The cholesterol-lowering effects were found to be even stronger in women with higher baseline levels of total cholesterol, reported researchers from the University of Minnesota, the University of Pittsburgh, and the University of Southern California.
“Current evidence from this trial suggests that GTE [green tea extract] may be recommended for cholesterol lowering, in particular in those with borderline or high cholesterol concentrations,” wrote the researchers in the American Journal of Clinical Nutrition.
“Green tea is an inexpensive, easily accessible, and popular drink and may indirectly lead to lower morbidity and mortality rates due to CVD through improving hyperlipidemia outcomes.”
Tea benefits
The study adds to an ever-growing body of science supporting the potential benefits of green tea (Camellia sinensis) and its constituents, most notably EGCG (epigallocatechin gallate).
Green tea contains between 30% and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. Oolong tea is semi-fermented tea and is somewhere between green and black tea. The four primary polyphenols found in fresh tealeaves are EGCG, epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).
The supplement used in this study was the Corban Complex GTB ingredient by Corban Laboratories/ Eniva Nutraceutics. The capsules were decaffeinated and provided 1,315 mg of catechins per day, consisting of 843 mg EGCG, 202 mg EG, 107 mg EGC, and 107 mg EC.
Study details
The new paper details results of an ancillary study of a randomized controlled trial investigating the effects of green tea extracts on breast cancer risk. The study involved 1,075 women randomly assigned to receive placebo or the green tea extract supplement for 12 months.
Results showed that, for the 936 women who completed this substudy, the green tea extract was associated with a 2.1% reduction in total cholesterol and a 4.1% reduction in LDL cholesterol, compared with increases of 0.7% and 0.9% in the placebo group, respectively.
“Surprisingly” triglyceride concentrations increased by 3.6% in the green tea group, compared with a 2.5% decrease in the placebo group.
“Among the bioactive green tea catechins, EGCG is of great interest because it is the most abundant and purported to be the main bioactive catechin responsible for the hypolipidemic effects of green tea,” wrote the researchers. “The exact mechanisms by which EGCG and green tea exert their lipid-lowering effects remain largely unknown. The hypothesized mechanisms are through the suppression of cholesterol biosynthesis, the interference of lipid absorption, and the increase in fecal excretion of cholesterol.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.116.137075
“Effects of green tea catechin extract on serum lipids in postmenopausal women: a randomized, placebo-controlled clinical trial”
Authors: H. Samavat et al.