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

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 [1-14 C]VLDL1 -TG and [9,10-3 H]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.