Lower brain glucose uptake is present before the onset of cognitive deterioration and may increase the risk of cognitive decline in Alzheimer's disease. Ketones are the brain's main alternative energy substrates. Medium-chain triglycerides (MCT) are rapidly beta-oxidized and are ketogenic. Large doses of MCT oil are linked to gastro-intestinal side effects due to incomplete absorption so the investigators examined whether homogenisation into a skim milk matrix (MCT-H) would both improve ketogenesis and reduce side-effects compared to MCT taken without homogenisation into a matrix (bulk MCT [MCT-B]).