Measuring VLDL1-Triglyceride and VLDL2-Triglyceride Kinetics in Men: Effects of Dietary Control on Day-to-Day Variability

Abstract

The aim of this study was to assess the impact of dietary control on VLDL₁- and VLDL₂-TG kinetics and associated metabolic parameters. Twelve overweight/obese men were randomized to a provided 3 day isocaloric diet with fixed macronutrient composition (diet group, n=6) or to their regular unrestricted diet (non-diet group, n=6). VLDL₁- and VLDL₂-TG turnovers were measured twice 2-4 weeks apart, using primed-constant infusion of ex vivo labeled [1-¹⁴C]VLDL₁-TG and [9,10-³H]VLDL₂-TG. Isocaloric diet intervention lowered the difference in the mean of both VLDL₂-TG secretion and clearance rate (p<0.01), and the coefficient of variation (CV) of VLDL₂-TG clearance rate (p<0.05). The difference in mean and CV of the other kinetic estimates (VLDL₁-TG secretion, clearance and oxidation rate) were lowered, but not significantly. The CV's of total triglyceride, VLDL₁-TG, and VLDL₂-TG concentrations were significantly lowered by diet intervention compared to regular diet; total triglyceride (31%-5%, p<0.01), VLDL₁-TG (42%-9%, p<0.01), and VLDL₂-TG (36%-10%, p<0.01). In conclusion, VLDL₁- and VLDL₂-TG kinetics show great day-to-day variability, which may be diminished by diet intervention. Therefore, standardized macronutrient intake prior to study days improves the probability of demonstrating significant outcomes of cross-sectional and intervention studies of VLDL₁-TG and VLDL₂-TG kinetics and metabolism.