Effect of Lactose on Blood Lipids

Each participant will undergo three experimental trials in a randomized, crossover research design. On each study day, participants will consume a test drink containing standardised amounts of carbohydrate and fat followed by collection of blood and breath samples to assess metabolic responses during the 6 hour postprandial period. Trials will be identical except for the type of carbohydrate contained within the test drink: 1) maltodextrin (glucose polymer), 2) lactose (galactose-glucose disaccharide) and 3) sucrose (fructose-glucose disaccharide).

Inclusion criteria

• Age: 18-50 years and premenopausal (for women)

Exclusion criteria

• Weight instability (>5 kg change in body mass within last 6 months)
• Diagnosis of any form of diabetes
• Intolerances or allergies to any of the study procedures (e.g. lactose intolerance)
• Galactose disorders (e.g. galactokinase deficiency, UDPgalactose-4-epimerase deficiency, galactose-1-phosphate uridyl transferase deficiency)
• Fructose malabsorption
• Inborn errors of fructose metabolism (e.g. fructokinase deficiency, aldolase B deficiency, fructose-1,6-bisphosphatase deficiency)
• Pregnant or lactating
• Any condition that could introduce bias to the study (e.g. diagnoses of lipid disorders, including cardiovascular disease, or therapies that alter lipid or glucose metabolism, such as statins or niacin).