Impact of Isocaloric Fructose and Glucose Diets on Lipid Metabolism Studied in Vivo by Multinuclear MR Spectroscopy

Patricia M. Nunes¹, Alan J. Wright¹, Andor Veltien¹, Jack JA van Asten¹, Cees J. Tack², John G. Jones³, Arend Heerschap¹

We investigated in vivo the effects of isocaloric fructose and glucose feeding of mice over 8 weeks on ectopic lipid deposition and hepatic energy status by MRS. Hepatic lipid sources were resolved into dietary, which was investigated in vivo with ₁H{¹³C}MRS after an oral bolus of [U-¹³C]lipids, and de novo lipogenesis which was assessed by ²H NMR spectroscopy using ²H₂O as tracer. Isocaloric fructose feeding had no effect on intramyocellular lipids, but significantly increased hepatic lipids, most likely by stimulating de novo lipogenesis and not by promoting dietary fat uptake. This occurs without expense of net hepatic energy, as shown by ³¹P MRS, unlike acute doses of fructose.