DNA extractions and Terminal Restriction Fragment Length Polymorphism (T-RFLP) and quantification of specific bacterial groups will be done by quantitative polymerase chain reaction (PCR) in accordance with the protocols the investigator has used and described earlier by the research group. As reference, a restricted number of samples will be analyzed with massively-parallel pyrosequencing of partial ribosomal ribonucleic acid (rRNA) ribosomal genes. The gut microbiota bacterial constitution (bacterial species) will be correlated to gastrointestinal symptoms and diseases, and changes in bio- and inflammatory markers.