A Clinical Trial about a Food Supplement Containing α-Lipoic Acid on Oxidative Stress Markers in Type 2 Diabetic Patients

Abstract

The aim of this study was to evaluate the effect of a food supplement containing α-lipoic acid and of a placebo on glyco-metabolic control and on oxidative stress markers in type 2 diabetics. We randomized 105 diabetics to either a supplementation containing 600 mg of α-lipoic acid, 165 mg of L-carnosin, 7.5 mg of zinc, and vitamins of group B, or a placebo, for three months. We evaluated body mass index, fasting plasma glucose (FPG), post-prandial-glucose (PPG), glycated hemoglobin (HbA_1c), fasting plasma insulin (FPI), HOMA-index (HOMA-IR), lipid profile, high sensitivity C-reactive protein (Hs-CRP), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA). There was a reduction of FPG, PPG, and HbA_1c with the food supplement containing α-lipoic acid compared with a baseline, and with the placebo. Concerning lipid profile, we observed a reduction of LDL-C, and Tg with the food supplement, compared with both the baseline, and the placebo. There was a reduction of Hs-CRP with the food supplement containing α-lipoic acid, both compared with the baseline and the placebo. An increase of SOD, and GSH-Px, and a decrease of MDA were reached by the food supplement containing α-lipoic acid, both compared with the baseline and the placebo. We can conclude that the food supplement containing α-lipoic acid, L-carnosin, zinc, and vitamins of group B improved glycemic control, lipid profile, and anti-oxidative stress markers.

Keywords: L-carnosin; malondialdehyde; oxidative stress; α-lipoic acid.

Figure 1

Biological functions of α-lipoic acid. α-lipoic acid (ALA) and its reduced form dihydrolipoic acid (DHLA) create a potent redox couple, often called a “universal anti-oxidant” for its capacity to regenerate several others anti-oxidants, such as vitamins C and E and glutathione. α-lipoic acid is also able to directly scavenge ROS, possesses metal chelating activity, and enhances the mitochondrial expression of key anti-oxidant enzymes. Through these properties, α-lipoic acid exerts different activities, from mitochondrial bioenergetics cofactor to stress response regulation and neuronal protection. Mitochondrial bioenergetic cofactor: α-lipoic acid is a key cofactor for mitochondrial bioenergetic enzymes, including pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes, stimulating glucose and lipid metabolism. It acts as an insulin-mimetic agent, regulating the IR/PI3K/Akt pathway, so it enhances the uptake and the utilization of glucose, improving glycemic control. Stress response regulation: α-lipoic acid responds to stress factors, inhibiting stress induced transcription factor activation, such as NF-κB and AP-1, and modulating pro-inflammatory signaling, hence the anti-inflammatory activity. Neuronal protection: it is also well known that α-lipoic acid improves diabetic polyneuropathies, while attention has only recently been focused on the capacity to attenuate the hyperalgesia through the modulation of T-type calcium and transient receptor potential (TRPA1) channels.