Age-dependent decrease of carnitine content in muscle of mice and humans.

Carnitine deficiency associated with impairment of muscle function has been described in infants and young adults as a result of inherited or acquired disease but there are no reports on carnitine levels in healthy aging people. In this paper we show a marked reduction of carnitine and its derivatives in muscle, and of long-chain acyl carnitine in heart of 6-month-old mice, when compared to animals of 6 weeks of age. Analysis of muscle samples of healthy humans of different ages showed a drastic reduction of carnitine and acetyl carnitine in the older subjects with a strong reverse correlation between age and carnitine levels.