Kavin Panneerselvam from the Kasturba Medical College in Mangalore, and Sundaram Kumaran from the University of Madras in India, gave L-carnitine and alpha-lipoic acid separately or together to young, middle aged, and older rats.
When the compounds, widely sold as dietary supplements and found naturally in products such as red meat and milk, were used together the researchers found that the concentration of free radicals in mitochondria, energy-producing organelles in their cells, were lower than when used independently or not at all.
It must be stressed that pure compounds were used in this study and not a commercially available dietary supplement.
The new research, published on-line in the journal Clinical Nutrition (doi: 10.1016/j.clnu.2006.02.005), divided 60 male albino Wistar rats into 10 groups, depending on age (young, middle-aged, or old) and supplementation with placebo (saline solution), L-carnitine only (300 mg per kg body weight per day), alpha-lipoic acid (100 mg per kg body weight per day), or both.
After 60 days of supplementation, the researchers found that the level of reactive oxygen species (ROS) generation in the older rats was significantly higher than in younger and middle-aged rats. Supplementation with the L-carnitine, alpha-lipoic acid combination reduced the level of ROS by 28 per cent, compared to placebo.
Supplementation with either compound independently only reduced the level of ROS by about nine per cent.
Similar benefits were observed for other markers of the ageing process including lipid peroxides and protein oxidation due to the combination supplement.
"Our study strongly suggests that supplementation of mitochondrial metabolites, carnitine and lipoic acid may prevent mitochondrial damage and restore mitochondrial function during ageing process," said the researchers.
"Alpha-lipoic acid protects mitochondria by removing free radicals and improves the recycling of other antioxidants. Carnitine is more potent in restoring mitochondrial energy production. Thus the combination is complementary," they concluded.
This supports previous work by Researchers at the University of California, Berkeley, and the Children's Hospital Oakland Research Institute led by Professor Bruce Ames. The University of California patented use of the combination of the two supplements to rejuvenate cells. Ames, through the Bruce and Giovanna Ames Foundation, and Hagen founded a company in 1999 called Juvenon to license the patent from the university.