During dietary fat absorption, the gut packages the majority of the fats into lipid particles that are secreted into blood circulation. The gut is also capable of storing a considerable amount of fats that can be released at a later time upon receiving certain stimulus signals. One of the signals is glucose ingestion. This protocol examines how glucose ingestion releases gut lipid store. Participants drink a fatty formula and 5-9 hours later drink either a glucose solution or water (as control). One hour later, duodenal biopsy specimen are taken for analysis of lipid stores in the gut cells.

Participants undergoing upper gastrointestinal endoscopy and duodenal biopsy for clinical indications are recruited after obtaining informed consent. They first have a high fat liquid formula. 5 to 9 hours later, half of the participants drink 50 grams of glucose in 50 ml of water. The other half drink 50 ml of water. 1 hour later, duodenal biopsy specimen are collected and stored for analysis of lipid stores in the gut using electron microscopy and proteins using proteomics.

Inclusion Criteria:

• Men and women, aged 18 to 60 years requiring endoscopy and duodenal biopsies for clinical indications, with no contraindications to the procedure, as judged by endoscopy doctor.
• Body mass index 20 to 27 kg/m2

Exclusion Criteria:

• Patients with active inflammatory bowel disease
• Patients with Celiac disease, exocrine pancreatic insufficiency or small bowel malabsorption
• Patients with active bowel malignancy
• Patients with diabetes mellitus or known/ suspected motility disorders of the gut
• Patients with decompensated liver disease
• Patients on ezetimibe or bile acid sequestrants
• Unstable cardiac or respiratory disease
• Any changes to medication in the preceding month