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

Effect of fibers on starch structural changes during hydrothermal treatment: multiscale analyses, and evaluation of dilution effects on starch digestibility

BACKGROUND

Dietary fibers (DFs) may influence the structural, nutritional and techno-functional properties of starch within food systems. Moreover, DFs have favorable effects on the digestive system and potentially a lower glycemic index. These potential benefits may change depending on DF type. Starch processed in the presence of soluble and insoluble fibers can undergo different structural and functional changes, and the present study investigated the effects of short-chain and long-chain inulin and cellulose on the structural and digestive properties of wheat starch.

RESULTS

The combined use of differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) provided insights into the structural changes in starch and inulin at different levels. Short-chain and long-chain inulin had higher water retention capacity and a potential to limit starch gelatinization. The FTIR results revealed an interaction between starch and inulin. Scanning electron microscopy analysis showed morphological changes in starch and inulin after the hydrothermal treatment. Cellulose fiber was not affected by the hydrothermal treatment and had no influence on starch behavior. The structural differences observed through XRD, FTIR and scanning electron microscopy analyses between starch with and without inulin fibers did not significantly impact starch digestibility, except for the dilution effect caused by adding DFs.

CONCLUSION

The present study highlights the importance of utilizing different analytical tools to assess changes in food samples at different scales. Although short-chain and long-chain inulin could potentially limit starch gelatinization, the duration of the heat treatment (90 °C for 10 min) was sufficient to ensure complete starch gelatinization. The dilution effect caused by adding fibers was the primary reason for the effect on starch digestibility. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Harnessing the power of resistant starch: a narrative review of its health impact and processing challenges

Starch is a primary energy storage for plants, making it an essential component of many plant-based foods consumed today. Resistant starch (RS) refers to those starch fractions that escape digestion in the small intestine and reach the colon where they are fermented by the microflora. RS has been repeatedly reported as having benefits on health, but ensuring that its content remains in food processing may be challenging. The present work focuses on the impact RS on health and explores the different processes that may influence its presence in foods, thus potentially interfering with these effects. Clinical evidence published from 2010 to 2023 and studying the effect of RS on health parameters in adult populations, were identified, using PUBMED/Medline and Cochrane databases. The search focused as well on observational studies related to the effect of food processes on RS content. While processes such as milling, fermentation, cooking and heating seem to have a deleterious influence on RS content, other processes, such as cooling, cooking time, storage time, or water content, may positively impact its presence. Regarding the influence on health parameters, there is a body of evidence suggesting an overall significant beneficial effect of RS, especially type 1 and 2, on several health parameters such as glycemic response, insulin resistance index, bowel function or inflammatory markers. Effects are more substantiated in individuals suffering from metabolic diseases. The effects of RS may however be exerted differently depending on the type. A better understanding of the influence of food processes on RS can guide the development of dietary intake recommendations and contribute to the development of food products rich in RS.

Nutrition at the Intersection between Gut Microbiota Eubiosis and Effective Management of Type 2 Diabetes

Nutrition is one of the most influential environmental factors in both taxonomical shifts in gut microbiota as well as in the development of type 2 diabetes mellitus (T2DM). Emerging evidence has shown that the effects of nutrition on both these parameters is not mutually exclusive and that changes in gut microbiota and related metabolites such as short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) may influence systemic inflammation and signaling pathways that contribute to pathophysiological processes associated with T2DM. With this background, our review highlights the effects of macronutrients, carbohydrates, proteins, and lipids, as well as micronutrients, vitamins, and minerals, on T2DM, specifically through their alterations in gut microbiota and the metabolites they produce. Additionally, we describe the influences of common food groups, which incorporate varying combinations of these macronutrients and micronutrients, on both microbiota and metabolic parameters in the context of diabetes mellitus. Overall, nutrition is one of the first line modifiable therapies in the management of T2DM and a better understanding of the mechanisms by which gut microbiota influence its pathophysiology provides opportunities for optimizing dietary interventions.

Effect of microwave followed by cooling on structural and digestive properties of pinhão starch

To increase its resistant content, native pinhão starch was modified using a microwave (300 W, 90 s) and subsequently cooled at 4 °C for 4, 8, 16, 24, and 72 h. The results demonstrated that all starches exhibited a crystalline structure of type C, with decreased crystallinity after modification. In the modified samples, the ratio of peaks 1047/1022 cm-1 and 995/1022 cm-1, as identified by FTIR, indicated a reduction in the crystalline region and damage to the double helix structure of starch granules. DSC analysis revealed that modified starches had lower gelatinization temperature range values due to the presence of more homogeneous crystals. Rheological analyses showed that starch suspensions obtained exhibited pseudoplastic fluid behavior and gel-like viscoelastic structure formation, with higher storage moduli in samples with longer cooling times. The microwave-modified starch, cooled for 72 h, exhibited higher digestion resistance, resulting in a 43.6 % increase in resistant starch content and a 26.1 % decrease in rapidly digestible starch compared to native starch. The results highlight that the modification of native pinhão starch using a microwave, followed by cooling at 4 °C for 72 h, presents a promising method for increasing the resistant starch content.

Dietary intake of total vegetable, fruit, cereal, soluble and insoluble fiber and risk of all-cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies

Objectives

To conduct a systematic review and meta-analysis of prospective cohort studies to investigate the association between total, vegetable, fruit, cereal, soluble and insoluble fiber intake and risk of all causes, cardiovascular disease (CVD), and cancer mortality and quantitatively assess the dose-response relation.

Methods

Eligible studies were identified by searching PubMed, Embase and Web of science before August 2023. Random effects models were used to calculate summary relative risk (RR) and 95% confidence intervals (CI) and restricted cubic splines to model the linear/non-linear association.

Results

The summary RR for all-cause, CVD and cancer mortality of dietary fiber was 0.90 (95% CI: 0.86,0.93), 0.87 (0.84,0.91), 0.91 (0.88,0.93), respectively. Significant association was observed for all-cause and CVD mortality with fruit, vegetable cereal and soluble fiber intake and cancer mortality with cereal fiber intake. No significant association was found for insoluble fiber, vegetable or fruit fiber intake and cancer mortality. Dose-response analysis showed a significant non-linear relation of dietary fiber intake with all-cause mortality, and linear relation for others.

Conclusions

Higher dietary fiber including different type and food sources of fiber intake were associated with lower risk of mortality. Our findings provide more comprehensive evidence on dietary fiber intake with mortality.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier: CRD42022338837.

Cross-linked phosphorylated RS4 wheat starch reduces glucose and insulin responses after 3 days of pre-feeding in healthy adults: an acute, double-blind, randomized controlled clinical trial

When this project was designed, there was no evidence that adding resistant starch to available carbohydrate (avCHO) reduced glycaemic and insulinaemic responses (GIR). We compared GIR elicited by a cookie containing cross-linked phosphorylated RS4 wheat starch (Fibersym®) (RS4XL) versus an avCHO-matched control-cookie (CC) after n = 15 adults had consumed RS4XL or CC daily for 3-days using a double-blind, randomised, cross-over design. The difference in glucose iAUC over 0-2 h (primary endpoint) (mmol × min/L) after RS4XL, (mean ± SEM) 106 ± 16, versus CC, 124 ± 16, was not significant (p = 0.087). However, RS4XL reduced 0-90 min glucose iAUC (72 ± 9 vs 87 ± 9, p = 0.022), peak glucose concentration (6.05 ± 0.36 vs 6.57 ± 0.31 mmol/L, p = 0.017) and 0-2 h insulin iAUC (189 ± 21 vs 246 ± 24 nmol × h/L, p = 0.020). These results show that RS4XL reduced postprandial glycaemic and insulinaemic responses when added to avCHO, but do not prove that the products of its colonic fermentation are required for this effect.

Evaluating the effect of prebiotics on the gut microbiome profile and β cell function in youth with newly diagnosed type 1 diabetes: protocol of a pilot randomized controlled trial

INTRODUCTION

Data show that disturbances in the gut microbiota play a role in glucose homeostasis, type 1 diabetes (T1D) risk and progression. The prebiotic high amylose maize starch (HAMS) alters the gut microbiome profile and metabolites favorably with an increase in bacteria producing short chain fatty acids (SCFAs) that have significant anti-inflammatory effects. HAMS also improves glycemia, insulin sensitivity, and secretion in healthy non-diabetic adults. Additionally, a recent study testing an acetylated and butyrylated form of HAMS (HAMS-AB) that further increases SCFA production prevented T1D in a rodent model without adverse safety effects. The overall objective of this human study will be to assess how daily HAMS-AB consumption impacts the gut microbiome profile, SCFA production, β cell heath, function, and glycemia as well as immune responses in newly diagnosed T1D youth.

METHODS AND ANALYSIS

We hypothesize that HAMS-AB intake will improve the gut microbiome profile, increase SCFA production, improve β cell health, function and glycemia as well as modulate the immune system. We describe here a pilot, randomized crossover trial of HAMS-AB in 12 newly diagnosed T1D youth, ages 11-17 years old, with residual β cell function. In Aim 1, we will determine the effect of HAMS-AB on the gut microbiome profile and SCFA production; in Aim 2, we will determine the effect of HAMS-AB on β cell health, function and glycemia; and in Aim 3, we will determine the peripheral blood effect of HAMS-AB on frequency, phenotype and function of specific T cell markers. Results will be used to determine the effect-size estimate of using HAMS-AB. We anticipate beneficial effects from a simple, inexpensive, and safe dietary approach.

ETHICS AND DISSEMINATION

The Institutional Review Board at Indiana University approved the study protocol. The findings of this trial will be submitted to a peer-reviewed pediatric journal. Abstracts will be submitted to relevant national and international conferences.

TRIAL REGISTRATION

NCT04114357; Pre-results.

Acute Effects of Dietary Fiber in Starchy Foods on Glycemic and Insulinemic Responses: A Systematic Review of Randomized Controlled Crossover Trials

Dietary fiber (DF) consumption has been associated with improved glycemic control in epidemiological and long-term interventional studies. However, its acute effects are not yet clear. This systematic review aims to elucidate the postprandial effects of DF in starchy products on glycemia and insulinemia. An electronic search of databases was conducted, and forty-one records met the inclusion criteria and underwent a risk-of-bias assessment. It was shown that soluble DF does not clearly affect glycemia in individuals with normal weight, while resistant starch may be more effective in flattening glycemic responses. Concerning insulinemia, both soluble DF and resistant starch have mixed results, with either favorable or no effects. Data on insoluble DF and glucose metabolism are scarce. The same mixed results for glycemia can be seen in healthy volunteers with overweight/obesity, while resistant starch seems to improve insulinemic responses. Finally, more studies need to examine the acute effects of DF in starchy foods on glucose metabolism and insulin secretion in individuals facing glucose abnormalities. Additionally, more studies are needed to prove whether ingesting high-fiber carbohydrate-containing products per se can result in blunted glycemic and insulinemic responses and which DF type and amount are more effective.

Effect of adding high concentrations of retrograded starch with different amylose content on the physicochemical properties and sensory attributes of Greek-style yogurt

It is well known that using retrograded starches confers many technological advantages, as well as health benefits when consumed in adequate doses; however, these properties are closely related to the type of starch and/or the treatment applied, therefore, it is of interest to add retrograded starch to popular products such as Greek yogurt. The aim of this work was to investigate the effect of adding two types of retrograded corn starch with different amylose content to a non-strained type of Greek-style yogurt. Retrograded starch from starch containing 27 % (RNS) or 70 % (RHS) amylose was added to yogurt at 0, 10, 12.5, or 15 g/100 g before storage at 4 °C for 14 d. The resistant starch (RS) content, pH, syneresis, flow behavior index, and consistency index, were measured every week. A sensory test was carried out in yogurt added with 12.5 g/100 g of retrograded starches to evaluate acceptability. Adding retrograded starch significantly reduced syneresis while increasing the consistency, firmness, and resistant starch content of the yogurt. No significant differences in general acceptance were observed in samples added with RNS when compared to control. Although a significant difference was observed after adding RHS, the acceptance of the product is still convenient. Adding a high concentration of retrograded starch could help to ensure doses enough for a prebiotic effect of RS with concentrations of 1.74 ± 0.37 to 2.32 ± 0.09 g/100 g and from 3.5 ± 0.08 to 4.21 ± 0.08 g/100 g when RNS or RHS is added while maintaining the quality characteristics of Greek-style yogurt during storage without compromising the acceptability.

Resistant starch improves cardiometabolic disease outcomes: A narrative review of randomized trials

Healthy dietary patterns with adequate fiber improve cardiometabolic (CM) outcomes and attenuate disease progression. Resistant starch (RS) is a fermentable fiber that affects CM outcomes; however, studies are heterogeneous and inconsistent. Thus, the purpose of this narrative review is to assess the impact of RS intake by type and amount on CM outcomes while considering subject characteristics and trial duration. Randomized crossover or parallel studies (n = 31) were selected and compared according to acute (1 day; n = 12), medium (>1-30 days; n = 8), or long (>30 days; n = 11) duration. Most acute trials in healthy adults showed improvements in postprandial glycemic outcomes irrespective of RS type or amount. However, a more pronounced reduction occurred when test meals did not match for available carbohydrate. Daily RS intake had a minimal effect on CM outcomes in medium duration trials, but insulin resistant adults had better glycemic control at 4 weeks. Several longer duration trials (8-12 weeks) showed favorable CM outcomes with daily RS intake in adults with type 2 diabetes (T2D), but not in those at risk for T2D. Furthermore, some studies reported improved lipids, inflammatory biomarkers, and heart rate. Future studies should consider matching for available carbohydrates between the RS and control groups to understand the gut microbiome's role. Furthermore, energy and fiber should be considered. Overall, the acute intake of RS improves glycemic outcomes, and consuming RS at for least 4 and up to 8 to 12 weeks in adults with prediabetes and T2D, respectively, appears to improve CM outcomes.

More than the main structural genes: Regulation of resistant starch formation in rice endosperm and its potential application

In the past decade, research on resistant starch has evoked interest due to the prevention and inhibition of chronic human diseases, such as diabetes, cancer, and obesity. Increasing the amylose content (AC) and resistant starch (RS) has been pivotal in improving the nutritional benefit of rice. However, the exact mechanism of RS formation is complex due to interconnected genetic factors regulating amylose-amylopectin variation. In this review, we discussed the regulatory factors influencing the RS formation centered on the transcription, post-transcriptional, and post-translational processes. Furthermore, we described the developments in RS and AC levels in rice compared with other high RS cereals. Briefly, we enumerated potential applications of high RS mutants in health, medical, and other industries. We contest that the information captured herein can be deployed for marker-assisted breeding and precision breeding techniques through genome editing to improve rice varieties with enhanced RS content.

Unlocking the Potential of High-Amylose Starch for Gut Health: Not All Function the Same

High-amylose starch has unique functional properties and nutritional values in food applications. This type of starch is generally resistant to enzymatic digestion in the gastrointestinal tract, and contains an increased fraction of resistant starch (RS), which is a type of dietary fiber. The digestion and fermentation of high-amylose starch in the gut are of current research interest, as the processes are related to its nutritional functionality. This review summarizes recent in vitro and in vivo studies on the digestion and fermentation of high-amylose starches from different botanical sources and those that have been obtained by modifications. The RS content and fermentation properties are compared among high-amylose starches. This review aims to provide a current understanding of the relationship between high-amylose starch structures and fermentation-related nutritional properties. The results of these studies suggest that both modifications and food processing of high-amylose starch result in distinct fermentation products and nutritional properties. The review provides insight into the potential future applications of diverse high-amylose starches as bioactive compounds to modulate colonic fermentation.

Acute postprandial gut hormone, leptin, glucose and insulin responses to resistant starch in obese children: a single blind crossover study

INTRODUCTION

Resistant starch (RS) has beneficial effects on postprandial glucose metabolism in both animals and adults. Hitherto, there have been no studies in children of the acute metabolic and hormonal effects of RS-containing meals.

OBJECTIVES

We aimed to compare serial plasma glucose, insulin, gut hormone, leptin profiles and satiety scores in obese children after meals containing variable amounts of RS.

METHODS

This was a single blind, non-randomised, crossover study of 20 obese children aged 10-14 years old without comorbidities. Three test meals containing rice (M1), rice cooked with coconut oil (M2), rice cooked in coconut oil with lentils (M3) were given in sequence after a 12-hour fast . Blood samples were analysed for glucose (PG), insulin, leptin, glucagon-like polypeptide (GLP) 1, ghrelin and peptide YY (PYY) at appropriate times between 0 and 180 min.

RESULTS

Meal M2 resulted in significantly lower postprandial glucose values compared with meal M1 (maximal incremental glucose, ∆C_max, p<0.05; area under the curve, ∆AUC_0-3, p<0.01) and meal M3 (maximal concentration, C_max, p<0.01; ∆C_max, p<0.001, and ∆AUC_0-3p<0.01). M2 also produced lower insulin values compared with M1 (p<0.05). Postprandial ghrelin was significantly higher after M1 compared with M3 (p<0.05). PYY, GLP1 and median satiety scores were not significantly different between the three meals.

CONCLUSION

This study shows that M2, the meal containing RS alone, induced beneficial effects on acute postprandial glucose, insulin and ghrelin concentrations in obese children without diabetes. Acute postprandial satiety scores were not significantly affected by the three meals.

TRIAL REGISTRATION NUMBER

SLCTR/2020/007.

Postprandial Glycemic Response to Whole Fruit versus Blended Fruit in Healthy, Young Adults

While increased intake of dietary fiber is known to reduce postprandial glycemic response, it is less understood whether the disruption of dietary fiber, in a blender, alters the postprandial glycemic response. We compared the postprandial glycemic response in 20 young, healthy college students (12 female, 8 male) after consuming whole fruit vs. blended fruit. The fruit included gala apple, with the seeds removed, and blackberries. We used a repeated measures two-way ANOVA with fruit treatment as the within-subject variable, sex as the between-subjects factor, and glucose maximum, glucose incremental area under the curve (iAUC), and 60 min glucose as dependent variables. Glucose maximum and glucose iAUC were significantly lower (p < 0.05) in blended fruit compared to whole fruit and 60 min glucose was marginally significantly lower (p = 0.057) in blended fruit compared to whole fruit. Sex was not a significant main effect and sex*treatment was not a significant interaction for any of the dependent variables. We hypothesize that a reduced glycemic response in blended apple and blackberries compared to whole apple and blackberries might be associated with the release of dietary fiber and nutritive components from ground blackberry seeds.

Glycemic and Insulinemic Responses of Healthy Humans to a Nutrition Bar with or without Added Fibersym® RW, a Cross-Linked Phosphorylated RS4-Type Resistant Wheat Starch

The current study compared postprandial glycemic and insulinemic responses to four nutrition bars containing two different doses of resistant starch type-4. Normoglycemic adults (n = 17) completed six treatments, consuming either 50 g or 30 g digestible carbohydrate as: dextrose beverages (DEX), control puffed wheat bars (PWB), or RS4 test bars (RS4). Glucose (mg/dL) and insulin (µIU/mL) were measured at baseline and 10, 20, 30, 60, 90, and 120 min. There was a main effect of dose and treatment on glucose incremental area under the curve (iAUC, ps < 0.001), such that RS4 (50 g: 941, 95% confidence interval (CI): 501, 1519; 30 g: 481, 95% CI: 186, 914) was lower than PWB (50 g: 1746, 95% CI: 1109, 2528; 30 g: 693, 95% CI: 331, 1188) and DEX (50 g: 1940, 95% CI: 1249, 2783; 30 g:1432, 95% CI: 883, 2114). There was a main effect of dose and treatment on insulin iAUC (ps < 0.001), such that RS4 (50 g: 1993, 95% CI: 1347, 2764; 30 g: 943, 95% CI: 519, 1493) was lower than PWB (50 g: 3501, 95% CI: 2625, 4502; 30 g: 1789, 95% CI: 1193, 256) and DEX (50 g: 3143, 95% CI: 2317, 4095; 30 g: 2184, 95% CI: 1519, 2970). Results demonstrate significantly lower glycemic and insulinemic responses following consumption of nutrition bars containing RS4, regardless of dose, when compared with puffed wheat bars and dextrose.

Acute effect of Melon Manis Terengganu peel powder on glycemic response, perceived satiety, and food intake: a randomized, placebo-controlled crossover trial in adults at risk of type 2 diabetes

BACKGROUND

Melon Manis Terengganu (MMT) peel has a high dietary fiber content, but there is no data examining its health benefits in adults at risk of type 2 diabetes. The objective of the study was to evaluate whether consumption of MMT peel powder improves glycemic response, satiety, and food intake in adults at risk of type 2 diabetes.

METHODS

An open-label, randomized, placebo-controlled, crossover design trial was conducted among adults (n = 30, ages 18-59 y) at risk of type 2 diabetes. They consumed Formulation 3 (formulated MMT peel powder) [A] and control (glucose) [B] with study breakfast based on randomly assigned treatment sequences (AB, BA) established by Research Randomizer ( www.randomizer.org ). Capillary blood glucose and perceived satiety were determined at baseline (0 min), 30, 60, 90 and 120 min, followed by a post-intervention food intake measurement.

RESULTS

The repeated measures analysis of variance (ANOVA) revealed significant time (F = 84.37, p <  0.001, η_p² = 0.744), condition (F = 22.89, p <  0.001, η_p² = 0.441), and time*condition effects (F = 24.40, p <  0.001, η_p² = 0.457) in blood glucose levels. Respondents (n = 30) who consumed Formulation 3 also had a significantly lower blood glucose 2-hour incremental area under the curve (iAUC) of 134.65 ± 44.51 mmol/L*min and maximum concentration (CMax) of 7.20 (7.10, 8.20) mmol/L with relative reduction of 26.8 and 13.3% respectively, when compared with control (p <  0.001). Besides, significantly greater perceived satiety, lower energy and fat intake as well as higher dietary fiber intake were also observed in the intervention group compared with the placebo group (p <  0.05). There were no marked side effects associated with the ingestion of the test products.

CONCLUSIONS

Short-term consumption of formulated MMT peel powder may improve glycemic response, increase perceived satiety and reduce food intake in adults at risk of type 2 diabetes with the potential to be utilized as a functional beverage. Medium-to long-term clinical trial is warranted to determine whether taking this formulated MMT peel powder on a daily basis has an influence on health outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05298111. Registered 28/03/2022.

Modulation of 1,2-Dicarbonyl Compounds in Postprandial Responses Mediated by Food Bioactive Components and Mediterranean Diet

Glycoxidative stress with the consequent generation of advanced glycation end products has been implied in the etiology of numerous non-communicable chronic diseases. During the postprandial state, the levels of 1,2-dicarbonyl compounds can increase, depending on numerous factors, including characteristics of the subjects mainly related to glucose metabolism disorders and nutritional status, as well as properties related to the chemical composition of meals, including macronutrient composition and the presence of dietary bioactive molecules and macromolecules. In this review, we examine the chemical, biochemical, and physiological pathways that contribute to postprandial generation of 1,2-dicarbonyl compounds. The modulation of postprandial 1,2-dicarbonyl compounds is discussed in terms of biochemical pathways regulating the levels of these compounds, as well as the effect of phenolic compounds, dietary fiber, and dietary patterns, such as Mediterranean and Western diets.

Whole grain germinated brown rice regulates intestinal immune homeostasis and gastrointestinal hormones in type 2 diabetic patients-a randomized control trial

Background: Whole grains present distinguished benefits to a handful of metabolic syndromes (MetS). However, the preventive effects of germinated brown rice (GBR), a new type of brown rice, on patients with type 2 diabetes (T2DM) are rarely reported. Objectives: To investigate whether replacing 100 g refined white rice (RWR) with equal GBR per day is effective in T2DM and its underlying mechanisms. Methods: Ninety-nine qualified T2DM patients (64.58 ± 5.06 years old) were recruited. All patients were randomly divided into GBR group (100 g d^-1 GBR for 12 weeks) and control group (keep the regular diet). Food frequency questionnaires, and fresh stool and serum samples were collected before and after the intervention, followed by various measurements. Results: Fasting blood glucose was obviously decreased after GBR intervention with an effective rate of 62%. Glycated hemoglobin (HbA1c) levels were decreased in the GBR group with no significance. In the GBR group, the abundance of beneficial bacteria in feces was increased, while harmful bacteria were decreased. The percentage of Bacteroides (57.2%) was largely increased. In addition, three types of short-chain fatty acids (SCFAs) including acetic acid, propanoic acid, and butyric acid were increased significantly by GBR (p < 0.05). The secretion of GLP and PYY in serum, two kinds of gastrointestinal hormones downstream of SCFAs, was stimulated by GBR (p < 0.01). Meanwhile, GBR intervention could balance the ratio of Treg/Th17 immune cells in PBMCs and reduce the levels of inflammatory factors including IL-6, IL-8, and LPS in serum, which improved the permeability of intestinal mucosa. Conclusions: GBR (100 g d^-1 for 12 weeks) has positive improvement in the fasting blood glucose for T2DM patients, which attributed to the recovery of intestinal homeostasis.

Does the Gut Microbiome Play a Role in Obesity in Type 1 Diabetes? Unanswered Questions and Review of the Literature

Evidence suggests that type 1 diabetes (T1D) risk and progression are associated with gut bacterial imbalances. Children with either T1D or islet antibody positivity exhibit gut dysbiosis (microbial imbalance) characterized by lower gram-positive to gram-negative gut bacterial ratios compared to healthy individuals, leading to a pro-inflammatory milieu. In addition, specific gut microbiome changes, including increased virulence factors, elevated phage, prophage, and motility genes, and higher amplitude stress responses, have been identified in individuals who have or are progressing towards T1D. Additionally, gut microbiome differences are associated with and thought to contribute to obesity, a comorbidity that is increasingly prevalent among persons with T1D. Obesity in T1D is problematic because individuals with obesity progress faster to T1D, have reduced insulin sensitivity compared to their lean counterparts, and have higher risk of complications. Animal and human studies suggest higher relative abundance of bacterial taxa associated with changes in bile acid and short chain fatty acid biosynthesis in obesity. However, it is unknown to what extent the gut microbiome plays a role in obesity in T1D and these worse outcomes. In this review, we aim to evaluate potential gut microbiome changes and associations in individuals with T1D who are obese, highlighting the specific gut microbiome changes associated with obesity and with T1D development. We will identify commonalities and differences in microbiome changes and examine potential microbiota-host interactions and the metabolic pathways involved. Finally, we will explore interventions that may be of benefit to this population, in order to modify disease and improve outcomes.

Finger millet-based muffin decreases insulin response in individuals with prediabetes in a randomised controlled trial

Millet is a grain high in polyphenols and antioxidants, which are bioactive compounds known to influence blood glucose response. The aim of this study was to compare the effect of finger millet muffin and wheat muffin on glycaemic response (GR), insulin response (IR), gastric emptying (GE) and satiety in healthy individuals and people with prediabetes. In a single-blind randomised controlled crossover trial at Oxford Brookes Centre for Nutrition and Health, fifteen healthy individuals and fourteen individuals with prediabetes were recruited between May and December 2017. The participants' GR (3 h), IR (3 h), GE (4 h) and satiety (4 h) were measured before and after the consumption of muffins. A mixed method ANOVA was used to compare GE and the incremental AUC (iAUC) for GR and IR between the participant groups and muffins. There was a significant interaction between participants and muffins on IR iAUC at 180 min (P = 0·042). A significant effect of muffins was found on the GR peak (P = 0·013). The millet muffin decreased the GR peak and IR iAUC compared with the wheat muffin in participants with prediabetes. A significant interaction between participants and muffins for GE ascension time Tasc (P = 0·017) was observed, with no effect of muffins on satiety AUC in the participant groups. This study suggested that polyphenol and fibre-rich finger millet may have the potential to influence the management of prediabetes.

Metabolite-based dietary supplementation in human type 1 diabetes is associated with microbiota and immune modulation

BACKGROUND

Short-chain fatty acids (SCFAs) produced by the gut microbiota have beneficial anti-inflammatory and gut homeostasis effects and prevent type 1 diabetes (T1D) in mice. Reduced SCFA production indicates a loss of beneficial bacteria, commonly associated with chronic autoimmune and inflammatory diseases, including T1D and type 2 diabetes. Here, we addressed whether a metabolite-based dietary supplement has an impact on humans with T1D. We conducted a single-arm pilot-and-feasibility trial with high-amylose maize-resistant starch modified with acetate and butyrate (HAMSAB) to assess safety, while monitoring changes in the gut microbiota in alignment with modulation of the immune system status.

RESULTS

HAMSAB supplement was administered for 6 weeks with follow-up at 12 weeks in adults with long-standing T1D. Increased concentrations of SCFA acetate, propionate, and butyrate in stools and plasma were in concert with a shift in the composition and function of the gut microbiota. While glucose control and insulin requirements did not change, subjects with the highest SCFA concentrations exhibited the best glycemic control. Bifidobacterium longum, Bifidobacterium adolescentis, and vitamin B7 production correlated with lower HbA1c and basal insulin requirements. Circulating B and T cells developed a more regulatory phenotype post-intervention.

CONCLUSION

Changes in gut microbiota composition, function, and immune profile following 6 weeks of HAMSAB supplementation were associated with increased SCFAs in stools and plasma. The persistence of these effects suggests that targeting dietary SCFAs may be a mechanism to alter immune profiles, promote immune tolerance, and improve glycemic control for the treatment of T1D.

TRIAL REGISTRATION

ACTRN12618001391268. Registered 20 August 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375792 Video Abstract.

Precision Nutrition Model Predicts Glucose Control of Overweight Females Following the Consumption of Potatoes High in Resistant Starch

Individual glycemic responses following dietary intake result from complex physiological processes, and can be influenced by physical properties of foods, such as increased resistant starch (RS) from starch retrogradation. Predictive equations are needed to provide personalized dietary recommendations to reduce chronic disease development. Therefore, a precision nutrition model predicting the postprandial glucose response (PPGR) in overweight women following the consumption of potatoes was formulated. Thirty overweight women participated in this randomized crossover trial. Participants consumed 250 g of hot (9.2 g RS) or cold (13.7 g RS) potatoes on two separate occasions. Baseline characteristics included demographics, 10-day dietary records, body composition, and the relative abundance (RA) and α-diversity of gut microbiota. Elastic net regression using 5-fold cross-validation predicted PPGR after potato intake. Most participants (70%) had a favorable PPGR to the cold potato. The model explained 32.2% of the variance in PPGR with the equation: 547.65 × (0 [if cold, high-RS potato], ×1, if hot, low-RS potato]) + (BMI [kg/m²] × 40.66)—(insoluble fiber [g] × 49.35) + (Bacteroides [RA] × 8.69)—(Faecalibacterium [RA] × 73.49)—(Parabacteroides [RA] × 42.08) + (α-diversity × 110.87) + 292.52. This model improves the understanding of baseline characteristics that explain interpersonal variation in PPGR following potato intake and offers a tool to optimize dietary recommendations for a commonly consumed food.

Efficiency of Resistant Starch and Dextrins as Prebiotics: A Review of the Existing Evidence and Clinical Trials

In well-developed countries, people have started to pay additional attention to preserving healthy dietary habits, as it has become common knowledge that neglecting them may easily lead to severe health impairments, namely obesity, malnutrition, several cardiovascular diseases, type-2 diabetes, cancers, hypertensions, and inflammations. Various types of functional foods were developed that are enriched with vitamins, probiotics, prebiotics, and dietary fibers in order to develop a healthy balanced diet and to improve the general health of consumers. Numerous kinds of fiber are easily found in nature, but they often have a noticeable undesired impact on the sensory features of foods or on the digestive system. This led to development of modified dietary fibers, which have little to no impact on taste of foods they are added to. At the same time, they possess all the benefits similar to those of prebiotics, such as regulating gastrointestinal microbiota composition, increasing satiety, and improving the metabolic parameters of a human. In the following review, the evidence supporting prebiotic properties of modified starches, particularly resistant starches and their derivatives, resistant dextrins, was assessed and deliberated, which allowed drawing an interesting conclusion on the subject.

Reformulation of Muffins Using Inulin and Green Banana Flour: Physical, Sensory, Nutritional and Shelf-Life Properties

This study demonstrates a scenario of industrial reformulation by developing muffins that resemble store-branded ones and testing the possibility of reformulating them using inulin and green banana flour (GBF). Ten different formulations were created through reducing 10% or 30% of sugar and/or fat. Physical characteristics, consumer acceptance and purchase preferences, baking losses, nutritional properties, shelf-life, as well as cost and industrial processability were considered and discussed. Results on physical properties showed that firmness had increased in reformulated muffins while springiness only decreased when both sugar and fat were reduced by 30% (p < 0.05). Texture and sensory properties of reformulated muffins were acceptable, and the purchase intent rate was high. Regarding the nutritional properties, muffins incorporating more than 10% of fibres allowed the addition of nutritional claims. The incremental area under the curve iAUC_120min of blood glucose in healthy adults (n = 13) was significantly lower than control after ingesting 30% reduced sugar or fat muffins using inulin (p < 0.01). The microbial profile was not affected by reformulation during storage at 25 °C for 10 days. This study concluded that there is a significant potential to industrially produce reduced sugar or fat muffins using inulin or GBF up to 30% without significantly deteriorating quality attributes.

Polysaccharide Derived from Nelumbo nucifera Lotus Plumule Shows Potential Prebiotic Activity and Ameliorates Insulin Resistance in HepG2 Cells

Polysaccharides are key bioactive compounds in lotus plumule tea, but their anti-diabetes activities remain unclear. The purpose of this study was to investigate the prebiotic activities of a novel polysaccharide fraction from the Nelumbo nucifera lotus plumule, and to examine its regulation of glucose metabolism in insulin-resistant HepG2 cells. The N. nucifera polysaccharide (NNP) was purified after discoloration, hot water extraction, ethanol precipitation, and DEAE-cellulose chromatography to obtain purified polysaccharide fractions (NNP-2). Fourier transform infrared spectroscopy was used to analyze the main structural characteristics and functional group of NNP-2. Physicochemical characterization indicated that NNP-2 had a molecular weight of 110.47 kDa and consisted of xylose, glucose, fructose, galactose, and fucose in a molar ratio of 33.4:25.7:22.0:10.5:8.1. The prebiotic activity of NNP-2 was demonstrated in vitro using Lactobacillus and Bifidobacterium. Furthermore, NNP-2 showed bioactivity against α-glucosidase (IC₅₀ = 97.32 µg/mL). High glucose-induced insulin-resistant HepG2 cells were used to study the effect of NNP-2 on glucose consumption, and the molecular mechanism of the insulin transduction pathway was studied using RT-qPCR. NNP-2 could improve insulin resistance by modulating the IRS1/PI3K/Akt pathway in insulin-resistant HepG2 cells. Our data demonstrated that the Nelumbo nucifera polysaccharides are potential sources for nutraceuticals, and we propose functional food developments from the bioactive polysaccharides of N. nucifera for the management of diabetes.

Dietary Fibre Modulates the Gut Microbiota

Dietary fibre has long been established as a nutritionally important, health-promoting food ingredient. Modern dietary practices have seen a significant reduction in fibre consumption compared with ancestral habits. This is related to the emergence of low-fibre “Western diets” associated with industrialised nations, and is linked to an increased prevalence of gut diseases such as inflammatory bowel disease, obesity, type II diabetes mellitus and metabolic syndrome. The characteristic metabolic parameters of these individuals include insulin resistance, high fasting and postprandial glucose, as well as high plasma cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Gut microbial signatures are also altered significantly in these cohorts, suggesting a causative link between diet, microbes and disease. Dietary fibre consumption has been hypothesised to reverse these changes through microbial fermentation and the subsequent production of short-chain fatty acids (SCFA), which improves glucose and lipid parameters in individuals who harbour diseases associated with dysfunctional metabolism. This review article examines how different types of dietary fibre can differentially alter glucose and lipid metabolism through changes in gut microbiota composition and function.

Consumption of Sourdough Breads Improves Postprandial Glucose Response and Produces Sourdough-Specific Effects on Biochemical and Inflammatory Parameters and Mineral Absorption

To evaluate responses to different sourdough breads, six groups of rats were fed a conventional refined wheat bread with no sourdough content (C_WhB); a leavened spelt bread baked with Rebola sourdough (Re_SpB); a durum wheat bread with Rebola sourdough (Re_DuB); or a multigrain bread leavened with Rebola (Re_MGB), Carla (Ca_MGB), or San Francisco sourdough (SF_MGB). Compared to C_WhB-fed rats, Re_SpB-, Re_DuB-, and Re_MGB-fed animals showed lower postprandial blood glucose levels, whereas SF_MGB-fed rats displayed a decreased postprandial blood insulin response and glucose and insulin products. The 3 week intake of Ca_MGB decreased blood triacylglycerols and the relative apparent absorption (RAA) of Fe²⁺, Cu²⁺, and Zn²⁺, whereas Re_MGB-fed animals showed lower serum levels of the MCP-1 inflammatory marker and decreased the Fe RAA. The 3 week consumption of the multigrain bread produced sourdough-specific effects. Thus, Re_MGB-fed animals displayed higher insulin concentrations than Ca_MGB- and SF_MGB-fed rats and decreased blood MCP-1 levels compared to those of Ca_MGB-fed animals. In addition, Ca_MGB-fed rats showed lower serum triacylglycerol concentrations than those of Re_MGB- and SF_MGB-fed animals, whereas SF_MGB-fed rats displayed higher RAA values of Ca²⁺, Cu²⁺, Fe²⁺, Mg²⁺, and Zn²⁺ than their Re_MGB and Ca_MGB counterparts. These sourdough-specific effects could be related to changes in the contents of sugars and organic acids, acidity, microbial composition, and proteolytic activity among sourdoughs. Hence, the consumption of sourdough breads improved postprandial blood glucose and insulin responses and produced sourdough-specific effects on RAA and serum insulin and triacylglycerol and MCP-1 levels in rats, showing that SF_MGB has the most promising beneficial effects.

Resistant Starch Combined with Whey Protein Increases Postprandial Metabolism and Lowers Glucose and Insulin Responses in Healthy Adult Men

Resistant starch (RS) and/or protein consumption favorably influence energy metabolism, substrate utilization, and weight management. The current study administered four different versions of a pancake breakfast containing waxy maize or RS with and without whey protein (WP) and measured postprandial thermogenesis (TEM), fuel utilization, and circulating satiation and appetite factors for 180 min in a group of healthy, adult men. On four separate visits to the laboratory, eight participants were administered four different pancake breakfast meal challenges using a single-blind, randomized crossover design: (1) waxy maize starch (WMS) control; (2) WMS and WP (WMS + WP); (3) RS; or (4) RS and WP (RS + WP). TEM (kcals/180 min) was significantly greater (p < 0.05) in RS + WP (45.11; confidence interval (CI), 33.81–56.41) compared to WMS (25.61; CI, 14.31–36.91), RS (29.44; CI, 18.14–40.74), and WMS + WP (24.64; CI, 13.34–35.94), respectively. Fat oxidation was enhanced (p < 0.05) after RS + WP compared to RS at 60 min (+23.10%), WMS at 120 min (+27.49%), and WMS and WMS + WP at 180 min (+35.76%; +17.31%, respectively), and RER was decreased with RS + WP versus the other three meals (mean differences: ≥−0.021). Insulin concentrations were decreased (p < 0.05) following RS + WP compared to WMS, whereas both RS (−46.19%) and RS + WP (−53.05%) insulin area under the curve (AUC) were greatly reduced (p < 0.01) compared to WMS. While limited by sample size, meals containing both RS and WP increased postprandial thermogenesis and fat oxidation, and lowered insulin response compared to isocaloric meals without this combination. Therefore, RS + WP may favorably impact energy metabolism and thus weight control and body composition under chronic feeding conditions.

Metabolic Responses to Native Wheat Starch (MidsolTM 50) versus Resistant Wheat Starch Type 4 (Fibersym® RW): Standard versus Marketplace Testing Protocols

BACKGROUND

To investigate the effect of resistant starch (RS) on acute glycemic or insulinemic responses, the FDA indicates that control and RS-enriched foods must contain equivalent amounts of digestible carbohydrate. However, RS-containing foods typically contain less digestible carbohydrate per serving than control foods. Thus, controlling for digestible carbohydrate may yield different responses as compared with controlling for serving size.

OBJECTIVE

The aim was to compare the postprandial metabolic responses to native wheat starch (NWS) versus RS type 4 (RS4) using digestible carbohydrate-matched portions compared with weight-matched portions.

METHODS

A single-blind, randomized-controlled crossover trial examined glycemic and insulinemic responses over 2 h following consumption of 4 cracker conditions and a dextrose beverage in apparently healthy participants (n = 14). Crackers provided 50 g of digestible carbohydrate using the FDA's meal-intervention protocol or 35 g of carbohydrate by weight for the marketplace substitution method. Crackers differed only by the type of starch additive: NWS (MidsolTM 50; MGP Ingredient, Inc.) or RS4 (Fibersym® RW; MGP Ingredients, Inc.). Glucose concentrations were assessed at baseline and at 15, 30, 45, 60, 90, and 120 min; insulin concentrations were measured at baseline and 30, 60, and 120 min.

RESULTS

There were no significant differences between 50 g digestible carbohydrate cracker conditions for glucose or insulin incremental AUC (iAUC). The 35 g carbohydrate by weight conditions were not different for glucose iAUC [mean (95% CI): 35 g NWS: 1317 (677, 2169); 35 g RS4: 701 (262, 1351); P > 0.05]. However, insulin iAUC was lower following 35 g RS4 compared with 35 g NWS [35 g RS4: 92 (1, 259); 35 g NWS: 697 (397, 1080); P < 0.01].

CONCLUSIONS

In healthy adults, consumption of RS4 crackers decreased postprandial insulin responses compared with NWS crackers when using the marketplace substitution method compared with the FDA standard testing method, with similar postprandial glucose responses. Comparisons of the FDA standard testing method and the marketplace substitution method should be investigated further to elucidate differential physiological impacts on consumers.

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.

Effects of Extrinsic Wheat Fiber Supplementation on Fecal Weight; A Randomized Controlled Trial

Higher fiber intake may confer beneficial effects on health. Our objective was to investigate the impact of 10 g extrinsic wheat fiber on fecal bulk. Therefore, we performed two randomized intervention studies in which we provided extrinsic wheat fiber-enriched products or appropriate control products for five days together with normal diet. In one trial, 10 participants received fiber-enriched food products, whereas in the second study, 19 participants supplemented their daily diet with fiber-enriched drinks. The main outcome variable of this intervention was fecal bulk. Other outcomes were gut microbiota composition, short chain fatty acids in feces, and stool consistency and frequency. Fecal wet weight was significantly increased (p < 0.02) with extrinsic wheat fiber-enriched foods. In contrast, ingestion of extrinsic wheat fiber in the form of drinks did not significantly change fecal wet weight. In both groups, fecal dry weight was not altered upon extrinsic wheat fiber supplementation. However, the intake of fiber-enriched foods resulted in higher acetic acid levels in feces compared to fiber-enriched drinks. Regarding gut microbiota profiles, extrinsic wheat fiber-enriched food products were not associated with substantial alterations. In conclusion, 10 g extrinsic wheat fiber added to a normal diet increased fecal bulk if administered in a solid food matrix, but not if applied in the form of drinks. DRKS, DRKS00015792.Registered 30 October 2018.

Novel Resistant Starch Type 4 Products of Different Starch Origins, Production Methods, and Amounts Are Not Equally Fermented when Fed to Sprague-Dawley Rats

SCOPE

The possible mechanisms of production of four novel resistant starch type 4 (RS4) products for total cecal fermentation in an in vivo rodent model are evaluated.

METHODS AND RESULTS

Forty weanling rats are randomly assigned to five groups (n = 8) for a 3-week study. Starches are the RS type 4 products, as 10% of weight of RS diets (RSA-RSD), and AMIOCA starch (100% amylopectin) comprises 53.6% weight of control (CON) and 43.6% weight of RS diets. The RS products vary by percent purity and origin (potato, corn, tapioca). At euthanasia, cecal contents, serum, GI tract, and abdominal fat are collected. RSB, RSC, and RSD fed rats have greater empty cecum weights, lower cecal content pH, higher cecal content wet weight, and higher total cecal content acetate and propionate than the CON and RSA fed rats. Two other indicators of fermentation, total cecal contents butyrate and glucagon-like peptide 1, do not have significant ANOVA F values, which require more subjects for 80% power.

CONCLUSION

RS4 products that are produced from different starch origins with varying amounts of RS4 content and different methods of production are not uniformly fermented in an in vivo model.

Yacon syrup reduces postprandial glycemic response to breakfast: A randomized, crossover, double-blind clinical trial

Yacon is a root rich in fructooligosaccharides (FOS), which act as prebiotics. Numerous studies have shown promising results in the technological aspects of producing yacon syrup. However, uncertainties exist concerning whether yacon syrup can modulate postprandial glucose and lipid profiles. In order to assess the effect of yacon syrup on postprandial glucose, insulin and triglyceride (TG) responses, a randomized, crossover, double-blind clinical intervention with 40 women (20 normal weight and 20 grade I obese) was performed. Participants underwent two-arms of intervention with at least a one-week wash-out period between visits. On each intervention day, after 12 h of fasting, an aliquot of blood was collected. For intervention A, volunteers consumed breakfast +40 g of placebo, whereas for intervention B, participants consumed breakfast +40 g of yacon syrup (14 g of FOS). Blood samples were drawn at 15, 30, 45, 60, 90, and 120 min. Glucose and insulin concentrations were lowered after yacon syrup intake as compared to placebo at following times: 30 min for glucose and 15, 30 and 45 min for insulin. In conclusion, yacon syrup has a postprandial decreasing effect glucose and insulin concentrations in adult women. This effect was not evident for triglyceride concentration. Clinical trial registry: RBR-33wf46. Available in: http://www.ensaiosclinicos.gov.br/rg/RBR-33wf46/.

Dietary fiber intake and glycemic control: coronary artery calcification in type 1 diabetes (CACTI) study

Background

Dietary fiber has been recommended for glucose control, and typically low intakes are observed in the general population. The role of fiber in glycemic control in reported literature is inconsistent and few reports are available in populations with type 1 diabetes (T1D).

Methods

Using data from the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study [n = 1257; T1D: n = 568; non-diabetic controls: n = 689] collected between March 2000 and April 2002, we examined cross-sectional (baseline) and longitudinal (six-year follow-up in 2006–2008) associations of dietary fiber and HbA1c. Participants completed a validated food frequency questionnaire, and a physical examination and fasting biochemical analyses (12 h fast) at baseline visit and at the year 6 visit. We used a linear regression model stratified by diabetes status, and adjusted for age, sex and total calories, and diabetes duration in the T1D group. We also examined correlations of dietary fiber with HbA1c.

Results

Baseline dietary fiber intake and serum HbA1c in the T1D group were 16 g [median (IQ): 11–22 g) and 7.9 ± 1.3% mean (SD), respectively, and in the non-diabetic controls were 15 g [median (IQ): 11–21 g) and 5.4 ± 0.4%, respectively. Pearson partial correlation coefficients revealed a significant but weak inverse association of total dietary fiber with HbA1c when adjusted for age, sex, diabetes status and total calories (r = − 0.07, p = 0.01). In the adjusted linear regression model at baseline, total dietary fiber revealed a significant inverse association with HbA1c in the T1D group [β ± SE = − 0.32 ± 0.15, p = 0.034], as well as in the non-diabetic controls [− 0.10 ± 0.04, p = 0.009]. However, these results were attenuated after adjustment for dietary carbohydrates, fats and proteins, or for cholesterol and triglycerides. No such significance was observed at the year 6 follow-up, and with the HbA1c changes over 6 years.

Conclusion

Thus, at observed levels of intake, total dietary fiber reveals modest inverse associations with poor glycemic control. Future studies must further investigate the role of overall dietary quality adjusting for fiber-rich foods in T1D management.

Substitution of Corn Starch with Resistant Starch Type 4 in a Breakfast Bar Decreases Postprandial Glucose and Insulin Responses: A Randomized, Controlled, Crossover Study

BACKGROUND

Resistant starches type 4 (RS4) are chemically modified starches that are resistant to digestion by human enzymes.

OBJECTIVE

We aimed to test our hypothesis that replacement of standard starch with RS4 in a baked breakfast bar would decrease postprandial glycemic and insulinemic responses in healthy adults.

METHODS

In this double-blind, randomized crossover study, 21 healthy adults [10 men; 20-45 y old; BMI (kg/m2): 19.3-27.0] consumed a baked breakfast bar containing tapioca-based RS4 (Actistar 75330; Cargill, Inc.) or a macronutrient-matched control bar, delivering 32 g and 4 g of dietary fiber, respectively. Primary outcome was the incremental area under the curve (iAUC0-120 min) for postprandial capillary glucose. Other outcomes included postprandial serum insulin iAUC0-120 min, glucose and insulin maximum concentration (Cmax), and time to Cmax (Tmax).

RESULTS

Median glucose iAUC0-120 min was 22% lower (P < 0.05) and median insulin iAUC0-120 min was 37% lower (P < 0.05) after consumption of the RS4 food compared with the control food. Glucose and insulin Cmax and Tmax were not significantly different (P > 0.05) between foods.

CONCLUSION

The results suggest that replacement of standard starch with tapioca-based RS4 is a practical approach for reducing available carbohydrate in products and achieving postprandial blood glucose management. This trial was registered at clinicaltrials.gov as NCT03239288.

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.