Effects of Barley and Oat Breads on Appetite
Phase: NA
Conditions: Healthy, Appetitive Behavior
Sponsor: TC Erciyes University

1 
 
Official Title of the study: Effects of Barley and Oat Breads 
on Appetite 
 
NCT number: NCT ID not yet assigned 
 
Document Date: 09 May 2018 (The date on which the 
uploaded document was approved by a human subjects 
protection review board.) 
 
This project was funded by the Erciyes University Scientific 
Research Projects Coordination Unit with a project number of 
TSA-2019-8761. 
 
 
 
 
 
 
 
 
 

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1. Background 
The prevalence of overweight and obesity worldwide increases significantly with concomitant 
diseases. Disruption of energy balance is known as the main cause of obesity. To maintain 
energy balance, weight control (dietary intervention, physical activity, behavioral therapy) 
results in short-term weight loss, but sustained weight maintenance is difficult. So alternative 
weight-loss strategies can be a solution (1). Epidemiological studies show that high dietary fiber 
intake is associated with lower body weight and waist circumference (2,3). The controlled 
intervention studies report that weight gain can be prevented by reducing appetite and energy 
intake with high dietary fiber intake (4–7). In addition, most studies show that high fiber intake 
is also associated with improved postprandial glycemic response (8). These potential beneficial 
effects of dietary fiber, which is divided into two as soluble and insoluble according to its 
physiological effects, can be attributed to ß-glucan, a type of soluble fiber (9). However, results 
from studies examining the effects of ß-glucan on appetite are not consistent and the underlying 
mechanisms are not yet clear. It is thought to contribute to a feeling of satiety by increasing the 
duration of oral exposure to food and abdominal distension and by increasing short-chain fatty 
acid production as a result of colonic fermentation (10–12). The hypothesis that ß-glucan affects 
appetite by acting on gastrointestinal hormones is still controversial (13). On the other hand, 
the blood-glucose-lowering properties of ß-glucan derived from oats and barley have been 
confirmed by the European Food Safety Authority (EFSA), with a health claim that 4 g ß-glucan 
can be used per 30 g of available carbohydrates per meal (14). The lowering effects of ß-glucan 
on blood glucose and insulin levels and blood pressure are speculated to be due to its prebiotic 
properties and its effects on weight loss (9). 
Overall, although studies have shown positive effects of ß-glucan on appetite and postprandial 
glycemic response, it is not yet clear whether this positive effect is due to ß-glucan or total 
dietary fiber intake. Also, since the majority of studies used products enriched with ß-glucan, 
little is known about the possible effects of dietary sources with ß-glucan in their natural form. 
In this study, the effects of breads derived from barley and oat, which are the best grain sources 
of ß-glucan, on appetite and postprandial glycemia were examined and the possible effects of 
its natural dietary sources were determined.  In addition, the effects of breads, which are a 
source of ß-glucan, on appetite and postprandial glycemia were evaluated by comparing not 
only with white bread (WB) but also with whole wheat bread (WWB), unlike previous studies. 
In this way, it was aimed to determine whether the possible positive effects were due to ß-
glucan or total dietary fiber intake. The selection of bread, which is the most commonly 
consumed grain-based food in European countries, as the test food will make it easier to add 
possible positive results to healthy eating recommendations and to their applicability. 
2. Objective 
This study aimed to compare the postprandial effects of ß-glucan on glycemia and appetite of 
breads derived from oats and barley, which are the best natural grain sources. In addition, the 
positive health effects of ß-glucan were sought to be determined independent of total dietary 
fiber intake, using not only WB as the control food but also WWB, which has a dietary fiber 
content equal to that of breads containing ß-glucan.  

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3. Materials and methods 
 
3.1. Participants and Study Design 
This study was planned as a multicenter, randomized, double-blind, and crossover. Approval 
was obtained from the Erciyes University Clinical Research Ethics Committee for the study 
(Decision No: 2018/259, Date: 09.05.2018). Twenty healthy adults (10 men, 10 women) 
between the ages of 19-35, with normal body weight (BMI 18.5-25 kg /m2) were included in 
the study. Exclusion criteria were applying an energy-restricted diet in the last three months, 
having a change in body weight >5 kg in the last three months, having a chronic disease such 
as diabetes and hypertension, or using a drug that affects the metabolism, having fasting glucose 
>100 mg/dl, smoking, exercising heavily, having chewing/swallowing difficulties or 
sensitivity/allergies to any food to be used in the study, vegans, pregnant and lactating women, 
and skipping breakfast meals. Participants were selected from among Erciyes University 
students and staff in accordance with the inclusion criteria. Before the participants were 
included in the study, they were informed about the study in accordance with the Declaration 
of Helsinki, and volunteers were asked to read and sign the informed consent form. 
The physical activity levels of the participants were evaluated simultaneously with dietary 
assessment by the International Physical Activity Questionnaire (IPAQ) short form at the 
beginning of the study and on each test day. Their dietary intakes were also assessed by the a-
24-hour dietary recall using a photographic atlas of food portion sizes to quantify the data. Diet 
composition was analysed by the BeBiS Nutrition Information System software version 8.2. 
Furthermore, body weight and height of participants were obtained at the beginning of the 
study, and BMI was calculated. Waist and hip circumference were measured using a non-elastic 
tape with the participants standing, with the face directed towards, shoulders relaxed, and the 
tape was positioned at a level parallel to the floor. The eating behaviors of all participants were 
also evaluated using the Dutch Eating Behavior Questionnaire before starting the study. Since 
the total score obtained from this questionnaire >3.5 is considered as restrictive eating behavior 
(15), these individuals were not included in the study. 
Since individuals were asked to fast for at least 12 hours before consuming the test meals and 
the postprandial response was more pronounced in the morning, breakfast was chosen as the 
test meal. On the day before each test meal, the participants were asked to consume their 
standard dinner at 20:00 and not consume any food or beverage (except water) after dinner, and 
not to do any physical activity other than their daily routine activities. In addition, test meals 
were consumed in the follicular phase of the menstrual cycle in order to control the possible 
effects of the menstrual cycle on appetite for female participants. Similar to previous studies 
(16,17), days 3-10 after the onset of menses were accepted as the follicular phase. 
Participants were served barley bread (BB), oat bread (OB), and wheat breads (WB and WWB) 
with a standard breakfast on four different days at least two days apart (18). Breads were 
prepared with similar amounts of energy, protein, fat, carbohydrate, and fiber (except WB). The 
test meal was served to the participants at 09:00 and they were asked to consume it within 15 
minutes. During the test period, participants were not allowed to eat or drink anything other 

4 
 
than water. On the first day of testing, participants were able to consume as much water as they 
wanted and the amount consumed was recorded. On the other test days, they were asked to 
consume the amount of water recorded on the first test day. In addition, the participants were 
allowed to watch movies, read books, play games on electronic devices (computer, cell phone, 
etc.), and do other sedentary activities during the test days, but they were not allowed to sleep. 
3.2.Chemical Analysis  
In this research, total fat, protein, ß-glucan, total available carbohydrate, and total dietary fiber 
analyzes were performed chemically in the flour and bread samples. Chemical analyzes were 
performed in parallel and in duplicate. Data were reported on dry matter and average values of 
at least two analyzes were taken. The energy value (kcal) per test portion was calculated using 
the weight (g) of each test portion and the formula [(4 x protein) + (9 x fat) + (4 x available 
carbohydrate)] (19). All chemical analyzes were conducted in Erciyes University Veterinary 
Faculty Food Hygiene and Technology Laboratory. 
All chemical analysis was performed as described above by taking a sample of several flours 
commonly available in Turkey. Among these flours, barley and oat flours with the highest ß-
glucan content were selected for baking bread as well as white flour and whole wheat flour 
having the most similar macronutrient content with barley and oat flours. A preliminary study 
was conducted to evaluate β-glucan content and bread baking tests were applied. For BB and 
OB, the content of β-glucan was targeted to be about 3 g in one serving. WB and WWB were 
used as reference and control foods, respectively. After the test breads were prepared, all the 
chemical analyzes described above were carried out again and the nutritional composition of 
the breads was found as in Table 1. 
Table 1. Energy and macronutrient contents of test breads 
 
White bread 
Whole-wheat bread 
Barley bread 
Oat bread 
Portion size (g) 
72 
73 
73 
70 
Energy (kcal) 
150 
147 
154 
133 
Carbohydrate (g) 
28.7 
27.3 
28.9 
23.9 
Protein (g) 
5.0 
5.7 
4.9 
4.7 
Fat (g) 
1.7 
1.7 
2.1 
2.0 
Dietary fiber (g) 
2.2 
6.8 
6.9 
9.0 
β-glucan (g) 
1.2 
1.4 
3.1 
3.2 
 
3.3.Baking The Test Breads 
For WB, WWB, BB, and OB, baking tests were performed using 100% white flour, whole 
wheat flour, barley flour, and oat flour, respectively. All breads have similar ingredients except 
the types of flour used. Dry yeast (2 g / 100 g), sugar (4 g / 100 g), salt (2 g / 100 g), and 
sunflower oil (4 g) in all breads were added (based on 100 g flour) (20). After resting for 30 
minutes at room temperature (25 °C), the samples were fired in an electric oven at 180 °C for 

5 
 
30 minutes (21)(20). One serving size slices were wrapped in aluminum foil and packed in 
plastic bags to prevent drying and stored at -18 °C until use (22). 
3.4.Test meals  
The foods and nutritional composition of the test breakfast meals are as in Table 2.  
Table 2. Nutritional composition of the component foods in test meals 
Foods 
Portion size 
(g) 
Energy 
(kcal) 
Carbohydrate 
(g) 
Protein  
(g) 
Fat  
(g) 
Feta cheese 
15 
34.8 
0.66 
1.8 
2.7 
Cheddar cheese 
24 
79.2 
0.48 
5.28 
6.24 
Olive 
24 
57.1 
0.30 
0.32 
4.79 
Honey 
20 
64 
16.6 
0.06 
- 
Black tea 
150 ml 
- 
- 
- 
- 
 
3.5.Postprandial Appetite and Glucose Assessment 
A visual analog scale (VAS) was used to assess appetite before breakfast and at 15, 30, 60, 90, 
120, 150, and 180 minutes after breakfast (23). Furthermore, the separate VAS components 
such as hunger, fullness, desire to eat, and prospective food consumption were combined to 
produce an additional measure termed ‘composite appetite score’. This validated average 
appetite score was calculated for each time point using the following equation: [(hunger + desire 
to eat + prospective food consumption + (100 - fullness)]/4 (24). 
For the postprandial glucose assessment, blood glucose measurements were made using a 
finger-tip glucometer (Accu-Check, Roche Diagnostics) at 0, 15, 30, 45, 60, 90, and 120 
minutes. 
3.6.Ad libitum Lunch 
At the end of three hours, the ad libitum lunch was served to the participants as a buffet-style, 
and the energy and macronutrient intakes in this meal were determined. All foods (meatballs, 
tuna, sauce pasta, yogurt, salad, white bread, apple, banana, yogurt drink, fruit juice, and water) 
were weighed using a calibrated kitchen scale with an accuracy of ±1g before being served. At 
lunch, the participants were asked to consume the foods they wanted and continue eating until 
they felt completely full. After the participants completed their consumption, the remaining 
amounts were reweighed and the difference with the initial amounts was accepted as the amount 
consumed. Energy and macronutrient values were calculated using The National Food 
Composition Database (TurKomp), and manufacturer labelling. 
 
 

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4. Statistical Analysis Plan  
 
4.1. Sample size  
A power-based sample size calculation based on previous research from Bo et al. (25) revealed 
that 16 participants were needed to provide 80% power to detect 5% difference between groups 
in primary outcomes. To allow discontinuation during the study, 20 participants (considering 
25% losses) were recruited.  
4.2. Data analysis 
Statistical analysis was performed using the SPSS Statistics (version 22.0) software. Data were 
expressed as the mean ± SD unless otherwise indicated. Normality was assessed using the 
histogram and normal Q-Q plots, and also Shapiro-Wilk test. Postprandial appetite and glucose 
responses were quantified as incremental area under the curve (iAUC) calculated according to 
the trapezoidal rule. One-way analysis of variance (ANOVA) for repeated measures was 
applied to determine statistical differences between groups. For all statistical analyses, p values 
less than 0.05 were considered to have statistical significance.  
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