Effects of Dietary Fiber on Affective Processes
Study Details
Study Description
Brief Summary
The effects of dietary fiber on psychobiological processes are examined in a sample of healthy volunteers.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
N/A |
Detailed Description
The study is an interventional triple-blind, placebo-controlled, parallel group design with 2 arms (placebo, dietary fiber). Healthy male participants adhere to their normal eating habits for the duration of the study (32 days). At the baseline study visit, measurements are taken in the lab, including biological samples and psychophysiological measurements. Participants then consume placebo or dietary fiber for 4 weeks and revisit the lab on day 32 for a second measurement of the outcomes of interest. Specifically, we investigate the effect of dietary fiber on affective processing, including stress sensitivity and fear-related processes (e.g. extinction learning). Volunteers also respond to questionnaires in relation to mood and GI symptoms, and provide biological samples (saliva, blood, faecal, and urine samples) for analysis of cortisol levels, circulating short chain fatty acids and serum BDNF, faecal SCFA and microbiota composition, and intestinal permeability, respectively.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Placebo Comparator: Placebo Refined cereal flour |
Dietary Supplement: Placebo
Refined cereal flour
|
| Active Comparator: Dietary fiber Fermentable cereal bran |
Dietary Supplement: Dietary fiber
Fermentable cereal bran
|
Outcome Measures
Primary Outcome Measures
- Stress sensitivity (cortisol) [through study completion, on average 1 year and 5 months]
Induction of cognitive, physical, and social stress using Maastricht Acute Stress Test. Stress hormone cortisol is quantified by gathering multiple saliva samples throughout the stress induction and recovery during both pre-intervention and post-intervention visit.
Secondary Outcome Measures
- Stress sensitivity (subjective) [through study completion, on average 1 year and 5 months]
Induction of cognitive, physical, and social stress using Maastricht Acute Stress Test. Participant rate how much stress, discomfort, and pain they feel on a 10-cm visual analogue scale, with higher values indicating greater stress, discomfort, and pain. This is done prior to stress induction, in the middle, and at the end at both pre- and post-intervention visits.
- Cortisol awakening response [through study completion, on average 1 year and 5 months]
Measuring chronic stress by quantifying cortisol in morning samples (5 samples taken form the moment of waking every 15 minutes for 1 hour) on the morning of the pre- and post-intervention visits.
- Fear [through study completion, on average 1 year and 5 months]
Exploring fear-related processes (conditioning, extinction, recall, and renewal) by means of a computerised task. Fear response is measured using skin conductance, and a skin conductance response is calculated.
- Fear (subjective) [through study completion, on average 1 year and 5 months]
Exploring fear-related processes (conditioning, extinction, recall, and renewal) by means of a computerised task. Fear response is measured subjectively by asking participants to indicate their expectancy of an aversive stimulus.
- Positive and Negative Affect Schedule (PANAS) [through study completion, on average 1 year and 5 months]
Assessing ratings on the subscales of PANAS, positive and negative affect. PA subscale scores range between 10-50, with higher scores indicating better outcome. NA subscale scores range between 10-50, with higher scores indicating worse outcome.
- Perceived Stress Scale (PSS) [through study completion, on average 1 year and 5 months]
Assessing ratings on PSS PSS scores range between 0-40 with higher scores indicating worse outcome.
- Depression, anxiety, and stress scales (DASS-21) [through study completion, on average 1 year and 5 months]
Assessing ratings on the subscales of DASS-21, depression, anxiety, and stress subscales. Higher scores on these subscales indicates a worse outcome. Normal (depression: 0 - 4; anxiety: 0 - 3; stress: 0 - 7), Mild (depression: 5 - 6; axiety: 4 - 5; stress: 8 - 9), Moderate (depression: 7 - 10; anxiety: 6 - 7; stress: 10 - 12), Severe (depression: 11 - 13; anxiety: 8 - 9; stress: 13 - 16), Extremely Severe (depression: 14 +; anxiety: 10 +; stress: 17 +).
- Leiden Index of Depression Sensitivity-Revised (LEIDS-R) [through study completion, on average 1 year and 5 months]
Assessing ratings on the subscales of LEIDS-R and its total score. This is a self-report on cognitive reactivity comprised of 34 items with six subscales. Hopelessness/suicidality; Acceptance/Coping; Aggression; Control/Perfectionism; Risk Aversion; Rumination.
- Gastrointestinal symptom rating scale (GSRS) [through study completion, on average 1 year and 5 months]
Assessing ratings on the subscales of GSRS and its total score. It has 5 subscales (Reflux, Diarrhea, Constipation, Abdominal Pain, and Indigestion Syndrome). Subscale scores range from 1 to 7 and higher scores indicates a worse outcome.
- Serum SCFA [through study completion, on average 1 year and 5 months]
Quantification of serum SCFA (μM) at pre- and post-intervention
- Faecal SCFA [through study completion, on average 1 year and 5 months]
Quantification of faecal SCFA in samples provided at pre- and post-intervention
- Intestinal permeability [through study completion, on average 1 year and 5 months]
Conducting a lactulose and mannitol test before and after the intervention
- Serum BDNF [1 year and 5 months]
Quantification of fasting serum BDNF levels (µg/mL)
Eligibility Criteria
Criteria
Inclusion Criteria:
-
Male participants
-
Age range 20-40 years
-
BMI range 18.5-27
-
Dutch or English as native-language
Exclusion Criteria:
-
previous or current neurological, psychiatric, gastrointestinal or endocrine disorders, or other relevant medical history
-
current or recent regular medication use
-
previous or current substance/alcohol dependence or abuse (> 2 units per day/14 units per week)
-
one or more diagnoses based on the mini-international neuropsychiatric interview
-
smoking
-
night-shift work
-
adherence to vegan or vegetarian diets
-
use of pre- or probiotics within one month preceding the study
-
use of antibiotics within 3 months preceding the study
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Habitual diet not exceeding consumption of 25 g of dietary fiber per day
-
previous experience with one of the tasks used in the study
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | UZ Leuven/Stresslab | Leuven | I Am Not In The U.S. Or Canada | Belgium | 3000 |
Sponsors and Collaborators
- KU Leuven
Investigators
None specified.Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- S62344