Researchers at China’s Sun Yat-sen University have discovered one of the mechanisms by which green tea helps lower cholesterol levels, as well as identified at least two of the specific chemicals responsible for the process.
Green tea has been an important component of traditional Chinese medicine for hundreds of years. More recently, scientific studies have supported wide-ranging health benefits, including lowering cholesterol levels.
For example, a meta-analysis of 14 separate randomized, controlled trials conducted on more than 1,000 people, published in the American Journal of Clinical Nutrition in 2011, found that people who consumed more green tea (or green tea extract) had significantly lower levels of LDL (“bad”) cholesterol and total cholesterol than people who consumed less, while levels of HDL (“good”) cholesterol were unchanged.
Most scientific research has focused on the polyphenolic compounds found in tea, many of which have been shown to either disrupt the body’s synthesis of cholesterol or to reduce cholesterol absorption by the gut. Because green tea contains so many polyphenolic compounds, however, researchers have had a hard time determining which of these are responsible for the cholesterol-lowering effects.
Tea chemicals bind to cholesterol precursors
For the current study, researchers focused on two chemicals in the catechin family, which prior studies have indicated may have a strong effect on cholesterol synthesis. More specifically, the researchers tested four separate tea polyphenols in the presence of three separate enzymes that the body uses for cholesterol synthesis. They found that both (-)-epicatechin-3-gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) were able to inhibit the activity of all three cholesterol-related enzymes simultaneously.
Armed with this data, the researchers used a computer model to analyze the interactions between the enzymes and the tea compounds. They found that all three cholesterol-precursor enzymes contain triangle-shaped binding pockets. ECG and EGCG both have shapes that allow them to form strong chemical bonds with all three of these enzymes at the same time.
The researchers are now using the same techniques to analyze other chemicals found in green tea, Chinese herbs and food supplements for their lipid-lowering potential.
“This work fills an important need to define the binding of components of natural products to key enzymes that may contribute to major pharmacological activities of traditional nutritional medicine,” said Basil Roufogalis of the University of Sydney, an expert on active components of herbal medicines who was not involved in the study. He noted that the research may eventually enable scientists to artificially synthesize drugs that mimic the activity of natural chemicals. This may allow doctors to intensify the cholesterol-lowering benefits of green tea without the side effects of other pharmaceutical drugs.
Green tea for whole body health
Studies have shown that tea benefits not just cholesterol levels but cardiovascular health in general. It also protects against neurodegenerative diseases. According to a study conducted by researchers from the University of Leeds and published in the Journal of Biological Chemistry in 2013, EGCG can actually halt the biological process believed to produce brain damage in Alzheimer’s disease.
It has been shown to lower the risk of liver disease, autoimmune diseases such as rheumatoid arthritis, tooth decay and cancers of the bladder, colon, esophagus, stomach and pancreas. Green tea may also help with weight loss and slow the progression of chronic diseases.
According to a study conducted by researchers at Tohoku University in Japan and published in the American Journal of Clinical Nutrition in 2012, people who drink five or more cups of green tea per day are less likely to develop frailty or disability as they age, and are more likely to remain independent.
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