Metabolism of uniformly labeled 13C-eicosapentaenoic acid and 13C-arachidonic acid in young and old men

Abstract

Background: Plasma eicosapentaenoic acid (EPA) and arachidonic acid (AA) concentrations increase with age. Objective: The aim of this study was to evaluate EPA and AA metabolism in young and old men by using uniformly labeled carbon-13 ( 13 C) fatty acids. Design: Six young (∼25 y old) and 6 old (∼75 y old) healthy men were recruited. Each participant consumed a single oral dose of 35 mg 13 C-EPA and its metabolism was followed in the course of 14 d in the plasma and 28 d in the breath. After the washout period of ≥28 d, the same participants consumed a single oral dose of 50 mg 13 C-AA and its metabolism was followed for 28 d in plasma and breath. Results: There was a time 3 age interaction for 13 C-EPA (P time 3 age = 0.008), and the shape of the postprandial curves was different between young and old men. The 13 C-EPA plasma half-life was∼ 2 d for both young and old men (P = 0.485). The percentage dose recovered of 13 C-EPA per hour as 13 CO 2 and the cumulative b-oxidation of 13 C-EPA did not differ between young and old men. At 7 d, however, old men had a s.2.2-fold higher plasma 13 C-DHA concentration synthesized from 13 C-EPA compared with young men (P age = 0.03). 13 C-AA metabolism was not different between young and old men. The 13 C-AA plasma half-life was ∼4.4 d in both young and old participants (P = 0.589). Conclusions: The metabolism of 13 C-AA was not modified by age, whereas 13 C-EPA metabolism was slightly but significantly different in old compared with young men. The higher plasma 13 C-DHA seen in old men may be a result of slower plasma DHA clearance with age.