Effect of 3-month L-arginine supplementation on insulin resistance and tumor necrosis factor activity in patients with visceral obesity

P. Bogdanski, J. Suliburska*, K. Grabanska, K. Musialik, A. Cieslewicz**, A. Skoluda**, A. Jablecka**

Department of Internal Medicine, Metabolic Disorders and Hypertension and **Department of Clinical Pharmacology, Poznan University of Medical Sciences, Poznan (Poland); *Department of Human Nutrition and Hygiene Poznan University of Life Sciences, Poznan (Poland)

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• Internal Medicine

BACKGROUND: The role of tumor necrosis factor alpha (TNF-alpha), one of the adipose tissue products, in the pathogenesis of insulin resistance is well-documented. Many recent studies have shown beneficial influence of L-arginine supplementation on cardiovascular system. However, molecular mechanisms of its positive actions are not fully elucidated.

AIM: The aim of the study was to evaluate the influence of L-arginine supplementation on tumor necrosis factor alpha, insulin resistance and selected anthropometric and biochemical parameters in patients with visceral obesity.

PATIENTS AND METHODS: 60 patients with visceral obesity were randomly assigned to either receive 9 g of L-arginine or placebo for 3 months. 20 healthy lean subjects were used as control. Selected anthropometrical measurements and blood biochemical analyses were performed at baseline and after 3-months. TNF-alpha and its soluble receptor 2 (sTNFR2) were assessed in both treated groups. Insulin resistance in the participants was evaluated according to the homeostasis model assessment-insulin resistance (HOMA-IR) protocol.

RESULTS: The concentration of insulin, TNF-α and sTNFR2 and HOMA-IR level in both obese groups significantly exceeded these observed in the control. Basal TNF-alpha and sTNFR2 concentrations were positively correlated with basal body mass index (BMI), waist circumference, percent of body fat and HOMA-IR. We found that 3-month L-arginine supplementation resulted in significant decrease of HOMA-IR and insulin concentration. Only insignificant tendency to decrease of TNF-alpha and sTNFR2 was observed.

CONCLUSIONS: Our results confirm TNF-alpha role in the complex pathogenesis of insulin resistance in patients with visceral obesity. 3-months L-arginine supplementation in a dose of 9 g improves insulin sensitivity in patients with visceral obesity with no impact on tumor necrosis factor alpha concentration.

Corresponding Author: Pawel Bogdanski, MD; e-mail: pawelbogdanski@wp.pl