Beneficial dose-independent influence of Camellia sinensis supplementation on lipid profile, glycemia, and insulin resistance in an NaCl-induced hypertensive rat model.

Green tea extract exerts favorable influence on the lipid profile and insulin resistance in the high-sodium intake arterial hypertension. A high-sodium diet (HSD) was introduced to thirty Wistar rats to create a model of hypertension. Rats were randomized into three groups, 10 animals each. The SK group consumed HSD. The SH2 group consumed HSD with 2 g of green tea extract in kg of diet. The SH4 group was fed HSD with 4 g of green tea extract in kg of diet. After six-week trial blood samples were collected. The serum concentrations of glucose, insulin and lipids were estimated, and insulin sensitivity was calculated using homeostatic model assessment (HOMA). Neither the high-sodium diet nor supplementation with green tea extract had any significant influence on the body mass of the animals in either group. Total cholesterol (TCH) and low-density lipoproteins (LDL) cholesterol serum concentrations were significantly smaller in both supplemented groups than in the SK group. The insulin level in the SH2 rats and HOMA in SH2 and SH4 groups were found to be significantly smaller than in the SK group. There were no differences in glucose concentrations between groups. Within the whole population, statistically significant positive correlations between HOMA and LDL, TCH were found. We conclude that in NaCl-induced hypertensive Wistar rats, supplementation with green tea extract produced a dose-independent beneficial and parallel effect on the lipid profile and insulin resistance.

The influence of orlistat, metformin and diet on serum levels of insulin-like growth factor-1 in obeses women with and without insulin resistance.

A range of studies showed confusing data about the relationship between obesity, weight reduction and circulating total insulin-like growth factor -1 (IGF-1). The aim of the study was to compare the influence of orlistat (IO), metformin (IM), or calorie-restricted diet (LC) on IGF-1, with special respect to insulin-resistance status. One hundred and fourteen obese women aged from 18 to 40 years were divided into insulin sensitive (IS) and insulin resistant (IR) groups and received a low calorie diet (LC), or an isocaloric diet and 500 mg metformin twice daily (IM), or isocaloric diet with 120 mg orlistat three times daily (IO). Before and after the intervention anthropometric parameters, serum lipid profile, serum concentrations of alanine aminotransferase, aspartate aminotransferase, insulin, glucose, IGF-1, HOMA-IR (homeostatic model assessment), and visceral adiposity index (VAI), and their changes were registered. Although the reductions in weight and body fat were comparable in IS and IR groups, only women with IR showed a significant increase in IGF-1 concentration as a result of all interventions. We found significant positive correlations of ΔIGF-1 with initial and Δ values of: HOMA-IR, triglyceride/high-density cholesterol ratio, VAI. IR premenopausal women show significant increase in IGF-1 serum concentrations regardless the method of intervention. The increase in IGF-1 was parallel to the improvement of insulin resistance parameters.

Improvement of serum adiponectin and leptin concentrations: effects of a low-calorie or isocaloric diet combined with metformin or orlistat - a prospective randomized open-label trial.

OBJECTIVE: We compared the effects of three weight loss interventions on serum concentrations of adiponectin and leptin in obese premenopausal women. PATIENTS AND METHODS: 114 obese Caucasian women were randomized into three groups receiving a low-calorie diet (LC; n = 39), an isocaloric diet with 500 mg of metformin twice a day (IM; n = 38), and an isocaloric diet with 120 mg of orlistat three times a day (IO; n = 37), for three months. Serum concentrations of adiponectin and leptin were evaluated, along with anthropometric and body composition parameters, at baseline and after the study. RESULTS: Both IO and LC, but not IM, caused an increase in serum adiponectin concentration (p < 0.01, p < 0.05 respectively). A decrease in serum leptin level was documented in the LC (p < 0.001), IM (p < 0.01), and IO group (p < 0.01). Beneficial changes in anthropometric and body composition values were observed following all interventions with the greatest advantage seen in the IO group. The strongest correlations, of Δadiponectin with Δbody weight (r = -0.54), ΔBMI (r = -0.49), ΔFAT [%] (r = -0.48), ΔFAT [kg] (r = -0.48), and Δlean [%] (r = 0.48); and of Δleptin with Δbody weight, ΔBMI, Δwaist, Δfat, and Δlean, were documented in the IO group. CONCLUSIONS: Beneficial effects were observed on serum leptin concentration, weight loss, and body composition for all interventions and in all examined groups, with the greatest advantage being associated with the orlistat treatment. Improvements in serum adiponectin concentrations resulted from the low-calorie and isocaloric diets with orlistat, but not from the isocaloric diet with metformin. We find these strategies more promising for the treatment of obesity and its related complications in obese premenopausal women.