The Oregon State University/Linus Pauling Institute website is highlighting a number of recent studies, especially from 2005-2006, which have examined the potential of acetyl-l-carnitine or L-carnitine, together with alpha lipoic acid, to counter the effects of aging in laboratory rats. Like the Linus Pauling Institute reviewer, we are looking forward to human clinical trials in the next few years to further define useful dosages and health benefits.
…two studies found that supplementing aged rats with either ALCAR [acetyl-l-carnitine] or alpha-lipoic acid, a mitochondrial cofactor and antioxidant, improved mitochondrial energy metabolism, decreased oxidative stress, and improved memory. Interestingly, co-supplementation of ALCAR and alpha-lipoic acid resulted in even greater improvements than either compound administered alone. Likewise, several studies have reported that supplementing rats with both L-carnitine and alpha-lipoic acid blunts the age-related increases in reactive oxygen species (ROS), lipid peroxidation, protein carbonylation, and DNA strand breaks in a variety of tissues (heart, skeletal muscle, brain). Improvements in mitochondrial enzyme and respiratory chain activities were also observed. While these findings are very exciting, it is important to realize that these studies used relatively high doses (100 to 300 mg/kg body weight/day) of the compounds and only for a short time (one month). It is not yet known whether taking relatively high doses of these two naturally occurring substances will benefit rats in the long-term or will have similar effects in humans. Clinical trials in humans are planned, but it will be several years before the results are available.