are pearl millet, finger millet, kodo millet, little millet, and sorghum which have a 13-35% lower GI than the control with high GI (>69). A meta-analysis also showed that all millets had significantly (p < 0.01) lower GI than white rice, refined wheat, standard glucose or white wheat bread except little millet which had inconsistent data. Long term millet consumption lowered fasting and post-prandial blood glucose levels significantly (p < 0.01) by 12 and 15%, respectively, in diabetic subjects. There was a significant reduction in HbA1c level (from 6.65 ± 0.4 to 5.67 ± 0.4%) among pre-diabetic individuals (p < 0.01) who consumed millets for a long period. Minimally processed millets were 30% more effective in lowering GI of a meal compared to milled rice and refined wheat. In conclusion, millets can be beneficial in managing and reducing the risk of developing diabetes and could therefore be used to design appropriate meals for diabetic and pre-diabetic subjects as well as for non-diabetic people for a preventive approach.

Relevance of dietary glycemic index, glycemic load and fiber intake before and during pregnancy for the risk of gestational diabetes mellitus and maternal glucose homeostasis

BACKGROUND & AIMS

To date, the prevalence of Gestational diabetes mellitus (GDM) in China was 17.5%. Given the substantial relevance of GDM for medium- and long-term health of both mother and offspring and the paucity of existing data on the link between maternal diet and glucose homeostasis during pregnancy in Asian population, additional studies are needed. To examine the relevance of dietary glycemic index (GI), glycemic load (GL) and fiber intake before and during pregnancy for the development of GDM and glucose homeostasis over the course of pregnancy.

METHODS

Cox proportional hazards analysis and linear mixed effects regressions were performed on data from 9317 women for whom three food frequency questionnaires (pre-pregnancy, 1^st and 2^nd trimesters) and biochemical measures during pregnancy were available. Investigated outcome variables included GDM risk, fasting plasma glucose (FPG), glycated hemoglobin (HbA_1C), and homeostasis model assessment insulin resistance (HOMA-IR) in the 1st, 2nd and 3rd trimesters.

RESULTS

Women in the highest tertile of dietary GI (or GL) before pregnancy, in the 1^st, or the 2^nd trimester respectively had a 12% (15%), 25% (23%) or 29% (25%) higher risk of developing GDM than those in the lowest tertile (all p for trend ≤ 0.02). Women with the highest dietary fiber intake before pregnancy, in the 1st or 2nd trimester had a 11%, 17% or 18% lower GDM risk (all p for trend ≤ 0.03). Moreover, increases in GI or GL and decreases in fiber intake over the course of pregnancy (1^st to 3^rd trimesters) were independently associated with adverse concurrent developments in FPG, HbA_1C and HOMA-IR (p ≤ 0.03).

CONCLUSIONS

Our study indicates that dietary GI, GL and fiber intake before and during pregnancy affects glucose homeostasis of pregnant Chinese women.

Potential contributions of the methodology to the variability of glycaemic index of foods

Glycaemic index (GI) testing provides a useful point of comparison between carbohydrate sources. For this comparison to be meaningful, the methods used to determine GI values need to be rigorous and consistent between testing events. This requirement has led to increasing standardization of the GI methodology, with an international standard developed in joint consultation with FAO/WHO (ISO 26642:2010) currently the most up to date document. The purpose of this review is to compare the international standard to methods of published studies claiming to have performed a GI test. This analysis revealed that the international standard permits a wide range of choices for researchers when designing a GI testing plan, rather than a single standardized protocol. It has also been revealed that the literature contains significant variation, both between studies and from the international standard for critical aspects of GI testing methodology. The primary areas of variation include; what glucose specification is used, which reference food is used, how much reference food is given, what drink is given during testing, the blood sampling site chosen and what assay and equipment is used to measure blood glucose concentration. For each of these aspects we have explored some of the methodological and physiological implications of these variations. These insights suggest that whilst the international standard has assisted with framing the general parameters of GI testing, further stan-dardization to testing procedures is still required to ensure the continued relevance of the GI to clinical nutrition.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.

Commercial Vinegar Tablets Do Not Display the Same Physiological Benefits for Managing Postprandial Glucose Concentrations as Liquid Vinegar

Objective

Research evidence suggests that vinegar may effectively reduce postprandial glucose in both healthy adults and those with type 2 diabetes. There is heightened consumer interest in commercially available vinegar tablets; however, it is not known whether these products lower postprandial glycemia to the same extent as liquid vinegar. This crossover trial examined the impact of liquid vinegar versus commercial vinegar tablet ingestion at the start of a meal on the 60-minute glucose excursion postmeal in healthy adults.

Methods

Twelve young men and women (22.6 ± 0.6 y; 21.2 ± 1.2 kg/m²) completed this 4-arm Latin square crossover trial. Testing was separated by one week and consisted of a test meal (64 g carbohydrate) consumed immediately following one of the four oral treatments: CON, 60 g water (control treatment); VIN, 25 g liquid vinegar (5% acidity; 1.25 g acetic acid) diluted with 35 g water; PILL, four vinegar tablets (1.50 g acetic acid) swallowed whole with 60 g water; and PILL-c, four crushed vinegar tablets dissolved in 60 g water. Capillary blood glucose was tested in the fasted state and at 30 and 60 minutes postmeal.

Results

The 60-minute glucose excursion varied significantly by treatment (iAUC: 4.9 ± 0.6, 3.4 ± 0.4, 4.9 ± 0.6, and 4.1 ± 0.5 mmol˖h/l for CON, VIN, PILL, and PILL-c, respectively; F (3, 33) = 3.037, p = 0.043; repeated measures ANOVA). Post hoc analysis revealed a 31% reduction in the glucose postmeal excursion for VIN in comparison to CON and PILL (p = 0.040 and p = 0.049, respectively).

Conclusions

These data suggest that commercial vinegar tablets taken whole at mealtime are not as effective as liquid vinegar for reducing the postmeal glucose excursion in young, healthy adults.

Nutritional Bar with Potato-Based Resistant Starch Attenuated Post-Prandial Glucose and Insulin Response in Healthy Adults

Resistant starch is a non-digestible starch fraction and is classified as fiber. Beyond naturally occurring fiber sources, starches can be modified to resist digestion, increase their fiber content and provide physiological benefits. The current study examined acute postprandial glycemic responses of VERSAFIBE™ 1490 resistant starch type-4, containing 90% total dietary fiber (TDF, AOAC (Association of Official Analytical Collaboration International) 991.43 method). In a double-blind, randomized, placebo-controlled, cross-over study, healthy adults (n = 38) consumed a nutritional bar containing either control (2 g), medium (21 g) or high (30 g) fiber. The test bars were matched with control for available carbohydrates, fat and protein. Venous glucose, insulin, and capillary glucose were measured. Mean ± SEM capillary glucose incremental area-under-curve (iAUC0)-120 min in min*mmol/L was lower (p < 0.005) for both fiber bars (136.2 ± 9.2 and 137.0 ± 10.4 for the medium and high fiber bars, respectively) compared to the control bar (174.9 ± 13.5). Mean venous insulin iAUC0-120 min in min*pmol/L was also lower for medium (8096.3 ± 894.5) and high fiber (7533.8 ± 932.9) bars, respectively, compared to the control bar (11871.6 ± 1123.9, p < 0.001). Peak capillary glucose and venous insulin concentrations were also significantly reduced (p < 0.001) after consumption of both fiber bars compared to the control bar. The results of this study suggest that nutritional bars containing potato based RS4 fiber reduced post-consumption glycemic and insulinemic responses when consumed by generally healthy adults.

In Vitro Starch Digestibility and Glycaemic Index of Fried Dough and Batter Enriched with Wheat and Oat Bran

A deep-fried dough/batter food (magwinya) consumed across different age groups and social strata in South Africa was investigated in this study for digestibility and estimated glycaemic index (eGI). In this research, we investigated the influence of bran type-wheat bran (WB) and oat bran (OB), and concentration (0-20% w/w) on the starch digestibility and eGI of magwinya. Rapidly available glucose (RAG) of control fried dough (60.31 g/100 g) was 33% less than fried batter (90.07 g/100 g). There was a significant reduction in RAG and an increase in slowly available (SAG) and unavailable glucose (UG) content of the fried products with OB and WB addition. The highest SAG content was observed in WB fried dough. Control fried batter had the highest eGI value (80.02) and control fried dough had medium eGI value (58.11). WB fried dough, fried batter, and OB fried dough were categorised as medium GI foods at eGI range of 56.46-58.39, 65.93-68.84 and 56.34-57.27, respectively. The eGI values of OB fried batter ranged from 73.57 to 80.03 and were thus classified as high GI foods. UG showed significant correlation with eGI (r = -0.892, -0.973, p < 0.01) and fat content (r = -0.590, -0.661, p < 0.01) for WB and OB fried products. These results reveal that ingredient modification through bran enrichment is effective for the regulation of starch digestion and reduction of eGI of deep-fried dough/batter foods.

Glycemic index of millet based food mix and its effect on pre diabetic subjects

Diet plays an important role in management of diabetes and foods having low glycemic index are gaining more importance as they delay the release of glucose in the blood. It is essential to develop low glycemic food mix from regionally available ingredients for use in daily dietaries. Hence, the present study was undertaken to assess the glycemic index of the traditional recipes prepared from developed millet based food mix and their effect on pre diabetic subjects. The developed millet based food mix had appreciable amount of protein (19.41 g/100 g) and dietary fibre (21.11 g/100 g). The traditional recipes viz., roti, dosa and dumpling (mudde) prepared from developed mix exhibited higher acceptance with good sensory parameters and are comparable to regional preparations. The glycemic index was found to be 37, 48 and 53 for dosa, mudde and roti respectively with a glycemic load of 11.05, 18.43 and 18.09. However, all the three developed products showed the relatively lower glycemic index (< 55) and moderate glycemic load of < 20. Further, dietary intervention on pre diabetic subjects revealed that there was a significant reduction in FBS (120.50 ± 18.73 to 97.81 ± 20.00) and HbA1c (6.14 ± 0.30 to 5.67 ± 0.40) indicating their preferable option in the management of diabetes mellitus.

Glycemic index of pulses and pulse-based products: a review

Pulses are a major source for plant-based proteins, with over 173 countries producing and exporting over 50 million tons annually. Pulses provide many of the essential nutrients and vitamins for a balanced and healthy diet, hence are health beneficial. Pulses have been known to lower glycemic index (GI), as they elicit lower post prandial glycemic responses, and can prevent insulin resistance, Type 2 diabetes and associated complications. This study reviews the GI values (determined by in vivo methodology) reported in 48 articles during the year 1992-2018 for various pulse type preparations consumed by humans. The GI ranges (glucose and bread as a reference respectively) for each pulse type were: broad bean (40 ± 5 to 94 ± 4, 75 to 93), chickpea (5 ± 1 to 45 ± 1, 14 ± 3 to 96 ± 21), common bean (9 ± 1 to 75 ± 8, 18 ± 2 to 99 ± 11), cowpea (6 ± 1 to 56 ± 0.2, 38 ± 19 to 66 ± 7), lentil (10 ± 3 to 66 ± 6, 37 to 87 ± 6), mung bean (11 ± 2 to 90 ± 9, 28 ± 1 to 44 ± 6), peas (9 ± 2 to 57 ± 2, 45 ± 8 to 93 ± 9), pigeon peas (7 ± 1 to 54 ± 1, 31 ± 4), and mixed pulses (35 ± 5 to 66 ± 23, 69 ± 42 to 98 ± 29). It was found that the method of preparation, processing and heat applications tended to affect the GI of pulses. In addition, removal of the hull, blending, grinding, milling and pureeing, reduced particle size, contributed to an increased surface area and exposure of starch granules to the amylolytic enzymes. This was subsequently associated with rapid digestion and absorption of pulse carbohydrates, resulting in a higher GI. High or increased heat applications to pulses were associated with extensive starch gelatinization, also leading to a higher GI. The type of reference food used (glucose or white bread) and the other nutrients present in the meal also affected the GI.

Glycemic Index of Wheat and Rice are Similar When Consumed as Part of a North Indian Mixed Meal

INTRODUCTION

Wheat is preferable over rice due to its lower glycemic index (GI). It is not known if the same is true when these staples are a part of mixed meals, hence we compared the Glycemic responses of wheat/rice containing mixed meals.

MATERIALS AND METHODS

Glycemic responses of 2 mixed meals were compared with reference meal (glucose) where each was designed to provide a total of 50 g of available carbohydrate (AvCHO), in 10 healthy adult volunteers as per recent recommendations. Test meal 1 comprised of a pulse preparation (green gram dal), a vegetable (ladies' finger), and 2 wheat chapattis. In test meal 2 these wheat chapattis were replaced by cooked rice supplying an equal amount of AvCHO. After an overnight fast of 10- 14 h, capillary blood glucose estimations were done subsequent to eating each test meal or glucose. GI of test meals was calculated by comparing their area under curve (AUCs) with AUC for glucose. GI of test meals were compared using unpaired t test.

RESULTS

The study sample comprised of 7 males and 3 females with mean age 30.9 ± 5.1y. The GI of test meal 1 (85.5 ± 11.8%) and test meal 2 (83.6 ± 11.4%) was not significantly different (P = 0.7095).

CONCLUSION

The present study found no differences in glycemic index of wheat chapatti and rice based mixed meals with equivalent AvCHO content of the staple.

Glycemic Index and Load of Selected Ethiopian Foods: An Experimental Study

BACKGROUND

Determining the glycemic index and load of foods has significant impact on meal planning for diabetes. However, there is no data on the glycemic index (GI) and glycemic load (GL) of Ethiopian foods. Therefore, the aim of this study was to analyze the glycemic index and glycemic load of Teff Injera, Corn Injera, and White Wheat Bread.

METHODS

Experimental study design was conducted among selected healthy adults. Teff Injera, Corn Injera, and White Wheat Bread were selected as test foods for the study, and glucose was used as the reference food. The postprandial glucose concentrations in the blood were recorded at 0, 15, 30, 45, 90, and 120 minutes. The relative glycemic index of each food was calculated, and the presence of statistical difference in glycemic index among the three foods was analyzed.

RESULTS

The mean age of the participants was 23 years (±1.6 years). The glycemic indexes of Teff Injera, White Wheat Bread, and Corn Injera were 36 (low), 46 (low), and 97 (high), respectively, and the glycemic loads were 7 (low), 14 (moderate), and 22 (high), respectively. There was a significant difference in glycemic index and load among the three food items (p < 0.001). Teff Injera had a much lower glycemic index and load compared with Corn Injera (p < 0.001) and White Wheat Bread (p = 0.03).

CONCLUSIONS

Teff Injera and White Wheat Bread have low glycemic index and are recommended to be consumed by diabetic patients, whereas Corn Injera has high glycemic index and is not recommended for diabetic patients. Therefore, Teff Injera should be considered globally in the dietary modification programs for diabetes.

The Effect of the Body Mass Indexes of Young Healthy Individuals on the Glyacemic Indexes of Traditional and Modified Vegetarian Meals

Blood glucose concentration increases after the consumption of any carbohydrate-containing meal. Several factors affect the course of glucose metabolism, including nutritional status. This study evaluated the effect of the nutritional statuses of adults on their glycaemic responses after the consumption of some vegetarian meals (dumplings with potato and curd cheese stuffing; curd cheese dumplings; pancakes with curd cheese), prepared according to the traditional recipe and a partly modified recipe. The 105 participants, aged 20-27 years, with different body mass indexes (BMI), took an oral glucose tolerance test after the intake of a standard glucose solution, and also after each meal (previously analysed for energy value and approximate composition). The consumption of each meal by participants with different nutritional statuses elicited different glycaemic responses, which were reflected in the diverse glycaemic indexes (GIs). The partial modification of the meal recipes contributed to lowering their GIs. Vast differences were observed in the glycaemic responses among the surveyed participants after the consumption of the same meals. The GIs of meals should be determined in different groups of people.

Glycemic Index and Insulinemic Index of Foods: An Interlaboratory Study Using the ISO 2010 Method

An official method for determining food glycemic index (GI) was published by the Organization for International Standardization (ISO) in 2010, but its performance has not been assessed. Therefore, we aimed to determine the intra- and inter-laboratory variation of food GI values measured using the 2010 ISO method. Three laboratories (Australia, Canada and France) determined the GI and insulinemic-index (II) of six foods in groups of 13–15 participants using the 2010 ISO method and intra- and inter-laboratory Standard Deviations (SDs) were calculated. Overall mean food GIs varied from 47 to 86 (p < 0.0001) with no significant difference among labs (p = 0.57) and no food × laboratory interaction (p = 0.20). Within-laboratory SD was similar among foods (range, 17.8–22.5; p = 0.49) but varied among laboratories (range 17.5–23.1; p = 0.047). Between-laboratory SD of mean food GI values ranged from 1.6 to 6.7 (mean, 5.1). Mean glucose and insulin responses varied among foods (p < 0.001) with insulin (p = 0.0037), but not glucose (p = 0.054), varying significantly among labs. Mean II varied among foods (p < 0.001) but not among labs (p = 0.94). In conclusion, we found that using the 2010 ISO method, the mean between-laboratory SD of GI was 5.1. This suggests that the ISO method is sufficiently precise to distinguish a mean GI = 55 from a mean GI ≥ 70 with 97–99% probability.

At a high dose even partially degraded beta-glucan with decreased solubility significantly reduced the glycaemic response to bread

Cereal beta-glucan can reduce post-prandial glycaemic responses, which makes it an interesting ingredient to improve the health impact of bread, a staple food with a high glycaemic index (GI). Here we compare the ability of different wheat-based breads prepared with oat bran concentrate and barley flour and a Norwegian type of soft wrap (lompe) for their ability to reduce glycaemic responses in healthy adults. Both breads with the highest beta-glucan content (3.8 g per serving) significantly reduced peak blood glucose rise (PBGR), incremental area under the blood glucose curve (iAUC) and GI compared to wheat control regardless of beta-glucan Mw and solubility. At a medium dose of 1.7 g per serving breads with beta-glucan of high MW and solubility significantly lowered iAUC, but not GI or PBGR compared to white bread. In contrast to previous studies, no significant correlation between viscosity after in vitro digestion and any of the glycaemia variables was found. However, the amount of soluble beta-glucan per serving was inversely correlated with GI. Lompe had a similar medium GI (63) than the high dose beta-glucan breads (56 and 64). However, while "lompe" had significantly lower amounts of rapidly digestible starch, no differences in in vitro starch digestion were found between the different breads. Instead, increased local viscosity at the intestinal border (e.g. soluble beta-glucan interacting with the mucus layer), dilution of nutrients (higher water content and serving size) and/or reduced gastric emptying are proposed as potential explanations for the lower glycaemic responses to high dose beta-glucan breads.

Comparative Effect of Low-Glycemic Index versus High-Glycemic Index Breakfasts on Cognitive Function: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aims to compare the effect of High-Glycemic Index (GI) versus Low-GI breakfasts on cognitive functions, including memory and attention, of children and adolescents. We systematically searched the MEDLINE (via PubMed), EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science databases, from their inception until June 2019. Articles comparing the effect of Low-GI versus High-GI breakfasts on the cognitive function (i.e., immediate memory, delayed memory, and attention) of children and adolescents were included. The DerSimonian and Laird method was used to compute the pooled effect sizes (ESs) and their respective 95% confidence intervals (CIs). The pooled ESs were 0.13 (95% CI: −0.11, 0.37) for immediate memory and 0.07 (95% CI: −0.15, 0.28) for delayed memory. For attention, the pooled ES was −0.01 (95% CI: −0.27, 0.26). In summary, GI breakfasts do not affect cognitive domains in children and adolescents.

Impact of oat processing on glycaemic and insulinaemic responses in healthy humans: a randomised clinical trial

Oats can be processed in a variety of ways ranging from minimally processed such as steel-cut oats (SCO), to mildly processed such as large-flake oats (old fashioned oats, OFO), moderately processed such as instant oats (IO) or highly processed in ready-to-eat oat cereals such as Honey Nut Cheerios (HNC). Although processing is believed to increase glycaemic and insulinaemic responses, the effect of oat processing in these respects is unclear. Thus, we compared the glycaemic and insulinaemic responses elicited by 628 kJ portions of SCO, OFO, IO and HNC and a portion of Cream of Rice cereal (CR) containing the same amount of available-carbohydrate (23 g) as the oatmeals. Healthy males (n 18) and females (n 12) completed this randomised, cross-over trial. Blood was taken fasting and at intervals for 3 h following test-meal consumption. Glucose and insulin peak-rises and incremental AUC (iAUC) were subjected to repeated-measures ANOVA using Tukey's test (two-sided P&lt;0·05) to compare individual means. Glucose peak-rise (primary endpoint, mean (sem) mmol/l) after OFO, 2·19 (sem 0·11), was significantly less than after CR, 2·61 (sem 0·13); and glucose peak-rise after SCO, 1·93 (sem 0·13), was significantly less than after CR, HNC, 2·49 (sem 0·13) and IO 2·47 (sem 0·13). Glucose iAUC was significantly lower after SCO than CR and HNC. Insulin peak rise was similar among the test meals, but insulin iAUC was significantly less after SCO than IO. Thus, the results show that oat processing affects glycaemic and insulinaemic responses with lower responses associated with less processing.

Glycemic response to low sugar apple juice treated with invertase, glucose oxidase and catalase

BACKGROUND/OBJECTIVES

Investigating the effect on post-prandial glycemic and venous serum insulin response of an apple drink following the conversion of its glucose to gluconate.

SUBJECTS/METHODS

In a double-blind randomized placebo-controlled clinical trial with cross-over design, 30 male adults with impaired fasting glucose (IFG) received a drink of 500 ml: 1. Verum: Apple juice treated with invertase, glucose oxidase/catalase (glucose 0.05 g; gluconate 18.2 g); 2.

CONTROL

Untreated apple juice (free glucose 8.5 g; bound glucose 6.7 g; gluconate below detection limit). Postprandial fingerprick capillary blood glucose and venous serum insulin were measured twice at baseline and at times 0 (start of drink), 15, 30, 45, 60, 90 and 120 min. Gastrointestinal symptoms, stool consistency and satiety were also assessed.

RESULTS

The incremental area under the curve (iAUC₁₂₀) of glucose levels (primary parameter) was significantly lower after verum (mean ± SD: 63.6 ± 46.7 min × mmol/l) compared to control (mean ± SD: 198 ± 80.9 min × mmol/l) (ANOVA F = 137.4, p < 0.001; α = 0.05). Also, iAUC₁₂₀ of venous serum insulin levels (secondary parameter) was significantly lower after verum (mean ± SD: 2045 ± 991 min × mmol/l) compared to control (3864.3 ± 1941 min × mmol/l), (ANOVA F = 52.94, p < 0.001; α = 0.025). Further parameters of glucose metabolism and ISI = 2/[AUC venous serum insulin × AUC glucose +1] were also improved after verum compared to control. Verum increased stool frequency and decreased stool consistency, as assessed by Bristol stool form scale.

CONCLUSIONS

By enzymatic treatment of apple juice its sugar content could be reduced by 21% and postprandial glycemic and venous serum insulin response by 68 and 47%, respectively resulting in a reduction of glycemic load by 74.6% without any adverse gastrointestinal side-effects.

Improving Rice Grain Quality: State-of-the-Art and Future Prospects

Rice grain quality encompasses complex interrelated traits that cover biochemical composition, cooking, eating, nutritional, and sensory properties. Because rice endosperm is composed mainly of starch, rice grain quality is traditionally defined by characterizing starch structure and composition, which is then subsequently correlated with functional properties of the grain. The current proxy tests routinely used to describe rice grain quality preferences are rather limited to the estimation of apparent amylose content, gelatinization temperature, and gel consistency. Additional tests that characterize starch property, viscoelasticity, grain texture, and aroma are also employed in more advanced laboratories. However, these tests are not routinely applied in breeding programs to distinguish cooking quality classes to reflect evolving consumer preference and market demand. As consumer preferences in Asia and all over the world are diverse due to varied demographics and culture, defining uniform attributes to capture regional grain quality preferences becomes more challenging. Hence, novel and innovative proxy tests are needed to characterize rice grain quality to meet the demand for consumer preferences of commercially-released cultivars. In this chapter, the current methods employed in rice grain quality monitoring are succinctly reviewed. Future prospects for improvement are identified, introducing cutting edge technologies that can facilitate high-throughput screening of rice diversity panels and breeding lines. Aside from addressing the requirements for quality improvement in the traditional inbred rice breeding programs, we also tackled the need to enhance grain quality in the hybrid rice sector.

Development of Low Glycemic Index Foods and Their Glucose Response in Young Healthy Non-Diabetic Subjects

Development of low glycemic-foods is important in the prevention and management of type 2 diabetes. In this context, we prepared four test foods (TFs) (two mixed mini-meals and two breakfast items) with low glycemic-components and assessed their glycemic index (GI) in young healthy non-diabetic volunteers with mean age of 29 yr, body mass index of 24 kg/m2, and fasting plasma glucose levels less than 4.62 mmol/L. Volunteers were given 50 g of glucose, as a reference food (RF) on the first day, and TFs, i.e. TF1 (mixed mini meal: roti made of wheat flour and chana dal+ curd), TF2 [mixed mini meal made of wheat, pearl barley, and Bengal gram flour (besan) mix with chana whole (unhusked chana+curd)], TF3 (pearl barley rawa upma), and TF4 (wheat rawa upma) were given 2-day intervals in the same order. Glucose levels at fasting conditions and after the consumption of RF and TFs at different time intervals (15, 30, 45, 60, 90, and 120 min) were measured, and the incremental area under curve (IAUC) for glucose and GI of the TFs were calculated. The glucose IAUC values at different time points were highest for TF2 (GI=71.9±7.4), while all other TFs had comparable GI in the range of 53.7~54.9. Among the various TFs, TF1, TF3, and TF4 exerted low to moderate glycemic response, and thus can be classified as low glycemic-foods. Nevertheless, these foods need to be tested for their efficacy in controlling and/or managing hyperglycemia and glucose over-load in diabetic subjects.

Blood glucose response after oral intake of lactulose in healthy volunteers: A randomized, controlled, cross-over study

AIM

To investigate possible changes of blood glucose levels after oral intake of lactulose in healthy subjects.

METHODS

The study was performed as prospective, randomized, two-part study with 4-way cross-over design with n = 12 in each study arm. Capillary blood glucose levels were determined over a time period of 180 min after intake of a single dose of 10 g or 20 g lactulose provided as crystal or liquid formulation. During the manufacturing process of lactulose, impurities with sugars (e.g., lactose, fructose, galactose) occur. Water and 20 g glucose were used as control and reference. Because lactulose is used as a functional food ingredient, it may also be consumed by people with impaired glucose tolerance, including diabetics. Therefore, it is of interest to determine whether the described carbohydrate impurities may increase blood glucose levels after ingestion.

RESULTS

The blood glucose concentration-time curves after intake of 10 g lactulose, 20 g lactulose, and water were almost identical. None of the three applications showed any changes in blood glucose levels. After intake of 20 g glucose, blood glucose concentration increased by approximately 3 mmol/L (mean C_max = 8.3 mmol/L), reaching maximum levels after approximately 30 min and returning to baseline within approximately 90 min, which was significantly different to the corresponding 20 g lactulose formulations (P < 0.0001). Comparing the two lactulose formulations, crystals and liquid, in the dosage of 10 g and 20 g, there was no difference in the blood glucose profile and calculated pharmacokinetic parameters despite the different amounts of carbohydrate impurities (1.5% for crystals and 26.45% for liquid). Anyhow, the absolute amount of single sugars was low with 0.3 g in crystals and 5.29 g in liquid formulation in the 20 g dosages. Lactulose was well tolerated by most volunteers, and only some reported mild to moderate mainly gastrointestinal side effects.

CONCLUSION

The unchanged blood glucose levels after lactulose intake in healthy subjects suggest its safe use in subjects with impaired glucose tolerance.

A Double-Blind, Randomized Controlled, Acute Feeding Equivalence Trial of Small, Catalytic Doses of Fructose and Allulose on Postprandial Blood Glucose Metabolism in Healthy Participants: The Fructose and Allulose Catalytic Effects (FACE) Trial

Recent literature suggests that catalytic doses (≤10 g/meal or 36 g/day) of D-fructose and D-allulose may reduce postprandial blood glucose responses to carbohydrate loads in people with and without type 2 diabetes by inducing glycogen synthesis. To assess the effect of small single doses of fructose and allulose on postprandial blood glucose regulation in response to a 75 g-oral glucose tolerance test (75 g-OGTT) in healthy individuals, we conducted an acute randomized, crossover, equivalence trial in healthy adults. Each participant randomly received six treatments, separated by a minimum one-week washout. Treatments consisted of a 75 g-OGTT with the addition of fructose or allulose at 0 g (control), 5 g or 10 g. A standard 75 g-OGTT protocol was followed with blood samples at −30, 0, 30, 60, 90, 120 min. The primary outcome was the difference in plasma glucose incremental area under the curve (iAUC). A total of 27 participants underwent randomization with data available from 25 participants. Small doses of fructose or allulose did not show a significant effect on plasma glucose iAUC or other secondary markers of postprandial blood glucose regulation in response to a 75 g-OGTT in healthy individuals. These results were limited by the low power to detect a significant difference, owing to greater than expected intra-individual coefficient of variation (CV) in plasma glucose iAUC. Overall, we failed to confirm the catalytic effects of small doses of fructose and allulose in healthy individuals. Future trials may consider recruiting larger sample sizes of healthy individuals. Trial registration: clinicaltrials.gov identifier, NCT02459834.

The Effect of Mode of Transport on Intraindividual Variability in Glycemic and Insulinemic Response Testing

The effect of light- to moderate-intensity exercise, such as that used as a mode of transport, on glycemic response testing is unclear. The aim was to investigate the effect of acute exercise (walking and cycling), simulated to act as a mode of transport, prior to glycemic response testing on the intraindividual variability of blood glucose and insulin. A total of 11 male participants visited the laboratory four times. Initially, they undertook a maximum oxygen uptake and two submaximal exercise tests. For the other three visits, they either rested (25 min), cycled, or walked 5 km followed by a 2-hr glycemic response test after consuming a glucose drink (50 g of available carbohydrate). The mean coefficient of variation of each transport group was below the International Organization for Standardization cutoff of 30%. The highest mean coefficient of variation of glucose area under the curve (AUC) was between the rest and the walking trials (30%) followed by walking and cycling (26%). For insulin AUC, the highest mean coefficient of variation was between walking and cycling (28%) followed by rest and walking (24%). The lowest glucose AUC and insulin AUC were between rest and cycling (25% and 14%, respectively). This study did not find differences (p > .05) between the conditions for glucose AUC (at 120 min, rest: 134.5 ± 104.6 mmol/L; walking: 115.5 ± 71.7 mmol/L; and cycling: 142.5 ± 75 mmol/L) and insulin AUC (at 120 min, rest: 19.45 ± 9.12 μmol/ml; walking: 16.49 ± 8.42 μmol/ml; and cycling: 18.55 ± 9.23 μmol/ml). The results indicate no difference between the tests undertaken; however, further research should ensure the inclusion of two rest conditions.

Postprandial glucose and insulin response to a high-fiber muffin top containing resistant starch type 4 in healthy adults: a double-blind, randomized, controlled trial

OBJECTIVES

VERSAFIBE™ 2470 resistant starch (RS) is an RS type 4 that is derived from high-amylose maize starch,70% total dietary fiber (TDF; AOAC method 2009.01). This was a randomized, double-blind, crossover study to evaluate the postprandial blood glucose and insulin responses of healthy adults (n = 28) after the consumption of a muffin top made with VERSAFIBE™ 2470 RS (11.6 g TDF fiber muffin top) or a control muffin top (0.9 g TDF).

METHODS

The muffin tops were matched for weight, total carbohydrate, sugars, protein, and fat. During each treatment period, subjects consumed a standard evening meal, fasted for 12 h, and arrived at the study clinic the following morning. Serum glucose, serum insulin, and capillary glucose were measured at 0, 15, 30, 45, 60, 90, and 120 min after muffin top consumption. The subjects completed a 7-d washout period between treatments.

RESULTS

The consumption of the fiber muffin top resulted in a significant 33% reduction in postprandial serum glucose incremental area under the curve from 0 to 120 min and an 8% decrease in maximum glucose concentration versus the control muffin (P = 0.037 and P = 0.007, respectively). The fiber muffin top reduced postprandial serum insulin incremental area under the curve from 0 to 120 min by 38% compared with the control muffin top (P <0.001), which aligns with the blood glucose data.

CONCLUSIONS

This study demonstrated that the inclusion of a practical dose of dietary fiber (11.6 g TDF) from VERSAFIBE™ 2470 RS in a bakery product significantly reduced postprandial glucose and insulin responses in healthy adults.

Type-4 Resistant Starch in Substitution for Available Carbohydrate Reduces Postprandial Glycemic Response and Hunger in Acute, Randomized, Double-Blind, Controlled Study

Resistant starch (RS) is a type of dietary fiber that has been acknowledged for multiple physiological benefits. Resistant starch type 4 (RS4) is a subcategory of RS that has been more intensively studied as new types of RS4 emerge in the food supply. The primary aim of this randomized, double-blind, controlled study was to characterize the postprandial glucose response in healthy adults after consuming a high fiber scone containing a novel RS4 or a low fiber control scone without RS4. Secondary aims included assessment of postprandial insulin response, postprandial satiety, and gastrointestinal tolerance. The fiber scone significantly reduced postprandial glucose and insulin incremental areas under the curves (43-45% reduction, 35-40% reduction, respectively) and postprandial glucose and insulin maximum concentrations (8-10% and 22% reduction, respectively). The fiber scone significantly reduced hunger and desire to eat during the 180 min following consumption and yielded no gastrointestinal side effects compared with the control scone. The results from this study demonstrate that a ready-to-eat baked-good, such as a scone, can be formulated with RS4 replacing refined wheat flour to yield statistically significant and clinically meaningful reductions in blood glucose and insulin excursions. This is the first study to report increased satiety after short-term RS4 intake, which warrants further investigation in long-term feeding studies.

Efficacy of different fibres and flour mixes in South-Asian flatbreads for reducing post-prandial glucose responses in healthy adults

PURPOSE

Type 2 diabetes (T2DM) is increasing, particularly in South-East Asia. Intake of high-glycaemic foods has been positively associated with T2DM, and feasible routes to reduce the glycaemic response to carbohydrate-rich staple foods are needed. The research question was whether different fibre and legume flour mixes in flatbreads lower postprandial glucose (PPG) responses.

METHODS

Using a balanced incomplete block design, we tested the inclusion of guar gum (GG), konjac mannan (KM) and chickpea flour (CPF) in 10 combinations (2/4/6 g GG; 2/4 g KM; 15 g CPF, and 10 or 15 g CPF plus 2 or 4 g GG) in 100 g total of a control commercial high-fibre flatbread flour mix ("atta") on PPG in 38 normal-weight adults. Self-reported appetite was an additional exploratory outcome. An in vitro digestion assay was adapted for flatbreads and assessed for prediction of in vivo PPG.

RESULTS

Flatbreads with 6 g GG, 4 g KM, and 15 g CPF plus 2 or 4 g GG reduced PPG ≥30 % (p < 0.01), while no other combinations differed significantly from the control. A statistical model with four in vitro parameters (rate of digestion, %RDS, AUC, carbohydrate level) was highly predictive of PPG results (adjusted R 2 = 0.89). Test products were similar to the control for appetite-related measures.

CONCLUSIONS

The results confirm the efficacy of specific additions to flatbread flour mixes for reducing PPG and the value of the in vitro model as a predictive tool with these ingredients and product format. This trial is registered at ClinicalTrials.gov with identifier NCT02671214.

The impact of diet-based glycaemic response and glucose regulation on cognition: evidence across the lifespan

The brain has a high metabolic rate and its metabolism is almost entirely restricted to oxidative utilisation of glucose. These factors emphasise the extreme dependence of neural tissue on a stable and adequate supply of glucose. Whereas initially it was thought that only glucose deprivation (i.e. under hypoglycaemic conditions) can affect brain function, it has become apparent that low-level fluctuations in central availability can affect neural and consequently, cognitive performance. In the present paper the impact of diet-based glycaemic response and glucose regulation on cognitive processes across the lifespan will be reviewed. The data suggest that although an acute rise in blood glucose levels has some short-term improvements of cognitive function, a more stable blood glucose profile, which avoids greater peaks and troughs in circulating glucose is associated with better cognitive function and a lower risk of cognitive impairments in the longer term. Therefore, a habitual diet that secures optimal glucose delivery to the brain in the fed and fasting states should be most advantageous for the maintenance of cognitive function. Although the evidence to date is promising, it is insufficient to allow firm and evidence-based nutritional recommendations. The rise in obesity, diabetes and metabolic syndrome in recent years highlights the need for targeted dietary and lifestyle strategies to promote healthy lifestyle and brain function across the lifespan and for future generations. Consequently, there is an urgent need for hypothesis-driven, randomised controlled trials that evaluate the role of different glycaemic manipulations on cognition.

Effects of breaking up prolonged sitting following low and high glycaemic index breakfast consumption on glucose and insulin concentrations

Purpose

Breaking up prolonged sitting can attenuate the postprandial rise in glucose and insulin. Whether such effects are dependent of the glycaemic index (GI) of the consumed carbohydrate is unknown. This study examined the acute effects of breaking up prolonged sitting following a low GI and a high GI breakfast on postprandial glucose and insulin concentrations.

Procedures

Fourteen adult males aged 22.1 ± 1.2 years completed four, 4 h experimental conditions: high GI breakfast followed by uninterrupted sitting (HGI-SIT), low GI breakfast followed by uninterrupted sitting (LGI-SIT), high GI breakfast followed by 2 min activity breaks every 20 min (HGI-ACT), and low GI breakfast followed by 2 min activity breaks every 20 min (LGI-ACT). Positive incremental area under the curve (iAUC) for glucose and insulin (mean [95% CI]) for each 4 h experimental condition was calculated. Statistical analyses were completed using linear mixed models.

Results

The sitting × breakfast GI interaction was not significant for glucose positive iAUC (P = 0.119). Glucose positive iAUC (mmol/L 4 h⁻¹) was significantly lower in the activity breaks conditions than the uninterrupted sitting conditions (2.07 [2.24, 2.89] vs. 2.56 [1.74, 2.40], respectively, P = 0.004) and significantly lower in the low GI conditions than the high GI conditions (2.13 [1.80, 2.45] vs. 2.51 [2.18, 2.84], respectively, P = 0.022). Insulin concentrations did not differ between conditions (P ≥ 0.203).

Conclusions

Breaking up prolonged sitting and lowering breakfast GI independently reduced postprandial glucose responses. This indicates that interrupting prolonged sitting and reducing dietary GI are beneficial approaches for reducing cardiometabolic disease risk.

A High Fiber Cookie Made with Resistant Starch Type 4 Reduces Post-Prandial Glucose and Insulin Responses in Healthy Adults

Distarch phosphate is a resistant starch type 4 (RS4) containing phosphodiester cross-links within and between starch molecules. This study examined the glycemic effects of VERSAFIBE 1490™ resistant starch, a distarch phosphate derived from potato, containing 90% total dietary fiber (TDF, AOAC 991.43 method). In this double-blind, randomized, placebo-controlled, cross-over study, 28 healthy adults consumed a cookie containing 24 g fiber from distarch phosphate (fiber cookie) or a control cookie containing 0.5 g fiber that was matched for fat, protein, and total carbohydrate content. Intravenous blood glucose, intravenous blood insulin, and capillary glucose were measured for two hours after cookie consumption. The fiber cookie reduced the post-prandial blood glucose incremental area under the curve from 0 to 120 minutes (iAUC0-120min) by 44% (p = 0.004) and reduced the maximum glucose concentration (Cmax0-120min) by 8% (p = 0.001) versus the control cookie. Consumption of the fiber cookie resulted in a significant 46% reduction of the post-prandial serum insulin iAUC0-120min (p < 0.001) and a 23% reduction in Cmax0-120min (p = 0.007) versus the control cookie. This study shows that distarch phosphate RS4 can be incorporated into a cookie and significantly reduce post-prandial glucose and insulin responses in healthy adults.

Glycemic indices, glycemic load and glycemic response for seventeen varieties of dates grown in Saudi Arabia

BACKGROUND

Dates are consumed worldwide, and are an important fruit for many individuals in Saudi Arabia. Currently, limited information is available on the glycemic indices of different date varieties.

OBJECTIVES

To determine the glycemic index (GI), glycemic load (GL) and glycemic response for 17 common date varieties in Saudi Arabia.

DESIGN

Prospective clinical trial on healthy subjects.

SETTING

College of Medicine, Qassim University, Buraydah, Saudi Arabia.

PATIENTS AND METHODS

The available carbohydrate content of Tamer stage dates was determined using standard laboratory methods. Healthy subjects (ten males and nine females) received 50 g of glucose (on three separate occasions) and 50 g equivalent of available carbohydrates from the seventeen varieties of date (each once). The GI and GL were then calculated.

MAIN OUTCOME MEASURE(S)

GI, GL, and glycemic response.

RESULTS

The mean (SEM) GI of the date samples was 55.2 (7.7) (range, 42.8-74.6). Sellaj and Maktoomi exhibited the highest GI (74.6 [10.1] and 71.0 [11.1]), respectively, whereas Shaqra, Sukkary, and Sag'ai had the lowest GI (42.8 [5.5], 43.4 [4.7] and 44.6 [6]), respectively. The GL of the date samples ranged from 8.5 to 24. Sellaj had a high GL (24), whereas Ajwah and Shaqra had a low GL (8.5 and 9.2). The analyses suggested no significant difference in GI between the date varieties. However, the GL values differed significantly between the 17 date varieties (P < .001).

CONCLUSION

The results provide reliable GI and GL values for 17 common date varieties in Saudi Arabia. The identification of date varieties with lower glycemic responses may help lower the GI of the diet of both healthy and diabetic Saudi individuals.

LIMITATIONS

We used dates at the Tamer stage, which may not be translatable to all types of dates.

Estimating the reliability of glycemic index values and potential sources of methodological and biological variability

BACKGROUND

The utility of glycemic index (GI) values for chronic disease risk management remains controversial. Although absolute GI value determinations for individual foods have been shown to vary significantly in individuals with diabetes, there is a dearth of data on the reliability of GI value determinations and potential sources of variability among healthy adults.

OBJECTIVE

We examined the intra- and inter-individual variability in glycemic response to a single food challenge and methodologic and biological factors that potentially mediate this response.

DESIGN

The GI value for white bread was determined by using standardized methodology in 63 volunteers free from chronic disease and recruited to differ by sex, age (18-85 y), and body mass index [BMI (in kg/m²): 20-35]. Volunteers randomly underwent 3 sets of food challenges involving glucose (reference) and white bread (test food), both providing 50 g available carbohydrates. Serum glucose and insulin were monitored for 5 h postingestion, and GI values were calculated by using different area under the curve (AUC) methods. Biochemical variables were measured by using standard assays and body composition by dual-energy X-ray absorptiometry.

RESULTS

The mean ± SD GI value for white bread was 62 ± 15 when calculated by using the recommended method. Mean intra- and interindividual CVs were 20% and 25%, respectively. Increasing sample size, replication of reference and test foods, and length of blood sampling, as well as AUC calculation method, did not improve the CVs. Among the biological factors assessed, insulin index and glycated hemoglobin values explained 15% and 16% of the variability in mean GI value for white bread, respectively.

CONCLUSIONS

These data indicate that there is substantial variability in individual responses to GI value determinations, demonstrating that it is unlikely to be a good approach to guiding food choices. Additionally, even in healthy individuals, glycemic status significantly contributes to the variability in GI value estimates. This trial was registered at clinicaltrials.gov as NCT01023646.