L‐Arginine infusion attenuates postprandial lipemia in healthy elderly

Abstract

Increased plasma concentration of L‐arginine enhances the production of nitric oxide (NO), which has been proposed to increase fat oxidation in skeletal muscle. The purpose of this study was to determine whether L‐arginine infusion lowered the increase in plasma triglycerides (TG) and increased the rate of oxidation of ingested fat in healthy elderly subjects following a fatty meal. On two separate days in the morning after an overnight fast, nine healthy elderly (8 males and 1 female, age, 68 ± 4 yr; body mass, 85.7 ± 10.8 kg; % body fat, 27 ± 3%; triglycerides, 78.1 ± 32.5 mgµdL−1; glucose, 91.9 ± 7.4 mgµdL−1) ingested whipping cream (0.4 g of fat per kg body weight) enriched with [13C]‐triolein. Plasma TG concentrations were measured in plasma from blood samples collected every hour during an 8‐h period following meal ingestion. Expired gases were measured every 2 hours to determine whole‐body fat oxidation. Subjects rested in bed for the duration of the trials. On one of these days, in a random order, 300 ml of 10% L‐arginine (arginine day) was infused during the first hour after the meal, whereas on the other day (control day) the same volume of saline was infused. Arginine infusion decreased the incremental TG area under the curve: control day, 99.7 ± 28.7 mgµdL−1µ8h−1; arginine day, 22.8 ± 24.2 mgµdL−1µ8h−1. The rate of oxidation of ingested fat was not different between the arginine and control days: 4.7 ± 0.4 μmolµkgFFM−1µ8h−1 versus 4.2 ± 0.5 µmol·kgFFM−1·8h−1 respectively. In conclusion, L‐arginine infusion attenuates postprandial lipemia in healthy elderly subjects, but this not mediated by an increase in the rate of oxidation of ingested fat.