Most of the studies involving the cholesterol-lowering effects of green tea involve the use of green tea’s active ingredient, catenin extract, as opposed to the beverage itself. The mechanism of action is largely unknown, but it appears to increase LDL receptor activity in the liver, prevent absorption of cholesterol in the intestines, lower low density lipoprotein (LDL), raise high density lipoprotein HDL), and lower total cholesterol.
One study examined the cholesterol lowering effect of 375 mg of catenin extract in 200 men and women with high cholesterol on a low fat diet. Researchers found that the catenin extract lowered total cholesterol by 11.3 percent, LDL cholesterol by 16.4 percent, triglycerides by 3.5 percent, and raised HDL by 2.3 percent. The catenin extract used in this study, however, was not pure and consisted of 75 mg of theaflavins (an antioxidant found in black teas), 150 mg of green tea catenins, and 150 mg of other tea polyphenols. Therefore, only a small portion of catenin extract derived from green tea was used in this study. Additionally, this study suggests that you would need to drink massive amounts of green tea to lower cholesterol and obtain the results seen in this study.
Some studies have shown catenin extract derived from green tea to lower total and LDL cholesterol levels by 60 percent and 80 percent respectively. However, most of these studies vary in the amount of catenin extract used and the condition of the participants. Despite these promising results, other studies have been unable to document the cholesterol-lowering effects of green tea. For instance, a most recent study concluded that 3.8 g of catenin extract (up to 18 cups a day of green tea) or six cups of green tea were not effective in lowering cholesterol. However, all the participants in the study were smokers. So, this result could be interpreted in two ways. First, this could suggest that smoking somehow negates the cholesterol-lowering ability of the catenins found in green tea. Second, these results could suggest that green tea catenins are ineffective in lowering cholesterol, thus conflicting with other studies that have suggested that green tea catenins do lower cholesterol. At this point, researchers do not know the answer to the question as to whether or not green tea catenins lower cholesterol. More studies would need to be performed to further investigate this question.
In 2006, a petition was filed with the FDA for green tea beverages to carry the health claim that they reduced cardiovascular disease. However, the Food and drug Administration denied this petition, citing that more evidence was needed in order verify this claim.
In summary, the current studies out there concerning green tea and its ability to lower cholesterol are conflicting and there has not been enough research done that would allow someone to definitely say that green tea lowers cholesterol.