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Completed

NCT Number: NCT04522258

Effects of Dietary Fiber on Affective Processes

The effects of dietary fiber on psychobiological processes are examined in a sample of healthy volunteers.

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Key information

Conditions

Emotions Fear Stress

Age range

20 year–40 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

UZ Leuven/Stresslab

Leuven, I Am Not in the U.S. Or Canada, 3000, Belgium

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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
  • Habitual diet not exceeding consumption of 25 g of dietary fiber per day
  • previous experience with one of the tasks used in the study

Treatment and study plan

Dietary fiber

Dietary Supplement

Fermentable cereal bran

Placebo

Dietary Supplement

Refined cereal flour

Primary outcomes

  1. Stress sensitivity (cortisol)

    Time frame: 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 outcomes

  1. Stress sensitivity (subjective)

    Time frame: 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.

  2. Cortisol awakening response

    Time frame: 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.

  3. Fear

    Time frame: 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.

  4. Fear (subjective)

    Time frame: 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.

  5. Positive and Negative Affect Schedule (PANAS)

    Time frame: 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.

  6. Perceived Stress Scale (PSS)

    Time frame: 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.

  7. Depression, anxiety, and stress scales (DASS-21)

    Time frame: 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 +).

  8. Leiden Index of Depression Sensitivity-Revised (LEIDS-R)

    Time frame: 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.

  9. Gastrointestinal symptom rating scale (GSRS)

    Time frame: 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.

  10. Serum SCFA

    Time frame: through study completion, on average 1 year and 5 months

    Quantification of serum SCFA (μM) at pre- and post-intervention

  11. Faecal SCFA

    Time frame: through study completion, on average 1 year and 5 months

    Quantification of faecal SCFA in samples provided at pre- and post-intervention

  12. Intestinal permeability

    Time frame: through study completion, on average 1 year and 5 months

    Conducting a lactulose and mannitol test before and after the intervention

  13. Serum BDNF

    Time frame: 1 year and 5 months

    Quantification of fasting serum BDNF levels (µg/mL)

Sponsors and collaborators

Lead sponsor

KU Leuven

Other

Registry information

Important dates

Study start
2019
Primary completion
2020
Study completion
2020
First posted
Aug 21, 2020
Registry last updated
Jan 7, 2021

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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