dairy products to your gut and brain

Conditions: Healthy; Constipation

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.

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

Eligibility criteria:
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

Keywords: diet fermented dairy gut-brain axis microbiota