Green Tea Extract Significantly Reduces Total, LDL Cholesterol In Study

Subjects taking capsules containing theaflavin-enriched green tea extract for three months saw their total cholesterol decrease 11.3% and their LDL cholesterol drop 16.4%, a trial published in the June 23 Archives of Internal Medicine reports.

Positive results were also noticeable after only four weeks, with the treatment group's average total cholesterol falling 6.7% and low-density lipoprotein cholesterol declining 9.6%, David Maron, MD, Vanderbilt University Medical Center, et al., state.

Improvements in the treatment group's high-density lipoprotein cholesterol levels were seen as well, rising 2.3% after consuming the extract for 12 weeks.

By comparison, Maron et al. note the placebo group showed "no significant changes in total cholesterol or LDL-C...during the study," while HDL levels fell .7% in the control group.

Moreover, the ratio of mean total cholesterol to HDL-C in the treatment group fell from 4.61 at baseline to 4.05 after three months, whereas the ratio "did not change significantly in the placebo group," going from 4.55 to 4.57 over the three-month period.

Due to the results, Maron et al. hypothesize long-term use of theaflavin-enriched green tea extracts could have significant results in the general population.

Noting observational and clinical trials have indicated that "each 1% reduction in LDL-C results in approximately a 1% to 1.5% reduction in the relative risk of major cardiovascular events," the researchers state long-term use of theaflavin-enriched green tea extracts "could reduce the risk of major cardiovascular events by 16% to 24%."

The randomized, double-blind, placebo-controlled parallel-group study involved 240 individuals, 220 of whom completed the trial. All participants had to be above age 17, diagnosed with mild to moderate hypercholesterolemia and on a low-fat diet.

Recruitment took place at six urban hospitals in China. Nashville-based Nashai Biotech sponsored the study, which was conducted in 2001, with the support of a grant from Wyeth Consumer Healthcare.

Each subject took either a capsule containing 75 mg theaflavins, 150 mg green tea catechins and 150 mg "other tea polyphenols" or a placebo every morning for 12 weeks.

Maron et al. also instructed the study participants to "maintain their habitual, traditional Chinese diet, including their customary intake of tea" throughout the course of the trial.

Clinic visits took place at baseline and at weeks four, eight and 12, always following a 12-hour fast. Body weight, compliance and adverse events were checked at each visit, while cholesterol levels were measured two weeks prior to baseline and at baseline, week four and week 12. Food diaries were collected at the baseline and week eight visits.

After checking the food diaries, the researchers concluded subjects who consumed a large amount of tea and took the tea extract supplement did not see better results than subjects taking the supplement who drank less tea. Drinkers of one to four cups of tea per day saw their LDL-C fall 17.3%, while those who drank five to 10 cups saw it fall 13.5% and non-tea drinkers experienced a 16.5% drop.

Maron and colleagues state their study "represents the first step in establishing the practicality, safety and LDL-C lowering efficacy of a tea product."

However, they note more research is needed to determine a tea extract's "long-term safety, the effective dosing range, the optimal timing of administration, the effect of dietary fat content, drug interactions, impact when coadministered with lipid-altering medications (especially statins) and generalizability to other ethnic and patient groups."

For example, Maron et al. point out that a study of the participants' food diaries showed their traditional Chinese diet consisted of "approximately 27% of total calories from fat, 6% of calories from saturated fat and 400 mg of cholesterol daily."

Americans, however, receive, on average, "33% of total calories from fat, 11% of total calories from saturated fat and 256 mg cholesterol per day."

The investigators also note the study participants "ate less dietary fat than the typical urban Chinese, perhaps because they had already been counseled to reduce their fat intake because of hypercholesterolemia."