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Cholesterol-Lowering Effect of a Theaflavin-Enriched Green Tea Extract - Cholesterol-Lowering Effect of a Theaflavin-Enriched Green Tea Extract
Description:
The goal of the study was to determine the effect of a tea extract capsule containing both black tea theaflavins and green tea catechins on the lipid profile of patients with mild to moderately elevated cholesterol.
Hypothesis:
A tea extract capsule containing both black tea theaflavins and green tea catechins would improve the lipid profile of patients with mild to moderately elevated cholesterol.
Study Design
Study Design:
Patients Screened: 540
Patients Enrolled: 240
Mean Follow Up: 12 weeks
Mean Patient Age: mean age 55 years
Female: 58%
Patient Populations:
Age ≥18 years; mild to moderate hypercholesterolemia (LDL-C, 130-190 mg/dl [3.4–4.9 mmol/l]); and on a low-fat diet
Exclusions:
Baseline triglyceride ≥350 mg/dl; uncontrolled hypertension (≥160/95 mm Hg); active pulmonary, hematologic, hepatic, gastrointestinal, or renal disease; premalignant or malignant disease; diabetes; thyroid dysfunction; history of coronary heart disease or other atherosclerotic disease; any pathological values among routine clinical chemistry or hematological parameters; consumption of ≥32% of daily energy from fat; body mass index ≥35; use of lipid-lowering medications; and use of cardiac or other vasoactive medications
Primary Endpoints:
Mean percentage changes in total cholesterol, LDL-C, HDL-C, and triglyceride levels compared with baseline
Drug/Procedures Used:
Patients were randomized to either theaflavin-enriched green tea extract in capsule form (n=120) or placebo (n=120). Each active study capsule contained theaflavins (75 mg), green tea catechins (150 mg), and other tea polyphenols (n=150). Patients were required to maintain a stable diet (including usual consumption of tea) and level of physical activity during the 12-week intervention.
Principal Findings:
Mean total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels were improved from baseline in the tea extract arm (total cholesterol -11.3%, p=0.01; LDL-C -16.4%, p=0.01), but high-density lipoprotein-C (HDL-C; 2.3%, p=0.27) and triglyceride levels (2.6%, p=0.47) did not differ.
The mean levels of total cholesterol (-0.7%, p=NS), LDL-C (0.3%, p=NS), HDL-C (-0.7%, p=0.67), and triglycerides (5.6%, p=0.14) did not change significantly in the placebo group. The total cholesterol to HDL ratio was reduced from 4.61 at baseline to 4.05 at 12 weeks in the tea extract arm (p<0.001), but did not change in the placebo group (4.55 to 4.57, p=0.85). LDL-C was lower at 12 weeks in the tea extract arm, both in patients who did not drink tea (-16.5%), as well as in patients who drank 1-4 cups of tea per day (-17.3%; p=0.73 for comparison vs. no tea drinkers) and in patients who drank 5-10 cups per day (-13.5%; p=0.39 vs. no tea drinkers).
Both arms consumed a low-fat diet at baseline and eight-week follow-up (21%-23% fat intake). No significant adverse events occurred.
Interpretation:
Among patients with mild to moderately elevated cholesterol, treatment with a tea extract capsule containing both black tea theaflavins and green tea catechins was associated with a reduction in total cholesterol and LDL levels. Several observational studies have demonstrated a similar benefit in cholesterol reduction with green tea, but the present trial is the first randomized, placebo-controlled trial to show such a benefit.
An earlier trial by Princen, et al. that tested a capsule containing 150 mg of green tea polyphenol, but no theaflavins, showed no effect on the lipid profile. While no specific analysis was performed on the mechanisms of action for the lipid improvements, the authors hypothesized potential mechanisms may include reduced micellar solubility and intestinal absorption of cholesterol, increased fecal excretion of fat and cholesterol, reduced hepatic cholesterol concentration, and upregulation of the LDL receptor in liver cells.
References:
Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med. 2003;163:1448-53.
Keywords: Polyphenols, Intestinal Absorption, Receptors, LDL, Hypercholesterolemia, Catechin, Cholesterol, Biflavonoids, Tea, Liver, Motor Activity, Diet, Fat-Restricted, Triglycerides
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