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Oat ??-glucan increases postprandial cholecystokinin levels, decreases insulin response and extends subjective satiety in overweight subjects
Abstract
This study recorded acute biochemical and subjective measures of satiety, followed by energy intake from a subsequent meal, after varying doses of beta-glucan in extruded breakfast cereals. Molecular weight, solubility and viscosity of beta-glucan products were determined. Seven male and seven female subjects (BMI 25-36 kg/m) consumed five breakfasts (different doses of beta-glucan sourced from two different technological processes) and dietary intake was measured after four hours. Blood was collected to measure glucose, insulin, ghrelin and cholecystokinin, and visual analogue scales measured subjective satiety. Molecular weight, solubility and viscosity indicated products were likely to increase luminal viscosity. beta-Glucan was found to decrease insulin secretion over 2 h (RMANOVA, p = 0.011) in a dose responsive manner from 2.16 to 5.68 g per serving (p = 0.007). Cholecystokinin levels increased linearly over the same range of beta-glucan concentrations (p = 0.002) in women. Subjective satiety was increased at a beta-glucan dose of 2.2 g (p = 0.039). Subsequent meal intake decreased by greater than 400 kJ with higher beta-glucan dose (>5 g). beta-Glucan improves satiety and release of cholecystokinin is likely to be part of the mechanism. Products with different sources of beta-glucan provide similar benefits but each product requires individual testing.
... • Beta Glucan has higher low-density lipoprotein (LDL) lowering effect on women than in men (women: 16 • Beta Glucan reduces cravings by balancing responsible hormones, increasing the healthy to unhealthy gut flora ratio and increasing satiety (Khoury, 2011;Slavin, 2013;Cloetens, 2012;Juvonen, 2009;Beck, 2009;JADA, 2008;Slavin, 2007;Dikeman, 2006). ...
... • Beta Glucan decreases calorie intake in the subsequent meal by greater than 96 calories (Beck, 2009;Vitaglione, 2009). That is about a 19% to 24% reduction in the next meal. ...
... • Beta Glucan slows the absorption of glucose, improves insulin sensitivity for 2 hours, and promotes lipolysis by 5% to 10% (Slavin, 2013;Cloetens, 2012;Khoury, 2011;Juvonen, 2009;Beck, 2009;JADA, 2008;Slavin, 2007;Dikeman, 2006). ...
Beta Glucan (3 g daily) reduces total cholesterol by 8.9% and non-high-density lipoprotein cholesterol levels by 12.1% over 8 weeks (Cicero et al., 2020). • Beta Glucan has higher low-density lipoprotein (LDL) lowering effect on women than in men (women: 16.3% (95% CI: 17.8 to 6.7) vs. men: 14.9% (95% CI: 14.1 to 5.9), in younger subjects (16.4% (95% CI: 17.5 to 8.3) vs. older 14.7% (95% CI: 17.1 to 5.2) (Cicero et al., 2020). • Beta Glucan causes 2.2 lbs (1 kg) weight loss per month (Khouri et al., 2011). • Beta Glucan reduces cravings by balancing responsible hormones, increasing the healthy to unhealthy gut flora ratio and increasing satiety (Khoury • Beta Glucan decreases calorie intake in the subsequent meal by greater than 96 calories (Beck, 2009; Vitaglione, 2009). That is about a 19% to 24% reduction in the next meal. • Beta Glucan slows the absorption of glucose, improves insulin sensitivity for 2 hours, and promotes lipolysis by 5%
... The ability of β-glucans to form a highly viscous solution in the gastrointestinal tract and to delay the absorption of nutrients might potentiate the feeling of satiety and decrease subsequent energy intake. However, several studies using β-glucans conclude differently [67][68][69][70][71]. Generally, a higher consumption of β-glucans (>5 g per meal) seems to induce higher satiety [67,68] than a lower amount (<5 g per meal) [69][70][71]. ...
... The ability of β-glucans to form a highly viscous solution in the gastrointestinal tract and to delay the absorption of nutrients might potentiate the feeling of satiety and decrease subsequent energy intake. However, several studies using β-glucans conclude differently [67][68][69][70][71]. Generally, a higher consumption of β-glucans (>5 g per meal) seems to induce higher satiety [67,68] than a lower amount (<5 g per meal) [69][70][71]. Both solid and liquid foods have a positive impact on satiety, but a study showed greater effectiveness with the consumption of beverages [68]. ...
... However, several studies using β-glucans conclude differently [67][68][69][70][71]. Generally, a higher consumption of β-glucans (>5 g per meal) seems to induce higher satiety [67,68] than a lower amount (<5 g per meal) [69][70][71]. Both solid and liquid foods have a positive impact on satiety, but a study showed greater effectiveness with the consumption of beverages [68]. β-glucans also exert favourable effects on intestinal function and gut health through an activity on intestinal microflora and bacterial metabolites [72]. ...
Cereal β-glucans are dietary fibres primarily found in oats and barley, and have several positive effects on health, including lowering the postprandial glucose response and the improvement of blood cholesterol levels. Cereal β-glucans have a specific combination of β-(1→4) and β-(1→3) linkages into linear long-chain polysaccharides of high molecular weight. Due to their particular structure, cereal β-glucans generate viscosity within the intestinal tract, which is thought to be the main mechanism of action responsible for their positive health effects. However, cereal grains are rarely consumed raw; at least one cooking step is generally required before they can be safely eaten. Cooking and processing methods more generally will modify the physicochemical characteristics of β-glucans, such as molecular weight, extractability and the resulting viscosity. Therefore, the health impact of β-glucans will depend not only on the dose administered, but also on the ways they are processed or converted into food products. This review aims at summarizing the different parameters that can affect β-glucans efficacy to improve glucose and lipid metabolism in humans.
... The consumption of whole grains has been associated with a modestly reduced risk of cardiovascular disease, type 2-diabetes, and obesity in adults [11][12][13]. Notably, β-glucan, the soluble fiber from oatmeal, has physiological and bioactive properties that may help to improve blood lipid levels, postprandial insulin levels, glucose responses, and subjective measures of satiety [14][15][16][17][18]. The US Food and Drug Administration (FDA) has also authorized a health claim for oats/oatmeal, which states: "the consumption of 3 g or more per day of β-glucan from oats or barley may reduce the risk of coronary heart disease" [19]. ...
... Oatmeal is one of the richest sources of the fiber β-glucan, which has been associated with improvement in blood cholesterol and postprandial glycemic and insulinemic responses, as well as with reduced risk of coronary heart disease (CHD) and increased satiety in adults [14][15][16][17][18][19]. In this study, we found that oatmeal consumers had a significantly higher intake of dietary fiber than breakfast skippers or consumers of "Doughnuts, sweet rolls, pastries", "Eggs and omelets", and "Ready-to-eat cereal, higher sugar". ...
Oatmeal is a whole grain (WG) food rich in fiber and other nutrients. The study objective was to compare diet quality and nutrient intake of children consuming oatmeal breakfasts to those of children consuming other breakfasts using the National Health and Nutrition Examination Survey (NHANES) 2011–2014. Dietary intake data from 5876 children aged 2–18 years were divided by breakfast food consumption: oatmeal breakfasts, “Doughnuts, sweet rolls, pastries”, “Pancakes, waffles, French toast”, “Eggs and omelets”, “Ready-to-eat cereal, lower sugar”, and “Ready-to-eat cereal, higher sugar” were used to assess diet quality and intake of food groups and nutrients using the USDA Healthy Eating Index-2015 (HEI-2015), Food Patterns Equivalents Database, and Food and Nutrient Database for Dietary Studies, respectively. As compared to consumers of other breakfasts or breakfast skippers, oatmeal consumers had consistently higher diet quality (4–16 points higher HEI 2015 total score, p < 0.05), higher WG intake (0.6–1.6 oz eq. higher, p < 0.05), and higher fiber and magnesium intakes compared to consumers of most other breakfasts or breakfast skippers. The results show that children consuming oatmeal breakfasts have better diet quality and increased intake of key nutrients compared to breakfast skippers and other breakfast consumers and suggest oatmeal may represent an important component of a healthy childhood diet.
... Similar to the glycaemic state, the quantity of consumption of βglucans is very important for the insulin response pattern (Khoury et al., 2012). A continuous decrease was observed in insulin release depending on β-glucan quantity in the oat consumed by over-weighted individuals, and 3.8 g of β-glucan has important effects (Beck et al., 2009b). Some studies found that effect of β-glucans on insulinaemia is independent from glycaemic effects (Bourdon et al., 1999;Juntunen et al., 2002). ...
... Studies investigating the effects of β-glucan intake on the individuals with type 1 diabetes are very limited (Frid et al., 2017;Rami et al., 2001). The limited number of studies carried out on type 1 diabetes may be caused by use of this fibre type for obesity and type 2 diabetes in general (Beck et al., 2009b;Braaten et al., 1994). Furthermore, since individuals with type 1 diabetes receive exogenous insulin injections, evaluation of the effects of β-glucan on blood glucose may be considered difficult in such a population. ...
Diabetes is a global burden and a significant public health problem all over the world with an increasing incidence. One of the important factors to prevent and treat diabetes is nutritional therapy. Epidemiological and short-term interventional studies emphasise the association between higher fibre intake and improvements in lipid profile as well as fasting and postprandial glycaemic control. Soluble fibres are more effective for management of diabetes, obesity, dyslipidaemia, hypertension, and different cancers when compared with insoluble fibres. The interest in beta (β)-glucans, soluble fibres has increased due to their multi-functional and bioactive characteristics. They are readiliy available from oat and barley grains. Fermentability and creation of high viscosity solutions in the human intestine constitute the basis of health benefits of β-glucans. β-glucans are important compounds for achieving decreased postprandial glucose and insulin responses, and different mechanisms that would explain glucose and insulin reducing effects have been suggested. The effects of β-glucans on glycaemic control depend on dose, consumption duration, physicochemical features, processing methods, and food form. A significant consideration focuses on consumption of β-glucans and β-glucan-included products that could play an important role in management of diabetes by reducing the risk of diabetes-associated complications.
... Blood was drawn to evaluate ghrelin, cholecystokinin levels, glucose, insulin, and visual analog scales were used to assess subjective satiety. The mechanism through which beta glucan promotes satiety is believed to include the release of cholecystokinin [66]. We expected that increasing dosages of beta-glucan would raise plasma PYY levels in overweight human adults. ...
Purpose of Review This study aims to review the hunger hormones in obesity management and the impact of oats in regulating these hormones for hunger suppression and body weight management. In this review, the impact of various edible forms of oats like whole, naked, sprouted, or supplemented has been investigated for their appetite hormones regulation and weight management.
Recent Findings The onset of obesity has been greatly associated with the appetite-regulating hormones that control, regulate,
and suppress hunger, satiety, or energy expenditure. Many observational and clinical studies prove that oats have a positive effect on anthropometric measures like BMI, waist circumference, waist-to-hip ratio, lipid profile, total cholesterol, weight, appetite, and blood pressure. Many studies support the concept that oats are rich in protein, fiber, healthy fats, Fe, Zn, Mg, Mn, free phenolics, ß-glucan, ferulic acid, avenanthramides, and many more. Beta-glucan is the most important bioactive component that lowers cholesterol levels and supports the defense system of the body to prevent infections. Hence, several clinical studies supported oats utilization against obesity, appetite hormones, and energy regulation but still, some studies have shown no or little significance on appetite.
Summary Results of various studies revealed the therapeutic potentials of oats for body weight management, appetite control, strengthening the immune system, lowering serum cholesterol, and gut microbiota promotion by increased production
of short-chain fatty acids.
... However, the meal quality was rated significantly more highly (p = 0.03) by participants who had Pomanox ® PE priming and drank the PJ than those taking PL (24.0 ± 8.9 mm versus 15.9 ± 12.1 mm, respectively). VAS tests have previously been viewed critically, and in some well-controlled studies, changes in VAS failed to predict subsequent reductions in food intake [3,9,38,40]. Another criticism of VAS is the reluctance of subjects to make full use of the scale, preferring either to avoid extreme responses or to record only their responses, thereby affecting the results [41]. ...
... However, the meal quality was rated significantly more highly (p = 0.03) by participants who had Pomanox ® PE priming and drank the PJ than those taking PL (24.0 ± 8.9 mm versus 15.9 ± 12.1 mm, respectively). VAS tests have previously been viewed critically, and in some well-controlled studies, changes in VAS failed to predict subsequent reductions in food intake [3,9,38,40]. Another criticism of VAS is the reluctance of subjects to make full use of the scale, preferring either to avoid extreme responses or to record only their responses, thereby affecting the results [41]. ...
There has been an increasing interest in nutraceuticals and functional foods in reducing appetite and to lose weight. We assessed the effect of oral pomegranate extract (PE) and PE juice (PJ) intake vs. placebo on satiety parameters in healthy volunteers. Twenty-eight subjects (mean age 34.5 ± 13.7 years, body mass index [BMI] 25.05 ± 3.91 kg/m2) were randomized to 3-week priming supplementation with PE (Pomanox®) or placebo. On week 3, satiety parameters were determined on 1 testing day after participants ingested a breakfast and a lunch meal with PJ juice, using 100-mm visual acuity scales (VAS) for hunger, desire to eat, fullness and satisfaction. Meal quality and palatability were also tested. The desire to eat was less at all time points in the PJ juice with PE priming group and participants were also less hungry (p = 0.044) than those who consumed placebo. There was an overall significant difference between the groups (p < 0.001). Participants in the PJ juice with PE priming group experienced significantly greater satisfaction (p = 0.036) and feeling of fullness (p = 0.02) than those in the placebo group. These findings suggest that consumption of PE could have the potential to modulate satiety indicators.
... It is low in digestible carbohydrates and rich in β-glucans, polyphenols, and flavonoids. It was reported that each gram of β-glucan in oat bran can reduce the area under the glucose curve by 4.35% (r = 0.507, p = 0.0008, n = 40) and the peak by 6.57% (r = 0.582, p < 0.0001) [4,5], probably owing to the high viscosity of oat β-glucan which can form a sticky solution in the intestinal tract, reduce the contact of food and digestive enzymes, and delay gastric emptying and the formation of blood glucose. Zhang et al. [6] pointed out that β-glucan enhanced the viscosity of the digestive tract through its own aggregation and intertwining and overlapping with starch, thus restricting water mobility and reducing the contact between digestive enzymes and starch, glucose, and small intestinal microvilli. ...
To investigate the effect of oat bran on bread quality and the mechanism of reducing the glycemic index (GI) of bread, wheat bran (10%, w/w, flour basis), oat bran (10%), and β-glucan (0.858%) were individually added to determine the expansion of dough, the specific volume, texture, color, GI, starch digestion characteristics, and α-amylase inhibition rate of bread. The results showed that the incorporation of wheat bran and oat bran both reduced the final expanded volume of the dough, decreased the specific volume of the bread, and increased the bread hardness and crumb redness and greenness values as compared to the control wheat group. The above physical properties of bran-containing bread obviously deteriorated while the bread with β-glucan did not change significantly (p < 0.05). The GI in vitro of bread was in the following order: control (94.40) > wheat bran (69.24) > β-glucan (65.76) > oat bran (64.93). Correspondingly, the oat bran group had the highest content of slowly digestible starch (SDS), the β-glucan group had the highest content of resistant starch (RS), and the control group had the highest content of rapidly digestible starch (RDS). For the wheat bran, oat bran, and β-glucan group, their inhibition rates of α-amylase were 9.25%, 28.93%, and 23.7%, respectively. The β-glucan reduced the bread GI and α-amylase activity by intertwining with starch to form a more stable gel network structure, which reduced the contact area between amylase and starch. Therefore, β-glucan in oat bran might be a key component for reducing the GI of whole oat bread.
... Based on several previous human studies, substantial evidence exists that suggests a minimal beta-glucan level is required (averaging 4 to 6 g) to perform appetite-regulating effects through circulating incretins [52][53][54]. However, pioneering studies that have evaluated the direct effect of beta-glucans on satiety parameters in dogs and that have shown positive results with low inclusion content (0.1% in the formulated diet) are quite scarce. ...
Background
Obesity is one of the most common nutritional disorders in dogs and cats and is related to the development metabolic comorbidities. Weight loss is the recommended treatment, but success is difficult due to the poor satiety control. Yeast beta-glucans are known as biological modifiers because of their innumerable functions reported in studies with mice and humans, but only one study with dogs was found. This study aimed to evaluate the effects of a diet supplemented with 0.1% beta-glucan on glucose, lipid homeostasis, inflammatory cytokines and satiety parameters in obese dogs. Fourteen dogs composed three experimental groups: Obese group (OG) with seven dogs with body condition score (BCS) 8 or 9; Lean group (LG) included seven non-obese dogs with a BCS of 5; and Supplemented Obese group (SOG) was the OG dogs after 90 days of consumption of the experimental diet.
Results
Compared to OG, SOG had lower plasma basal glycemic values (p = 0.05) and reduced serum cholesterol and triglyceride levels. TNF-α was lower in SOG than in OG (p = 0.05), and GLP-1 was increased in SOG compared to OG and LG (p = 0.02).
Conclusion
These results are novel and important for recognizing the possibility of using beta-glucan in obesity prevention and treatment.
... As revealed in Fig. 2 E, sol with greater viscosity increased the secreting of the CCK-8, resulting in the greater iAUC in the later stage of the observation. Beck, Tosh, Batterham, Tapsell & Huang (2009) also found that consuming a meal with high viscosity increased the secretion of the CCK-8. Besides, no significant difference was shown among group C, T1, and T2 in both the earlier and later stage, while the iAUC of group T3, T4, and T5 was significantly greater than that of group C, T1, and T2 ( p < 0.05). ...
Understanding the correlations between dietary fibers' physical properties and postprandial appetite response helps to design novel functional products with satiety enhancing capability. In the present study, the partially degraded konjac glucomannan (Pd-KGM) was obtained by applying the heterogeneous hygrothermal degradation method, and its flow behavior was studied for guiding the preparation of sols with equi-concentration but differed in viscosity. The appetite-regulating effects derived from the sol viscosity were explored by monitoring the appetite hormone response and the feeding behavior of rats after they were given the Pd-KGM sols. By lowering the secretion of ghrelin, elevating the plasma concentration of GLP-1, PYY3-36, and CCK-8, and stabilizing blood glucose and insulin fluctuation, the sol with increased viscosity showed an improved satiety-enhancing capability. Moreover, the transition point from feeding to resting was advanced in rats given a more viscous sol, resulting in a significantly decreased feed intake (p<0.05). We further explored the correlations between sol viscosity and its nutritional effects relating to appetite regulation depending on the quantitative data obtained in this study. Excluding the plasma glucose and CCK-8, a strong linear correlation (Pearson coefficient > 0.7) emerged between the appetite hormone and the sol viscosity, especially for the GLP-1, which its Pearson coefficient was 0.946, indicating a very highly correlated relationship between them. Thus, these results revealed the feasibility of regulating appetite by taking advantage of sol viscosity.
... The consumption of β glucan rich diet could reduce the risk of obesity which was attributed to its association with appetite and satiety. It have been reported that consumption of β glucan reduces gastrointestinal motility and food intake by modulating the release of various appetite-regulating hormone-like peptide YY (PYY), glucagon-like peptide 1(GLP-1), and cholecystokinin (CCK) (Beck et al. 2009). Yet further investigations are needed to confirm these mechanisms. ...
Polylactic acid (PLA) is a biodegradable polymer made up of lactic acid monomers. It is being increasingly produced today because of its potential applications in textile industry, pharmaceutical, packaging, bioremediation, and many more. The commercial production of lactic acid enantiomers is mostly done using renewable materials such as lignocellulosic and starchy biomass along with the milk-processing industry by-products like whey. Homofermentative and heterofermentative lactic acid bacteria (LAB) are most widely used for production. However, some cyanobacteria, fungi, and yeast have also been reported for efficient lactic acid fermentation. Genetic engineering and molecular biology approaches are being continuously used for strain improvement for more efficient and economic production. Fermentation has been commercially performed in batch, fed-batch, and continuous mode with the use of techniques like membrane filtration, reactive extraction, and others for separation from the broth. PLA can be composed of either pure l-isomer or d-isomer or both d, l-lactic acid depending upon the requirement and use. Polymerization processes such as polycondensation, ring-opening polymerization, and direct methods like azeotropic dehydration and enzymatic polymerization are used to form PLA from lactic acid monomers. This paper discusses the need of PLA and the methods used for its commercial production along with its structural properties and wide range applications.
... A recent study found that a NDP from flaxseed contributed to satiety through up-regulation of GLP-1, which might further increase the level of adiponectin and promote lipid metabolism via AMP-Activated Protein Kinase (AMPK) regulation [13]. Several studies also have demonstrated that NDPs intake is positively associated with the level of PYY [103,104] and CCK [105]. CCK can inhibit the activity of hunger-stimulating neuropeptide Y in the hypothalamus [8]. ...
Nowadays, obesity in humans is a huge challenge requiring effective, readily available, and low-risk alternative treatments. Intake of edible Non-Digestible Polysaccharides (NDPs) is regarded as a promising strategy to combat obesity. Herein, an overview of the behavior of NDPs in the Gastrointestinal (GI) tract and its association with anti-obesity effect is summarized. Both the in vitro and in vivo of such investigations are discussed. Results show that NDPs can reach the large intestine to mediate the gut microbiota with the extent of regulation varies among NDPs with different chemical structures. The possible anti-obesity mechanisms associated with behavior of NDPs in the GI tract include: (i) inhibition of fat absorption, (ii) modification of gut microbiota and their metabolites such as short-chain fatty acids, (iii) regulation of bile acid profiles, (iv) modulation on appetite and satiety effect, and (v) protection of intestinal barrier. However, more efforts are required to clarify the exact behavior and their beneficial effects of NDPs within GI tract. This paper will provide an overlook of recent advances for better understanding anti-obesity activity of NDPs.
•An overview of in vitro and in vivo studies on the behavior of edible Non-Digestible Polysaccharides (NDPs) in the Gastrointestinal (GI) tract is presented.
•The anti-obesity mechanisms of NDPs based on their GI behavior are discussed.
... Other microbiota-fermentable fibers (i.e. prebiotics), including from beans [229,230], guar gum [231], β-glucan [232,233] and other short-chain fatty acids (i.e. butyrate) [234] have also been associated with increased CCK release, supporting microbiota influences on the CCK system. ...
In 1973, Gibbs, Young, and Smith showed that exogenous cholecystokinin (CCK) administration reduces food intake in rats. This initial report has led to thousands of studies investigating the physiological role of CCK in regulating feeding behavior. CCK is released from enteroendocrine I cells present along the gastrointestinal (GI) tract. CCK binding to its receptor CCK1R leads to vagal afferent activation providing post-ingestive feedback to the hindbrain. Vagal afferent neurons’ (VAN) sensitivity to CCK is modulated by energy status while CCK signaling regulates gene expression of other feeding related signals and receptors expressed by VAN. In addition to its satiation effects, CCK acts all along the GI tract to optimize digestion and nutrient absorption. Diet-induced obesity (DIO) is characterized by reduced sensitivity to CCK and every part of the CCK system is negatively affected by chronic intake of energy-dense foods. EEC have recently been shown to adapt to diet, CCK1R is affected by dietary fats consumption, and the VAN phenotypic flexibility is lost in DIO. Altered endocannabinoid tone, changes in gut microbiota composition, and chronic inflammation are currently being explored as potential mechanisms for diet driven loss in CCK signaling. This review discusses our current understanding of how CCK controls food intake in conditions of leanness and how control is lost in chronic energy excess and obesity, potentially perpetuating excessive intake.
... Possible mechanisms for the prolonged satiety feelings may be linked to the gel forming ability of soluble β-glucan and other soluble fibres, and the bulking effect of insoluble fibres [154]. In addition, a release of appetite suppressants such as cholecystokinin was shown in response to the consumption of β-glucan at a minimum dose of 3.8 g per day, in a study done using 14 human subjects (7 male and 7 female) [155]. ...
The consumption of whole grain products is often related to beneficial effects on consumer health. Dietary fibre is an important component present in whole grains and is believed to be (at least partially) responsible for these health benefits. The dietary fibre composition of whole grains is very distinct over different grains. Whole grains of cereals and pseudo-cereals are rich in both soluble and insoluble functional dietary fibre that can be largely classified as e.g., cellulose, arabinoxylan, β-glucan, xyloglucan and fructan. However, even though the health benefits associated with the consumption of dietary fibre are well known to scientists, producers and consumers, the consumption of dietary fibre and whole grains around the world is substantially lower than the recommended levels. This review will discuss the types of dietary fibre commonly found in cereals and pseudo-cereals, their nutritional significance and health benefits observed in animal and human studies.
... Des études sur culture primaire de cellules de colon de souris nourries avec un régime riche en ARs ont montré une surexpression des ARNm des précurseurs du glucagon (GLP-1, GLP-2) et de PYY (288,290). Concernant la CCK, moins d'études ont été réalisées mais montrent néanmoins une augmentation de ses concentrations plasmatiques suite à la consommation d'un régime supplémenté en gomme de guar (20 g/j) ou β-glucane (6-16 g/j) (264,291,292). ...
Une des causes de l’augmentation de la prévalence de l’obésité et des maladies chroniques au niveau mondial (notamment dans les pays occidentaux) est la consommation de régimes hypercaloriques. A l’inverse la consommation d’un régime riche en fibres alimentaires est favorable à une bonne santé. Or la consommation de fibres alimentaires dans les pays occidentaux (20 g/j en France) est inférieure aux recommandations alimentaires préconisées par les organismes de santé (30 g/j). Un des moyens possibles d’augmenter l’ingestion des fibres est la mise à disposition d’aliments enrichis en fibres, et en particulier de fibres capables d’impacter favorablement sur la santé métabolique (les fibres fermentescibles). L’objectif de ma thèse a donc été de déterminer si, chez des mini-porcs en situation de surnutrition, une supplémentation en un mélange de fibres fermentescibles inclues dans un aliment de consommation courante (le pain) était capable de limiter l’apparition des désordres métaboliques associés au développement de l’obésité. Quatorze mini-porcs femelles ont été nourries 2 mois avec un régime en surnutrition enrichi en saccharose (10% p/p) et huile de palme (10% p/p) supplémenté ou non avec un mélange de fibres (25 g/j, pectine, inuline et amidons résistants) inclues dans un pain (250 g/j). Les animaux ont été cathétérisés au niveau intestinal et hépatique pour mesurer les flux nets splanchniques de nutriments durant l’adaptation aux régimes expérimentaux. Des fèces ont été prélevés pour analyser le microbiote et son activité. A l’euthanasie des animaux (après 56 jours de traitement nutritionnel), des tissus (jéjunum, caecum, foie, muscle, tissu adipeux) ont été prélevés pour un phénotypage métabolique (histologie, transcrits de gènes, protéomique).Nous avons mis en évidence que la supplémentation en fibres fermentescibles, après 2 mois de surnutrition, permettait de limiter la prise de poids corporelle, l’accumulation de gouttelettes lipidiques dans le foie et stimulait l’activité oxydative des tissus périphériques (comme le muscle). La moindre accumulation de gouttelettes lipidiques dans le foie est associée à une réduction de l’entrée des lipides (Fabp1) et une baisse probable de la lipogenèse (Srebp-1c). Ce mécanisme, confirmé par l’analyse des flux de nutriments, a induit une augmentation de la biodisponibilité en nutriments énergétiques vers les tissus périphériques. Les nutriments en excès sont pris en charge par le muscle via une augmentation de l’activité oxydative (↑ ARNm Pgc1α, Pparα, Nrf2, Acox, Ucp2, sdha, Cpt1-m). Ces modulations de dialogue foie- muscle avec la supplémentation en fibres pourrait passer par GLP1 et/ou GLP2 synthétisés par les cellules L de l’intestin (↑ ARNm de GCG jéjunum) et par une stimulation de la signalisation par les acides gras à chaine courte (AGCC) dans le caecum (↑ ARNm GPR41) mais probablement pas par une action directe des AGCC sur les tissus périphériques. Ces résultats montrent donc une amélioration du profil métabolique des mini-porcs en surnutrition lors de la supplémentation en fibres alimentaires fermentescibles via une réorganisation de l’utilisation des nutriments entre le foie et les tissus périphériques et une adaptation de leurs activités métaboliques. La quantité de fibres et de pain supplémentées dans notre étude, raisonnable, permet d’envisager une étude chez l’homme pour valider ces concepts et la stratégie nutritionnelle.
... Soluble fibre, particularly β-glucans, increase viscosity, and their solubility may promote satiety [56]. Breakfasts varying in β-glucan (2.2 g to 5.7 g) seem to cause a significant decrease in IR and an increase in satiety, in a dose-responsive manner [57]. These values were higher than the amount of β-glucan provided by oats in the FB (estimated to be at least 1.5 g), and despite an additional contribution from baobab, the values were perhaps still too low to have an appreciable effect on satiety. ...
A whole diet which combines multiple functional foods benefits metabolic risk factors and cognition, but evidence supporting meal to meal benefits, which individuals may find easier to implement, is limited. This study developed a functional food breakfast (FB), using polyphenol-rich ingredients selected for their gluco-regulating and cognitive-enhancing properties, and compared it to a control breakfast (CB). For study 1, total polyphenols were determined using the Folin–Ciocalteu method, and sugar release by in vitro digestion, in frozen and fresh samples. In study 2, healthy adults (n = 16) consumed an FB, CB and ready-to-eat breakfast cereal (RTEC) in a randomised crossover design. Glucose (GR) and insulin response (IR), satiety, mood and memory were measured over 180 min. The FB was a rich source of polyphenols (230 mg) compared to the CB (147 mg) (p < 0.05), and using frozen muffins did not compromise the polyphenol content or sugar release. Peak GR was highest after the RTEC (p < 0.05), and the insulin area under the curve (AUC) was lowest in the FB at 60, 120, 180 min and peak (p < 0.05). There were no effects on GR AUC, mood, satiety or memory. Reductions in GR peak and IR following consumption of the FB support the inclusion of functional ingredients at breakfast.
... These results were approximately consistent with many previous studies. 78,80,81 They claimed that the secretion of CCK-8 was elevated 2 h after the consumption of the meal with increased viscosity. Besides, differences between the groups kept getting smaller as the digestion process progressed. ...
Konjac glucomannan (KGM) is associated with satiety-enhancing property by imparting the food matrix with high viscosity. In the present study, rheology tests on KGM sol with different viscosity were conducted to understand their flow behavior as they presented in the mouth and stomach, and the in vitro gastric emptying characteristics of the KGM was examined with a human gastric simulator. Then, their effects on subjective appetite, glycemia, and appetite-related hormones (insulin, GLP-1, PYY3-36, CCK-8, Ghrelin) response were investigated by conducting a randomized, single-blind, crossover trial in 22 healthy adults (11 female and 11 male, mean age (y): 23.2±2.0, BMI (kg/m2): 20.6±2.1). Blood samples and ratings for subjective appetite were collected at regular time intervals after the subjects fed the four test breakfasts (one control treatment and three experimental treatments) on four different days. An ad libitum lunch was provided to the subjects once they consumed the breakfasts, and their food intake was recorded. As the viscosity increased, the gastric emptying rate was delayed even though a large part of the chyme viscosity was lost during digestion. The satiating capacity of the test breakfast was significantly enhanced as its increased viscosity, and subjects’ sensation for hunger, fullness, desire-to-eat, and prospective food consumption differed significantly (p=0.006, 0.000, 0.002 and 0.001, respectively) between treatments. The secretion of glycemia and satiety-related hormones were beneficially modulated by the increased viscosity of the test meal, but only a small decrease in ad libitum food intake was observed after the intervention of those viscous test breakfasts. Overall, elevating meal viscosity moderately by using the KGM would contribute to combating the challenge of hunger for people in bodyweight management.
... Kilolu bireylerde özellikle yulaf β-glukanının etkisiyle insülin salınımında azalma olduğu gösterilmiş ve günlük 3.8 gr β-glukan tüketiminin önemli olduğu ortaya konmuştur. 16 FDA da koroner kalp hastalığı riskini azaltmak için gerekli olan çözünür liflerin diyetle günlük alım miktarını belirlemiş ve yulaf, arpa veya her ikisinin kombinasyonu olan besinlerle günlük en az 3 gr β-glukan tüketilmesini önermiştir. 17 Tip 2 diyabeti olan hastalarla yapılmış olan ve gruplardan birinin Amerika Diyabet Birliği'nin önerdiği diyetle beslendiği, diğerinin ise β-glukan içeren düşük kalorili bir diyetle beslendiği randomize kontrollü bir çalışmada,β-glukan içeren diyetle beslenen grubun HbA 1 C düzeyinde daha fazla iyileşme olduğu gösterilmiştir. ...
... Oat bran is rich in soluble fiber and beta-glucans, which may help to suppress hunger hormones such as ghrelin and boost fullness hormones such as cholecystokinin, and thus, may support weight loss (Beck, Tosh, Batterham, Tapsell, & Huang, 2009). Furthermore, there is evidence supporting a lower prevalence of obesity in adults who consume olive oil regularly (Soriguer et al., 2009). ...
Type 2 diabetes is an epidemic public health issue worldwide. It is common among adults and is more severe among overweight and obese subjects. This study was conducted to evaluate the effects of a low‐energy diet with and without oat bran and olive oil supplements on body mass index, blood pressure, and serum lipids in women with diabetes. It was conducted for three months among 78 participants after dividing them into six groups. Groups 2 to 6 were received low‐energy diet (1,600 kcal/day), with or without oat bran (10 g/day) and olive oil (5 g/day) supplements. Weight, height, blood pressure, and serum lipids were measured. A low‐energy diet with and without oat bran and olive oil supplements lowers body mass index in subjects by 0.9%–6.0% on average. It also lowers systolic and diastolic blood pressure by 1.0%–9.0% and 4.8%–12.6%, respectively. Serum triglycerides were declined in groups 2, 3, and 4 by 27.2%, 17.3%, and 1.7%, respectively, but not significantly. Total cholesterol was dropped significantly by 8.3% only when the low‐energy diet was used with oat bran supplement among obese subjects, while LDL cholesterol was dropped significantly by 20.0% only when it was used with oat bran and olive oil supplements among subjects with high serum triglycerides. Proper control of type 2 diabetes among overweight and obese adults is needed to control cardiovascular complications. This could be accomplished by following a low‐energy diet and incorporating healthy foods such as oat and olive oil into the usual diet. Proper control of type 2 diabetes among overweight and obese adults is needed to control cardiovascular complications. This could be accomplished by following a low‐energy diet and incorporating healthy foods such as oat and olive oil into the usual diet.
... The two main properties characterizing dietary fibers, fermentability [1,2] and viscosity [3][4][5], affect energy intake [6][7][8][9], weight gain, fat accumulation and the lipid profile [8,[10][11][12][13][14]. On the one hand, fermentable fibers such as fructo-oligosaccharide (FOS) have a potent shortterm inhibitory effect on food intake and promote a decrease in body weight [15,16]. ...
... The combination of PS and OBG proves to be efficacious by tackling cholesterol metabolism at the gut level from two angles: increased clearance of cholesterol from circulation via the inhibition of bile acid reabsorption and reduction in cholesterol absorption at the micellar level. Moreover, the addition of OBG to PS therapy potentially extends its health benefits beyond cholesterollowering as OBG has been shown to: significantly lower postprandial blood glucose concentrations by suppressing glucose uptake [34] and delaying gastric emptying [35]; increase postprandial fullness and satiety in healthy [36] and overweight/obese [37] individuals and promotes colonic fermentation by gut microbiota to produce short-chain fatty acids [38e40], which play various roles such as mediating calorie intake [41,42] and inhibiting endogenous cholesterol synthesis [38,43]. Findings from this study demonstrate a complementary action between high-MW OBG and PS for cholesterol-lowering in hypercholesterolaemic adults. ...
Background & aims:
Oat β-glucan (OBG) and phytosterols (PS) are known to lower blood cholesterol levels via different mechanisms. Combination of high molecular weight (MW) OBG and PS in a single functional food could have complementary and/or synergistic effects for optimising heart health. The aim of this study was to investigate the effects of dietary supplementation with high-MW OBG with or without PS on plasma lipids in hypercholesterolaemic individuals.
Methods:
In a double-blinded, placebo-controlled, 2 × 2 factorial trial, participants were randomised to receive biscuits fortified with either no PS or OBG (PL, n = 18) or 2 g PS (PS, n = 18), 3 g OBG (OBG, n = 18), or combination of 2 g PS and 3 g OBG (PS-OBG, n = 18) per day for 6 weeks. Primary outcome was fasting plasma total cholesterol (TC) and secondary outcomes were LDL-cholesterol, LDL-C; HDL-cholesterol, HDL-C; triglycerides, TG and TC to HDL-cholesterol (TC:HDL) ratio.
Results:
TC and LDL-C were significantly lowered following PS (-4.6% and -7.6% respectively; p < 0.05), OBG (-5.7% and -8.6%; p < 0.01) and PS-OBG (-11.5% and -13.9%; p < 0.0001) administration. The reduction in TC in the PS-OBG group was significantly greater compared to PL (p < 0.001) and PS (p < 0.05). PS-OBG group had a significantly greater reduction in LDL-C compared to PL (p < 0.01) but not in comparison to PS or OBG groups. TC:HDL ratio was significantly reduced following PS-OBG (-8.9%; p < 0.01) only, and there was no significant difference found between groups. Plasma TG reduced by 8.4% following PS-OBG, however, this was statistically non-significant. Plasma HDL-C remained unchanged across all groups.
Conclusions:
Dietary supplementation with high-MW OBG and PS in a single functional food enhances their lipid-lowering potential. Blood cholesterol lowering by PS and OBG is additive. Delivery of these two bioactive nutrients in a single food allows optimisation of their lipid-lowering effects and may provide added heart health benefits with enhanced compliance. The trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au/(ACTRN12618001455257).
... Increase in the fermentation of short chain fatty acid and reduction in gastric emptying can increase insulin sensitivity, reduce insulin secretion stimulating fat oxidation and reduce fat storage 13,60-62 . Beta-glucan also induces satiety and stimulates cholecystokinin release to reduce appetite 63 . ...
Background & objective(s):
Obesity is a worldwide epidemic and a common medical condition associated with a variety of chronic diseases. Cereal beta-glucans are soluble fibers with potential health benefits. A number of randomized controlled trials (RCTs) have investigated the effect of cereal beta-glucan consumption on weight, but these results have not been summarized in a meta-analysis. The purpose of this study was to investigate the effect of cereal beta-glucan consumption on body weight, body mass index, waist circumference and a total energy intake.
Methods:
Studies were identified using MEDLINE/PubMed, Scopus and Cochrane databases. Screening of relevant articles and references was carried out until December 2018. There were no language restrictions. This systematic review and meta-analysis was performed using the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
Results:
Twenty eligible studies were identified and analyzed. Our study found a significant reduction in body weight and body mass index (BMI) following beta-glucan consumption (weighted mean difference [WMD]: -0.77 kg, 95% CI: -1.49, -0.04) and (WMD: -0.62 kg/cm2, 95% CI: -1.04, -0.21), respectively. There was no significant effect on waist circumference and energy intake. A subgroup analysis showed that a beta-glucan dose of ≥ 4 g/day lead to an increase in energy intake.
Conclusion:
The findings of this study indicates that cereal beta-glucan consumption seems to decrease body weight and BMI, but has no effect on waist circumference and energy intake.
... The foods, containing plenty of fibres, are used to prevent and/or treat nonalcoholic fatty-liver disease (Ross, Godin, Minehira, & Kirwan, 2013). The outer layer of the oat (Avena sativa), known as oat bran, is an excellent source of dietary fibre, which contains B-complex vitamins, protein, fat and minerals (Beck, Tosh, Batterham, Tapsell, & Huang, 2009). The effectiveness of oat brans in lowering the liver cholesterol have also been reported (Grajeta, 1999). ...
Oat (Avena sativa) bran, a by-product during oat grain processing, is a excellent source of fibre, vitamins and phytochemicals. The health benefits of dietary fibre have long been established. In the present study, the antioxidant and hepatoprotective effects of oat bran extracts were investigated. The extracts showed strong 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), hydroxyl, superoxide radicals scavenging and reducing power activities in vitro. In addition, the extracts (50 mg/kg mouse) significantly reduced the levels of malondialdehyde and hepatic damage marker enzymes (aspartate transaminase and alanine transaminase), proinflammatory cytokines as well as elevated SOD, CAT, and GPx enzymes expressions in LPS-treated (1 mg/kg body weight) BALB/c mice. Therefore, the present study strongly suggests that both oat bran extracts could be excellent raw materials for manufacturing functional food due to its protective effect on hepatic liver damage and excellent antioxidant activity.
... It is known that PYY has an anorexigenic effect [39], while ghrelin has an orexigenic effect [40]. Human studies have shown that consumption of oat beta-glucan results in an increase in PYY plasma concentration [41], as well as barley beta-glucan consumption, which also increases PYY plasma concentration and, in addition, reduces ghrelin plasma concentration [42]. The increase in PYY plasma concentration may be due to a direct effect of short chain fatty acids (SCFA), produced from the microbial fermentation in the large intestine, on the GPR43 receptor present in the L cells of the intestinal mucosa, which are responsible for the secretion of PYY [37,43]. ...
The aim of this study was to evaluate the effects of oat beta-glucan supplementation on metabolic, physiological, immunological and nutritional variables in adult dogs. Fourteen dogs were fed a control diet or a diet supplemented with 1% beta-glucan during 71 days. Serum concentrations of glucose, total cholesterol and lipoprotein fractions, as well as plasma concentrations of peptide YY and ghrelin, were determined. In addition, coefficient of total tract apparent macronutrient digestibility (CTTAD), food intake and fecal output, score, and pH were evaluated. For evaluation of immunological variables, serum concentrations of interleukin-4 and interferon gamma were determined on days 0, 57 and 71, which corresponded to blood collection prior to beta-glucan supplementation, and at 7 and 14 days post first and second dose of vaccination (Pneumodog®, Merial, Campinas, Brazil), respectively. Animals fed the supplemented diet showed (P
... Que ce soient les polyphénols ou les vitamines, leur ingestion permet une amélioration de la résistance à l'oxydation des LDL, et ainsi une protection contre l'athérosclérose (502). Les β-glucanes de l'avoine augmentent également le niveau de satiété (550). Les avantages pour la santé sont expliqués selon les mécanismes dont les fibres sont à l'origine. ...
L’alimentation est un acte naturel qui permet à chacun de se nourrir et d’apporter à l’organisme les composantes essentielles dont il a besoin. Toutes les habitudes alimentaires ne s’équivalent cependant pas, et lorsqu’elle n’est pas équilibrée, l’alimentation peut même se révéler nocive. Tandis que les maladies infectieuses sont en constante diminution dans les pays occidentaux, de nouvelles maladies, non transmissibles, sont-elles en augmentation, comme c’est le cas pour le surpoids ou l’obésité qui touchent respectivement 2 milliards et 650 millions de personnes dans le monde. Les régimes alimentaires dérivent d’habitudes culturelles qui sont parfois historiques, et il est alors intéressant d’étudier les régimes en vogue au paléolithique, à l’Antiquité, et de comment ils ont évolué au fur et à mesure des siècles pour arriver aujourd’hui à une alimentation qui fait place à l’industrialisation et à la mondialisation. Plusieurs modes alimentaires se sont ancrés dans les habitudes culturelles parmi lesquels le régime méditerranéen, véritable patrimoine immatériel de l’UNESCO, et le régime d’Okinawa au Japon, qui sont présents dans des régions possédant un taux élevé de centenaires, mais c’est également le cas d’autres moins sains tel que le régime typique américain. Parallèlement à ces régimes culturels qui définissent certaines populations, d’autres émergent, dérivant d’une extrapolation de recommandations médicales, comme c’est le cas du régime végétarien ou sans gluten. Chacun de ces régimes présente alors un impact significatif sur l’apparition des maladies chroniques non transmissibles que sont les maladies cardiovasculaires et métaboliques. Enfin, il est également possible de noter le lien très étroit entre alimentation et génétique, de nouvelles disciplines apparaissent. C’est le cas de la nutrigénétique qui définit la façon dont les variations génétiques affectent la réponse aux aliments, alors que le terme nutrigénomique est utilisé lorsque l’on parle de l’interaction entre les aliments et les gènes et comment ces derniers sont affectés.
... In addition to providing exact quantification, when specific DF ingredients are used, other details should also be given. For example, the degree of methylation of pectin (19), the degree of purification of β-glucan (20), and the ratio of mannuronic and guluronic acid in alginate (21,22). This is because the physical properties of DF and thus physiologic outcomes are highly dependent on the molecular structure of the specific materials used. ...
Dietary fiber (DF) comprises a wide range of naturally occurring and modified materials with substantial variations in physical and chemical properties and potential physiologic effects. Although nutrition studies testing the effects of DF usually provide extensive detail on the physiologic responses, many still fail to adequately report the type and properties of the DF itself. This weakens the ability to directly replicate and compare studies and to establish structure-function relations. We outline the factors that affect DF functionality and provide 4 overarching recommendations for the characterization and reporting of DF preparations and DF-containing foods in nutrition research. These relate to 1) undertaking characterization methods that reflect the study hypothesis; 2) adequate reporting of DF source, quantity, and composition; 3) measurement of DF rheological properties; and 4) estimation of the DF fermentation rate and extent. Importantly, the food matrix of the test products should also be considered, because this can influence DF functionality and hence the apparent DF efficacy for health-relevant outcomes. Finally, we point out differences in DF functionality to be considered in acute and longer-term trials, the need to design the control treatment according to the research question, and the importance of reporting the amount and type of DF in the background diet.
Cereal β-glucans are beneficial health ingredients that reduce cholesterolemia and postprandial glycaemia. However, their impact on digestive hormones and gut microbiota is not yet fully established. Two randomized, double-blind, controlled studies were conducted. In the first study, 14 subjects ingested a breakfast with or without β-glucan from oats (5.2 g). Compared to the control, β-glucan increased orocecal transit time (p = 0.028) and decreased mean appetite score (p = 0.014) and postprandial plasma ghrelin (p = 0.030), C-peptide (p = 0.001), insulin (p = 0.06), and glucose (p = 0.0006). β-glucan increased plasma GIP (p = 0.035) and PP (p = 0.018) without affecting leptin, GLP-1, PYY, glucagon, amylin, or 7α-hydroxy-4-cholesten-3-one, a biomarker of bile acid synthesis. In the second study, 32 subjects were distributed into 2 groups to ingest daily foods with (3 g/day) or without β-glucan for 3 weeks; stools were collected before/after treatment. No changes in fecal microbiota composition/diversity (deep sequencing) were detected with β-glucans. These results indicate that acute intake of 5 g β-glucan slows transit time and decreases hunger sensation and postprandial glycaemia without affecting bile-acid synthesis, these changes being associated with decreased plasma insulin, C-peptide, and ghrelin, and increased plasma GIP and PP. However, regular daily intake of 3 g β-glucan is not sufficient to have an effect on fecal microbiota composition.
The aim of this study was to determine the effects of fermentation and food matrix on the ACE inhibitory activities of the peptides obtained after in vitro gastrointestinal digestion, protein profiles (SDS-PAGE) and β-glucan amounts of oat products. Furthermore, the physicochemical and microbiological properties of fermented oat drinks and oat yogurt-like product obtained from oat fermentation were evaluated. Oat grains were mixed with a certain ratio of water 1:3 w/v (oat:water, yogurt consistency) and 1:5 w/v (oat:water, drink consistency), and this mixture was fermented with yogurt culture and probiotic Lactobacillus plantarum and fermented drinks and yogurt were produced. The results indicated that the fermented oat drink and the oat yogurt-like product had L. plantarum viability over 107 cfu/g. After the in vitro gastrointestinal digestion of the samples, the hydrolysis levels ranged from 57.70 % to 82.06 %.The hydrolysis level of the samples with fermented-drink consistency was significantly higher than the samples with yogurt consistency (p < 0.05).The SDS-PAGE profiles of the non-digested samples showed that the bands had molecular weights of 12-15 kDa and around 35 kDa. Bands whose molecular weights were around 35 kDA disappeared after gastric digestion. ACE inhibitory activities of the fractions composed of molecular weights of 2 kDa and 2-5 kDa obtained after in vitro gastrointestinal digestion of the oat samples were in the range of 46.93-65.91 %. The effect of fermentation on the ACE inhibitory activities of the peptide mixture with molecular weights between 2 and 5 kDa was not statistically significant, however, fermentation caused an increase in the ACE inhibitory activities of the peptide mixture with a molecular weight<2 kDa (p < 0.05). The β-glucan amounts of fermented and non-fermented oat products were in the range of 0.57-1.28 %. The β-glucan amounts detected after gastric digestion decreased considerably and β-glucan could not be detected in the supernatant after gastrointestinal digestion. This indicated that β-glucan did not solubilize in the supernatant (bioaccessible) and remained in the pellet. In conclusion, fermentation is a valuable process for releasing peptides with moderately high ACE inhibitory effects from the parent oat proteins.
According to cohort studies, cereal fiber, and whole-grain products might decrease risk for type 2 diabetes (T2DM), inflammatory processes, cancer, and cardiovascular diseases. These associations, mainly affect insoluble, but not soluble cereal fiber. In intervention studies, soluble fiber elicit anti-hyperglycemic and anti-inflammatory short-term effects, partially explained by fermentation to short-chain fatty acids, which acutely counteract insulin resistance and inflammation. ß-glucans lower cholesterol levels and possibly reduce liver fat. Long-term benefits are not yet shown, maybe caused by T2DM heterogeneity, as insulin resistance and fatty liver disease – the glycometabolic points of action of soluble cereal fiber – are not present in every patient. Thus, only some patients might be susceptive to fiber. Also, incretin action in response to fiber could be a relevant factor for variable effects. Thus, this review aims to summarize the current knowledge from human studies on the impact of soluble cereal fiber on glycometabolic gastrointestinal hormones. Effects on GLP-1 appear to be highly contradictory, while these fibers might lower GIP and ghrelin, and increase PYY and CCK. Even though previous results of specific trials support a glycometabolic benefit of soluble fiber, larger acute, and long-term mechanistic studies are needed in order to corroborate the results.
Dietary fibers prevent obesity through reduction of hunger and prolongation of satiety. A number of mechanical and endocrine signals from gastrointestinal tract are stimulated by fibers and their fermentation products, reach regions of brain involved in the regulation of appetite, and ultimately reduce food intake. Gastric distention, delayed gastric emptying, prevention of hypoglycemic, increased amounts of unabsorbed nutrients reaching to the ileum, and stimulation of enteroendocrine cells for secretion of cholecystokinin, glucagon-like peptide-1 (GLP-1), and peptide YY are among mechanisms of fibers in decreasing hunger and prolongation of satiety. Fermentation of fibers produces short-chain fatty acids that also stimulates enteroendocrine cells to secrete GLP-1 and PYY. Randomized controlled trials have shown reductions in energy intake and body weight along with increased satiation and reduced hunger following consumption of fibers. Prospective cohort studies have confirmed these results but the extent of weight loss in some studies has been small. Controversies exist between studies particularly for the effect of fibers on the gastrointestinal hormones, subsequent food intake, and the resultant weight loss. More studies are needed before a clear conclusion can be drawn especially for the effect of fibers on appetite-related hormones and weight loss.
β-Glucans are a class of soluble dietary fibers that are present mainly in cereals like wheat, oats, barley, and rye among others. They play a crucial role in the viscosity and tribology of cereal foods when being utilized as thickener, stabilizers, gelling and emulsifying agents. β-glucans, due to their high fiber content and complex polysaccharide nature can be explored for the use of prebiotic sources thus improving gut health. They also reduce the glycemic index of foods as a result of a physiological activity generated due to high viscosity in them. Other health benefits associated with β-glucans include reducing serum cholesterol, controlling diabetes, reducing the incidence of cardiovascular diseases, cancer, hypertension among others. The valuable rheological properties and physiological responses of β-glucans advance their utilization in the food, nutraceutical and pharmaceutical industry. This chapter focuses on the variable functionality of β-glucans obtained from several cereal sources, as well as physiological functionalities and their application in various food formulations.Keywordsβ-GlucansDietary fiberFunctional propertiesBiological activities
Background
Diabetes mellitus, which is one of the most prevalent chronic diseases, is a major cause of the increase in morbidity and mortality in humans. To relieve hyperglycaemia in diabetic patients, the control of blood glucose levels through the use of a low glycaemic index diet is highly recommended. In view of the predominant contribution of dietary starch to blood glucose, low starch digestibility foods can certainly benefit diabetic patients. Hence, food technologists have attempted to design foods with lowered starch digestibility by using various strategies, and the application of soluble dietary fibre (SDF) has attracted a considerable amount of attention.
Scope and approach
This work aimed to present an updated overview of the evidence, factors, and possible mechanisms of the impacts of SDF on starch digestibility.
Key findings and conclusions
First, the in vitro, in vivo, and clinical evidence of SDF on starch digestibility was summarized. The SDF-starch digestibility relationship was found to be dependent on the nature of SDF and starch. The former factor included the type, application dose, charge, and molecular weight, and the latter mainly involved the type and physical state. Additionally, the mechanism underlying these concepts was explored, and it was found that SDF functions as follows: 1) the modification of the multiscale structure of starch or the involved food; 2) an increase in the viscosity of intestinal contents; 3) decreases in the activities of amylolytic enzymes; and 4) the regulation of the levels of hormones or other metabolites related to starch digestion. Finally, the perspectives and directions of future efforts were proposed in pursuing a full understanding of the underlying mechanism and more valuable data for designing healthy foods.
The current review examines the totality of the evidence to determine if there exists a relationship between β‐glucan and body weight and adiposity and whether such a relationship is a consistent, causal and plausible one. Observational studies suggest an association between oat (i.e., β‐glucan) intake and reduced body weight, waist circumference and adiposity. High and moderate quality randomized controlled trials that were specifically designed to evaluate the efficacy of β‐glucan on anthropometric outcomes were given the highest weight. Several of these studies indicated a causal relationship between β‐glucan consumption and reduction in body weight, BMI, and at least one measure of body fat within diets that were not calorie-restricted. A review of additional animal and human evidence suggests multiple plausible mechanisms by which β‐glucan may impact satiety perception, gastric emptying, gut hormones, gut microbiota and short chain fatty acids in the complex interplay of appetite and energy regulation.
Diets supplemented with protein and fiber are well known to reduce food intake and weight gain; however, less is known about the combined effects of protein and fiber on energy balance and gut microbiota composition. We compared effects of diets containing egg or whey protein with cellulose or inulin fiber on energy balance, gut microbiota, hormones and metabolites. Male obese rats (n=8/group) were allocated to 4 diets: Egg albumin + Cellulose (EC), Egg albumin + Inulin (EI), Whey protein + Cellulose (WC), and Whey protein +Inulin (WI). Results reveal that diet-induced hypophagia was transient with EC and prolonged with EI and WI, compared to WC. Importantly, CCK-1 receptor antagonist (Devazepide) attenuated the hypophagic effects of EC, EI and WI. Further, EC, EI and WI decreased respiratory quotient, energy expenditure, weight and adiposity gains, and improved glycemia, relative to WC. Propranolol (β1-β2-receptor blocker) attenuated diet-induced changes in energy expenditure. Transcript abundance of thermogenic markers in brown adipose tissue, plasma hormones and metabolites especially acyl-carnitines and glycerophospholipids, were differentially altered by diets. Diet explained 25% of compositional differences in cecal microbiomes, but diets with same fiber type did not differ. Microbiota differing between groups also strongly correlated with gut hormones and metabolites. Species most strongly correlated to a marker for butyrate production were in highest abundance in inulin diets. Together, these findings indicate that inulin enriched diets containing egg or whey protein improved energy balance, decreased adiposity, and modulated gut microbiota and metabolites, with CCK signaling partly mediating the satiety effects of diets.
Background
To date, several researchers have investigated the association between dietary fibre consumption and satiety. However, there is no study that includes both inulin and β-glucan to compare energy intake (EI) and satiety ratings.
Aim
The current study investigated the effects of two dietary fibres, β-glucan and inulin, on satiety and food intake.
Methods
The study was carried out among 24 woman over 18 years of age. The dietary fibres β-glucan (6 g/day) or inulin (6 g/day) were consumed by participants for five weeks. On the first and fifth week visits, the participants consumed a standard breakfast followed by an ad libitum test meal. Appetite was assessed using visual analogue scales (VAS) before and after breakfast. EI was measured at the test meal using plate waste.
Results
Both dietary fibres significantly reduced the VAS scores of hunger, prospective food consumption and desire to eat, and increased satiety compared with the control group. However, the area under curve data for the VAS scores did not exhibit a significant difference. Significant reductions in EI and anthropometric values between the first and fifth week measures were observed in both dietary fibre groups. Statistically significant changes occurred in the body weight [-1.25 (1.27) kg], body mass index [-0.41 (0.42) kg/m ² ], waist circumference [-1.25 (1.04) cm] and waist/hip ratio [-0.01(0.01)] in the β-glucan group, whereas a statistically significant change occurred in body fat percentage in the inulin group [-2.16% (7.49)].
Conclusions
Overall, these findings demonstrate that the participants consuming β-glucan over the course of the five weeks had less EI, felt less hunger and had more satiety.
It is known that obesity has reached epidemic proportions and its management is of high clinical importance. In this chapter we will discuss recent data about the role of nutraceuticals and functional foods in obesity and body weight management, including the mechanisms responsible for their favorable effects. In addition, the impact of healthy dietary patterns on weight loss will be addressed. Apart from influencing the imbalance between energy intake and output, nutraceuticals may prevent and/or decrease the development of oxidative stress and inflammation in obesity, as well as favorably influence other cardiovascular disease risk factors, thereby limiting obesity-related complications. A place for nutraceuticals in daily clinical practice is emerging, but the current evidence supporting their use is still limited. Further research will lead to the development of novel nutraceuticals/functional foods/dietary patterns to successfully prevent and/or combat obesity.
To determine the effect of oat β‑glucan (OBG) on acute glucose and insulin responses and identify significant effect modifiers we searched the MEDLINE, EMBASE, and Cochrane databases through October 27, 2020 for acute, crossover, controlled feeding trials investigating the effect of adding OBG (concentrate or oat-bran) to carbohydrate-containing test-meals compared to comparable or different carbohydrate-matched control-meals in humans regardless of health status. The primary outcome was glucose incremental area-under-the-curve (iAUC). Secondary outcomes were insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two reviewers extracted the data and assessed risk-of-bias and certainty-of-evidence (GRADE). Data were pooled using generic inverse-variance with random-effects model and expressed as ratio-of-means with [95% CIs]. We included 103 trial comparisons ( N = 538). OBG reduced glucose iAUC and iPeak by 23% (0.77 [0.74, 0.81]) and 28% (0.72 [0.64, 0.76]) and insulin by 22% (0.78 [0.72, 0.85]) and 24% (0.76 [0.65, 0.88]), respectively. Dose, molecular-weight, and comparator were significant effect modifiers of glucose iAUC and iPeak. Significant linear dose-response relationships were observed for all outcomes. OBG molecular-weight >300 kg/mol significantly reduced glucose iAUC and iPeak, whereas molecular-weight <300 kg/mol did not. Reductions in glucose iAUC (27 vs 20%, p = 0.03) and iPeak (39 vs 25%, p < 0.01) were significantly larger with different vs comparable control-meals. Outcomes were similar in participants with and without diabetes. All outcomes had high certainty-of-evidence. In conclusion, current evidence indicates that adding OBG to carbohydrate-containing meals reduces glycaemic and insulinaemic responses. However, the magnitude of glucose reduction depends on OBG dose, molecular-weight, and the comparator.
Obesity is a serious public health issue associated to several chronic ailments like type 2 diabetes, cancer, heart disease and respiratory ailments caused by modern lifestyle approaches and unhealthy eating habits. Appropriate lifestyle pattern and behavior interventions are crucial to weight loss success, but maintaining is extremely challenging. Advancements in technology and increasing demands from people triggered expansion of research into the niche areas of herbal medicine and natural products to develop innovative drug delivery system. The present review focusses on the various nanocarrier approaches for the delivery of herbal drugs such as liposomes, Solid Lipid Nanoparticles (SLN), phytosomes, magnetic nanoparticles, nanosized micelles, as an alternative anti-obesity treatment that proved to be a therapy with lesser side effects and improved therapeutic efficacy. In future, herbal nanotherapeutics will have a greater impact on the anti-obesity treatment, replacing the several conventional treatment regimes. Abundant natural materials have been explored for the obesity treatment potential such as Garcinia cambogia, green tea, apple cider, chia seeds, Panax ginseng, etc. Solubility and stability issues of the phytoconstituents are the major limiting determinants that led to the formulation development of carriers for the delivery of herbal drugs providing better therapeutic efficacy. Combining the herbal medicine knowledge with the nanotechnology emerged as lucrative area for formulating effective herbal nanotherapy for obesity treatment.
Cereal β glucans are linear polymer of β-D-glucose unit linked via (1–3)(1–4) glycosidic bonds. These water-soluble polysaccharides are natural component of the endosperm and aleurone cells of Poaceae family. Numerous studies documented the significant health benefits of β glucan beyond basic nutrition. Regular consumption of β glucan is effective in lowering glycemic index of food and serum cholesterol levels, controlling blood glucose and insulin levels, preventing constipation, decreasing the risk of colorectal cancer, and enhancing the immune system by protecting the body from bacterial and parasitic infections. β glucan also possesses various functional properties such as stabilizing, thickening, gelation, and emulsification. These functional and nutritional benefits of β glucan mainly depend on its concentration, molecular structure, and molecular weight. Over the last few years, β glucan has gained renewed interest in the food industry due to their diverse physicochemical properties that aid in development of new cereal products. To meet the rising demand of the consumer for functional food, modern food technology aimed at utilizing β glucan for the development of new products and delivering numerous health benefits to the community. This chapter presents the sources, structure, positive physiological effects of β glucans, and its utilization as functional ingredient in food industries.
Identified over 80 years ago, pantothenic acid is an essential vitamin, which serves as the metabolic precursor for coenzyme A (CoA). In the form of CoA and as a component of acyl carrier protein, pantothenic acid is a participant in myriad metabolic reactions involving lipids, proteins, and carbohydrates. Though essential, pantothenic acid deficiency in humans is rare due to its ubiquitous distribution in foods of both animal and plant origin. Supplementation with pantothenic acid or its derivatives may have some health benefits, but further investigation into various health claims is necessary before any specific recommendations may be given.
Objectives
The efficacy of oat beta-glucan (OBG), a viscous soluble fibre, on postprandial glycemic outcomes may depend on the nature of the control and the dose and molecular weight (MW) utilized. We undertook a systematic review and meta-analysis of acute clinical trials to determine whether these features mediate the glycemic response to OBG.
Methods
MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched through October 2, 2019. We included acute, single-meal feeding, controlled trials investigating the effect of OBG (concentrate or oat bran) added to a carbohydrate-containing meal compared to a comparable meal (matched control) or a different carbohydrate-containing meal (unmatched control). Two reviewers extracted the data and assessed the risk of bias. The primary outcome was incremental area under the curve (iAUC) for blood glucose. Data were pooled using the generic-inverse variance method with random effects model and expressed as ratio of means with [95% Cis].
Results
We included 93 trial comparisons (N = 432). OBG reduced glucose iAUC by 23% (0.77 [0.73 to 0.81]). The effect was not significantly different between matched and unmatched controls (P = 0.17). Dose and MW were significant effect modifiers (P < 0.01). OBG doses per 30 g available carbohydrate of <1.5 g, 1.5 to <2.5 g, 2.5 to <3.5 g, 4.5 to <5.5 g, and >5.5 g OBG led to reductions of 9% (0.91 [0.81 to 1.02]), 14% (0.86 [0.80 to 0.93]), 17% (0.83 [0.76 to 0.90]), 31% (0.69 [0.64 to 0.74)], and 39% (0.61 [0.56 to 0.66]), respectively. Low MW OBG (<300,000 g/mol) had no effect (1.00 [0.94 to 1.07]) but medium MW (300,000 to <1000,000 g/mol) and high MW (>1000,000 g/mol) OBG led to significant reductions of 23% (0.77 [0.69 to 0.87]) and 32% (0.68 [0.63 to 0.73]), respectively.
Conclusions
Current evidence indicates that the addition of oat beta-glucan to carbohydrate-containing meals reduces the postprandial glycemic response. However, the magnitude of the reduction depends on the dose and the molecular weight of the oat beta-glucan.
Funding Sources
INQUIS Clinical Research Ltd. (formerly GI Labs), and PepsiCo Global R&D.
Viscous soluble dietary fibers (VSDF) have received much attention for their potential role in energy regulation through the reduction of energy intake due to increased satiety. The aim of our study was to investigate the effects of low and high viscosities of xanthan and guar gum solutions on postprandial nutrient intake and plasma biomarkers of nutrient metabolism by an in vivo animal experiment. This study examined the effects of short-term and long-term intake of different VSDF on metabolism and physical condition in rats. On the third day the 4 h food intake (FI) after gavage of the high viscosity xanthan gum (HX) group was decreased from 13.07 g to 6.79 g and the blood glucose (BG) 30 min postprandial was lowered from 14.1 mmol/L to 7.9 mmol/L compared to Control. The amount of gastrointestinal chyme in the HX group was significantly higher than the other groups after 2 h of gavage. The long-term (3 weeks) consumption of VSDF reduced the rats' FI, body weight, fasting blood glucose, apparent protein digestibility, insulin and leptin concentrations, indicating that VSDF may reduce weight gain by inhibiting nutrient digestion. The long-term intake of VSDF increased the length of the small intestine. HX group had the lowest weight gain and nutrient digestion than the other groups.
Obesity is a multifactorial chronic disease or syndrome caused by an imbalance in energy expenditure and intake. Obesity and its associated complications make it has the fifth leading cause for global mortality. The benefits of the current anti-obesity treatment regimen have been masked by high cost and numerous adverse effects. Therefore, many researchers focus on plant-derived/natural products or altered dietary pattern for the management of obesity and its related complications (co-morbidities). Several epidemiological studies also confirmed that the consumption of functional foods/nutraceuticals could considerably lower the risk of various chronic diseases like obesity, diabetic mellitus, and cancer but the underpinning mechanism is still unclear. This comprehensive review brief on the prevalence of obesity, complications related obesity, current treatment regimen and the importance of functional foods and nutraceuticals (molecular mechanism) for the management of body weight and alleviates its co-morbid conditions. This is the first comprehensive review revealing the in-depth anti-obesity mechanism of various popular functional foods and nutraceuticals with special reference to randomized clinical trials (RCTs). Overall, this contribution would signify the importance and beneficial role of functional foods/nutraceuticals on weight management (anti-obesity) to convey the current treatment status related to clinical trials which would help in the development of novel functional foods/nutraceuticals for combatting obesity and its co-morbidities.
The prevalence of type 2 diabetes mellitus (T2DM) has been increasing throughout the world. The cereals, as the high carbohydrate food and dominant portion of diet, have crucial impacts on glycemic control, especially for T2DM. Both components in whole cereals and processing are closely related to their glycemic response. The consumption of whole cereals is shown to reduce the risk of T2DM. The starch characteristic of cereal determines its hydrolysis rate and glycemic response. The soluble and insoluble dietary fiber, phenolic compounds, and other bioactive constituents may slow down the starch hydrolysis. Besides, they have other physiological mechanisms in regulation of T2DM, such as amelioration of lipid disorder, antioxidant, anti-inflammation, and regulation of gut microbiota, which contribute to further improvement of metabolic symptoms. Cereals are subjected to processing before consumption, which is involved in mechanical force, bioprocessing, thermal treatment, and cooling. The processing induces changes in nutritional composition and physical structure compared to the raw kernels. The key influences of processing on glycemic response are the starch gelatinization and starch retrogradation. However, physical structure of cereal and interactions among starch and other compounds greatly contribute to various glycemic responses of cereal products. This review highlights recent findings on the influences of both bioactive constituents and processing on the antidiabetic effects and physiological properties of cereals.
Obesity is a global epidemic characterized not only by excessive fat deposition but also by important complications such as nonalcoholic liver steatosis. Beneficial antiobesogenic effects have been described for some mushrooms. The current study aimed to demonstrate the protective effect of Agaricus bisporus (AB) supplementation against the metabolic alterations induced by high-fat-diet (HFD) feeding. Eight-week-old C57BL/6J mice were fed for 10 weeks with one of the following diets: (1) control diet (n = 7), (2) HFD (n = 7), (3) HFD supplemented with 5% AB (n = 9), and (4) HFD supplemented with 10% AB (n = 9). A pair-fed group was also included for the 10% AB group (n = 6). The impact of AB supplementation on food intake, body weight gain, and liver and fat pad weights was examined. Biochemical, histological, and molecular parameters were also analyzed. Dietary supplementation with 10% AB reduced the HFD-induced increase in body, epididymal, and mesenteric fat weights (p < 0.01, p < 0.05, and p < 0.05, respectively). Supplementation with AB also reduced liver damage in a dose-dependent manner (p < 0.01 and p < 0.001). This effect was confirmed by histological analysis that showed that liver steatosis was markedly reduced in mice fed with AB. The beneficial properties of 10% AB supplementation appear to be mediated through a decrease in food intake and via stimulation of mesenteric and hepatic free-fatty acid beta-oxidation, along with a decrease in epidydimal and hepatic expression of CD36. In conclusion, supplementation with AB prevents excessive body weight gain and liver steatosis induced by HFD consumption.
Viscosity generated by oat β-glucan induces gastrointestinal mechanisms that influence appetite. Two oat-based ready-to-eat cereals (RTEC) with similar amounts of β-glucan but differing in their protein and sugar content were compared for their effects on appetite. Forty-seven healthy individuals, ≥18 years old, enrolled in a crossover trial consumed RTEC1 or RTEC2 in random order at least a week apart. Breakfasts contained 250kcals cereal and 105kcals fat-free milk. Subjective ratings of appetite were completed at baseline, and at 30, 60, 120, 180 and 240 minutes after consumption of the breakfast meals. Responses were analyzed as area under the curve (AUC) and per time-point. Significance was set at α=0.05. Fullness (p=0.01) and stomach fullness (p=0.02) were greater with RTEC 1 compared to RTEC 2 at 240 minutes. Stomach fullness (p=0.01) was greater at 30 minutes, and desire to eat (p=0.04) was reduced at 120 minutes with RTEC2 compared to RTEC1. There was no difference in the AUC for hunger, fullness, stomach fullness, desire to eat, or prospective intake. Ready-to-eat cereals containing similar amounts of oat β-glucan differed in the timing of significant differences in fullness or desire to eat, but appetite ratings over a four hour period did not differ.
The current study explored the impact of cereal food structure on digestion and satiety. Food structure is important for acceptability, functionality and health effects. Cereal foods contribute significantly to energy and nutrient intakes in the diets worldwide. The benefits of consuming a diet rich in whole grain and dietary fibre (DF) are evident, and cereal DF complex is most likely behind the beneficial effects.
The first part of the study investigated the effect of bread structure on mastication-induced structure disintegration, starch hydrolysis and dissolution of compounds from bread matrices. Despite the structural differences among the studied rye and wheat breads, there were only small differences in mastication processes. However, rye breads disintegrated to smaller particles than wheat bread and starch tended to hydrolyse at a slower rate by salivary α-amylase. A large array of compounds was dissolved from masticated breads to saliva. Specifically, peptides and amino acids were dissolved from rye breads and sugars from wheat bread.
The relevance of food structure to satiety was explored in the second part of the study. Among rye products with different structures and similar chemical compositions, portions of wholemeal rye bread or extruded wholemeal rye puffs and juice were more effective than the portion of extruded wholemeal rye flakes and juice to maintain some aspects of satiety. Intense oral processing did not relate to satiety response but perceived pleasantness and satiety expectations did. Less pleasant food portions resulted in enhanced satiety as well as those that were anticipated already prior to ingestion to be satiating. Oat bran added to juice was more effective in maintaining the feelings of satiety and fullness compared to oat bran incorporated in biscuit matrix.
The results showed that disintegration of bread structure and the release of compounds differed between bread types already in mastication. The current study was the first to explore the dissolution of compounds from food, namely bread, after mastication using non-targeted metabolomics approach. The significance of the released compounds warrants further research. The study also showed that food structure is of importance for the postprandial satiety responses of high fibre cereal foods. Perceptions of food, such as liking and expectations, as well as interactions of solid and liquid components (hydration and dissolution) of meal in stomach, are suggested to explain the observed differences in satiety responses.
Background:
Most persons with type 2 diabetes are overweight and obesity worsens the metabolic and physiologic abnormalities associated with diabetes.
Objective:
The objective of this review is to assess the effectiveness of lifestyle and behavioral weight loss and weight control interventions for adults with type 2 diabetes.
Methods:
Search methods: Studies were obtained from computerized searches of multiple electronic bibliographic databases, supplemented with hand searches of selected journals and consultation with experts in obesity research.
Selection criteria:
Studies were included if they were published or unpublished randomized controlled trials in any language, and examined weight loss or weight control strategies using one or more dietary, physical activity, or behavioral interventions, with a follow-up interval of at least 12 months.
Data collection and analysis:
Effects were combined using a random effects model.
Main results:
The 22 studies of weight loss interventions identified had a 4,659 participants and follow-up of 1 to 5 years. The pooled weight loss for any intervention in comparison to usual care among 585 subjects was 1.7 kg (95 % confidence interval [CI] 0.3 to 3.2), or 3.1% of baseline body weight among 517 subjects. Other main comparisons demonstrated non significant results: among 126 persons receiving a physical activity and behavioral intervention, those who also received a very low calorie diet lost 3.0 kg (95% CI -0.5 to 6.4), or 1.6% of baseline body weight, more than persons receiving a low-calorie diet. Among 53 persons receiving identical dietary and behavioral interventions, those receiving more intense physical activity interventions lost 3.9 kg (95% CI -1.9 to 9.7), or 3.6% of baseline body weight, more than those receiving a less intense or no physical activity intervention. Comparison groups often achieved significant weight loss (up to 10.0 kg), minimizing between-group differences. Changes in glycated hemoglobin generally corresponded to changes in weight and were not significant when between-group differences were examined. No data were identified on quality of life and mortality.
Authors conclusions:
Weight loss strategies using dietary, physical activity, or behavioral interventions produced small between-group improvements in weight. These results were minimized by weight loss in the comparison group, however, and examination of individual study arms revealed that multicomponent interventions including very low calorie diets or low calorie diets may hold promise for achieving weight loss in adults with type 2 diabetes.
Oats contain 3-5% of mixed linked beta-glucan, or (1-3), (1-4) β-D-glucan, referred to hereafter as beta-glucan. Oat beta-glucan is a viscous, and soluble dietary fibre component. Soluble and viscous dietary fibres, including the beta-glucan present in oats are associated with two major health promoting effects, i.e. the attenuation of postprandial plasma glucose and insulin levels and the control of cholesterol. Increased viscosity in the intestine delays absorption of glucose and suppresses absorption of cholesterol and reabsorption of bile acids. In spite of its apparent key role physiologically the viscosity of beta-glucan has been discussed relatively little in terms of analytical procedures. In clinical studies performed with oats, the viscosity of beta-glucan has been properly documented in only a few cases. Viscosity of beta-glucan in foods and in the food digest depends on solubility, concentration and molecular weight. A food manufacturer aiming at health-promoting products must pay attention not only to sufficient concentration of beta-glucan (dose) in the raw material, but also to the processing methods that will ensure sufficient solubility of beta-glucan and minimize enzymatic or mechanical breakdown of the beta-glucan molecule. We have been working both with different food processes utilising oat fractions high in beta-glucan and with the development of a method for viscosity determination of the soluble beta-glucan fibre. This review discusses some of the aspects related to the development with a method that could predict the behaviour of beta-glucan in oat processing with respect to its anticipated physiological functions.
The effects of a meal with and without soluble dietary fiber in the form of E-glucan on short- term satiety and glucose response were investigated in 19 overweight subjects. Subjects con- sumed four isocaloric test meals consisting of a glucose solution or wheat (0 g of E-glucan), a wheat-barley mixture (1 g of E-glucan), or barley (2 g of E-glucan) served as cooked cereal with low-fat strawberry yogurt. Subjects used visual analog scales (VAS) to rate their hunger, full- ness, satisfaction, thirst, nausea, and drowsiness at timed intervals before and after consumption of each test meal. Blood glucose was measured periodically, and energy intake was recorded 2 hr after consumption of each test meal. In women peak glucose responses and area under the curve were significantly lower after consumption of 2 g of E-glucan compared with consumption of 0 or 1 g of E-glucan. VAS ratings did not significantly differ among cereals. In men no effect of E- glucan on glucose response was observed, and E-glucan had only a marginal effect on VAS rat- ings. Energy intake was not affected by E-glucan level in either women or men. The findings in- dicate that acute reduction of glycemic response in overweight women requires the consumption of at least 2 g of E-glucan per meal, and greater amounts of E-glucan per meal may be required to achieve substantial satiety effects in overweight women and men.
The viscosity of soluble fibers such as β-glucan depends on their concentration in solution and molecular weight (MW) distribution. We investigated whether freezing treatment of oat bran muffins affected the physicochemical properties of β-glucan, and its physiological effective-ness in lowering postprandial blood glucose response. A controlled range of β-glucan solubility was achieved by subjecting oat bran muffins containing two levels of β-glucan to repeated freeze-thaw temperature cycling. β-Glucan solubilized by in vitro digestion extraction was measured by flow-injection analysis. MW distributions of β-glucan were analyzed using size-exclusion chromatography. β-Glucan solubility decreased as the number of freeze-thaw cycles increased, while MW distribution of β-glucan decreased slightly. Peak blood glucose rise (PBGR) after fresh muffins (8 and 12 g of β-glucan/serving) was significantly lower than that after muffins (8 and 12 g of β-glucan/serving) treated with four freeze-thaw (FT) cycles (1.84 ± 0.2 vs. 2.31 ± 0.1 mmol/L, P = 0.007). Compared with the control whole wheat muffins, the reduction in incremental area under the glucose response curve (AUC) after fresh muffins (8 and 12 g of β-glucan/serving) was nearly twice that after 4 FT cycles (43.3 ± 4.4% vs. 27.0 ± 5.4%, P = 0.016). A significant inverse linear relationship was found between the log [concentration] of extractable β-glucan and PBGR (r2 = 0.85, P = 0.01), and AUC (r2 = 0.71, P = 0.03). The results show that reduction of β-glucan solubility in foods attenuates its physiological effectiveness in lowering postprandial glycemia.
Cereal Chem. 85(2):211–217 Oat bran muffins, containing 4 or 8 g of β-glucan per two-muffin serv-ing, were prepared with or without β-glucanase treatment to produce a range of β-glucan molecular weights from 130,000 to just over 2 million. Following an overnight fast, the glycemic responses elicited by the un-treated and treated muffins was measured in 10 healthy subjects and compared with a control whole wheat muffin. Taken all together, the 4-g β-glucan/serving muffins reduced blood glucose peak rise (PBGR) by 15 ± 6% compared with the control. The 8-g β-glucan/serving muffins had a significantly greater effect (44 ± 5% reduction compared with the control, P < 0.05). The efficacy of the muffins decreased as the molecular weight was reduced from a 45 ± 6% reduction in PBGR (P < 0.05) for the un-treated muffins (averaged of both serving sizes) to 15 ± 6% (P < 0.05) for muffins with the lowest molecular weight. As the molecular weight was reduced from 2,200,000 to 400,000, the solubility of the β-glucan in-creased from a mean of 44 to 57%, but as the molecular weight was fur-ther decreased to 120,000, solubility fell to 26%. There was a significant correlation (r 2 = 0.729, P < 0.001) between the peak blood glucose and the product of the extractable β-glucan content and the molecular weight of the β-glucan extracted.
Complete solubilisation of barley or malt β-glucan was obtained by extraction with dilute acid. Investigation of the extraction
procedure by high performance size exclusion chromatography indicates that originally water insoluble high molecular weight
β-glucan is solubilized by degradation to smaller fragments. The fluorescence emitted by the specific complex formed between
Calcofluor and β-glucan in solution was used to measure the total β-glucan content of barley and malt samples. Examination
of the residues after the extraction with dilute acid by degradation with (1→3)(1→4)-β-D-glucanase and by fluorescence microscopy of Calcofluor stained residues confirmed the complete extraction of the β-glucan.
Comparison between the Calcofluor-FIA method and the enzymatic method ofMcCleary andGlennie-Holmes (20) revealed a high correlation between the values obtained by the two methods. 39 barleys and 57 malts were analysed for
β-glucan content with the two methods and linear correlation coefficients of r = 0.977 and r = 0.986, respectively, were found.
The system enables a large number of barley or malt β-glucan determinations to be performed within a short period of time
with a minimum of manpower. The method is suitable for standard routine analysis in quality control laboratories.
To evaluate the impact of an extruded muesli product based on beta-glucan-rich oat bran on postprandial glycaemia and insulinaemia. SUBJECT/DESIGN: The study is divided in two series. Blood glucose and serum insulin responses were studied after subjects consuming test meals including a serving of muesli with 3 g (series 1) and 4 g (series 2) of beta-glucans, respectively. The muesli was a component in a single serving packet with muesli and yoghurt. This was served together with white wheat bread in the morning after an overnight fast. The compositions were standardized to contain 50 g available carbohydrates. As a reference meal a serving packet without beta-glucans was included. The study was performed at Applied Nutrition and Food Chemistry, Lund University, Sweden. Nineteen and thirteen healthy volunteers with normal body mass index were recruited for series 1 and 2, respectively.
Muesli with 3 g of beta-glucans, included in a mixed bread meal, gave no significant differences in glycaemic response compared to a reference meal without muesli and beta-glucans. In contrast, muesli with 4 g of beta-glucans significantly (P<0.05) lowered the glucose and insulin responses compared to the reference meal.
Muesli enriched with 4 g of beta-glucans reduces postprandial glucose and insulin levels to a breakfast based on high glycaemic index products. A total of 4 g of beta-glucans from oats seems to be a critical level for a significant decrease in glucose and insulin responses in healthy people.
Viscous fibers, including beta-glucan in oat bran, favorably affect satiety as well as postprandial carbohydrate and lipid metabolism. However, effects of fiber viscosity on modulation of satiety-related gut hormone responses are largely unknown. We examined the effects of modified oat bran, with or without its natural viscosity, on sensations of appetite and satiety-related gastrointestinal (GI) hormone responses to establish the relevance of viscosity of beta-glucan in oat bran. Twenty healthy, normal-weight participants (16 female, 4 male, aged 22.6 +/- 0.7 y) ingested 2 isocaloric (1250 kJ) 300-mL oat bran beverages with low or high viscosity (carbohydrates, 57.9 g; protein, 7.8 g; fat, 3.3 g; fiber, 10.2 g) after a 12-h fast in randomized order. Viscosity of the low-viscosity oat bran beverage was reduced by beta-glucanase treatment. Blood samples were drawn before and 15, 30, 45, 60, 90, 120, and 180 min after beverage consumption. The oat bran beverage with low viscosity induced a greater postprandial increase in satiety (P = 0.048) and plasma glucose (P < 0.001), insulin (P = 0.008), cholecystokinin (P = 0.035), glucagon-like peptide 1 (P = 0.037), and peptide YY (P = 0.051) and a greater decrease in postprandial ghrelin (P = 0.009) than the beverage with high-viscosity oat bran. Gastric emptying as measured by paracetamol absorption was also faster (P = 0.034) after low-viscosity oat bran beverage consumption. In conclusion, viscosity differences in oat beta-glucan in a liquid meal with identical chemical composition strongly influenced not only glucose and insulin responses, but also short-term gut hormone responses, implying the importance of food structure in the modulation of postprandial satiety-related physiology.
Studies in animals suggest a physiological role for glucagon-like peptide-1-(7-36)-amide (GLP-1) in regulating satiety. The role of GLP-1 in regulating food intake in man has, however, not been investigated. Subjects-Sixteen healthy male subjects were examined in a double blind placebo controlled fashion.
The effect of graded intravenous doses (0, 0.375, 0.75, and 1.5 pmol/kg/min) of synthetic human GLP-1 on food intake and feelings of hunger and satiety was tested in healthy volunteers.
Graded GLP-1 infusions resulted in a dose dependent reduction in food intake (maximal inhibition 35%, p<0.001 v control) and a similar reduction in calorie intake (32%; p<0.001). Fluid ingestion was also reduced by GLP-1 (18% reduction, p<0.01). No overt side effects were produced by GLP-1, but subjects experienced less hunger and early fullness in the period before a meal during GLP-1 infusion at the highest dose (p<0.05).
Intravenous infusions of GLP-1 decrease spontaneous food intake even at physiological plasma concentrations, implying an important role for GLP-1 in the regulation of the early satiety response in humans.
To examine reproducibility and validity of visual analogue scales (VAS) for measurement of appetite sensations, with and without a diet standardization prior to the test days.
On two different test days the subjects recorded their appetite sensations before breakfast and every 30 min during the 4.5 h postprandial period under exactly the same conditions.
55 healthy men (age 25.6+/-0.6 y, BMI 22.6+/-0.3 kg¿m2).
VAS were used to record hunger, satiety, fullness, prospective food consumption, desire to eat something fatty, salty, sweet or savoury, and palatability of the meals. Subsequently an ad libitum lunch was served and energy intake was recorded. Reproducibility was assessed by the coefficient of repeatability (CR) of fasting, mean 4.5 h and peak/nadir values.
CRs (range 20-61 mm) were larger for fasting and peak/nadir values compared with mean 4.5 h values. No parameter seemed to be improved by diet standardization. Using a paired design and a study power of 0.8, a difference of 10 mm on fasting and 5 mm on mean 4.5 h ratings can be detected with 18 subjects. When using desires to eat specific types of food or an unpaired design, more subjects are needed due to considerable variation. The best correlations of validity were found between 4.5 h mean VAS of the appetite parameters and subsequent energy intake (r=+/-0.50-0.53, P<0.001).
VAS scores are reliable for appetite research and do not seem to be influenced by prior diet standardization. However, consideration should be given to the specific parameters being measured, their sensitivity and study power. International Journal of Obesity (2000)24, 38-48
Accumulating data indicate that a diet characterized by low glycaemic-index (GI) foods not only improves certain metabolic ramifications of insulin resistance, but also reduces insulin resistance per se. Epidemiological data also suggest a protective role against development of non-insulin-dependent diabetes mellitus and cardiovascular disease. A major disadvantage in this connection is the shortage of low-GI foods, and many common starchy staple foods, such as bread products, breakfast cereals and potato products, have a high GI. Studies in our laboratory show that it is possible to significantly lower the GI of starchy foods, for example by choice of raw material and/or by optimizing the processing conditions. Such low-GI foods may or may not influence glucose tolerance at a subsequent meal. Consequently, certain low-GI breakfasts capable of maintaining a net increment in blood glucose and insulin at the time of the next meal significantly reduced post-prandial glycaemia and insulinaemia following a standardized lunch meal, whereas others had no 'second-meal' impact. These results imply that certain low-GI foods may be more efficient in modulating metabolism in the long term. Although the literature supports a linear correlation between the GI and insulinaemic index (II) of foods, this is not always the case. Consequently, milk products elicited elevated IIs, indistinguishable from a white bread reference meal, despite GIs in the lower range. This inconsistent behaviour of milk products has not been acknowledged, and potential metabolic consequences remain to be elucidated.
The recently discovered orexigenic peptide ghrelin is produced primarily by the stomach and circulates in blood at levels that increase during prolonged fasting in rats. When administered to rodents at supraphysiological doses, ghrelin activates hypothalamic neuropeptide Y/agouti gene-related protein neurons and increases food intake and body weight. These findings suggest that ghrelin may participate in meal initiation. As a first step to investigate this hypothesis, we sought to determine whether circulating ghrelin levels are elevated before the consumption of individual meals in humans. Ghrelin, insulin, and leptin were measured by radioimmunoassay in plasma samples drawn 38 times throughout a 24-h period in 10 healthy subjects provided meals on a fixed schedule. Plasma ghrelin levels increased nearly twofold immediately before each meal and fell to trough levels within 1 h after eating, a pattern reciprocal to that of insulin. Intermeal ghrelin levels displayed a diurnal rhythm that was exactly in phase with that of leptin, with both hormones rising throughout the day to a zenith at 0100, then falling overnight to a nadir at 0900. Ghrelin levels sampled during the troughs before and after breakfast correlated strongly with 24-h integrated area under the curve values (r = 0.873 and 0.954, respectively), suggesting that these convenient, single measurements might serve as surrogates for 24-h profiles to estimate overall ghrelin levels. Circulating ghrelin also correlated positively with age (r = 0.701). The clear preprandial rise and postprandial fall in plasma ghrelin levels support the hypothesis that ghrelin plays a physiological role in meal initiation in humans.
Various botanical and structural characteristics of starchy food modify the postprandial glucose and insulin responses in humans.
We investigated what factors in grain products affect human glucose and insulin responses and elucidated the mediating mechanisms.
Ten men and 10 women [mean age: 28 +/- 1 y; mean body mass index (in kg/m(2)): 22.9 +/- 0.7] with normal glucose tolerance were recruited. The test products were whole-kernel rye bread, whole-meal rye bread containing oat beta-glucan concentrate, dark durum wheat pasta, and wheat bread made from white wheat flour. Paracetamol, a marker of the rate of gastric emptying, was added to the breads during baking. Each product provided 50 g available carbohydrate and was served in random order with breakfast (except for the beta-glucan rye bread, which was served at the last visit). Fasting and 8 postprandial blood samples were collected at intervals of 15-30 min for 3 h to determine plasma glucose, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), serum insulin, and paracetamol concentrations. The in vitro starch hydrolysis, the structural characteristics (by light microscopy), and the molecular weight of beta-glucan in the test products were analyzed.
Glucose responses and the rate of gastric emptying after consumption of the 2 rye breads and pasta did not differ from those after consumption of white wheat bread. However, insulin, GIP, and GLP-1 responses, except for GLP-1 responses to the rye bread containing oat beta-glucan concentrate, were lower after the consumption of rye breads and pasta than after consumption of white wheat bread.
Postprandial insulin responses to grain products are determined by the form of food and botanical structure rather than by the amount of fiber or the type of cereal in the food. These effects may be mediated through GIP and GLP-1.
Epidemiologic studies that directly examine changes in whole-grain consumption in relation to weight gain are sparse, and characterization of this association has been obscured by methodologic inconsistencies in the assessment of whole grains.
We aimed to ascertain the associations between changes in new quantitative estimates of whole-grain intake and 8-y weight gain among US men.
The study was conducted in a prospective cohort of 27 082 men aged 40-75 y at baseline in 1986. Data on lifestyle factors were obtained periodically by using self-reported questionnaires, and participants measured and reported their body weight in 1986 and 1994.
In multivariate analyses, an increase in whole-grain intake was inversely associated with long-term weight gain (P for trend < 0.0001). A dose-response relation was observed, and for every 40-g/d increment in whole-grain intake from all foods, weight gain was reduced by 0.49 kg. Bran that was added to the diet or obtained from fortified-grain foods further reduced the risk of weight gain (P for trend = 0.01), and, for every 20 g/d increase in intake, weight gain was reduced by 0.36 kg. Changes in cereal and fruit fiber were inversely related to weight gain. No associations were observed between changes in refined-grain or added germ consumption and body weight.
The increased consumption of whole grains was inversely related to weight gain, and the associations persisted after changes in added bran or fiber intakes were accounted for. This suggests that additional components in whole grains may contribute to favorable metabolic alterations that may reduce long-term weight gain.
Cholecystokinin (CCK) is associated with fat-induced satiety.
The primary objective of the present study was to determine, in an acute meal setting, whether the availability of dietary fat for alimentary processing, and hence the stimulation of CCK, affects the postmeal satiety response in men and women.
In a within-subjects design, subjects (8 men, 7 women) consumed 1 of 3 isoenergetic mixed-food test meals 1 wk apart in random order. The test meals contained 30% of energy from fat, of which more than two-thirds was derived from whole almonds, almond oil, or a mix of safflower and corn oils. Visual analogue scales were used to assess indexes of satiety at defined time points up to 6 h after meal consumption. Blood was sampled at corresponding time points for measurement of CCK, glucose, insulin, and triacylglycerol. Subsequent food intake was also assessed.
All meals suppressed hunger and induced a pattern of satiety that was sex-specific and corresponded with the CCK response. Women had higher plasma CCK concentrations and experienced greater satiety after the almond oil and control meals (fat as oil) than after the whole almond meal (fat in whole food structure). Men showed no differential response among meals for CCK and satiety. Plasma triacylglycerol differed by time among meals but not by sex, and no significant differences in glucose and insulin were found.
The satiety response to dietary fat provided in oil or whole food form is influenced by sex and is dependent on the availability of fat to stimulate CCK release in women but not in men.
Background: Various botanical and structural characteristics of starchy food modify the postprandial glucose and insulin responses in humans.
Objective: We investigated what factors in grain products affect human glucose and insulin responses and elucidated the mediating mechanisms.
Design: Ten men and 10 women [mean age: 28 ± 1 y; mean body mass index (in kg/m²): 22.9 ± 0.7] with normal glucose tolerance were recruited. The test products were whole-kernel rye bread, whole-meal rye bread containing oat β-glucan concentrate, dark durum wheat pasta, and wheat bread made from white wheat flour. Paracetamol, a marker of the rate of gastric emptying, was added to the breads during baking. Each product provided 50 g available carbohydrate and was served in random order with breakfast (except for the β-glucan rye bread, which was served at the last visit). Fasting and 8 postprandial blood samples were collected at intervals of 15–30 min for 3 h to determine plasma glucose, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), serum insulin, and paracetamol concentrations. The in vitro starch hydrolysis, the structural characteristics (by light microscopy), and the molecular weight of β-glucan in the test products were analyzed.
Results: Glucose responses and the rate of gastric emptying after consumption of the 2 rye breads and pasta did not differ from those after consumption of white wheat bread. However, insulin, GIP, and GLP-1 responses, except for GLP-1 responses to the rye bread containing oat β-glucan concentrate, were lower after the consumption of rye breads and pasta than after consumption of white wheat bread.
Conclusions: Postprandial insulin responses to grain products are determined by the form of food and botanical structure rather than by the amount of fiber or the type of cereal in the food. These effects may be mediated through GIP and GLP-1.
The glycaemic index (GI) is a ranking of foods based on the post prandial blood glucose response in comparison with a reference food. The GI concept has been successfully applied to diabetes management, sports performance and appetite research, or wherever fluctuations in blood sugar levels are considered important. In recent years it has become the accepted method of classifying carbohydrate foods and nearly 600 separate foods have been tested, with values for most common western foods, many ethnic foods and pure sugar solutions. Despite early controversy, most studies have found the GI concept to be reproducible, predictable within the context of mixed meals and clinically useful in long term studies of carbohydrate and lipid metabolism. In Australia, the GI concept has stepped out of the research arena and is being used as an education tool in several diabetes education centres and sports clinics. GI research has exploded many widely-held assumptions about sugars and starches. Foods containing starches more often have high glycaemic index (GI). In fact, foods containing sugars don't often have a high GI value and restriction of sugars actually raises the overall GI of the diet. Furthermore, there is no major distinction in terms of their GI between foods containing naturally-occurring sugars and those made with refined sugars. The GI of foods correlates well with insulin responses and as such has implications for the primary prevention of non-insulin-dependent diabetes mellitus and coronary heart disease.
A simple and quantitative method for the determination of (1→3) (1→4)-β-D-glucan in barley flour and malt is described. The method allows direct analysis of β-glucan in flour and malt slurries. Mixed-linkage β-glucan is specifically depolymerized with a highly purified (1→3) (1→4)-β-D-glucanase (lichenase), from Bacillus subtilis, to tri-, tetra- and higher degree of polymerization (d.p.) oligosaccharides. These oligosaccharides are then specifically and quantitatively hydrolysed to glucose using purified β-D-glucosidase. The glucose is then specifically determined using glucose oxidase/peroxidase reagent. Since barley flours contain only low levels of glucose, and maltosaccharides do not interfere with the assay, removal of low d.p. sugars is not necessary. Blank values are determined for each sample allowing the direct measurement of β-glucan in maltsamples.α-Amylasedoes not interfere with the assay. The method issuitable for the routineanalysis of β-glucan in barley samples derived from breeding programs; 50 samples can be analysed by a single operator in a day. Evaluation of the technique on different days has indicated a mean standard error of 0–1 for barley flour samples containing 3–8 and 4–6% (w/w) β-glucan content.
Cereal Chem. 81(3):356-360 Oats, different oat fractions as well as experimental and commercial oat-based foods, were extracted with hot water containing thermostable α-amylase. Average molecular weight and molecular weight distributions of β-glucan in extracts were analyzed with a calibrated high-performance size-exclusion chromatography system with Calcofluor detection, specific for the β-glucan. Oats, rolled oats, oat bran, and oat bran concentrates all had high Calcofluor average molecular weights (206 × 10 4 to 230 × 10 4
Cereal Chem. 74(6):705–709 The extractability and molecular weight of β-glucan in oat bran, oat bran muffins, and oat porridge and the changes taking place during proc-essing and storage were studied. The β-glucan was extracted using hot water and a thermostable α-amylase and by an in vitro system that simulated human digestion. Molecular weight (MW) of the extracted β-glucan was determined using high-performance size-exclusion chroma-tography. Hot-water treatment extracted 50–70% of total β-glucan in oat bran samples and rolled oats. The chromatographic peak MW of extracted β-glucan was in the 1.4–1.8 × 10 6 range. Using the in vitro digestion system, 12–33% of total β-glucan in bran and rolled oats was solubilized, and peak MW was in the same range as β-glucan extracted by hot-water treatment. In muffins, 30–85% of total β-glucan was solubilized by in vitro digestion, with a major difference in extractability among muffins from different recipes. Peak MW of extracted β-glucan was lower in all muffins when compared to original bran. During frozen storage, extractable β-glucan decreased by >50% in all muffins, but no change in peak MW of extracted β-glucan was detected.
Milling fractions of hull-less barley, and dough and bread with hull-less barley flour (40%) and wheat flour (60%) were analysed in an investigation of how the properties of (1→3, 1→4)-β-glucan were affected by milling, dough formation and bread making. Calcofluor average molecular weight and molecular weight distribution and the cellotriosyl/cellotetraosyl ratio of the (1→3, 1→4)-β-glucan were determined. Four different hull-less barley samples were milled to produce straight-run white flours, shorts, bran and whole-meal flours. The molecular weight distributions were unimodal for all fractions, and the range was between 117×104 and 188×104. These parameters were similar for all barleys, although was somewhat lower in white flour and bran fractions and somewhat higher in shorts and whole-meal. The cellotriosyl/cellotetraosyl ratio (1.5–1.8) was also similar in all fractions. Doughs and breads were made to study how flour type (sifted or whole-meal barley flour), water content, yeast, mixing time and fermentation time affect (1→3, 1→4)-β-glucan. The molecular weight distribution of (1→3, 1→4)-β-glucan was polymodal with two or three populations for all doughs and breads, and the decreased with increasing mixing and fermentation time. These results indicated that (1→3, 1→4)-β-glucan was degraded by endogenous β-glucanases in the barley and/or wheat flour. The molecular weight was not significantly affected by bread-baking and other factors. After mixing and fermentation the cellotriosyl/cellotetraosyl ratio was about 1.7–1.8 and was thus not significantly different from that of the flour blends. Thus to retain high molecular weight (1→3, 1→4)-β-glucan, which is important for its cholesterol-lowering effect, it is thus important to keep the mixing and fermentation time as short as possible when baking hull-less barley bread.
In addition to the well-known effects of reducing blood cholesterol and affecting glycaemic response, dietary fibre of oat bran has been shown to have numerous other physiological effects. It delays gastric emptying, diminishes absorption of nutrients, affects the motility in the small bowel, and prolongs satiety after the meal. In the large bowel, soluble dietary fibre increases the fermentation activity, especially production of butyric acid, enhances growth and colonisation of some probiotic bacterial strains, increases production of microbial mass and thereby aids the removal of nitrogen via faeces. It also increases wet weight of stools, thereby alleviating constipation. Short-chain fatty acids formed enhance cell proliferation of the colonic mucosa. According to the present view, this reduces the risk of colon cancer. In addition to the effects of the viscosity of the intestinal contents and colon fermentation, the physiological effects are in part mediated via insulin and gastrointestinal hormone secretion. Papers documenting these effects are reviewed.
To test the a priori hypothesis that consumption of oats will lower the blood total cholesterol level and to assess modifiers and confounders of this association.
A computerized literature (MEDLINE) search and the Quaker Oats Co identified published and unpublished trials as of March 1991. Raw data were requested for all trials.
Trials were included in summary effect size estimates if they were randomized and controlled, if a formal assessment of diet and body weight changes occurred, and, if raw data were not received, if there was enough information in the published report to perform calculations.
Twenty trials were identified. Using the methods of DerSimonian and Laird, a summary effect size for change in blood total cholesterol level of -0.13 mmol/L (-5.9 mg/dL) (95% confidence interval [CI], -0.19 to -0.017 mmol/L [-8.4 to -3.3 mg/dL]) was calculated for the 10 trials meeting the inclusion criteria. The summary effect size for trials using wheat control groups was -0.11 mmol/L (-4.4 mg/dL) (95% CI, -0.21 to -0.01 mmol/L [-8.3 to -0.38 mg/dL]). Calculation of Keys scores demonstrated that substituting carbohydrates for dietary fats and cholesterol did not account for the majority of blood cholesterol reduction. Larger reductions were seen in trials in which subjects had initially higher blood cholesterol levels (greater than or equal to 5.9 mmol/L [greater than or equal to 229 mg/dL]), particularly when a dose of 3 g or more of soluble fiber was employed.
This analysis supports the hypothesis that incorporating oat products into the diet causes a modest reduction in blood cholesterol level.
Studies in rodents have shown that short-term increases in dietary fat result in fat cell enlargement and insulin resistance. In humans, although high-fat diets have been associated with obesity, little is known about the specific metabolic effects of these diets. In this study we explored possible associations between habitual dietary composition and insulin sensitivity. Twenty-two lean and 23 obese subjects were characterized by dietary history (food frequency questionnaire), anthropometrics, oral glucose tolerance, and insulin sensitivity (SI, from the minimal model). As shown previously, body mass index was positively correlated with percent of energy intake as fat (r = 0.47, P = 0.001). Increasing fat intake was also associated with diminished SI (r = -0.41, P = 0.01). In contrast, SI was positively correlated with fiber intake (r = 0.43, P = 0.007). Multivariate analysis confirmed the importance of dietary fiber for SI. We conclude that habitually low dietary fiber intake, along with elevated dietary fat, correlates with diminished SI in otherwise healthy lean and obese subjects.
The effects of sterilization and oat bran enrichment of pasta on the glucose and insulin responses in healthy subjects were evaluated. Cooked and canned spaghetti and cooked fettucini without and with enrichment with oat bran (28%) were compared. Further, the effects of various low- and high-temperature drying conditions for spaghetti, cooking time and sterilization on the starch digestion rate and content of enzyme-resistant starch (RS) in vitro were also studied. Various cooking quality data were also determined to allow interpretation of results. The incremental glucose area (0-120 min) produced by canned spaghetti was twice the area of that produced by cooked spaghetti (69.03 vs 35.45 mmol/l x min, P less than 0.01). The incremental insulin area (0-120 min) was also significantly higher with canned spaghetti (17,500 vs 12,600 pmol/l x min, P less than 0.05). The rapid digestion was caused by excessive swelling of starch during sterilization that promoted a very soft texture of the spaghetti. Enrichment of fettucini with oat bran reduced slightly the incremental insulin area (15,600 vs 20,100 pmol/l x min, P less than 0.05, for 0-120 min), but did not significantly reduce the glucose area. Drying conditions and cooking times could be varied within broad limits without affecting the rate of starch digestion in vitro of cooked spaghetti. In sterilized spaghetti the content of resistant starch was higher than that found in cooked 'al dente' spaghetti (2.2-3.4 vs 0.5 mg/100 mg total starch). In conclusion, sterilization influences the nutritional properties of starch in pasta by substantially increasing the glucose and insulin responses and by formation of resistant starch. The effect of oatbran environment is restricted mainly to a slight decrease in the insulin response.
Sixty slightly overweight women were treated with a weight-reducing diet for 12 weeks in a randomized, double-blind, placebo-controlled study. In addition to the diet 30 women received dietary fibre tablets, whereas the remaining 30 women received identical-looking placebo tablets. During the trial both groups experienced a significant reduction in body weight (P less than 0.01). The mean weight loss 8.5 kg (7.5-9.5 kg) in the fibre group was significantly higher than that of the placebo group 6.7 kg (4.8-8.0 kg) (P less than 0.01). Both serum triglyceride and serum cholesterol concentrations were significantly lowered (P less than or equal to 0.02) after treatment in both groups. No significant differences were detected between the groups. Both systolic and diastolic blood pressure were significantly reduced (P less than 0.01) in the fibre group. No significant reduction in blood pressure was found in the placebo group. Side-effects, which were gastrointestinal in nature, were of low frequency. We conclude that supplementation with dietary fibre of the form used in this study is useful in the treatment of overweight women.
This report describes the construction of a questionnaire to measure three dimensions of human eating behavior. The first step was a collation of items from two existing questionnaires that measure the related concepts of 'restrained eating' and 'latent obesity', to which were added items newly written to elucidate these concepts. This version was administered to several populations selected to include persons who exhibited the spectrum from extreme dietary restraint to extreme lack of restraint. The resulting responses were factor analyzed and the resulting factor structure was used to revise the questionnaire. This process was then repeated: administration of the revised questionnaire to groups representing extremes of dietary restraint, factor analysis of the results and questionnaire revision. Three stable factors emerged: (1) 'cognitive restraint of eating', (2) 'disinhibition' and (3) 'hunger'. The new 51-item questionnaire measuring these factors is presented.
The construct validity and the test-retest reliability of a self-administered questionnaire about habitual physical activity were investigated in young males (n = 139) and females (n = 167) in three age groups (20 to 22, 25 to 27, and 30 to 32 yr) in a Dutch population. By principal components analysis three conceptually meaningful factors were distinguished. They were interpreted as: 1) physical activity at work; 2) sport during leisure time; and 3) physical activity during leisure time excluding sport. Test-retest showed that the reliability of the three indices constructed from these factors was adequate. Further, it was found that level of education was inversely related to the work index, and positively related to the leisure-time index in both sexes. The subjective experience of work load was not related to the work index, but was inversely related to the sport index, and the leisure-time index in both sexes. The lean body mass was positively related the the work index, and the sport index in males, but was not related to the leisure-time index in either sex. These differences in the relationships support the subdivision of habitual physical activity into the three components mentioned above.
This study was conducted to determine the relationships among the specific components of dietary fat and carbohydrate and body fatness in lean and obese adults.
Body composition determination was performed on each subject by hydrostatic weighing at residual volume. Subsequently, the individual components of dietary fat and carbohydrate were examined relative to body fatness using a 3-day food diary and a food frequency questionnaire.
Subjects were 23 lean (11.1 +/- 2.9% body fat) men, 23 obese (29.2 +/- 3.8% body fat) men, 17 lean (16.7 +/- 3.3% body fat) women, and 15 obese (42.7 +/- 3.9% body fat) women who volunteered for free diet and body composition analyses. Inclusion criteria were 15% body fat for lean men, 25% for obese men, 20% for lean women, and 35% for obese women.
Group comparisons for dietary variables were made with a multivariate analysis of variance.
No differences were found between lean and obese subjects for energy intake or total sugar intake, but obese subjects derived a greater portion of their energy from fat (33.1 +/- 2.6% and 36.3 +/- 2.3% for obese men and women, respectively, vs 29.1 +/- 1.3% and 29.6 +/- 2.0%, lean men and women, respectively). Percent of fat intake for saturated, monounsaturated, and polyunsaturated fats was not different among groups. Obese subjects derived a greater percentage of their sugar intake from added sugars than lean subjects (38.0 +/- 3.5% vs 25.2 +/- 2.0%, respectively, for men; 47.9 +/- 8.0% vs 31.4 +/- 3.4%, respectively, for women). Dietary fiber was lower for obese men (20.9 +/- 1.8 g) and women (15.7 +/- 1.1 g) than for lean men (27.0 +/- 1.8 g) and women (22.7 +/- 2.1 g).
Obesity is maintained primarily by a diet that is high in fat and added sugar and relatively low in fiber. Alterations in diet composition rather than energy intake may be a weight control strategy for overweight adults.
ALFEERI, MARGARET AH, JOCELINE POMERLEAU, D MICHAEL GRACE AND LORRAINE ANDERSON. Fiber intake of normal weight, moderately obese and severely obese subjects. Obes Res.
The lack of dietary fiber may be a contributing factor in obesity. This study examined the fiber intake of three weight groups: normal (20.0≤BMI≤27.0), moderately obese (27.1≤BMI≤39.9) and severely obese (BMI≥40.0). Each group contained 50 subjects. Detailed 3-day food records were used to gather the nutritional data. Fiber intake in the normal weight group was 18.8 ± 9.3 grams, the moderately obese consumed 13.3 ± 5.8 grams of fiber and the severely obese 13.7 ± 5.7 grams. Total fiber intake in grams was found to be significantly higher in the lean group (p<0.05) and was positively associated with sex and education level with men and more highly educated individuals consuming more fiber. Using regression analysis total fiber in grams and fiber in g/1000 kcalories was inversely associated with BMI after adjusting for sex, age, education level and income (p<0.01). A high fiber diet may help to promote a negative energy balance by causing early satiety secondary to gastric distention. Dietitians and physicians need to emphasize the importance of a high fiber diet to their obese patients.
To determine if source and amount of carbohydrate affected postprandial glucose and insulin responses, seven nondiabetic subjects consumed 0, 25, 50, 75 or 100 g carbohydrate (total carbohydrate minus total dietary fiber) portions of barley, spaghetti, bread or potato. By ANOVA, both source and amount of carbohydrate had significant effects on incremental response areas for capillary glucose (P = 0.001), plasma glucose (P = 0.01) and plasma insulin (P = 0.03), but there was no source x amount interaction. By regression analysis, source of carbohydrate explained a similar amount of the variability of glucose and insulin responses, 46-64%, as the amount of carbohydrate, 47-57%. Together, carbohydrate source and amount accounted for 85-94% of the variability of mean glucose and insulin responses. We conclude that, for individual foods with different glycemic indices, both source and amount of carbohydrate influence the postprandial glucose and insulin responses of nondiabetic subjects.