Effect of Novel Maize-based Dietary Fibers on Postprandial Glycemia and Insulinemia

Gastrointestinal Tolerability and Acute Glycemic Response of Oligosaccharides and Polysaccharides from Cellulose and Xylan in Healthy Adults: Two Double-Blinded, Randomized, Controlled, Cross-over Trials

OBJECTIVE

The aim of this study was to investigate the gastrointestinal tolerability, glycemic and insulinemic responses of Plant Fiber Extract (PFE), a mixture comprising of oligosaccharides and polysaccharides derived from cellulose and xylan.

METHODS

Two double-blind, randomized, controlled, cross-over trials were conducted in healthy adults. In the first trial, participants (n = 29) consumed either 25, 35 or 45 g per day of PFE or resistant maltodextrin (Control) for 14 days. The occurrence and severity of gastrointestinal (GI) symptoms, stool parameters, and safety outcomes were evaluated with a combination of surveys and blood analysis respectively. In the second trial (n = 20), the post-prandial glycemic and insulinemic responses after the ingestion of 20 g of PFE diluted in water or incorporated into chocolate chips was measured and then compared to that of glucose and regular chocolate, respectively.

RESULTS

For all timepoints (0, 7 and 14 days), within any given dose group, there was no statistically significant difference in the GI symptoms score between PFE and Control. Further, for each test product (PFE or Control), no difference was observed in the same dose group from days 0 and 14. Stool consistency score and number of participants experiencing loose or watery stools was similar between products. No serious adverse events were reported and neither PFE nor Control significantly altered blood or urine safety parameters. The glycemic and insulinemic responses after PFE ingestion in comparison to glucose were 12% and 8% respectively. The glycemic and insulinemic responses after consuming chocolate containing PFE were 20% of that of regular chocolate.

CONCLUSION

PFE was well-tolerated by healthy volunteers in doses up to 45 g/day and it elicited comparatively low glycemic and insulinemic responses when consumed alone or when incorporated into a food product.

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.

Age-Dependent Prebiotic Effects of Soluble Corn Fiber in M-SHIME® Gut Microbial Ecosystems

Soluble corn fiber (SCF) has demonstrated prebiotic effects in clinical studies. Using an in vitro mucosal simulator of the human intestinal microbial ecosystem (M-SHIME^®) model, the effects of SCF treatment on colonic microbiota composition and metabolic activity and on host-microbiome interactions were evaluated using fecal samples from healthy donors of different ages (baby [≤ 2 years], n = 4; adult [18-45 years], n = 2; elderly [70 years], n = 1). During the 3-week treatment period, M-SHIME^® systems were supplemented with SCF daily (baby, 1.5, 3, or 4.5 g/d; adult, 3 or 8.5 g/d; and elderly, 8.5 g/d). M-SHIME^® supernatants were evaluated for their effect on the intestinal epithelial cell barrier and inflammatory responses in lipopolysaccharide. (LPS)-stimulated cells. Additionally, short-chain fatty acid (SCFA) production and microbial community composition were assessed. In the baby and adult models, M-SHIME^® supernatants from SCF treated vessels protected Caco-2 membrane integrity from LPS-induced damage. SCF treatment resulted in the expansion of Bacteroidetes, Firmicutes, and Bifidobacterial, as well as increased SCFA production in all age groups. SCF tended to have the greatest effect on propionate production. These findings demonstrate the prebiotic potential of SCF in babies, adults, and the elderly and provide insight into the mechanisms behind the observed prebiotic effects.

The Effects of Soluble Dietary Fibers on Glycemic Response: An Overview and Futures Perspectives

The properties of each food, composition, and structure affect the digestion and absorption of nutrients. Dietary fiber (DF), especially viscous DF, can contribute to a reduction in the glycemic response resulting from the consumption of carbohydrate-rich foods. Target and control of postprandial glycemic values are critical for diabetes prevention and management. Some mechanisms have been described for soluble DF action, from the increase in chyme viscosity to the production of short-chain fatty acids resulting from fermentation, which stimulates gastrointestinal motility and the release of GLP-1 and PYY hormones. The postprandial glycemic response due to inulin and resistant starch ingestion is well established. However, other soluble dietary fibers (SDF) can also contribute to glycemic control, such as gums, β-glucan, psyllium, arabinoxylan, soluble corn fiber, resistant maltodextrin, glucomannan, and edible fungi, which can be added alone or together in different products, such as bread, beverages, soups, biscuits, and others. However, there are technological challenges to be overcome, despite the benefits provided by the SDF, as it is necessary to consider the palatability and maintenance of their proprieties during production processes. Studies that evaluate the effect of full meals with enriched SDF on postprandial glycemic responses should be encouraged, as this would contribute to the recommendation of viable dietary options and sustainable health goals.

Moderate intakes of soluble corn fibre or inulin do not cause gastrointestinal discomfort and are well tolerated in healthy children

We investigated the gastrointestinal (GI) tolerance of soluble corn fibre (SCF) compared with inulin in children 3-9 years old. SCF (3-8 g/d for 10d) was tolerated as well as inulin: no differences were identified in stool frequency and consistency, proportion of subjects with at least one loose stool or reporting symptoms during bowel movement. Compared to inulin, 6 g/d of SCF lowered gas severity in children aged 3-5 years old. No differences were noted for alpha and beta diversity, relative abundance of Bacteroidota, Firmicutes, Ruminococcaceae, or the Firmicutes to Bacteroidota ratio. Relative abundance of some specific strains (i.e. Anaerostipes, Bifidobacterium, Fusicatenibacter, Parabacteroides) varied depending on the fibre type and dose level. Fortification at a level of 6-8 g/d of SCF and/or inulin could help addressing the fibre gap without any GI discomfort.

Effects of xanthan and konjac gums on pasting, rheology, microstructure, crystallinity and in vitro digestibility of mung bean resistant starch

The effects of different concentrations of xanthan and konjac gums on the pasting, rheological properties, microstructure, crystallinity, and digestibility of mung bean resistant starch (MRS) were investigated. Based on the results of pasting properties, the adjunction of gums increased the peak, breakdown, and final viscosities of resistant starch. Compared with resistant starch, the addition of gum significantly increased the K value and dynamic moduli (G', G") of MRS with increasing gum concentration. This finding indicates that the mixtures had higher viscoelasticity. Mixtures with xanthan gum of MRS had larger starch particle compared with MRS, as revealed by SEM. All starches showed B and V-type crystallinity with high crystallinity. MRS had the highest summation of resistant starch (RS) and slowly digestible starch (SDS) of 71.89%. MRS had the lowest hydrolysis rate, which obviously decreased from 71.89% to 57.71% with increasing konjac gum from 0 to 0.30%.

A Randomized, Double-Blind, Crossover Study to Determine the Available Energy from Soluble Fiber

OBJECTIVE

Determining the available energy (caloric value) of dietary non-digestible fibers that are fermented to varying degrees by intestinal microbes and metabolized to short chain fatty acids is important for provision of accurate information to food and beverage manufacturers for reformulation and labeling purposes. The objective of this human study was to determine the available energy of soluble fiber products by measuring post consumption breath hydrogen, with inulin as a control.

METHODS

PROMITOR^® Soluble Corn Fiber 70 (SCF70) and PROMITOR^® Soluble Corn Fiber 85B (SCF85B) are Tate & Lyle dietary fiber products with 70% and 85% fiber, respectively. The fiber portion of these products is structurally representative of the fiber portion of all PROMITOR^® SCF products. The study conducted was a randomized, double-blind, crossover design. Breath hydrogen was quantified following consumption of beverages consisting of 8 oz. of water and: inulin (control), SCF70, or SCF85B at 5, 10, or 15 g (total ingredient weight, "as is"). Subjects were generally healthy men and women (N = 19), age 18 to 34 years, with body mass index (BMI) 19.3 to 24.8 kg/m². The primary outcome was incremental area under the curve over 10 h (iAUC0-10 h) for inulin, SCF70, and SCF85B at each dose. The available energy (kcal/g ingredient and kcal/g fiber) from SCF70 and SCF85B at each dose was then calculated using inulin as the reference.

RESULTS

Results demonstrated that breath hydrogen production was significantly lower following consumption of SCF70 and SCF85B compared to inulin at all consumption amounts. There were no significant differences in breath hydrogen production following consumption of SCF70 compared to SCF85B.

CONCLUSION

The available energy per gram of fiber was not significantly different between the SCF70 and SCF85B PROMITOR^® products. The available energy of the fiber portion of PROMITOR^® SCF products was determined to be 0.2 kcal/gram.

The Role of Soluble Corn Fiber on Glycemic and Insulin Response

Increasing prevalence of type 2 diabetes mellitus (T2DM) in Asia has prompted the exploration of dietary fibers as an ingredient to attenuate glycemic response (GR). This study aims to compare the effects of replacing 50% of total carbohydrate with soluble corn fiber (SCF) or maltodextrin on the GR and insulin response (IR). In this randomized cross-over study, twenty-two healthy Chinese males aged between 21-60 years were recruited. The participants consumed glucose beverages and four test meals comprising SCF or maltodextrin in glutinous rice or as a drink. Repeated-measure ANOVA was used to compare the incremental area under the curve values of glucose (iAUGC) and insulin (iAUIC) of all the foods. Relative response (RR) of the beverages were also calculated and compared using paired t-test. SCF treatments had significantly lower iAUGC (p-value < 0.05) and iAUIC (p-value < 0.001) as compared to all treatments. Both treatments (rice and beverage) of maltodextrin were not significantly different from glucose (p-value > 0.05). Maltodextrin beverage had significantly increased postprandial GR and insulin secretion by 20% and 40%, respectively, when compared to SCF beverage (p-value < 0.001). This study shows that the inclusion of SCF into the diet is beneficial in controlling the postprandial GR. Replacing total carbohydrates with SCF effectively lowers GR and IR.

Effects of Resistant Starch Ingestion on Postprandial Lipemia and Subjective Appetite in Overweight or Obese Subjects

Reports surrounding the role of resistant starch (RS) on postprandial lipemia in humans are scarce. The aim of the present study is to examine the effects of resistant starch on the postprandial lipemic response, subjective measures of appetite, and energy intake in overweight and obese subjects. In a randomized, single-blind, crossover study, 14 overweight/obese participants ate a high-fat breakfast (679 kcal, 58% from fat) and a supplement with native banana starch (NBS), high-amylose maize starch (HMS), or digestible maize starch (DMS) on three separate occasions. All supplements provided were matched by the available carbohydrate content, and the RS quantity in NBS and HMS supplements was identical. Appetite was estimated using visual analogue scale (VAS) and an ad libitum test meal. Postprandial glycemia, triglycerides, cholesterol, high-density lipoprotein (HDL) cholesterol, and insulin excursions did not differ between treatments. Subjective appetite measures of satiety were significantly increased after HMS; however, no effects on energy intake were observed during the ad libitum test meal. These findings suggest that a single acute dose of RS cannot be expected to improve postprandial lipemia in subjects with overweight or obesity on a high-fat meal. However, the potential benefits of long-term supplementation should not be ruled out based on these results.

The effects of soluble corn fibre and isomaltooligosacharides on blood glucose, insulin, digestion and fermentation in healthy young males and females

Dietary fibre refers to nutrients in the diet that gastrointestinal enzymes do not digest. If properly labelled, dietary fibres should not significantly elevate blood glucose or insulin and should ferment in the large intestine. Because of the recent rise in low-carbohydrate products on the market, consumers use these various fibres without adequate knowledge concerning whether or not these ingredients affect any blood parameters and constitute a dietary fibre. The aim of this study was to examine the impact of isomaltooligosaccharides (IMO) as compared to soluble corn fibre (SCF) consumption on blood glucose, insulin and breath hydrogen responses in healthy young men and women. After an overnight fast, nine individuals consumed 25 g of either placebo (PLA), IMO or SCF. Breath hydrogen was significantly higher in the SCF condition than in the IMO and PLA at 90, 120, 150 and 180 min (p < 0.0001). Blood glucose and insulin were higher in the IMO condition (p < 0.0001) at 30 min compared to the SCF or PLA conditions, which were not significantly different from each other. These data suggest that IMO does not constitute a dietary fibre and instead should be explored as a slow-digesting carbohydrate.

The effect of soluble fiber dextrin on postprandial appetite and subsequent food intake in healthy adults

OBJECTIVES

This crossover study investigated the effect of consuming a beverage that contains soluble fiber dextrin (SFD) on appetite and food intake in adults to test the hypothesis that beverages that contain 10 or 20 g of fiber from SFD would be more satiating than the control beverage.

METHODS

Forty-one participants consumed lunch with a beverage that contained 0 g, 10 g, or 20 g of fiber from SFD. Appetite questionnaires were completed and blood samples collected immediately before lunch and at regular intervals over the following 150 min. Then, participants were provided with an afternoon snack and the amount eaten was recorded. Participants then left the laboratory but were asked to complete hourly appetite questionnaires and record food intake for the remainder of the day.

RESULTS

Consuming SFD had no effect on appetite over the 150 min after consumption of the lunch meal (P > 0.05). Hunger and desire to eat were lower and fullness higher after consumption of the beverage that contained 20 g of fiber from SFD (P < 0.05) after participants left the laboratory. There was no effect of consuming SFD on food intake at the snack meal or for the rest of the day (P > 0.05). Plasma glucose-dependent insulintropic polypeptide was lower during the 150 min after consumption of 20 g fiber from the SFD beverage (P < 0.05). There was no treatment effect on the plasma concentration of other biomarkers of glycemic response or appetite (P > 0.05).

CONCLUSIONS

Overall, the study results did not show an effect of SFD on appetite, food intake, and plasma markers of appetite for the first 150 min postconsumption. Further research is required to quantify how SFD influences appetite several hours after consumption.

Insights into the protective role of solid lipid nanoparticles on rosmarinic acid bioactivity during exposure to simulated gastrointestinal conditions

The evaluation of the digestion effects on bioactive solid lipid nanoparticles (SLN) was performed. For this purpose, witepsol and carnauba SLN loaded with rosmarinic acid (RA) were exposed to the simulated gastrointestinal tract (GIT) conditions prevailing in stomach and small intestine. The simulation of intestinal epithelium was made with a dialysis bag and intestinal cell culture lines. Changes on SLN physical properties, RA release and absorption profiles were followed at each step. Combination of digestion pH and enzymes showed a significant effect upon SLN physical properties. Zeta potential values increased at stomach conditions and decreased at small intestine simulation. Also, at intestine, SLN increased their sizes and released 40-60% of RA, maintaining its initial antioxidant activity values. Sustained release of 40% of RA from SLN was also observed in dialysis tube. At CaCo-2 cell line, both types of SLN showed similar absorbed RA % (ca. 30%). Nevertheless, in CaCo-2/HT29x mix cell lines, for carnauba SLN a lower adsorption RA % was observed than for witepsol SLN. Solid lipid nanoparticles protected RA bioactivity (in terms of antioxidant activity) until reaching the intestine. A controlled release of RA from SLN was achieved and a significant absorption was observed at intestinal cells. Overall, SLN produced with witepsol showed a higher stability than carnauba SLN.

Reducing the global burden of type 2 diabetes by improving the quality of staple foods: The Global Nutrition and Epidemiologic Transition Initiative

BACKGROUND

The prevalence of type 2 diabetes has been reaching epidemic proportions across the globe, affecting low/middle-income and developed countries. Two main contributors to this burden are the reduction in mortality from infectious conditions and concomitant negative changes in lifestyles, including diet. We aimed to depict the current state of type 2 diabetes worldwide in light of the undergoing epidemiologic and nutrition transition, and to posit that a key factor in the nutrition transition has been the shift in the type and processing of staple foods, from less processed traditional foods to highly refined and processed carbohydrate sources.

DISCUSSION

We showed data from 11 countries participating in the Global Nutrition and Epidemiologic Transition Initiative, a collaborative effort across countries at various stages of the nutrition-epidemiologic transition whose mission is to reduce diabetes by improving the quality of staple foods through culturally-appropriate interventions. We depicted the epidemiologic transition using demographic and mortality data from the World Health Organization, and the nutrition transition using data from the Food and Agriculture Organization food balance sheets. Main staple foods (maize, rice, wheat, pulses, and roots) differed by country, with most countries undergoing a shift in principal contributors to energy consumption from grains in the past 50 years. Notably, rice and wheat products accounted for over half of the contribution to energy consumption from staple grains, while the trends for contribution from roots and pulses generally decreased in most countries. Global Nutrition and Epidemiologic Transition Initiative countries with pilot data have documented key barriers and motivators to increase intake of high-quality staple foods. Global research efforts to identify and promote intake of culturally-acceptable high-quality staple foods could be crucial in preventing diabetes. These efforts may be valuable in shaping future research, community interventions, and public health and nutritional policies.

A resistant-starch enriched yogurt: fermentability, sensory characteristics, and a pilot study in children

The rising prevalence of obesity and the vulnerability of the pediatric age group have highlighted the critical need for a careful consideration of effective, safe, remedial and preventive dietary interventions.  Amylose starch (RS2) from high-amylose maize (HAM) ferments in the gut and affects body weight.   One hundred and ten children, of 7-8 (n=91) or 13-14 (n=19) years of age scored the sensory qualities of a yogurt supplemented with either HAM-RS2 or an amylopectin starch.  The amylopectin starch yogurt was preferred to the HAM-RS2-enriched yogurt by 7-8 year old panelists ( P<0.0001).  Appearance, taste, and sandiness scores given by 13- to 14-year-old panelists were more favorable for the amylopectin starch yogurt than for HAM-RS2-enriched yogurt ( P<0.05).  HAM-RS2 supplementation resulted in acceptable (≥6 on a 1-9 scale) sensory and hedonic ratings of the yogurt in 74% of subjects.  Four children consumed a HAM-RS2-enriched yogurt for four weeks to test its fermentability in a clinical trial.  Three adolescents, but not the single pre-pubertal child, had reduced stool pH ( P=0.1) and increased stool short-chain fatty acids (SCFAs) ( P<0.05) including increased fecal acetate ( P=0.02), and butyrate ( P=0.089) from resistant starch (RS) fermentation and isobutyrate ( P=0.01) from protein fermentation post-treatment suggesting a favorable change to the gut microbiota.  HAM-RS2 was not modified by pasteurization of the yogurt, and may be a palatable way to increase fiber intake and stimulate colonic fermentation in adolescents.  Future studies are planned to determine the concentration of HAM-RS2 that offers the optimal safe and effective strategy to prevent excessive fat gain in children.

Health benefits of prebiotic fibers

This chapter describes the various compounds that can act as prebiotic fibers: their structure, occurrence, production, and physiological effects (health effects) will be presented. The basis for the description is the latest definitions for dietary fibers and for prebiotics. Using as much as possible data from human studies, both the fiber and the prebiotic properties will be described of a variety of compounds. Based on the presented data the latest developments in the area of prebiotics, fibers and gut and immune health will be discussed in more detail as they show best what the potential impact of prebiotics on health of the human host might be.

Health properties of oca (Oxalis tuberosa) and yacon (Smallanthus sonchifolius)

Andean roots and tubers are underexploited crops; many contain compounds beneficial to health, so a greater knowledge of their properties is important for encouraging their consumption.

In vitro gastrointestinal digestibility of native, hydroxypropylated and cross-linked wheat starches

The digestibility and estimated glycemic indices (GI) of native (NWS), cross-linked (CLWS) and hydroxypropylated wheat starches (HPWS) were obtained byin vitroenzymatic hydrolysis.

Effect of novel fiber ingredients on ileal and total tract digestibility of energy and nutrients in semi-purified diets fed to growing pigs

BACKGROUND

Consumption of different dietary fibers may influence the digestibility of carbohydrates and other nutrients. Therefore the objectives of this experiment were to determine the effect of novel fiber ingredients on the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), crude protein (CP) and total dietary fiber (TDF) in pigs and to calculate the standardized digestibility of analyzed TDF in four novel fiber ingredients.

RESULTS

The AID of DM and GE in diets containing novel fiber ingredients was less (P < 0.05) than in a maltodextrin diet. Addition of cellulose or pullulan, but not resistant starch (RS) 60, RS 75 or soluble corn fiber 70, reduced (P < 0.05) the AID of CP. The average ileal and total tract endogenous losses of analyzed TDF were calculated at 25.25 and 42.87 g kg⁻¹ DM intake, respectively.

CONCLUSION

Addition of novel fiber ingredients to a maltodextrin-based diet had different effects on the AID of DM, CP, GE and TDF. Measurements of the standardized digestibility of analyzed TDF may be a better indicator of TDF fermentability than measurements of AID and ATTD of TDF, because some endogenous metabolites may be analyzed as TDF.

The maximum single dose of resistant maltodextrin that does not cause diarrhea in humans

The objective of the present study was to determine the maximum dose of resistant maltodextrin (Fibersol)-2, a non-viscous water-soluble dietary fiber), that does not induce transitory diarrhea. Ten healthy adult subjects (5 men and 5 women) ingested Fibersol-2 at increasing dose levels of 0.7, 0.8, 0.9, 1.0, and 1.1 g/kg body weight (bw). Each administration was separated from the previous dose by an interval of 1 wk. The highest dose level that did not cause diarrhea in any subject was regarded as the maximum non-effective level for a single dose. The results showed that no subject of either sex experienced diarrhea at dose levels of 0.7, 0.8, 0.9, or 1.0 g/kg bw. At the highest dose level of 1.1 g/kg bw, no female subject experienced diarrhea, whereas 1 male subject developed diarrhea with muddy stools 2 h after ingestion of the test substance. Consequently, the maximum non-effective level for a single dose of the resistant maltodextrin Fibersol-2 is 1.0 g/kg bw for men and >1.1 g/kg bw for women. Gastrointestinal symptoms were gurgling sounds in 4 subjects (7 events) and flatus in 5 subjects (9 events), although no association with dose level was observed. These symptoms were mild and transient and resolved without treatment.

Comparison of two different in vivo models and an in vitro model for caloric determination of four novel fiber ingredients

The objective of this study was to compare two in vivo methods using pigs and roosters and an in vitro method for determining the caloric value of four fiber sources [i.e., two resistant starches (RS 60 and RS 75), soluble corn fiber (SCF 70), and pullulan]. Metabolizable energy (ME) in pigs and true metabolizable energy (TMEn) in roosters were determined by using 72 barrows and 24 roosters, respectively. A two-step in vitro procedure was used to quantify monosaccharides released. Results of the two in vivo experiments corresponded well with RS 75 having the least caloric value (7.55 MJ/kg in pigs; 6.19 MJ/kg in roosters) and pullulan having the greatest caloric value (12.21 MJ/kg in pigs; 13.94 MJ/kg in roosters). The caloric values for all the fiber ingredients were less (P < 0.05) than in MD both in pigs and in roosters. Despite some limitations, results of the in vitro procedure corresponded well with the in vivo experiments where the concentration of glucose hydrolyzed from RS 60, RS 75, and SCF 70, but not pullulan, was less (P < 0.05) than the concentration of glucose hydrolyzed from MD. However, the greatest accuracy was obtained in the in vivo experiments.

Effect of polydextrose and soluble maize fibre on energy metabolism, metabolic profile and appetite control in overweight men and women

High-fibre diets offer several beneficial health effects. The objective of the present study was to investigate whether replacement of 30 % of the available carbohydrates with polydextrose (PDX) or soluble maize fibre (SCF) at breakfast and lunch would result in an increased fat oxidation rate and satiety, which may be of relevance for body weight control and diabetes prevention. In a single-blind, randomised cross-over study, eighteen overweight men and women underwent four different dietary interventions, which consisted of a PDX diet, a SCF diet and two control diets (full energetic and isoenergetic, comparable with PDX with respect to g or energy percentage of macronutrients, respectively). Glycaemic profile, energy expenditure and substrate oxidation were measured for 24 h in a respiration chamber. Circulating insulin, NEFA and TAG concentrations were determined over a 14 h period during daytime. Appetite ratings were assessed using visual analogue scales. The replacement of available carbohydrates with PDX or SCF reduced the peak glucose response, which was accompanied by reduced postprandial insulin responses. Moreover, higher concentrations of circulating NEFA were observed after consumption of both fibre diets, which were accompanied by an increased fat oxidation over 24 h. This effect was mainly attributed to the lower energetic value of the fibre diets and not to the fibres per se. Besides increasing fat oxidation, PDX exerted a pronounced suppressive effect on appetite ratings. The replacement of available carbohydrates with PDX may be of special interest because of its beneficial effects on metabolic profile and it may affect body weight control in the long term.

Blending of soluble corn fiber with pullulan, sorbitol, or fructose attenuates glycemic and insulinemic responses in the dog and affects hydrolytic digestion in vitro

The objective of these experiments was to measure in vitro hydrolytic digestion and glycemic and insulinemic responses of select carbohydrate blends, all containing the novel carbohydrate soluble corn fiber (SCF). Two SCF that varied in their method of production were used to formulate the carbohydrate blends. One set of blends contained a SCF that was spray dried (SCFsd) and then blended with different amounts of either pullulan, sorbitol, or fructose. The other set of blends contained a SCF produced using longer evaporation time (SCF) and then blended with different ratios of pullulan, sorbitol, and fructose. Free sugar concentrations found in the individual SCFsd and SCF substrates were low but varied. Spray-dried soluble corn fiber had a reduced free sugar concentration compared with SCF (2.8 vs. 14.2%). Glucose was the main free sugar found in both SCFsd and SCF but at different concentrations (2.7 vs. 12.7%, respectively). The majority of the SCFsd blends were completely hydrolyzed to their monosaccharide components. Glucose accounted for most of the hydrolyzed monosaccharides for SCFsd and all the SCFsd blends. Hydrolyzed monosaccharide concentrations for the SCF:pullulan:sorbitol:fructose blends followed similar trends to the SCFsd blends where greater percentages of fructose and sorbitol resulted in decreased (P < 0.05) hydrolyzed monosaccharide concentrations. The SCFsd blends had intermediate to high amounts of monosaccharides released as a result of in vitro hydrolytic digestion. The SCFsd:pullulan blends were more digestible in vitro (approximately 91%; P < 0.05) than SCFsd:fructose or SCFsd:sorbitol. Total released monosaccharides were high in SCFsd blends containing either 50% fructose or sorbitol, but the combination resulted in reduced concentrations of glucose released (P < 0.05). The SCF:pullulan:sorbitol:fructose blends also had intermediate to high released monosaccharides as a result of in vitro hydrolytic digestion. All SCF blends resulted in decreased glycemic and insulinemic responses compared with the maltodextrin control (P < 0.05) using a canine model. The addition of pullulan reduced the glycemic response compared with maltodextrin at all concentrations, but only 50:50 SCFsd:pullulan resulted in a reduction of the glycemic response compared with SCFsd alone (P < 0.05). The addition of fructose and sorbitol in the blends had the greatest impact on glycemic and insulinemic responses, even at concentrations as low as 5% of the blends. Overall, SCF and their blends may prove beneficial as components of low glycemic foodstuffs.

Gastrointestinal effects of resistant starch, soluble maize fibre and pullulan in healthy adults

Fibre has been shown to exert a number of benefits on gastrointestinal (GI) health, yet its intake is low. Addition of novel fibres to food products may increase fibre intake and improve gut health. The objective of the present study was to evaluate the influence of three novel fibres on GI outcomes in healthy human subjects. A total of twenty healthy participants (ten men and ten women) with normal BMI (23 (sem 2) kg/m2) participated in the present randomised, double-blind, cross-over study with five treatment periods. Participants consumed a maltodextrin control or 20–25 g/d fibre from soluble maize fibre (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). The treatment periods were 7 d with a 3-week washout between the periods. Stool samples were collected on day 7 of each period, and GI tolerance was assessed via a questionnaire on days 1 and 6. There were no treatment differences in stool weight or consistency. SCF significantly reduced stool pH and increased total SCFA production compared with RS and control. RS+P significantly increased the percentage of butyrate compared with all the other treatments. Overall, GI symptoms were minimal. SCF+P led to the highest GI score on day 1, while RS+P had the highest score on day 6. Both SCF treatments caused a significant shift in the gut microbial community. These functional fibres are generally well tolerated, have minimal effects on laxation and may lead to beneficial changes in SCFA production in healthy adults.

Resistant starch and pullulan reduce postprandial glucose, insulin, and GLP-1, but have no effect on satiety in healthy humans

The aim of this study was to determine the effects of three novel fibers on satiety and serum parameters. In a randomized, double-blind, crossover design, fasted subjects (n=20) consumed a low-fiber control breakfast or one of four breakfasts containing 25 g of fiber from soluble corn fiber (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). Visual analog scales assessed appetite, and blood samples were collected to measure glucose, insulin, ghrelin, and glucagon-like peptide-1 (GLP-1). The fiber treatments did not influence satiety or energy intake compared to control. RS+P significantly reduced glucose, insulin, and GLP-1, but neither SCF treatment differed from control. To conclude, these fibers have little impact on satiety when provided as a mixed meal matched for calories and macronutrients. Additional research regarding the physiological effects of these novel fibers is needed to guide their use as functional ingredients in food products.

Evaluation of digestive tolerance of a soluble corn fibre

BACKGROUND

To assess consumers' acceptance of a new fibre, it is essential to evaluate its digestive tolerance after ingestion. We aimed to determine the tolerance of increasing dosages of Promitor™ Soluble Gluco Fibre (SGF; Tate&Lyle, Hoffman Estates, IL, USA) up to 70 g fibre per day using a validated gastrointestinal composite score.

METHODS

A composite score of gastrointestinal tolerance integrating gastrointestinal symptoms, stool frequency and consistency was applied. To statistically validate this composite score, the gastrointestinal tolerance of inulin (10 g versus 20 g containing, respectively, 9 g versus 18 g of fibre) was assessed in 18 healthy volunteers in a randomised double-blind placebo-controlled cross-over study. Second, in a double-blind placebo-controlled cross-over study with 20 healthy volunteers, the gastrointestinal tolerance of SGF in both acute and 'spread over the day' conditions of consumption was assessed.

RESULTS

By contrast to 10 g, 20 g of inulin demonstrated a significant difference in composite score compared to placebo [P < 0.001, difference = 7.6; 95% confidence interval (CI) = 3.8-11.3]. These values were considered as reference during the second study. In acute conditions, 40 g of SGF fibre was the highest (threshold) dose tested that indicates the digestive tolerance criteria (difference from placebo on the composite score <7.6 and upper limit of the 95% CI <11.3); this is twice the amount tolerated for inulin. In 'spread over the day' conditions, 65 g of SGF fibre was the threshold dose (P < 0.001, difference = 6.5; 95% CI = 3.4-9.5).

CONCLUSIONS

The results of the present study demonstrate that 40 g of SGF fibre, when consumed as a single dose, and 65 g of SGF fibre, when consumed in multiple-doses, across the day are well-tolerated by healthy volunteers.

Filling America's fiber intake gap: summary of a roundtable to probe realistic solutions with a focus on grain-based foods

Current fiber intakes are alarmingly low, with long-term implications for public health related to risk of coronary heart disease, stroke, hypertension, certain gastrointestinal disorders, obesity, and the continuum of metabolic dysfunctions including prediabetes and type 2 diabetes. Eating patterns high in certain fibers are known to lower LDL cholesterol and blood pressure, lower blood glucose, and decrease insulin resistance in people with prediabetes and type 2 diabetes; help with both weight loss and maintenance; and improve bowel regularity and gastrointestinal health. With >90% of adults and children who fall short of meeting their daily fiber recommendations, the 2010 Dietary Guidelines for Americans once again classified fiber as a nutrient of concern. Despite efforts over the past decade to promote adequate fiber through fruit, vegetable, and whole-grain intakes, fiber consumption has remained flat at approximately half the daily recommended amount. The public health implications of inadequate fiber intake prompted the roundtable session "Filling America's Fiber Gap: Probing Realistic Solutions," which assembled nutrition researchers, educators, and communicators to identify challenges, opportunities, and realistic solutions to help fill the current fiber gap. The roundtable discussions highlighted the need for both consumer and professional education to improve acceptance for and inclusion of grain-based foods with added fiber as one strategy for increasing fiber intakes within daily energy goals.

Beta glucan: health benefits in obesity and metabolic syndrome

Despite the lack of international agreement regarding the definition and classification of fiber, there is established evidence on the role of dietary fibers in obesity and metabolic syndrome. Beta glucan (β-glucan) is a soluble fiber readily available from oat and barley grains that has been gaining interest due to its multiple functional and bioactive properties. Its beneficial role in insulin resistance, dyslipidemia, hypertension, and obesity is being continuously documented. The fermentability of β-glucans and their ability to form highly viscous solutions in the human gut may constitute the basis of their health benefits. Consequently, the applicability of β-glucan as a food ingredient is being widely considered with the dual purposes of increasing the fiber content of food products and enhancing their health properties. Therefore, this paper explores the role of β-glucans in the prevention and treatment of characteristics of the metabolic syndrome, their underlying mechanisms of action, and their potential in food applications.

Soluble fiber dextrins and pullulans vary in extent of hydrolytic digestion in vitro and in energy value and attenuate glycemic and insulinemic responses in dogs

The objective of this research was to measure in vitro hydrolytic digestion characteristics, glycemic and insulinemic responses, and true metabolizable energy (TMEn) content of select soluble fiber dextrins (SFDs) and pullulans. The SFDs were derived either from tapioca starch or from corn starch. The pullulans were of low, intermediate, and high molecular weight. Soluble fiber dextrins varied in digestibility, with all substrates resulting in low to intermediate in vitro monosaccharide digestion. Pullulans were nearly completely hydrolyzed after simulated hydrolytic digestion. The glycemic response with dogs varied widely among SFDs, with all but one SFD substrate having lower glycemic response than maltodextrin (Malt). The pullulans all resulted in low glycemic values. Lower relative insulinemic responses (RIR) compared to the Malt control were noted for all SFDs and pullulans. True metabolizable energy (TMEn) values for SFDs obtained using roosters were lower than for Malt, with tapioca-based SFDs having numerically higher values than corn-based SFDs. Pullulans resulted in higher TMEn values than did SFDs. Soluble fiber dextrins and pullulans may be suitable candidates for reduced calorie and glycemic foodstuffs.

Soluble fiber dextrin enhances the satiating power of beverages

This study compared the effects of four types of fiber on satiety and energy intakes at the next meal using a standard double-blinded preload study design. Study participants (14 men and 22 women) each took part in 6 study sessions. Study preloads were a combination of a solid snack and a liquid beverage (energy range 0.78-0.83 MJ) containing four different types of fiber: soluble fiber dextrin (12 g), soluble corn fiber (11.8 g), polydextrose (11.8 g), and resistant starch (11.2g). All four fibers were compared to two control conditions of equal volume: an isoenergetic, low-fiber preload and a lower-energy, low-fiber preload. All preloads were presented twice for a total of 0.35-1.65 MJ and 1-24 g fiber. Satiety ratings were collected for 20 min intervals for 220 min during the morning testing session. A test meal was served at 1200 h and plate waste measured. The five higher-energy preloads led to higher fullness and lower hunger ratings compared to the low-energy control but were not significantly different from each other. Relative to the isoenergetic control, only soluble fiber dextrin significantly suppressed energy intakes (p=0.023). Supplementing beverages with soluble fiber dextrin affects short term energy intake and may have implications for weight control.