November 2012
A double-blind, placebo-controlled trial published in June 2012 reports that green tea extract alters insulin resistance and cardiovascular risk factors in obese, hypertensive subjects. Green tea (Camellia sinensis) contains catechins with potent antioxidant and free-radical scavenging activity.
The subjects included 56 obese individuals with hypertension. The subjects received 379 mg of green tea extract or placebo daily for three months. The researchers assessed the subjects for key measures, including blood pressure, plasma lipid and glucose levels, creatinine levels for kidney function, and insulin levels and insulin resistance at the beginning of the study and again after three months of supplementation. The investigators also evaluated levels of the inflammatory markers tumor necrosis factor-alpha and C-reactive protein (CRP), as well as total antioxidant status.
The researchers found that, after three months of supplementation with green tea extract, both systolic and diastolic blood pressure significantly decreased compared to the placebo group. In addition, fasting serum glucose, insulin levels and insulin resistance also decreased in the green tea extract group compared to the placebo group.
The green tea extract group also had significantly lower levels of the inflammatory markers tumor necrosis factor-alpha and CRP and higher total antioxidant status. Furthermore, the researchers showed that the subjects in the green tea extract group had reductions in total and low-density lipoprotein (LDL) cholesterol and triglycerides, and increased high-density lipoprotein (HDL) cholesterol.
The study authors stated, “In conclusion, daily supplementation with 379 mg of green tea extract favorably influences blood pressure, insulin resistance, inflammation and oxidative stress, and lipid profile in patients with obesity-related hypertension.”
Reference:
Bogdanski P, et al. Nutr Res. 2012;6:421-7.
Source: Green Tea Modulates Several Cardiovascular Risk Factors
