Research appearing in Nutrition Research (2006; 26(11): 604-607) looked at the effect drinking green tea had on cholesterol. For four weeks, the 29 healthy subjects were given a liter of green tea each day. At the end of the study, there was a decrease in LDL (bad) cholesterol, with a mean reduction of 8.9%. There was a mean 4% increase in HDL (good) cholesterol, with a 6% decrease in the ratio of total cholesterol to HDL cholesterol.
Other research in the European Journal of Clinical Nutrition (2006; 60(11): 1330-6) looked at the effect oolong tea had on fat absorption. In the double-blind, placebo-controlled study, 12 healthy adults drank either polyphenol-enriched oolong tea or a placebo after consuming 38 grams of fat (in potato chips eaten 30 minutes after lunch and dinner). Fat in the feces was measured for 10 days. After a seven-day washout period the placebo group and the group drinking the tea switched places and the experiment was repeated. It was found that more fat was excreted when the oolong tea was consumed after the potato chips. The oolong tea also caused more cholesterol to be excreted.