Primary Outcome Measures: | |
1. |
Microbiota composition baseline vs after intervention using 16S RNA gene sequencing [ Time Frame: faecal samples collected before and after intake of bread for 3 weeks ]
Difference in gut microbiota composition in faecal samples before (baseline) and after intake of six slices of bread for 3 weeks (after intervention) using 16S RNA gene sequencing |
Secondary Outcome Measures: | |
1. |
Microbiota composition whole grain rye bread vs control bread using 16S RNA gene sequencing [ Time Frame: faecal samples collected before and after intake of bread for 3 weeks ]
Difference in gut microbiota composition in faecal samples between the study arms using 16S RNA gene sequencing |
2. |
Concentrations of circulatory short-chain fatty acids SCFA [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of SCFA between and within intervention groups after intake of bread for 3 weeks |
3. |
Concentrations of faecal SCFA [ Time Frame: faecal samples collected before and after intake of bread for 3 weeks ]
Difference in faecal levels of SCFA between and within intervention groups after intake of bread for 3 weeks |
4. |
Concentrations of blood glucagon like peptide-1 (GLP-1) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of GLP-1 between and within intervention groups after intake of bread for 3 weeks |
5. |
Concentrations of blood glucagon like peptide-2 (GLP-2) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of GLP-2 between and within intervention groups after intake of bread for 3 weeks |
6. |
Concentrations of blood peptide YY (PYY) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of PYY between and within intervention groups after intake of bread for 3 weeks |
7. |
Concentrations of blood gastric inhibitory polypeptide (GIP) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of GIP between and within intervention groups after intake of bread for 3 weeks |
8. |
Concentrations of blood neuroactive peptide Y (NPY) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of NPY between and within intervention groups after intake of bread for 3 weeks |
9. |
Concentrations of blood brain-derived neurotrophic factor (BDNF) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of BDNF between and within intervention groups after intake of bread for 3 weeks |
10. |
Concentrations of blood cytokines [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of cytokines between and within intervention groups after intake of bread for 3 weeks |
11. |
Concentrations of blood alkylresorcinols [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of alkylresorcinols between and within intervention groups after intake of bread for 3 weeks |
12. |
Concentrations of blood lipopolysaccharide-binding protein (LBP) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of LBP between and within intervention groups after intake of bread for 3 weeks |
13. |
Concentrations of blood soluble CD-14 (sCD-14) [ Time Frame: blood samples collected before and after intake of bread for 3 weeks ]
Difference in blood levels of sCD-14 between and within intervention groups after intake of bread for 3 weeks |
14. |
Concentrations of sugars in urine [ Time Frame: urine samples collected before and after intake of bread for 3 weeks ]
Difference on intestinal permeability between and within intervention groups after intake of bread for 3 weeks measured by the excretion of sugars contained in a multi-sugar solution |
15. |
Concentrations of saliva cortisol during stress test [ Time Frame: Saliva samples collected before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test ]
Difference in saliva levels of cortisol produced during stress test between and within intervention groups after intake of bread for 3 weeks |
16. |
Concentrations of saliva alpha-amylase during stress test [ Time Frame: Saliva samples collected before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test ]
Difference in saliva levels of a-amylase produced during stress test between and within intervention groups after intake of bread for 3 weeks |
Other Outcome Measures: | |
1. |
Gastrointestinal symptoms measured by Gastrointestinal Symptom Rating Scale in Irritable Bowel Syndrome (GSRS-IBS) [ Time Frame: 3 weeks ]
Difference in the frequency and severity of gastrointestinal symptoms between and within intervention groups after the intake of bread for 3 weeks. The GSRS-IBS contains 13 self-report items rated on a 6-point Likert scale ranging from 1 (no discomfort at all) to 7 (very severe discomfort). Total scores range from 0 to 78. |
2. |
Food habits measured by an electronic food frequency questionnaire Mealq [ Time Frame: 3 weeks ]
Survey of participants' food habits before and during the intake of bread for 3 weeks |
3. |
Food habits measured by a Food diary [ Time Frame: 3 days ]
Survey of participants' food habits before and during the intake of bread for 3 weeks |
4. |
Physical activity measured by the International Physical Activity Questionnaire (IPAQ) [ Time Frame: 3 days ]
Survey of participants' physical activities before and during the intake of bread for 3 weeks. The IPAQ contains 7 self-report questions and the categorical score is divided into 3 levels: low (less than 600 metabolic equivalent-minutes/week), moderate (at least 600 metabolic equivalent-minutes/week) or high (at least 1500 metabolic equivalent-minutes/week). |
5. |
Quality of life measured by the Euro Quality of Life questionnaire [ Time Frame: once before and after intake of bread for 3 weeks ]
Survey of participants' well-being before and during the intake of bread for 3 weeks. It records the patient's self-rated health on a vertical visual analogue scale where the endpoints are labelled from 0 (worst imaginable health state) to 100 (best imaginable health state). |
6. |
Perceived stress measured by a Visual analog scale questionnaire [ Time Frame: before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test ]
Difference in the perceived stress during a stress test between and within intervention groups after the intake of bread for 3 weeks |
7. |
Cognitive control using Eriksen flanker task (Flanker task) [ Time Frame: once before and after intake of bread for 3 weeks ]
Difference in cognitive control between and within intervention groups after the intake of bread for 3 weeks |
8. |
Working memory performance using a modified N-back task combined with recent-probes item-recognition task (Sternberg task) [ Time Frame: once before and after intake of bread for 3 weeks ]
Difference in working memory between and within intervention groups after the intake of bread for 3 weeks |
9. |
Electrocardiogram (ECG) using the Biopac system [ Time Frame: once before and after intake of bread for 3 weeks ]
Difference in heart rate variability during a stress test between and within intervention groups after the intake of bread for 3 weeks |
10. |
Electrodermal activity (EDA) using the Biopac system [ Time Frame: once before and after intake of bread for 3 weeks ]
Difference in skin conductivity during a stress test between and within intervention groups after the intake of bread for 3 weeks. Electrodes to measure EDA will be placed on the subjects' left palm. Skin conductivity measures will include skin conductivity level (SCL), the number of skin conductivity responses (SCR), and the amplitude of SCR. |