Evaluation of oxidative stress in diabetic patients after supplementation with a standardised red orange extract

Diabetes mellitus is associated with a high oxidative stress level, resulting from an imbalance between free radicals or reactive oxygen species production and the antioxidant systems. Inhibition of these oxidative processes by co-adjuvant therapy could therefore prevent, or at least delay, the onset and/or the development of long-term diabetic complications. Dietary supplementation with plant biophenols may be a successful strategy to decrease this risk of pathological complications. The Red Orange Complex (ROC) is a standardized red orange extract containing, as its main active principles, phenolic compounds (anthocyanins, flavanones and hydroxycinnamic acids) as well as ascorbic acid. The aim of the present preliminary study was to evaluate the effects of short-term (2 mo) dietary supplementation with ROC (50 mg/d, orally) on some serum non-invasive biomarkers of oxidative stress (total antioxidant status, or TAS, levels of thiol groups and levels of free radicals) in a group of 33 patients with Type 2 diabetes, in comparison with a group of 28 healthy volunteers. The results obtained demonstrate that in diabetic patients supplementation with ROC can improve blood levels of thiol groups on proteins (an indirect measurement of glutathione activity in serum); furthermore, it can elicit a marked decrease in serum free radical levels, in patients with high blood oxidative stress status. However, ROC supplementation appeared unable to modify serum TAS. Finally, the glycemic profile remained stable during the study period in all subjects, and no unpleasant side effects were reported. In conclusion, the treatment of diabetic patients with ROC might be of therapeutic benefit in order to protect against diabetes complications that are partially due to uncontrolled lipid oxidation.