DAG5 is one of Lifelines' additional assessments (see also: DAG1, DAG2, DAG3 and DAG4). DAG is the abbreviation of DArmGezondheid, or “Gastrointestinal health” in Dutch.

There is increasing insight into the role of bacterial composition in the intestine and upon the occurrence of (chronic) diseases. Previous research in DAG1 (DEEP) demonstrated the relation of the microbiome and lipids, but also many other diseases and intrinsic and extrinsic factors. Previous research in DAG3 (DAG3) described the gut microbioom in a larger cohort.

Longitudinal analyses in 350 Lifelines DEEP participants that were also part of the DAG3 collection, showed that microbiome individual specific patterns could be stable for >3 years. However, it was also observed that some microbial changes were related to individual’s changes over time were in line with individual’s changes in their healthy status, lifestyle and medication usage (REFERENCE).

The purpose of DAG4 was to extent the amount of participants with longitudinal data and longitudinal biological samples, that gives an unique opportunity to study the long-term dynamics of the gut microbiome and its relation to developing and progressing of diseases and phenotypes.

In DAG5 another follow up stool sample is collected.

A total of approximately <NUMBER> participants were included in the DAG5 dataset:

• Alle participants we aged 18 years or older.
• … participants were also included in the (DEEP) dataset
• … participants were also included in the (DAG3) dataset
• ~… participants were genotyped in the UGLI project.

Besides the samples used to generate the microbiome data, questionnaires were also sent to participants to gather phenotypic data on gastrointestinal health symptoms by means of Rome III criteria questionnaire (Longstreth etal 2006) and the Bristol Stool Form Scale (O’Donnell etal 1990).