Acetyl-l-carnitine is the acetylated form of l-carnitine, and the two compounds share similar energy and metabolism promoting properties. Found naturally in the body, acetyl-l-carnitine supports the availability of acetyl-CoA, an important energy generating metabolite. In addition, it supports healthy mitochondrial function and cell membrane stability. The acetyl group from acetyl-l-carnitine is also responsible for production of acetylcholine, an important neurotransmitter for optimal mental functioning. The efficacy of long-term acetyl-l-carnitine supplementation was evaluated in a double blind, placebo-controlled, randomized trial involving 130 elderly individuals for a one-year period. In this trial, acetyl-l-carnitine supported healthy cognitive function, memory and attention. In another randomized double blind study, three-month acetyl-l-carnitine supplementation provided statistically significant support for mental function, including memory and attention, compared to placebo. A multicenter trial of 481 volunteers indicated memory, behavioral and emotional support with acetyl-l-carnitine supplementation. In an evaluation of 28 elderly individuals using acetyl-l-carnitine or placebo, the supplemented group experienced enhanced emotional well-being.