A new study published in Gastroenterology investigated associations between symptoms and intestinal gas production following sugar provocation tests, to elucidate mechanisms of functional gastrointestinal disorders (FGID). In this study, fructose and lactose breath tests was carried out in 2,042 patients with FGID (based on Rome III criteria), referred to a gastroenterology practice between January 2008 and December 2011. Medical and diet histories were collected from all participants. The results identified 11 gastrointestinal (GI) and central nervous system (CNS) symptom profiles; hydrogen and methane breath concentrations that changed significantly with time following sugar ingestion. The severity scores for the GI and CNS symptoms correlated following ingestion of sugars. On the other hand, only GI symptoms associated with hydrogen and methane gas production. The study identified clusters of GI and CNS symptoms in response to fructose of lactose ingestion. It was stated that the association between specific symptoms and breath gas concentrations indicate distinct mechanisms of FGID pathogenesis, such as changes in the microbiome or mechanical and chemical sensitization.