Researchers, led by Jiankang Liu from the Institute for Brain Aging and Dementia at the University of California (Irvine), report that the nutrients work together, or synergistically - a result not previously reported. "The strong synergistic effect of the combination of LA and ALC in [fat cells] adipocytes suggests that these two nutrients complement each other's function in mitochondrial biogenesis," wrote the authors in the journal Diabetologia. Talking to NutraIngredients.com, Liu said: "The paper in Diabetologia is the first paper using adipocytes showing that the combination of alpha-lipoic acid and acetyl-L-carntitine may be more effective than individuals to ameliorating diabetes and obesity and also elucidating the mechanisms of the mitochondrial biogenesis synergistically." Lipoic acid (LA) has been linked to a host of health benefits, including enhancing heart and artery health, immune and brain functions and has been shown to support weight reduction. Likewise, carnitine, a "conditionally essential nutrient" is an increasingly popular ingredient in dietary supplements intended for weight loss and sports. Three different forms of the compound are commonly available: L-carnitine (LCAR), acetyl-L-carnitine (ALCAR), and propionyl-L-carnitine (PLCAR), although the latter is only available in Europe. There is no evidence to suggest that there is any inherent differences between the forms. A risk assessment from scientists at the Council for Responsible Nutrtion (CRN), published in the journal Regulatory Toxicology and Pharmacology (doi: 10.1016/j.yrtph.2006.06.007) reported that an adult human observed safe limit (OSL) of 2000 mg for the nutrient. The new study measured the activity of mitochondria in adipocytes in the presence of LA and/or LCAR at a concentration of 0.1, 1 and 10 micromoles per litre for 24 hours. The mass of the mitochondria and their oxygen consumption were measured, in addition to several genetic markers. Liu and co-workers report that the combination of LA and LCAR increased the mass, oxygen consumption, mitochondrial DNA expression, and fatty acid oxidation in the fat cells. "However, the treatments with LA or ALC alone at the same concentrations showed little effect on mitochondrial function and biogenesis," noted the researchers. Speaking to this website, Dr. Liu noted: "Lipoic acid and acetyl-L-carnitine have become very hot after our reports on the complementary effects on improving memory and ambulatory activity in old rats," relating to studies published in the Proceedings of the National Academy of Science in 2002 (Vol. 99, Pages 1870-1875, 1876-1881, and 2356-61). Looking ahead to the next stage of the research, the scientists said that the combination of the nutrients should be tested in animals with insulin resistance. This would enable them to "determine whether such combinations might be an effective nutrient intervention for ameliorating mitochondrial dysfunction in vivo." An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030. In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132 billion, with $92 billion being direct costs from medication, according to 2002 American Diabetes Association figures. Source: Diabetologia 2008, Volume 51, Pages 165-174, doi: 10.1007/s00125-007-0852-4 "R-alpha-Lipoic acid and acetyl-L-carnitine complementarily promote mitochondrial biogenesis in murine 3T3-L1 adipocytes" Authors: W. Shen, K. Liu, C. Tian, L. Yang, X. Li, J. Ren, L. Packer, C.W. Cotman, J. Liu
A combination of lipoic acid and acetyl-L-carnitine may boost the function of mitochondria - the cell's power stations - suggests research with implications for diabetes and obesity.