Constipation, Healthy
Conditions
Keywords
Diet, Fermented dairy, Gut-brain axis, Microbiota
Brief summary
The goal of this intervention study is to compare the effects of fermented dairy and non-fermented dairy on bowel habits and cognitive performance in healthy women with defecations every other day or less. Furthermore, the study aims to explore underlying mechanisms linking the gut and the brain. In addition, a sub-study will be conducted to explore differences in gut and brain measures between women with daily (reference group) and few (intervention group) weekly bowel movements, respectively, and to explore associations between measures of gut- and brain function.
Detailed description
Participants in the intervention study (n=60) will consume 300g of fermented dairy (yogurt) or non-fermented dairy (milk) daily for 4 weeks. After a washout period of at least 4 weeks, the participants will consume the alternative dairy product (yogurt or milk) for 4 weeks. The participants will collect samples at home and be tested at the institute before and after each condition (yogurt or milk). Participants in the sub-study (n=40) will not undergo any dairy interventions and they will only take part in the baseline assessments. Prior to all visits at the institute, the participants are asked to complete some study activities at home, including: * consumption of sweet corns to estimate whole gut transit time * collection of fecal- and urine samples * measurement of methane and hydrogen in breath * reporting of gastrointestinal symptoms, including stool frequency and Bristol Stool Scale During all visits at the institute, the participants will undergo tests and measurements, including: * measurement of methane and hydrogen in fasting breath * collection of fasting blood samples * completion of cognitive tests * recordings of electrophysiological signals of the gut and the brain * completion of questionnaires assessing mood, quality of life, and physical activity, among others
Interventions
OTHERFermented dairy
Participants will consume 300g of yogurt daily for 4 weeks as an integral part of their habitual diet, substituting other food items.
OTHERNon-fermented dairy
Participants will consume 300g of milk daily for 4 weeks as an integral part of their habitual diet, substituting other food items.
Sponsors
University of Copenhagen
University of Aarhus
APC Microbiome Ireland
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Investigator)
Intervention model description
Two 4-week intervention periods separated by a washout period of at least 4 weeks. The crossover intervention will include 60 participants. Another 40 participants will only complete the first (baseline) visit.
Eligibility
Sex/Gender
FEMALE
Age
45 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Self-reported defecations every second day or less (intervention study only) * Willing to consume 300g milk/yogurt on a daily basis (intervention study only) * Owns a smartphone (iOS 11.0 and later or Android 5.0 and up) * Understand Danish or English
Exclusion criteria
* Current pregnancy or lactation * Dairy allergy or intolerance * Prior diagnosis of psychiatric or neurological illness * Current diagnosis of depression, anxiety, or stress * Prior diagnosis of metabolic or gastrointestinal disease (e.g., cardiovascular disease, diabetes, chronic constipation or diarrhea, inflammatory bowel diseases (IBD), celiac disease, small intestinal bacterial overgrowth (SIBO), cancer, etc.) * Use of antibiotics within the last month * Use of peroral corticosteroids (inhalers excepted) * Use of medications that alter normal bowel function and metabolism (e.g., laxatives, antidiarrheal agents, narcotics, diuretics, anticonvulsants, etc.) * Use of neuroactive medications (e.g., antidepressants, anxiolytics, anticonvulsants, antipsychotics, antiparkinsonian, etc.) * Concurrent participation in another trial * Any condition that makes the project responsible researcher doubt the feasibility of the volunteer´s participation
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Difference in change from baseline in defecation frequency between the interventions | Baseline and 4 weeks | Participants will report all bowel movements in a defecation diary in the week leading up to the intervention (baseline) and in the last week of the intervention (week 4) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Difference in change from baseline in cognitive performance between the interventions | Baseline and 4 weeks | Changes in cognitive performance will be quantified by cognitive index comprising memory, attention, and psychomotor speed. A composite cognitive score will be calculated as the standard score. Z-score will be assessed with the baseline variance between 0 and 1. Memory: number of errors made by the participant. Lower number of errors indicating better outcome. Attention: latency (speed of response), probability of false alarms and sensitivity. Faster speed of response indicating better outcome and lower number of false alarms indicating better outcome. Psychomotor speed: lower values indicating faster reaction time and better outcome |
| Difference in change from baseline in phase-amplitude coupling between gastric slow-wave activity and cortical alpha activity between the interventions | Baseline and 4 weeks | Gastric and cortical electrical activity will be measured by electrogastrography (EGG) and electroencephalography (EEG), respectively, to investigate the phase-amplitude coupling between the infra-slow (\~ 0.05 Hz) gastric phase and the amplitude of the cortical alpha rhythm (10-11 Hz) |
| Difference in change from baseline in whole gut transit time between the interventions | Baseline and 4 weeks | Whole gut transit time will be estimated by sweet-corn passage time |
| Difference in change from baseline in stool consistency between the interventions | Baseline and 4 weeks | Changes in stool consistency will be estimated by the Bristol Stool Scale. The scale ranges from type 1 (hard stool) to type 7 (loose stool) |
| Difference in change from baseline in stool moisture between the interventions | Baseline and 4 weeks | Fecal water content in percentage of stool weight will be measured |
| Difference in change from baseline in fecal abundance of Lactobacillus acidophilus between the interventions | Baseline and 4 weeks | Marker of compliance. Will be assessed by fecal microbiota sequencing |
| Difference in change from baseline in self-reported gastrointestinal symptoms between the interventions | Baseline and 4 weeks | Changes in subjective gastrointestinal symptoms will be reported by participants using a visual analog scale.The scale ranges from 0 (no symptoms) to 10 (very bad symptoms) |
Countries
Denmark
Outcome results
None listed