Irritable bowel syndrome patients with diarrhoea (IBS-D) often report intolerance to milk; however, the mechanism underlying these symptoms is unknown.
Dr Dai and colleagues assessed the role of psychological factors, immune activation and visceral sensitivity on the development of lactose intolerance (LI) in IBS-D patients.
The research team identified 55 IBS-D patients, and 18 healthy controls with lactase deficiency that underwent a 20-g lactose hydrogen breath test (LHBT).
Patients were categorized as lactose malabsorption [LM] or malabsorption plus increase in total symptom score (TSS) [LI].
Measurements included psychological status, enteric biopsies with quantification of mast cells, T-lymphocytes and enterochromaffin cells, serum cytokines, rectal sensitivity before and after lactose ingestion.
|The severity of abdominal symptoms after lactose ingestion was associated with anxiety|
|Alimentary Pharmacology & Therapeutics|
The research team noted that LI was more prevalent in IBS-D patients than healthy controls.
IBS-D patients with LI had higher levels of anxiety than those with LM, increased mucosal mast cells compared with LM, and healthy controls, raised serum TNF-α compared with LM and healthy controls, and increased rectal sensitivity after lactose ingestion compared with LM or healthy controls.
The team observed that the severity of abdominal symptoms after lactose ingestion was associated with the increase in visceral sensitivity after lactose intake, mast cells, and anxiety.
Dr Dai's team concludes, "IBS-D patients with lactose intolerence are characterized by anxiety, mucosal immune activation and increased visceral sensitivity after lactose ingestion."
"The presence of these biomarkers may indicate an IBS phenotype that responds to dietary therapy and/or mast cell stabilizers."