No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effects of Oats on Obesity, Weight Management, and Satiety
Abstract
Results from prospective epidemiological studies suggest that a diet rich in whole grains such as oats can help regulate body weight. High habitual consumption of whole grains is inversely associated with body mass index and body weight gain. In addition, increasing consumption of fermentable dietary fibers appears to increase plasma levels of appetite-suppressing gastrointestinal hormones, which may reduce energy intake and promote long-term weight loss. However, clinical intervention studies have not clearly demonstrated that eating oats or oat β-glucan modulates body weight or alters appetite in a manner expected to facilitate weight loss in adults. In general, more well-controlled clinical trials are needed to clarify the relationship between increased consumption of oats or oat β-glucan and regulation of appetite and body weight.
... Die Ballaststoffe des Hafers sind überwiegend fermentierbar, sodass sie von Darmbakterien verstoffwechselt werden und in der Folge die Plasmaspiegel appetitzügelnder Magen-Darm-Hormone erhöhen. Dies kann zu einer Verringerung der Energieaufnahme beitragen und eine langfristige Gewichtsabnahme fördern [33]. ...
... Bisher fehlen jedoch klinische Interventionsstudien, die den Zusammenhang zwischen dem Verzehr von Hafer bzw. Hafer-Beta-Glucan und einer Appetit-und Gewichtsregulierung zweifelsfrei belegen können [33]. ...
Oats as a food has a 1000-year-old tradition in Central Europe. The most common form of oats is oat flakes. For this purpose, the oat grain is first skinned, then heat treated, rolled into flakes and finally dried. Non-drug therapies play a central role in the treatment of people with type 2 diabetes mellitus (T2DM). Oat Days have been known for more than 100 years to improve the metabolic situation in diabetes. The main factor responsible for the effects of oats is probably the oat-specific fiber beta-glucan, which is currently the focus of scientific interest.
... Therefore, it can pass into the colon. This fiber can absorb a considerable amount of water, resulting in increased satiety that helps to control body weight (Cook et al., 2013). In terms of dietary fiber production, the use of chemicals in its production process is a serious concern of consumers (Neltner, 2016). ...
To avoid using a strong alkaline in a dietary fiber extraction process and to reduce residual chemical waste, a natural alkaline solution was tested to extract cellulose fiber from banana peels. A charcoal ash solution could extract fiber from banana peels, and it had a cellulose purity of 74 %, which is comparable to NaOH-treated fiber in terms of its physical and chemical properties. In addition to using fewer chemicals and less complicated techniques, the proposed green technology could extract cellulose at least 10 h faster than the traditional method. Not only dietary fiber was obtained, but the wastewater of this extraction process contained useful phytochemical compounds and it also showed the potential of being a brown fabric dye. Thus, this study reveals a zero-waste concept with green technology by the reuse of agricultural wastes and converting wastewater from the process into value-added products.
... absorbing many water molecules. The swelled cellulose can improve satiety, which effectively manages bodyweight (Cook et al., 2013). On the other hand, the ingestion of soluble fiber-rich foods provides superior health benefits, including blood glucose and cholesterol management (Jovanovski et al., 2019) and reduction of heart disease risk and functions as a fermentable substrate (Tamargo et al., 2019). ...
Cellulose is a kind of dietary fiber that resists digestion and absorption in the human body. In addition to health benefits of cellulose ingestion with regard to body weight management, this fiber may also provide prebiotic activity if its solubility can be enhanced. In this study, cellulose extracted from banana peels was modified by enzymatic and diluted-acid hydrolysis in order to obtain the partially hydrolyzed cellulose, which is a water-soluble fiber, and prebiotic activity involving Lactobacillus plantarum, L. casei, and Escherichia coli was evaluated. The results revealed that enzymatic hydrolysis by Celluclast® provided higher contents of water-soluble cellulose and cellodextrins than did diluted-acid hydrolysis. The sugar pattern by thin layer chromatography also indicated that cellobiose and cellotriose significantly supported the growth and lactic acid production of probiotic strains. After enzymatic hydrolysis, the water-soluble cellulose was kept in 2 forms; 1) solution, and 2) dried powder. However, the dried powder could not be utilized as a sole carbon source by those bacteria since the lyophilization technique dramatically reduced the solubility of the sample. Interestingly, cellulose solution could promote the growth of L. plantarum TISTR2075, but it did not support the growth of E. coli TISTR073. This finding provides a positive prebiotic index value, which is higher than those from inulin, a commercially well-known prebiotic fiber. Therefore, this study presents a novel perspective on consumption of cellulose as a prebiotic fiber.
... Mixed-linkage (1−→3)(1−→4)-β-D-glucan (β-glucan) is a linear polysaccharide composed of D-glucose monomers joined by (1−→4)-glycosidic bonds (∼70%) with an occasional (1−→3)glycosidic bonds (∼30%; Wood et al., 1991). β-glucan is the major soluble fiber in oat and barley (Johansson et al., 2008) and has shown to have physiological benefits including plasma cholesterol lowering (AbuMweis et al., 2010a;Whitehead et al., 2014), reduction of postprandial glycaemic responses (Braaten et al., 1991;Tappy et al., 1996;Jenkins et al., 2002), and weight management via increasing satiety (Maki et al., 2010;Cook et al., 2014). Previous investigations into the mechanisms underlying these beneficial effects are limited to the action of β-glucan in the upper gastrointestinal (GI) tract; however, since humans lack enzymes for the digestion of β-glucan and other dietary fibers, the majority of these compounds are fermented in the lower GI tract via carbohydrate active enzymes (CAZymes) produced by gut microbiota, potentially resulting in compositional and functional shifts in the microbiome (Cantarel et al., 2012;Chassard and Lacroix, 2013). ...
The physiological cholesterol-lowering benefits of β-glucan have been well documented, however, whether modulation of gut microbiota by β-glucan is associated with these physiological effects remains unknown. The objectives of this study were therefore to determine the impact of β-glucan on the composition of gut microbiota in mildly hypercholesterolemic individuals and to identify if the altered microbiota are associated with bioactivity of β-glucan in improving risk factors of cardiovascular disease (CVD). Using a randomized, controlled crossover study design, individuals received for 5-week either a treatment breakfast containing 3 g high molecular weight (HMW), 3 g low molecular weight (LMW), 5 g LMW barley β-glucan, or wheat and rice. The American Heart Association (AHA) diet served as the background diet for all treatment groups. Phases were separated by 4-week washout periods. Fecal samples were collected at the end of each intervention phase and subjected to Illumina sequencing of 16S rRNA genes. Results revealed that at the phylum level, supplementation of 3 g/d HMW β-glucan increased Bacteroidetes and decreased Firmicutes abundances compared to control (P < 0.001). At the genus level, consumption of 3 g/d HMW β-glucan increased Bacteroides (P < 0.003), tended to increase Prevotella (P < 0.1) but decreased Dorea (P < 0.1), whereas diets containing 5 g LMW β-glucan and 3 g LMW β-glucan failed to alter the gut microbiota composition. Bacteroides, Prevotella, and Dorea composition correlated (P < 0.05) with shifts of CVD risk factors, including body mass index, waist circumference, blood pressure, as well as triglyceride levels. Our data suggest that consumption of HMW β-glucan favorably alters the composition of gut microbiota and this altered microbiota profile associates with a reduction of CVD risk markers. Together, our study suggests that β-glucan induced shifts in gut microbiota in a MW-dependent manner and that might be one of the underlying mechanisms responsible for the physiological benefits of β-glucan.
Zusammenfassung
Ziel Befragung von Fachkräften zum aktuellen therapeutischen Einsatz von Hafertagen bei Menschen mit Typ-2-Diabetes (T2D) und anderen Erkrankungen im stationären und ambulanten Bereich in Deutschland.
Methodik Es wurde eine online-basierte, quantitative Umfrage durchgeführt, an der initial 232 Fachkräfte (Diabetesberater*innen, Ärzt*innen, Ernährungsfachkräfte) teilnahmen, 82 Personen beendeten die Umfrage innerhalb der ersten drei Fragen. Zu den übrigen Fragen erfolgten minimal 109 und maximal 150 Antworten. Eine zusätzlich durchgeführte PubMed-Recherche identifizierte drei Studien zu den Stoffwechseleffekten von Hafertagen bei Menschen mit T2D.
Ergebnisse Fast alle Teilnehmenden, die von den therapeutischen Effekten der Hafertage gehört hatten, halten diese für sinnvoll und empfehlen sie Ihren Patient*innen (94%). Als häufigste Gründe für den Einsatz der Hafertage wurden T2D (85%), Insulinresistenz/Prä-Diabetes (81%) und Fettleber (81%) genannt. Deutlich öfter als die strengen (6%) seien modifizierte Hafertage (93%) zu empfehlen. Die Befragten gaben an, dass bei den Patient*innen, die die Hafertagen einsetzten, positive Effekte auf die benötigte Insulinmenge (bei 70%) und auf die Nüchtern-Blutglukosewerte (bei 60%) zu beobachten waren. Am häufigsten werden die Hafertage an einem Tag pro Woche (50%) beziehungsweise an zwei Tagen pro Monat (41%) durchgeführt. In der Literatur wurden drei Interventionsstudien identifiziert, welche zeigten, dass Hafertage zu einer signifikanten Senkung der Insulindosis führten. Bei zwei der Studien konnte vier Wochen nach den Hafertagen ein verminderter HbA1c-Wert nachgewiesen werden. Darüber hinaus gibt es zahlreiche Daten zu den Effekten von Hafer-Beta-Glucan bei T2D, aber auch bei anderen Indikationen wie Fettleber, Fettstoffwechselstörungen und Adipositas.
FazitDie Umfrage bestätigt die hohe Akzeptanz von Hafertagen in der Therapie bei Menschen mit T2D im stationären und ambulanten Bereich.
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.
Wheat is the most widely grown cereal crop in the world. It is the main material of major staple food in many diets, providing a large proportion of daily energy intake [1]. The demand for wheat for human consumption is also increasing globally, including in countries which are climatically unsuited for wheat production, due to the adoption of Western-style diets. After grinding, wheat flour can be used for the preparation of bread, steamed bread, biscuits, noodles, and other foods; wheat flour also can be fermented into beer, alcohol, liquor (such as vodka), or biomass fuel.
Background: Research studies examining foods are important, because they account for biological interactions that might otherwise be lost in the analysis of individual nutrients. Single-nutrient studies are also needed to explore the mechanisms by which foods may be protective.
Objective: Our objective was to examine associations between whole grains, refined grains, and cereal fiber and chronic disease risk factors.
Design: In a cross-sectional analysis of participants in the Baltimore Longitudinal Study of Aging, associations between dietary intakes and risk factors were examined with multivariate linear regression analysis. Dietary intakes were assessed with 7-d dietary records and quantified in g/d.
Results: Compared with subjects in the lowest quintile (Q1) of whole-grain intake, subjects in the highest quintile (Q5) had lower body mass index (BMI; in kg/m²; Q1: 25.5; Q5: 24.8; P for trend <0.0001) and weight (Q1: 75.0 kg; Q5: 72.4 kg; P for trend = 0.004) and smaller waist circumference (Q1: 87.4 cm; Q5: 85.0 cm; P for trend = 0.002). Whole grains were also inversely associated with total cholesterol (P for trend = 0.02), LDL cholesterol (P for trend = 0.04), and 2-h glucose (P for trend = 0.0006). Associations between cereal fiber and anthropometrics and plasma lipids were similar. In subgroup analyses, refined grains were positively associated with fasting insulin among women (P for trend = 0.002).
Conclusions: Similar associations of whole grains and cereal fiber with weight, BMI, waist circumference, plasma cholesterol, and 2-h glucose were observed, suggesting that cereal fiber and its constituents may in part mediate these relations. Refined grains were associated with fasting insulin among women but not men. Additional research should explore potential interaction effects with BMI, sex, age, and genes.
The microbial communities that colonize different regions of the human gut influence many aspects of health. In the healthy state, they contribute nutrients and energy to the host via the fermentation of nondigestible dietary components in the large intestine, and a balance is maintained with the host's metabolism and immune system. Negative consequences, however, can include acting as sources of inflammation and infection, involvement in gastrointestinal diseases, and possible contributions to diabetes mellitus and obesity. Major progress has been made in defining some of the dominant members of the microbial community in the healthy large intestine, and in identifying their roles in gut metabolism. Furthermore, it has become clear that diet can have a major influence on microbial community composition both in the short and long term, which should open up new possibilities for health manipulation via diet. Achieving better definition of those dominant commensal bacteria, community profiles and system characteristics that produce stable gut communities beneficial to health is important. The extent of interindividual variation in microbiota composition within the population has also become apparent, and probably influences individual responses to drug administration and dietary manipulation. This Review considers the complex interplay between the gut microbiota, diet and health.
Several regulatory bodies have approved a health claim on the cholesterol-lowering effects of oat β-glucan at levels of 3·0 g/d. The present study aimed to test whether 1·5 g/d β-glucan provided as ready-to-eat oat flakes was as effective in lowering cholesterol as 3·0 g/d from oats porridge. A 6-week randomised controlled trial was conducted in eighty-seven mildly hypercholesterolaemic ( ≥ 5 mmol/l and < 7·5 mmol/l) men and women assigned to one of three diet arms (25 % energy (E%) protein; 45 E% carbohydrate; 30 E% fat, at energy requirements for weight maintenance): (1) minimal β-glucan (control); (2) low-dose oat β-glucan (1·5 g β-glucan; oats low - OL) or (3) higher dose oat β-glucan (3·0 g β-glucan; oats high - OH). Changes in total cholesterol and LDL-cholesterol (LDL-C) from baseline were assessed using a linear mixed model and repeated-measures ANOVA, adjusted for weight change. Total cholesterol reduced significantly in all groups ( - 7·8 (sd 13·8) %, - 7·2 (sd 12·4) % and - 5·5 (sd 9·3) % in the OH, OL and control groups), as did LDL-C ( - 8·4 (sd 18·5) %, - 8·5 (sd 18·5) % and - 5·5 (sd 12·4) % in the OH, OL and control groups), but between-group differences were not significant. In responders only (n 60), β-glucan groups had higher reductions in LDL-C ( - 18·3 (sd 11·1) % and - 18·1 (sd 9·2) % in the OH and OL groups) compared with controls ( - 11·7 (sd 7·9) %; P = 0·044). Intakes of oat β-glucan were as effective at doses of 1·5 g/d compared with 3 g/d when provided in different food formats that delivered similar amounts of soluble β-glucan.
Normal meals are highly viscous, and viscosity is a key factor in influencing gastric emptying of food. However, the process of meal dilution and mixing is difficult to assess with the use of conventional methods. The aim of this study was to validate an in vivo, novel, noninvasive, echo-planar magnetic resonance imaging (EPI) technique, capable of monitoring the viscosity of a model meal, and to use this to investigate the effects of viscosity on gastric emptying, meal dilution and satiety. Healthy volunteers (n = 8) ingested 500 mL of locust bean gum (0.25, 0.5, 1.0 or 1.5 g/100 g), nonnutrient, liquid meals of varying viscosities, and labeled with a nonabsorbable marker, phenol red. Meal viscosity was calibrated against the water proton transverse relaxation rate (T(2)(-1)) in vitro before ingestion, thus viscosity was measured in vivo via EPI measurements of T(2)(-1). Viscosity and dilution were also measured directly using nasogastric aspirates. Gastric volumes as measured by EPI, fullness, appetite and hunger were also assessed serially. Before ingestion, the log of initial meal viscosity was linearly related to T(2)(-1) (n = 8, r(2) = 0.95). Similarly, T(2)(-1) measured in vivo was also linearly related to the viscosity of the aspirates (r(2) = 0.88). All meals underwent rapid dilution, leading to a reduction in viscosity, which was greatest for the most viscous meal (P < 0.01). Surprisingly, despite the fact that the initial meal viscosity varied 1000-fold, there was only a small delay in gastric emptying (P for trend < 0.05). The area under the curve for satiety increased with initial meal viscosity, whereas that for hunger decreased (P < 0.05). In conclusion, the viscosity of a meal in vivo can be measured noninvasively using EPI. The stomach responds to meal ingestion by rapid intragastric dilution, causing a reduction of meal viscosity, and gastric emptying is minimally delayed. However, increased viscosity is associated with more prolonged satiety.
Dietary fibres have many functions in the diet, one of which may be to promote control of energy intake and reduce the risk of developing obesity. This is linked to the unique physico-chemical properties of dietary fibres which aid early signalling of satiation and prolonged or enhanced sensation of satiety. Particularly the ability of some dietary fibres to increase viscosity of intestinal contents offers numerous opportunities to affect appetite regulation. Few papers on the satiating effect of dietary fibres include information on the physico-chemical characteristics of the dietary fibres being tested, including molecular weight and viscosity. For viscosity to serve as a proxy for soluble dietary fibres it is essential to have an understanding of individual dietary fibre viscosity characteristics. The goal of this paper is to provide a brief overview on the role of dietary fibres in appetite regulation highlighting the importance of viscosity.
Consumption of 3 g oat β-glucan/d is considered sufficient to lower serum LDL cholesterol, but some studies have shown no effect. LDL cholesterol lowering by oat β-glucan may depend on viscosity, which is controlled by the molecular weight (MW) and amount of oat β-glucan solubilized in the intestine (C).
Our 2 primary objectives were to determine whether consumption of 3 g high-MW oat β-glucan/d would reduce LDL cholesterol and whether LDL cholesterol lowering was related to the log(MW × C) of oat β-glucan.
In a double-blind, parallel-design, multicenter clinical trial, subjects with LDL cholesterol ≥3.0 and ≤5.0 mmol/L (n = 786 screened, n = 400 ineligible, n = 19 refused, n = 367 enrolled, and n = 345 completed) were randomly assigned to receive cereal containing wheat fiber (n = 87) or 3 g high-MW (2,210,000 g/mol, n = 86), 4 g medium-MW (850,000 g/mol, n = 67), 3 g medium-MW (530,000 g/mol, n = 64), or 4 g low-MW (210,000 g/mol, n = 63) oat β-glucan/d (divided doses, twice daily) for 4 wk.
LDL cholesterol was significantly less with 3 g high-MW, 4 g medium-MW, and 3 g medium-MW oat β-glucan cereals than with the wheat-fiber cereal by 0.21 (5.5%; 95% CI: -0.11, -0.30; P = 0.002), 0.26 (6.5%; 95% CI: -0.14, -0.37; P = 0.0007), and 0.19 (4.7%; 95% CI: -0.08, -0.30; P = 0.01) mmol/L, respectively. However, the effect of 4 g low-MW oat β-glucan/d (0.10 mmol/L) was not significant (2.3%; 95% CI: 0.02, -0.20). By analysis of covariance, log(MW × C) was a significant determinant of LDL cholesterol (P = 0.003). Treatment effects were not significantly influenced by age, sex, study center, or baseline LDL cholesterol.
The physicochemical properties of oat β-glucan should be considered when assessing the cholesterol-lowering ability of oat-containing products; an extruded breakfast cereal containing 3 g oat β-glucan/d with a high-MW (2,210,000 g/mol) or a medium-MW (530,000 g/mol) lowered LDL cholesterol similarly by ≈0.2 mmol/L (5%), but efficacy was reduced by 50% when MW was reduced to 210,000 g/mol. This trial was registered at www.clinicaltrials.gov as NCT00981981.
Soluble fibre has been proposed to suppress appetite-related perceptions and it could thus contribute favourably to the regulation of energy intake and the increasing obesity problem.
To investigate the effect of an oat ingredient rich in beta-glucan on perceived satiety at different dietary fibre (DF) concentrations, energy levels and viscosity levels.
A total of 29 healthy volunteers, age 19-39, mean BMI 23.2 kg/m(2) participated in this study. Measurement of subjective perceptions (satiety, fullness, hunger, desire to eat something/the sample food and thirst) was performed during a 180-min period after ingestion of the sample. There were altogether six samples: two beverages without fibre at energy levels 700 and 1,400 kJ; two beverages containing 5 or 10 g oat DF (2.5 and 5 g oat beta-glucan, respectively) at energy level 700 kJ, one beverage containing 10 g oat DF/1,400 kJ and one beverage containing 10 g enzymatically treated oat DF with low viscosity at energy level 700 kJ. Each beverage portion weighted 300 g. The order of the samples was randomised for each subject and evaluated during six separate days. The results are reported in three sets of samples: 'fibre', 'energy' and 'viscosity'.
In the fibre set, the beverages containing 5 or 10 g of fibre had a larger area under curve (AUC) for perceived satiety and smaller AUC for hunger compared to the beverage without fibre, but no significant dose-response relationship was detected. Increasing the energy content from 700 to 1,400 kJ in the energy set did not affect the satiety-related perceptions. In the viscosity set, the beverage with low-viscosity beta-glucan increased satiety-related perceptions from no fibre containing beverage, but less compared to the beverage with the same amount of fibre and higher viscosity.
Addition of an oat ingredient rich in beta-glucan and high viscosity of beverages enhance post-meal satiety induced by beverages. The effect was, however, not related to the amount of ingested fibre or energy.
The prevalence of obesity increased in the United States between 1976-1980 and 1988-1994 and again between 1988-1994 and 1999-2000.
To examine trends in obesity from 1999 through 2008 and the current prevalence of obesity and overweight for 2007-2008.
Analysis of height and weight measurements from 5555 adult men and women aged 20 years or older obtained in 2007-2008 as part of the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US population. Data from the NHANES obtained in 2007-2008 were compared with results obtained from 1999 through 2006.
Estimates of the prevalence of overweight and obesity in adults. Overweight was defined as a body mass index (BMI) of 25.0 to 29.9. Obesity was defined as a BMI of 30.0 or higher.
In 2007-2008, the age-adjusted prevalence of obesity was 33.8% (95% confidence interval [CI], 31.6%-36.0%) overall, 32.2% (95% CI, 29.5%-35.0%) among men, and 35.5% (95% CI, 33.2%-37.7%) among women. The corresponding prevalence estimates for overweight and obesity combined (BMI > or = 25) were 68.0% (95% CI, 66.3%-69.8%), 72.3% (95% CI, 70.4%-74.1%), and 64.1% (95% CI, 61.3%-66.9%). Obesity prevalence varied by age group and by racial and ethnic group for both men and women. Over the 10-year period, obesity showed no significant trend among women (adjusted odds ratio [AOR] for 2007-2008 vs 1999-2000, 1.12 [95% CI, 0.89-1.32]). For men, there was a significant linear trend (AOR for 2007-2008 vs 1999-2000, 1.32 [95% CI, 1.12-1.58]); however, the 3 most recent data points did not differ significantly from each other.
In 2007-2008, the prevalence of obesity was 32.2% among adult men and 35.5% among adult women. The increases in the prevalence of obesity previously observed do not appear to be continuing at the same rate over the past 10 years, particularly for women and possibly for men.
Epidemiological evidence shows an inverse relationship between dietary fibre intake and body weight gain. Oat beta-glucan, a soluble fibre alters appetite hormones and subjective satiety in acute meal test studies, but its effects have not been demonstrated with chronic consumption. The present study aimed to test the effects in women of two different doses of oat beta-glucan on weight loss and hormones associated with appetite regulation. In a 3-month parallel trial, sixty-six overweight females were randomised into one of three 2 MJ energy-deficit diets: a control and two interventions including 5-6 g or 8-9 g beta-glucan. Anthropometric and metabolic variables (blood glucose level, insulin, total cholesterol (TC), LDL, HDL, TAG and leptin), together with markers of appetite regulation (cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), ghrelin, peptide YY (PYY) and PYY3-36) were measured at baseline and at 3 months. After 3 months, all groups lost weight (P < 0.001) and showed a reduced waist circumference (P < 0.001). The study sample also showed reductions in TC, LDL, HDL, leptin, PYY, GLP-1 values (all P < 0.001) and an increase in CCK levels (P < 0.001). No significant differences were noted between the groups for all outcome values except PYY levels (P = 0.018). In broad terms, the addition of oat beta-glucan did not enhance the effect of energy restriction on weight loss in mildly overweight women, although wide variations in observed results suggests that individual responsiveness may be an issue.
Type 2 diabetes is associated with a higher cardiovascular risk and there has been a growing interest in using dietary intervention to improve lipid profile and glucose control. The present work aims at analysing the effects of the enrichment of a normal diet with beta-glucan (3.5 g/d) in free-living type 2 diabetic subjects for 2 months, using a palatable soup. This trial was a parallel, placebo-controlled, double-blinded randomised study performed in fifty-three type 2 diabetic subjects. During a 3-week run-in period, subjects daily consumed a ready meal control soup (without beta-glucan). For the following 8 weeks, subjects were randomly assigned to consume daily either a control soup or a beta-glucan soup. Changes in lipid profile (total cholesterol (TC), HDL- and LDL-cholesterol (HDLc and LDLc), apo B and TAG) and in glucose control (HbA1c and fasting glucose) were measured. There was no significant alteration in lipid profile in the two groups (TC, HDLc, LDLc and apo B). TAG decreased significantly in the beta-glucan group compared with the control group ( - 0.12 (SD 0.38) v. 0.12 (SD 0.44) mmol/l, P = 0.03). HbA1c and fasting glucose were not reduced in any group. A single daily ingestion of 3.5 g beta-glucan, as required by official dietary recommendations, for 8 weeks did not change the lipid profile and HbA1c in type 2 diabetic subjects. To improve the metabolic profile of type 2 diabetic subjects in the long term, the quantity, the food vectors and the tolerability of beta-glucan products may be re-evaluated.
We have previously shown that gut microbial fermentation of prebiotics promotes satiety and lowers hunger and energy intake in humans. In rodents, these effects are associated with an increase in plasma gut peptide concentrations, which are involved in appetite regulation and glucose homeostasis.
Our aim was to examine the effects of prebiotic supplementation on satiety and related hormones during a test meal for human volunteers by using a noninvasive micromethod for blood sampling to measure plasma gut peptide concentrations.
This study was a randomized, double-blind, parallel, placebo-controlled trial. A total of 10 healthy adults (5 men and 5 women) were randomly assigned to groups that received either 16 g prebiotics/d or 16 g dextrin maltose/d for 2 wk. Meal tolerance tests were performed in the morning to measure the following: hydrogen breath test, satiety, glucose homeostasis, and related hormone response.
We show that the prebiotic treatment increased breath-hydrogen excretion (a marker of gut microbiota fermentation) by approximately 3-fold and lowered hunger rates. Prebiotics increased plasma glucagon-like peptide 1 and peptide YY concentrations, whereas postprandial plasma glucose responses decreased after the standardized meal. The areas under the curve for plasma glucagon-like peptide 1 and breath-hydrogen excretion measured after the meal (0-60 min) were significantly correlated (r = 0.85, P = 0.007). The glucose response was inversely correlated with the breath-hydrogen excretion areas under the curve (0-180 min; r = -0.73, P = 0.02).
Prebiotic supplementation was associated with an increase in plasma gut peptide concentrations (glucagon-like peptide 1 and peptide YY), which may contribute in part to changes in appetite sensation and glucose excursion responses after a meal in healthy subjects.
A high intake of dietary fibre has been suggested to support the regulation of energy intake and satiety, which could contribute favourably to the increasing obesity problem.
To investigate the effects of three fibres differing in chemical and physical properties on perceived satiety and hunger-related attributes.
A total of 19 healthy volunteers, age 18-30, mean BMI 23.2 kg/m(2) participated in the study. Measurement of food and satiety-related perceptions with ten attributes was performed by using 10-unit graphic intensity scales during a 120 min period after the ingestion the sample. The attributes evaluated were satiety, hunger (unipolar and bipolar scale), appetite, fullness, desire to eat something/sweet/savoury/the sample food and thirst. The sample foods used were a beverage without fibre, a guar gum beverage, a wheat bran beverage, an oat beta-glucan beverage and wheat bread was used as the control. The fibre content of the samples was 0 g (beverage without fibre), 2.4 g (wheat bread), 7.8 g (guar gum) or 10.5 g (wheat bran and oat beta-glucan beverage) per 400 g/1,000 kJ portion.
The area under curve (AUC) for perceived satiety was higher (169 vs. 83 cm min; t test P = 0.026) and the desire to eat was lower (AUC -179 vs. -83 cm min; t test P = 0.008) for the guar gum beverage as compared to the beverage without fibre. Also the beverage with oat beta-glucan increased fullness and showed a trend of increasing perceived satiety and decreasing the desire to eat more than the beverage without fibre.
Our results support the idea that dietary fibre in beverages can enhance their perceived satiety and decrease the desire to eat more than a beverage without fibre.
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.
An increase in gastrointestinal viscosity or colonic fermentation is suggested to improve appetite control and reduce food intake. It has been proposed that beta-glucan and fructooligosaccharide (FOS) are food ingredients that increase gastrointestinal viscosity and colonic fermentation, but the results are inconclusive.
The objective was to test the effect of FOS, beta-glucan, or a combination thereof on appetite ratings and food intake over 2 consecutive days.
In a 4-way balanced-order, crossover, double-blind design, 21 healthy volunteers [mean body mass index (in kg/m(2)) 25.9] consumed a meal-replacement bar at 0900 and an ad libitum lunch at 1300 on 2 consecutive days. On day 1 only, the subjects consumed a second (identical) bar at 1700 and a fixed snack at 1900. The control bar contained 0.3 g beta-glucan from 6.8 g oats (control), and the 3 equicaloric test bars contained an additional 0.9 g beta-glucan (from 8.0 g barley), 8 g FOS, or 0.9 g beta-glucan + 8 g FOS. Appetite scores and subsequent ad libitum test meal intakes were measured. Viscosities in response to bar consumption were determined under simulated gastric conditions. The results were analyzed by analysis of covariance.
The addition of beta-glucan, FOS, or a combination thereof did not affect appetite ratings or food intake, although the addition of beta-glucan to the bar doubled gastric viscosity (841 compared with 351 mPa . s).
Consumption of beta-glucan, FOS, or a combination thereof in meal-replacement bars at the levels tested for 2 consecutive days does not improve appetite control. Efficacy may have improved if the consumption period was longer, if the content of beta-glucan was greater, or if a form of beta-glucan that generates even higher gastric viscosity was consumed. This trial was registered at (clinicaltrials.gov) as NCT00776256.
Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are anti-diabetes/obesity hormones secreted from the gut after meal ingestion. We have shown that dietary-resistant starch (RS) increased GLP-1 and PYY secretion, but the mechanism remains unknown. RS is a fermentable fiber that lowers the glycemic index of the diet and liberates short-chain fatty acids (SCFAs) through fermentation in the gut. This study investigates the two possible mechanisms by which RS stimulates GLP-1 and PYY secretion: the effect of a meal or glycemic index, and the effect of fermentation. Because GLP-1 and PYY secretions are stimulated by nutrient availability in the gut, the timing of blood sample collections could influence the outcome when two diets with different glycemic indexes are compared. Thus we examined GLP-1 and PYY plasma levels at various time points over a 24-h period in RS-fed rats. In addition, we tested proglucagon (a precursor to GLP-1) and PYY gene expression patterns in specific areas of the gut of RS-fed rats and in an enteroendocrine cell line following exposure to SCFAs in vitro. Our findings are as follows. 1) RS stimulates GLP-1 and PYY secretion in a substantial day-long manner, independent of meal effect or changes in dietary glycemia. 2) Fermentation and the liberation of SCFAs in the lower gut are associated with increased proglucagon and PYY gene expression. 3) Glucose tolerance, an indicator of increased active forms of GLP-1 and PYY, was improved in RS-fed diabetic mice. We conclude that fermentation of RS is most likely the primary mechanism for increased endogenous secretions of total GLP-1 and PYY in rodents. Thus any factor that affects fermentation should be considered when dietary fermentable fiber is used to stimulate GLP-1 and PYY secretion.
The aim of this study was to produce a validated satiety index of common foods.
Isoenergetic 1000 kJ (240 kcal) servings of 38 foods separated into six food categories (fruits, bakery products, snack foods, carbohydrate-rich foods, protein-rich foods, breakfast cereals) were fed to groups of 11-13 subjects. Satiety ratings were obtained every 15 min over 120 min after which subjects were free to eat ad libitum from a standard range of foods and drinks. A satiety index (SI) score was calculated by dividing the area under the satiety response curve (AUC) for the test food by the group mean satiety AUC for white bread and multiplying by 100. Thus, white bread had an SI score of 100% and the SI scores of the other foods were expressed as a percentage of white bread.
There were significant differences in satiety both within and between the six food categories. The highest SI score was produced by boiled potatoes (323 +/- 51%) which was seven-fold higher than the lowest SI score of the croissant (47 +/- 17%). Most foods (76%) had an SI score greater than or equal to white bread. The amount of energy eaten immediately after 120 min correlated negatively with the mean satiety AUC responses (r = -0.37, P < 0.05, n = 43) thereby supporting the subjective satiety ratings. SI scores correlated positively with the serving weight of the foods (r = 0.66, P < 0.001, n = 38) and negatively with palatability ratings (r = -0.64, P < 0.001, n = 38). Protein, fibre, and water contents of the test foods correlated positively with SI scores (r = 0.37, P < 0.05, n = 38; r = 0.46, P < 0.01; and r = 0.64, P < 0.001; respectively) whereas fat content was negatively associated (r = -0.43, P < 0.01).
The results show that isoenergetic servings of different foods differ greatly in their satiating capacities. This is relevant to the treatment and prevention of overweight and obesity.
The changes in plasma insulin, enterostatin, lipid, and glucose levels during weight reduction were studied in 32 subjects having a body mass index of 25-35. The 31 subjects who completed the study followed for 23 weeks an energy-restricted dietary regimen which included a new oat-based soup as the main meal once or twice daily. The intake of energy decreased from 8.9 to 6.2 MJ/day from 0 to 22 weeks, the energy percentage from fat decreased from 35 to 30%, and the intake of dietary fiber increased from 21 to 25 g/10 MJ. The body weight decreased from 83 to 78 kg after 6 weeks and to 77 kg after 23 weeks. Plasma glucose had decreased significantly from 5.4 to 5.2 mmol/l, and plasma insulin from 122 to 98 pmol/l after 23 weeks. In contrast, the plasma enterostatin concentration did not vary significantly over five sampling times, the mean values ranging from 25 to 30 nmol/l. Plasma cholesterol declined from 5.6 to 5.2 mmol/l, low-density lipoprotein cholesterol from 3.8 to 3.3, and plasma triglycerides from 1.5 to 1.3 mmol/l from 0 to 23 weeks. High-density lipoprotein cholesterol increased from 1.1 to 1.3 mmol/l. It is concluded that an energy-restricted regimen leading to lower plasma insulin, triglyceride, and low-density lipoprotein cholesterol levels did not significantly affect the plasma enterostatin concentration in overweight subjects. A new oat-based liquid food as a part of the dietary regimen was well tolerated.
The relationship between the intragastric distribution, dilution, and emptying of meals and satiety was studied using noninvasive magnetic resonance imaging techniques in 12 healthy subjects with four polysaccharide test meals of varying viscosity and nutrient content as follows: 1) low-viscosity nonnutrient, 2) low-viscosity nutrient, 3) high-viscosity nonnutrient, and 4) high-viscosity nutrient. Increasing the nutrient content of the high-viscosity meal delayed gastric emptying from 46 +/- 9 to 76 +/- 6 min (P < 0.004), whereas increasing viscosity had a smaller effect. The volume of secretions within the stomach 60 min after ingestion was higher for the high-viscosity nutrient meal (P < 0.04). A simple model to calculate the total volume of secretion added to the test meal is presented. Color-coded dilution map images showed the heterogeneous process of progressive gastric dilution of high-viscosity meals, whereas low-viscosity meals were uniformly diluted. Fullness was found to be linearly related to total gastric volumes for the nutrient meals (R(2) = 0.98) and logarithmically related for the nonnutrient meals (R(2) = 0.96). Fullness was higher for high- compared with low-viscosity meals (P < 0.02), and with the nutrient meals this was associated with greater antral volumes (P < 0.05).
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.
Recent findings suggest that Western diets based on highly palatable foods are likely to be much less satiating than more traditional diets or those typical of less developed countries. In particular, some alternative crops (for example, buckwheat, oat, barley, spelt, rye, quinoa, amaranth) seem to be of great nutritional interest and to represent important recipes for healthier and typical regional foods. The objective of the present study was to investigate the effect on subsequent food intake and feelings of satiety of alternative oat bread, oat and buckwheat pasta and of quinoa as compared with their wheat counterparts and rice, respectively. Three different experiments (one specific for each alternative crop food) were conducted, all with a within-subjects design. The preloading paradigm strategy was used. Results showed that preload energy level influenced total energy intake (preload plus ad libitum test meal intake), larger preloads inducing more eating than smaller preloads. No effect of formulation was observed on energy intake, as the consumption of alternative crop formulations did not decrease the total energy intake as compared with that of the counterparts. Satiating efficiency indices (SEI) for alternative crop foods were higher with respect to traditional cereal foods. In particular, white bread was the least satisfying food (SEI =0.2) and the different time of consumption (for lunch or as a snack) did not affect energy intake. In conclusion, oat or buckwheat formulations, and also quinoa, may be exploited for their potential impact on eating behaviour, particularly considering they are good sources of functional substances.
Prospective studies have suggested that substituting whole grain for refined grain products may lower the risk of overweight and obesity. Breakfast cereal intake is a major source of whole and refined grains and has also been associated with having a lower BMI. The aim of this study was to prospectively assess the association between whole and refined grain breakfast cereal intakes and risk of overweight (BMI >or= 25 kg/m(2)) and weight gain.
We examined 17,881 U.S. male physicians 40 to 84 years of age in 1982 who were free of cardiovascular disease, diabetes mellitus, and cancer at baseline and reported measures of breakfast cereal intake, weight, and height.
Over 8 and 13 years of follow-up, respectively, men who consumed breakfast cereal, regardless of type, consistently weighed less than those who consumed breakfast cereals less often (p value for trend = 0.01). Whole and refined grain breakfast cereal intake was inversely associated with body weight gain over 8 years, after adjustment for age, smoking, baseline BMI, alcohol intake, physical activity, hypertension, high cholesterol, and use of multivitamins. Compared with men who rarely or never consumed breakfast cereals, those who consumed >or=1 serving/d of breakfast cereals were 22% and 12% less likely to become overweight during follow-up periods of 8 and 13 years (relative risk, 0.78 and 0.88; 95% confidence interval, 0.67 to 0.91 and 0.76 to 1.00, respectively).
BMI and weight gain were inversely associated with intake of breakfast cereals, independently of other risk factors.
Weight gain and risk of type 2 diabetes are inversely associated with a high intake of insoluble cereal fibres. Because nutrient-induced changes of 'satiety hormones' from the gut may play a role in this process, we evaluated the effects of purified insoluble fibres on postprandial responses of plasma peptide YY (PYY), serum ghrelin and satiety as secondary outcome measures of a study investigating effects of cereal fibres on parameters of glucose metabolism. Fourteen healthy women were studied on six occasions in a randomized, single-blind, controlled crossover design. After 24 h run-in periods and 10 h overnight fasts, subjects ingested isoenergetic and macronutrient matched portions of control white bread or fibre-enriched bread (wheat-fibre or oat-fibre) at 08.15 hours. Gut hormones and hunger scores were measured for 300 min. Basal PYY and ghrelin concentrations were not different between the test meals (P>0.15). Postprandial responses of PYY and ghrelin were blunted after the intake of wheat-fibre (total area under the curve (AUC) PYY, 177.9 (SEM 8.1) (pmol/l) min; P=0.016; ghrelin 51.0 (SEM 2.5) (pmol/l) min; P=0.003), but not after oat-fibre (PYY 226.7 (SEM 25.7) (pmol/l) min; P>0.15; ghrelin 46.2 (SEM 1.6) (pmol/l) min; P=0.127), compared to control (PYY 247.5 (SEM 25.6) (pmol/l) min; ghrelin 42.5 (SEM 1.3) (pmol/l) min). Postprandial hunger scores were unaffected by the different test meals (P>0.15). Thus, oat- and wheat-fibre consumption result in different postprandial responses of PYY and ghrelin, but interestingly do not differ in satiety effects.
To assess the effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress.
A randomized, double-blind, controlled clinical trial.
The trial was conducted at two clinics.
Ninety-seven men and women with resting systolic blood pressure 130-179 mm Hg and/or diastolic blood pressure 85-109 mm Hg were randomly assigned to consume foods containing oat beta-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period.
Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the beta-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m(2)), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the beta-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments.
The results of the present trial suggest beneficial effects of foods containing beta-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.
Dietary fiber measurements are essential to assessment of the potential therapeutic and preventive effects of fiber intake. Ideally, dietary fiber analyses should measure all components—soluble polysaccharides, noncellulosic polysaccharides, cellulose, and lignin—and the constituent sugars of the soluble and noncellulosic polysaccharides. We modified existing techniques to measure reproducibly the total dietary fiber, polysaccharide, and lignin components and the sugar constituents of selected foods. Soluble-fiber content as percentage of total dietary fiber for groups of foods averaged 32% for cereal products, 32% for vegetables, 25% for dried beans, and 38% for fruits. Lignin content, estimated gravimetrically, was approximately 1.4 g/100 g dry wt for 24 foods. Detailed fiber measurements are critical for evaluating the potential health benefits of dietary fiber intake.
Context Dietary composition may affect insulin secretion, and high insulin levels,
in turn, may increase the risk for cardiovascular disease (CVD).Objective To examine the role of fiber consumption and its association with insulin
levels, weight gain, and other CVD risk factors compared with other major
dietary components.Design and Setting The Coronary Artery Risk Development in Young Adults (CARDIA) Study,
a multicenter population-based cohort study of the change in CVD risk factors
over 10 years (1985-1986 to 1995-1996) in Birmingham, Ala; Chicago, Ill; Minneapolis,
Minn; and Oakland, Calif.Participants A total of 2909 healthy black and white adults, 18 to 30 years of age
at enrollment.Main Outcome Measures Body weight, insulin levels, and other CVD risk factors at year 10,
adjusted for baseline values.Results After adjustment for potential confounding factors, dietary fiber showed
linear associations from lowest to highest quintiles of intake with the following:
body weight (whites: 174.8-166.7 lb [78.3-75.0 kg], P<.001;
blacks: 185.6-177.6 lb [83.5-79.9 kg], P = .001),
waist-to-hip ratio (whites: 0.813-0.801, P = .004;
blacks: 0.809-0.799, P = .05), fasting insulin adjusted
for body mass index (whites: 77.8-72.2 pmol/L [11.2-10.4 µU/mL], P = .007;blacks: 92.4-82.6 pmol/L [13.3-11.9 µU/mL], P = .01) and 2-hour postglucose insulin adjusted for body
mass index (whites: 261.1-234.7 pmol/L [37.6-33.8 µU/mL], P = .03; blacks: 370.2-259.7 pmol/L [53.3-37.4 µU/mL], P<.001). Fiber was also associated with blood pressure
and levels of triglyceride, high-density lipoprotein cholesterol, low-density
lipoprotein cholesterol, and fibrinogen; these associations were substantially
attenuated by adjustment for fasting insulin level. In comparison with fiber,
intake of fat, carbohydrate, and protein had inconsistent or weak associations
with all CVD risk factors.Conclusions Fiber consumption predicted insulin levels, weight gain, and other CVD
risk factors more strongly than did total or saturated fat consumption. High-fiber
diets may protect against obesity and CVD by lowering insulin levels.
Dietary starch and fiber, particularly the fermentable content, may be important for long-term weight loss and the prevention and management of Type 2 diabetes. Resistant starch and most dietary fibers are fermented in the colon producing short chain fatty acids. Free fatty acid receptors 2 and 3 are two recently discovered receptors. The main ligands for these receptors are short chain fatty acids. These receptors are found on enteroendocrine L-cells in the colon where they stimulate the release of anorectic hormones (glucagon-like peptide-1 and peptide tyrosine tyrosine) and on adipocytes where they can exert improvements to insulin sensitivity. Recent studies have shown that supplementing the diet with fermentable fiber can have a positive effect on weight loss and insulin sensitivity. Further investigations with high-risk populations are warranted to determine if long-term dietary interventions with fermentable fibers can protect against or delay the progression of Type 2 diabetes.
This viewpoint aims to 1) review the available scientific literature on the relationship between whole grain consumption and body weight regulation; 2) evaluate the potential mechanisms whereby whole grain intake may help reduce overweight and 3) try to understand why epidemiological studies and clinical trials provide diverging results on this topic. All the prospective epidemiological studies demonstrate that a higher intake of whole grains is associated with lower BMI and body weight gain. However, these results do not clarify whether whole grain consumption is simply a marker of a healthier lifestyle or a factor favoring "per se" lower body weight. Habitual whole grain consumption seems to cause lower body weight by multiple mechanisms such as lower energy density of whole grain based products, lower glycemic index, fermentation of non digestible carbohydrates (satiety signals) and finally by modulating intestinal microflora. In contrast with epidemiological evidence, the results of few clinical trials do not confirm that a whole grain low-calorie diet is more effective in reducing body weight than a refined cereal diet, but their results may have been affected by small sample size or short duration of the intervention. Therefore, further intervention studies with adequate methodology are needed to clarify this question. For the time being, whole grain consumption can be recommended as one of the features of the diet that may help control body weight but also because is associated with a lower risk to develop type 2 diabetes, cardiovascular diseases and cancer.
Dietary fibres are believed to reduce subjective appetite, energy intake and body weight. However, different types of dietary fibre may affect these outcomes differently. The aim of this review was to systematically investigate the available literature on the relationship between dietary fibre types, appetite, acute and long-term energy intake, and body weight. Fibres were grouped according to chemical structure and physicochemical properties (viscosity, solubility and fermentability). Effect rates were calculated as the proportion of all fibre-control comparisons that reduced appetite (n = 58 comparisons), acute energy intake (n = 26), long-term energy intake (n = 38) or body weight (n = 66). For appetite, acute energy intake, long-term energy intake and body weight, there were clear differences in effect rates depending on chemical structure. Interestingly, fibres characterized as being more viscous (e.g. pectins, β-glucans and guar gum) reduced appetite more often than those less viscous fibres (59% vs. 14%), which also applied to acute energy intake (69% vs. 30%). Overall, effects on energy intake and body weight were relatively small, and distinct dose-response relationships were not observed. Short- and long-term effects of dietary fibres appear to differ and multiple mechanisms relating to their different physicochemical properties seem to interplay. This warrants further exploration.
Weight loss and consumption of viscous fibers both lower low-density lipoprotein (LDL) cholesterol levels. We evaluated whether or not a whole-grain, ready-to-eat (RTE) oat cereal containing viscous fiber, as part of a dietary program for weight loss, lowers LDL cholesterol levels and improves other cardiovascular disease risk markers more than a dietary program alone.
Randomized, parallel-arm, controlled trial.
Free-living, overweight and obese adults (N=204, body mass index 25 to 45) with baseline LDL cholesterol levels 130 to 200 mg/dL (3.4 to 5.2 mmol/L) were randomized; 144 were included in the main analysis of participants who completed the trial without significant protocol violations.
Two portions per day of whole-grain RTE oat cereal (3 g/day oat b-glucan) or energy-matched low-fiber foods (control), as part of a reduced energy ( approximately 500 kcal/day deficit) dietary program that encouraged limiting consumption of foods high in energy and fat, portion control, and regular physical activity.
Fasting lipoprotein levels, waist circumference, triceps skinfold thickness, and body weight were measured at baseline and weeks 4, 8, 10, and 12.
LDL cholesterol level was reduced significantly more with whole-grain RTE oat cereal vs control (-8.7+/-1.0 vs -4.3+/-1.1%, P=0.005). Total cholesterol (-5.4+/-0.8 vs -2.9+/-0.9%, P=0.038) and non-high-density lipoprotein-cholesterol (-6.3+/-1.0 vs -3.3+/-1.1%, P=0.046) were also lowered significantly more with whole-grain RTE oat cereal, whereas high-density lipoprotein and triglyceride responses did not differ between groups. Weight loss was not different between groups (-2.2+/-0.3 vs -1.7+/-0.3 kg, P=0.325), but waist circumference decreased more (-3.3+/-0.4 vs -1.9+/-0.4 cm, P=0.012) with whole-grain RTE oat cereal. Larger reductions in LDL, total, and non-high-density lipoprotein cholesterol levels and waist circumference were evident as early as week 4 in the whole-grain RTE oat cereal group.
Consumption of a whole-grain RTE oat cereal as part of a dietary program for weight loss had favorable effects on fasting lipid levels and waist circumference.
Peptide Y-Y (PYY) is an anorexigenic hormone implicated in appetite control, and beta-glucan is a fiber known to affect appetite. We hypothesized that plasma PYY levels would increase in overweight human adults consuming increasing doses of beta-glucan. The objective was to test whether the effect could be seen with beta-glucan delivered through extruded cereals containing a high beta-glucan oat bran with demonstrated high molecular weight and solubility. Fourteen subjects consumed a control meal and 3 cereals of varying beta-glucan concentration (between 2.2 and 5.5 g), and blood samples were collected over 4 hours. Analysis of raw PYY data showed a trend toward significant increases over 4 hours. An increasing dose of beta-glucan resulted in higher levels of plasma PYY, with significant differences between groups from 2 to 4 hours post test-meal. Data for the area under the curve analysis also approached significance, with post hoc analysis showing a difference (P = .039) between the control and the highest dose of beta-glucan (5.5 g). The PYY levels at 4 hours were significantly different between the control and high-dose meal test (P = .036). There was a significant dose response, with a positive correlation between the grams of beta-glucan and PYY area under the curve (r(2) = 0.994, P = .003). The optimal dose of beta-glucan appears to lie between 4 and 6 g, with the effects on PYY mediated by viscosity and concentration. Meal-test studies examining a range of hormones should measure hormones over a minimum of 4 hours and record meal intake for even longer time frames.
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.
Previous studies have shown that the water-soluble dietary fibre betaglucan, a natural component of oats, reduces cholesterol and postprandial hyperglycaemia. The aim of the present study was to investigate the effect of betaglucan-enriched bread consumption on the lipid profile and glucose homoeostasis of patients with type 2 diabetes (T2D).
We conducted a randomized, double-blind study in which 46 patients with T2D and LDL-C greater than 3.37 mmol/l (130 mg/dl) were randomized to incorporate into their diet, for 3 weeks, either bread enriched with betaglucan (providing 3g/day of betaglucan) or white bread without betaglucan.
The consumption of bread containing betaglucan led to significant reductions (vs the control group) in LDL-C of 0.66 mmol/l (15.79%) versus 0.11 mmol/l (2.71%) (P=0.009), in total cholesterol of 0.80 mmol/l (12.80%) versus 0.12 mmol/l (1.88%) (P=0.006), in Fasting plasma insulin (FPI) of 3.23 microU/ml versus an increase of 3.77 microU/ml (P=0.03) and in Homa-IR (Homoeostasis model assessment-insulin resistance) by 2.08 versus an increase of 1.33 (P=0.04).
Betaglucan enriched bread may contribute to the improvement of the lipid profile and insulin resistance in patients with T2D.
Products enriched with oat beta-glucan have been shown to reduce postprandial glucose and insulinemic responses. The aim of this study was to evaluate the effect of an extruded muesli product based on oat beta-glucan on the rate of gastric emptying, postprandial blood glucose and satiety in healthy subjects.
Gastric emptying rate (GER) was measured by standardized real-time ultrasonography. Twelve healthy subjects were assessed using a randomized crossover double blind trial. The meals were administered after 8 hours' fasting after measuring the subject's normal fasting blood glucose level. Blood glucose measurements were made before, 30 and 60 min after the end of the meal. Satiety scores were estimated 15 and 90 min after the end of the meal. The GER was calculated as the percentage change in the antral cross-sectional area 15 and 90 minutes after ingestion of vanilla yoghurt with muesli containing 4 g oat beta-glucan (GER1) or vanilla yoghurt with muesli containing cornflakes (GER2).
The median values were 60% for GER1 and 44% for GER2. The effect of 4 g oat beta-glucan on the rate of gastric emptying was not statistically significant compared with corn flakes. Muesli with 4 g oat beta-glucan lowered the postprandial glucose response significantly compared to the cornflakes meal (p = 0.045). The effect of oat beta-glucan on satiety was not statistically significantly.
The results of this study suggest that intake of muesli with 4 g oat beta-glucan does not affect the gastric emptying rate or satiety but lowers the postprandial blood glucose response, indicating that the GER does not regulate the blood glucose level.
We projected future prevalence and BMI distribution based on national survey data (National Health and Nutrition Examination Study) collected between 1970s and 2004. Future obesity-related health-care costs for adults were estimated using projected prevalence, Census population projections, and published national estimates of per capita excess health-care costs of obesity/overweight. The objective was to illustrate potential burden of obesity prevalence and health-care costs of obesity and overweight in the United States that would occur if current trends continue. Overweight and obesity prevalence have increased steadily among all US population groups, but with notable differences between groups in annual increase rates. The increase (percentage points) in obesity and overweight in adults was faster than in children (0.77 vs. 0.46-0.49), and in women than in men (0.91 vs. 0.65). If these trends continue, by 2030, 86.3% adults will be overweight or obese; and 51.1%, obese. Black women (96.9%) and Mexican-American men (91.1%) would be the most affected. By 2048, all American adults would become overweight or obese, while black women will reach that state by 2034. In children, the prevalence of overweight (BMI >/= 95th percentile, 30%) will nearly double by 2030. Total health-care costs attributable to obesity/overweight would double every decade to 860.7-956.9 billion US dollars by 2030, accounting for 16-18% of total US health-care costs. We continue to move away from the Healthy People 2010 objectives. Timely, dramatic, and effective development and implementation of corrective programs/policies are needed to avoid the otherwise inevitable health and societal consequences implied by our projections .
The effects of insulin injections (0.1, 1, 10 and 40 mU) into the paraventricular hypothalamus (PVN) were investigated in an open-circuit calorimeter. Wistar rats were tested, with no food available during the tests. The 0.1 and 1 mU doses had no effects on either respiratory quotient or energy expenditure. The 10 mU dose increased respiratory quotient which indicates increased dependency on carbohydrates as an energy substrate. The same dose had no effects on thermogenesis. In contrast, the 40 mU dose decreased respiratory quotient which indicates increased dependency on fats as an energy substrate. The higher dose also increased thermogenesis. Since neither dose significantly affected locomotor activity, the metabolic data are not confounded with activity effects. These data indicate that insulin in the PVN produces a primary modulation of the metabolic parameters central to maintaining energy balance. In separate experiments, the 4 doses of insulin reduced food intake and body weight over a 24 h period. They also produced a dose-related increase in blood glucose concentration over a one hour period. Taken together, these findings are interpreted in a model in which insulin in the PVN acts as a signal indicating increased body fat. This increases thermogenesis, fat utilization and glycemic levels, and inhibits feeding. The net effect of this integrated metabolic-behavioural response is a regulatory reduction in body fat.
Dietary fiber measurements are essential to assessment of the potential therapeutic and preventive effects of fiber intake. Ideally, dietary fiber analyses should measure all components--soluble polysaccharides, noncellulosic polysaccharides, cellulose, and lignin--and the constituent sugars of the soluble and noncellulosic polysaccharides. We modified existing techniques to measure reproducibly the total dietary fiber, polysaccharide, and lignin components and the sugar constituents of selected foods. Soluble-fiber content as percentage of total dietary fiber for groups of foods averaged 32% for cereal products, 32% for vegetables, 25% for dried beans, and 38% for fruits. Lignin content, estimated gravimetrically, was approximately 1.4 g/100 g dry wt for 24 foods. Detailed fiber measurements are critical for evaluating the potential health benefits of dietary fiber intake.
Although fiber has been increasingly recognized as an important dietary constituent, controversy and confusion still exist about the physiologic effects of fiber. Specifically, the independent ability of dietary fiber to lower serum lipid levels is controversial. The purpose of this article is to review available evidence regarding the impact of soluble fibers on serum lipid levels. Soluble fibers appear to have a greater potential to alter serum lipid levels than do insoluble fibers. Significant reduction in the level of serum total cholesterol by soluble fiber was found in 68 of the 77 (88%) human studies reviewed. Of the studies measuring low-density lipoprotein cholesterol, 41 of 49 (84%) reported significant reductions. No significant changes were reported in 43 of the 57 (75%) studies that reported high-density lipoprotein cholesterol and/or in 50 of the 58 (86%) studies that measured triglyceride levels.
To explore mechanisms whereby unabsorbed nutrients in the ileum inhibit the upper gut ("ileal brake"), we perfused the canine ileum or colon and monitored phase 3 in the duodenum. Fasting motility was recorded when the ileum or colon was perfused with 154 mM NaCl, a mixed isotonic nutrient solution (Ensure), or individual nutrients (maltose, casein hydrolysates, or sodium oleate). Blood samples were collected before and during the perfusions. The ileum was also perfused with 154 mM NaCl while peptide YY (PYY) was infused by vein. In both sets of experiments, plasma levels of PYY, neurotensin, and glucagon-like peptide-1 (GLP-1) were measured. Ileal or colonic perfusion of Ensure delayed phase 3 [migrating motor complexes (MMC)] in the duodenum, inhibited ileal motility, and increased plasma levels of PYY and GLP-1. Ileal casein and oleate and colonic casein also delayed the duodenal MMC. The MMC cycle length and plasma levels of PYY were closely correlated. Intravenous PYY prolonged the MMC cycle; an intravenous dose of 100 pmol.kg-1.h-1 of PYY mimicked the effects of ileal Ensure. These results support the hypothesis that PYY, and possibly GLP-1, participate in the ileal brake. This negative feedback loop also affects the distal small bowel. The proximal colon also triggers the feedback inhibition of gut motility (colonic brake).
Many people experience great difficulty in preventing energy intake from outstripping energy expenditure. Eating high-fat foods can facilitate the development of short-term positive energy balances by influencing satiation and satiety, the processes that control the size of eating episodes and the strength of postingestive appetite inhibition, respectively. An important feature of these processes is the relative potency of orosensory, postingestive (preabsorptive), and postabsorptive signals. Foods high in dietary fat have a weak effect on satiation, which leads to a form of passive overconsumption, and a disproportionately weak effect on satiety (joule-for-joule compared with protein and carbohydrate). This overconsumption (high-fat hyperphagia) is dependent upon both the high energy density and the potent sensory qualities (high palatability) of high-fat foods. A positive fat balance does not appear to generate a tendency for behavioral compensation, and there appears to be almost no autoregulatory link between fat oxidation and fat intake. The Leeds High Fat Study has found a higher frequency of obesity among high-fat than low-fat consumers, but the relationship between fat consumption and obesity is not a biologic imperative: analysis of the pathways between daily fat intakes and patterns of eating has revealed high-risk eating episodes. The physiologic responses to fat ingestion appear to be weak compared with the potent orosensory properties of high-fat foods, and such responses cannot prevent overconsumption. A first stage in a health program should be to prevent passive overconsumption.
Fiber regulates the rate and site of lipid and carbohydrate digestion and absorption and thus can modify the alimentary responses to a meal. When fiber sources containing viscous polysaccharides are included in a meal, a slower rate of carbohydrate and lipid absorption will modify the alimentary hormone and lipid responses.
We investigated in 11 healthy men the response of insulin, glucose, cholecystokinin, and lipid to 2 test meals containing beta-glucan.
One of the meals was high in fiber (15.7 g) and the other meal was low in fiber (5.0 g). The low-fiber meal contained pasta made with wheat flour. The high-fiber meals contained pasta prepared by replacing 40% of the wheat with 2 types of barley flour: barley naturally high in beta-glucan and the other a flour enriched in beta-glucan during processing.
Plasma glucose and insulin concentrations increased significantly after all meals but the insulin response was more blunted after the barley-containing meals. The test meals were low in fat (25% of energy) but elicited an increase in plasma triacylglycerol and cholecystokinin. Cholecystokinin remained elevated for a longer time after the barley-containing meals. After the low-fiber meal, plasma cholesterol concentrations did not change significantly; however, 4 h after the barley-containing meals, the cholesterol concentration dropped below the fasting concentration and was significantly lower than that after the low-fiber meal.
Carbohydrate was more slowly absorbed from the 2 high-fiber meals. Consumption of the barley-containing meals appeared to stimulate reverse cholesterol transport, which may contribute to the cholesterol-lowering ability of barley.
To investigate the effects of oats, a cereal rich in soluble fiber, on body composition changes and dietary compliance during consumption of a weight loss diet.
Subjects were 41 healthy men and women aged 18 to 78 years. Weight maintenance energy requirements were established over two weeks during consumption of a control diet with low soluble fiber content. Subjects then consumed a hypocaloric diet for six weeks, either consuming a low soluble fiber control diet or a diet containing 45 g/1000 kcal rolled oats, a whole grain cereal rich in soluble fiber (mean energy deficit -895+/-18 kcal/day relative to weight maintenance energy requirements). Changes in body fat and fat-free mass were determined by underwater weighing, and dietary compliance was assessed using the urinary osmolar excretion rate technique. In a final phase of the study, subjects ate ad libitum for six months, and changes in body weight and composition were monitored.
There was no significant effect of the oat-containing diet on body weight or composition changes during the hypocaloric regimen or in the subsequent ad libitum period. In addition, fecal energy excretion was not significantly different between groups. However, there were non-significant trends indicating reduced hunger in the oat group compared to controls (frequency of hunger 2.5+/-0.5 vs. 3.6+/-0.4, P=0.1). In addition, fewer oat subjects were non-compliant (four versus seven subjects dropped out or had urinary osmolar excretions greater than 130% of values predicted from dietary intake), but again the difference was not significant.
These results suggest that use of a cereal rich in soluble fiber in a closely monitored hypocaloric feeding regimen does not improve weight loss or dietary compliance. Further studies are needed to examine the possibility that cereals containing soluble fiber may have effects on hunger and dietary compliance that could be important in less tightly controlled protocols than the one described here.
Dry beans lower plasma cholesterol, an effect that has been associated with both the fiber and the protein content of beans. The objective of this study was to determine the acute hormone and lipid responses to a test meal that contained dry beans as a source of dietary fiber. A crossover design was employed in which men consumed the test meal and a control meal in random order. Both meals contained egg, bread, jelly, orange juice, milk and margarine. The high fiber meal contained white beans, whereas the low fiber (control) meal contained rice and dry milk. The men maintained their normal dietary pattern and fasted overnight before the study days. After a fasting blood sample was drawn, the men consumed the test meal and blood samples were collected over the next 6 h. Blood samples were analyzed for cholecystokinin (CCK), insulin and glucose. Plasma was separated into lipoprotein fractions and the triglyceride, cholesterol, apolipoprotein (apo) B100 and B48 content of triglyceride-rich lipoproteins determined. Insulin and glucose responses did not differ significantly between test meals; however, the CCK response was twice as high after the bean-containing meal than after the low fiber meal (P = 0.03). The increase in apo B48 concentration was significantly higher after the bean meal than after the low fiber meal (P < 0.05). Adding beans to a meal to increase fiber content prolongs the postprandial presence of intestinally derived lipoproteins and augments the CCK response to the meal.
Hypertension, dyslipidemia and overweight contribute substantially to cardiovascular disease risk. One of the most effective methods for improving high blood pressure and lipid profiles is loss of excess weight. Other recommendations for reducing cardiovascular risk include changes in dietary micronutrient, macronutrient and fiber intakes. To better define a diet for reduction in cardiovascular risk, 43 adults (body mass index 26.4 +/- 3.3, range 20.5-33.9 kg/m(2)) participated in an 8-wk study to determine the effects of two diets on weight, blood pressure, lipids and insulin sensitivity. For 2 wk, weight was maintained and all subjects consumed a control diet. For the next 6 wk, subjects consumed one of two hypocaloric diets (maintenance energy minus 4.2 MJ/d): the control diet (n = 21) or a diet containing oats [45 g/(4.2 MJ dietary energy. d), n = 22]. There was no significant difference between groups in changes in weight loss (control -4.0 +/- 1.1 kg, oats -3.9 +/- 1.6 kg, P = 0.8). The oats diet resulted in greater decreases in mean systolic blood pressure (oats -6 +/- 7 mm Hg, control -1 +/- 10 mm Hg, P = 0.026), whereas diastolic blood pressure change did not differ between the two groups (oats -4 +/- 6 mm Hg, control -3 +/- 5 mm Hg, P = 0.8). The oat diet resulted in significantly greater decreases in total cholesterol (oats -0.87 +/- 0.47 mmol/L, control -0.34 +/- 0.5 mmol/L, P = 0.003) and LDL cholesterol (oats -0.6 +/- 0.41 mmol/L, control -0.2 +/- 0.41mmol/L, P = 0.008). In summary, a hypocaloric diet containing oats consumed over 6 wk resulted in greater improvements in systolic blood pressure and lipid profile than did a hypocaloric diet without oats.
Accumulating evidence indicates that energy-yielding beverages evoke weaker appetitive responses than more solid food items, but the properties responsible have not been characterized. The present study attempted to isolate an influence of viscosity. At weekly intervals, 84 adults ingested 325-ml (220 kcal) shakes that were matched on weight, volume, temperature, energy, macronutrient content, energy density, rate of consumption, cognitive expectations, palatability, appearance, and requirements for mechanical processing, but varied in viscosity. Twice appetitive ratings were obtained over the subsequent 4 h, while all intake was proscribed, and twice ratings were kept until the first spontaneous eating occasion comprised of > or =100 kcal. Dietary intake was recorded over the 24 h after shake ingestion. Significantly greater and more prolonged reductions of hunger were observed with the thicker shake. No significant differences were noted in the size or time to first meal or 24 h energy intake. These data indicate viscosity exerts an independent inverse effect on hunger in humans.
The pancreatic hormone, insulin, has been hypothesized to be an important regulator of food intake. Consistent with this hypothesis is the finding that exogenous insulin, in doses that do not affect blood glucose, reliably suppresses food intake and body weight. However, previous experiments have utilized a long-term delivery paradigm, in which insulin is administered via osmotic minipump and changes in body weight and food intake are measured across days. In separate experiments, we report that acute central injections of insulin can reduce food intake. In Experiment 1, injection of insulin (8 mU) into the third cerebral ventricle reliably suppressed intake of pelleted rat chow beginning at onset of the rats' dark phase. In Experiment 2, central insulin reliably and dose dependently suppressed intake of a 1-h 15% sucrose meal in the middle of the light phase. These data suggest that insulin can reduce food intake in acute delivery paradigms and provide another means by which to assess the roles of other central systems in the mediation of insulin's effects on energy homeostasis.
We investigated the effect of fruit intake on body weight change.
Hypercholesterolemic, overweight (body mass index > 25 kg/m2), and non-smoking women, 30 to 50 y of age, were randomized to receive, free of charge, one of three dietary supplements: apples, pears, or oat cookies. Women were instructed to eat one supplement three times a day in a total of six meals a day. Participants (411 women) were recruited at a primary care center of the State University of Rio de Janeiro, Brazil. Fifty-one women had fasting blood cholesterol levels greater than 6.2 mM/L (240 mg/dL) and 49 were randomized. Subjects were instructed by a dietitian to eat a diet (55% of energy from carbohydrate, 15% from protein, and 30% from fat) to encourage weight reduction at the rate of 1 kg/mo.
After 12 wk of follow-up, the fruit group lost 1.22 kg (95% confidence interval = 0.44-1.85), whereas the oat group had a non-significant weight loss of 0.88 kg (0.37-2.13). The difference between the two groups was statistically significant (P = 0.004). To explore further the body weight loss associated with fruit intake, we measured the ratio of glucose to insulin. A significantly greater decrease of blood glucose was observed among those who had eaten fruits compared with those who had eaten oat cookies, but the glucose:insulin ratio was not statistically different from baseline to follow-up. Adherence to the diet was high, as indicated by changes in serum triacylglycerols, total cholesterol, and reported fruit intake. Fruit intake in the oat group throughout treatment was minimal.
Intake of fruits may contribute to weight loss.
To examine the effect of dietary fiber intake on blood pressure (BP).
Randomized, double-blind, placebo-controlled trial.
A total of 110 trial participants aged 30 to 65 years who had untreated, but higher than optimal BP or stage-1 hypertension were recruited from the community in New Orleans, Louisiana, USA.
Study participants were randomly assigned to receive 8 g/day of water-soluble fiber from oat bran or a control intervention.
Nine BP measurements were obtained by trained observers using random-zero sphygmomanometers, over three clinical visits, at the baseline and termination visits of the trial. An average of the nine measurements was used to determine mean BP at the baseline and termination visits.
The net changes [95% confidence interval, (CI)] in systolic blood pressure were -1.8 mmHg (-4.3 to 0.8, P = 0.17) following 12 weeks, -2.2 mmHg (-5.3 to 1.0, P = 0.18) following 6 weeks, and -2.0 mmHg (-4.4 to 0.3, P = 0.09) for an average of the 6- and 12-week visits. The corresponding net changes (95% CI) in diastolic blood pressure were -1.2 mmHg (-3.0 to 0.5, P = 0.17) following 12 weeks, -0.8 mmHg (-3.1 to 1.4, P = 0.47) following 6 weeks, and -1.0 mmHg (-2.6 to 0.5, P = 0.19) for an average of the 6- and 12-week visits.
Our findings suggest that a diet rich in fiber may have a moderate BP-lowering effect and indicate the need for further investigation of this important question.
Humans appear to have a genotype that permits, or even encourages, an energy intake that is greater than energy expenditure when food is available. This was functional throughout most of human evolution but is less so in the current environment of inexpensive, palatable, and readily available foods. To achieve dietary goals of weight loss or maintenance, attempts have been made to influence appetitive sensations through the manipulation of the physical properties of foods, their composition, or their pattern of consumption. This has led to limited success, in part, because measurement of appetitive sensations is difficult but, more fundamentally, because the association between appetite and food choice or intake is not robust. This article critically reviews the most common methods for assessment of appetite and the effects of selected food constituents on appetitive sensations. Translation of current knowledge to dietetic practice must be made cautiously.
A healthy diet is a key factor in the prevention of cardiovascular disease, the leading cause of death for women in industrialized countries. In this regard, soluble fibers may have beneficial effects on the plasma lipoprotein/lipid profile. The objective of the present study was to investigate the plasma lipoprotein/lipid response to dietary fibers in overweight premenopausal women within a randomized controlled trial.
Following a 2-week run-in phase, 34 premenopausal women (age: 22-53 years) were randomly assigned either to the control group (no supplement) or to the treatment group, which received 2 oat bran-enriched muffins per day (28 g/day of oat bran) during 4 weeks.
Supplementation with oat bran had a beneficial effect on plasma HDL-C levels. Indeed, compared to the control group (n = 16), a mean increase in plasma HDL-C levels of 11.2% was observed in women eating the oat bran supplement (n = 18) (p = 0.01), whereas the total cholesterol/HDL-C ratio decreased by 7.0% (p = 0.002). Results were similar after adjustment for age, apo E genotype and weight change.
These results suggest that oat bran-rich foods have beneficial effect on the metabolic profile of overweight women. Integration of these foods as part of a healthy diet may, therefore, improve the cardiovascular risk profile of women.