Researchers report that the fatty acid conjugated linoleic acid (CLA) and the antioxidant R-alpha-lipoic acid act synergistically to improve the ability of insulin to escort glucose into cells. This was reported in a study published in the September 2003 journal Metabolism.
Both CLA and R-Lipoic Acid have been shown to individually enhance glucose tolerance and insulin action in insulin-resistant, obese rats. Until now, however, no study has investigated the effect on insulin resistance when these two substances are combined.
In the current study, researchers sought to determine whether treatment with CLA and R-lipoic acid in combination would enhance glucose absorption to a greater extent than either substance used individually. The study authors administered either CLA, R-lipoic acid, or a combination of both nutrients to obese rats for 20 days at low or high doses.
Whereas low-dose R-lipoic acid (10 mg/kg body weight) alone did not alter glucose metabolism, low-dose CLA (0.3 g/kg) induced a significant increase in insulin-triggered glucose transport, but only in certain muscles. Low-dose combination therapy, on the other hand, caused the greatest enhancement of insulin's ability to improve glucose transport in a wider range of muscles. In fact, there was a 50% reduction in protein carbonyls, a marker of tissue oxidative stress caused by free radicals. There was also a 33% reduction in muscle triglycerides.
The researchers concluded, "These findings support a significant interaction between low doses of CLA and R-lipoic acid for enhancement of insulin action on skeletal muscle glucose transport, possibly via reductions in muscle oxidative stress and in lipid storage."
Teachey MK, Taylor ZC, Maier T, Saengsirisuwan V, Sloniger JA, Jacob S, Klatt MJ, Ptock A, Kraemer K, Hasselwander O, Henriksen EJ. Interactions of conjugated linoleic acid and lipoic acid on insulin action in the obese Zucker rat. Metabolism. 2003 Sep;52(9):1167-74.