Effects of intravenous supplementation with α-tocopherol in patients receiving total parenteral nutrition containing medium- and long-chain triglycerides

Objective: To compare the effects of a lipid emulsion containing medium-chain triglycerides (MCT) and supplemented with alpha-tocopherol to a conventional long-chain triglyceride (LCT) emulsion. Design: Randomised double blind study. Setting: Department of Internal Medicine, Antwerp University Hospital. Subjects and interventions: Twenty-four patients with an indication for total parenteral nutrition for a minimum of 10 days were randomly assigned to two groups: group E received as lipid source MCT/LCT (50/50) supplemented with 100 mg DL-alpha-tocopherol/day and group C received LCT Blood samples were analysed at inclusion, after 4-6 and after 9-11 days, Results: In group E, serum alpha-tocopherol doubled from 11.4 +/- 6.9 at inclusion to 20.9 +/- 7.9 and to 23.8 +/- 8.8 mug/ml after 4 and 9 days, respectively, but did not change in group C (P = 0.008). Production of thiobarbituric acid-reacting substances (TBARS) after 120 min incubation with copper decreased from 66 +/- 34 at inclusion to 29 +/- 25 nmol MDA/mg LDL and VLDL-cholesterol after 4 and to 42 +/- 17 after 9 days (P = 0.022 when compared to group C, which underwent no significant changes). Velocity of production of fluorescent products decreased in group E but not in group C (P = 0.026). Conclusions: Supplementation of TPN containing MCT/LCT with 100 mg DL-alpha-tocopherol/day leads to a doubling in serum alpha-tocopherol and to a decrease in the susceptibility of LDL and VLDL to peroxidation in vitro.