To guarantee accurate measurement of microbiota and shirt chain fatty acids (SCFA), only fresh faecal samples will be analyzed.Faecal samples will be collected within 1 hour of voiding and will immediately be transported to the laboratory for analysis of microbiota. The faecal sample will be homogenized using a sterile stainless steel Waring blender and aliquots of each specimen and will be frozen at -80°C until DNA is extracted.