Metabolic fate of fructose ingested with and without glucose in a mixed meal

Abstract

Ingestion of pure fructose stimulates de novolipogenesis and gluconeogenesis. This may however not be relevant to typical nutritional situations, where fructose is invariably ingested with glucose. We therefore assessed the metabolic fate of fructose incorporated in a mixed meal without or with glucose in eight healthy volunteers. Each participant was studied over six hours after the ingestion of liquid meals containing either 13 C-labelled fructose, unlabeled glucose, lipids and protein (Fr + G) or 13 C-labelled fructose, lipids and protein, but without glucose (Fr), or protein and lipids alone (ProLip). After Fr + G, plasma 13 C-glucose production accounted for 19.0% ± 1.5% and 13 CO2 production for 32.2% ± 1.3% of 13 C-fructose carbons. After Fr, 13 C-glucose production (26.5% ± 1.4%) and 13 CO2production (36.6% ± 1.9%) were higher (p< 0.05) than with Fr + G. 13 C-lactate concentration and very low density lipoprotein VLDL 13 C-palmitate concentrations increased to the same extentwith Fr + G and Fr, while chylomicron 13 C-palmitate tended to increase more with Fr + G. These data indicate that gluconeogenesis, lactic acid production and both intestinal and hepatic de novolipogenesis contributed to the disposal of fructose carbons ingestedtogether with a mixed meal. Co-ingestion of glucose decreased fructose oxidation and gluconeogenesis and tended to increase 13 C-pamitate concentration in gut-derived chylomicrons, but not in hepatic-borne VLDL-triacylglycerol (TG). This trial was approved by clinicaltrial. gov. Identifier is NCT01792089. © 2014 by the authors; licensee MDPI, Basel, Switzerland.