Green tea comes from the leaves of the Camellia sinensis plant. You can drink it as a beverage by brewing the dried leaves with boiling water, or you can get it as a dietary supplement in which the dried leaves are formulated into capsules. The health benefits that you get from green tea are due to substances called polyphenols, which have powerful antioxidant properties. Before you use green tea capsules or any other dietary supplement, you should consult your doctor about possible side effects and drug interactions.
If you're interested in using your diet as a way to keep your cholesterol under control, you should consider green tea. Researchers analyzed the results of 14 clinical trials of the effects of green tea beverage or extract on cholesterol blood levels in 1,136 adult subjects. They found that both the beverage and the extract markedly lowered total cholesterol and LDL or "bad" cholesterol blood levels and left the HDL or "good" cholesterol unchanged. The team from the Chinese Academy of Medical Sciences in Beijing published the findings in the August 2011 issue of "The American Journal of Clinical Nutrition."
For people who suffer from obesity, getting to a healthier body weight is an urgent medical need, and research shows green tea can help. In a clinical trial of obese subjects, researchers found that those who consumed two green tea capsules a day for eight weeks lost 5.5 pounds while those who drank plain water did not lose weight. The trial results, published in the February 2010 issue of the "Journal of the American College of Nutrition," indicate that green tea extract may be able to help people with obesity as they struggle to lower their risk of heart attack, stroke and type 2 diabetes.
Researchers found that women with breast cancer who took green tea extract twice a day for six months showed significantly lower blood levels of two tumor growth factors than women who took a placebo. The Columbia University Medical Center team that did the research theorizes that green tea extract may someday be useful for breast cancer prevention. Researchers reported their findings at the annual conference of the American Association for Cancer Research in 2012.
In a one-year clinical trial, men at high risk for prostate cancer took either 600 milligrams per day of green tea extract in capsule form or took a placebo. At the end of the study, 30 percent of the men in the placebo group had developed prostate cancer, but only 3 percent of the green tea group developed it. Researchers hope that green tea extract might help to prevent prostate cancer in high-risk men. The results of the trial appeared in the January 15, 2006 issue of "Cancer Research."
- MedlinePlus: Green Tea
- The American Journal of Clinical Nutrition: Green Tea Intake Lowers Fasting Serum Total and LDL Cholesterol in Adults: a meta-Analysis of 14 Randomized Controlled Trials
- Journal of the American College of Nutrition: Green Tea Supplementation Affects Body Weight, Lipids and Lipid Peroxidation in Obese Subjects with Metabolic Syndrome
- American Association for Cancer Research: Mechanisms of Action for Green Tea Extract in Breast Cancer Prevention Identified
- Cancer Research: Chemoprevention of Human Prostate Cancer by Oral Administration of Green Tea Catechins in Volunteers with High-Grade Prostate Intraepithelial Neoplasia: A Preliminary Report from a One-Year Proof-of-Principal Study
Robert DiPardo has been a pharmaceutical chemist for more than 30 years. He has co-authored several scientific publications on cardiovascular disease, osteoarthritis, Alzheimer's disease and other therapeutic areas. DiPardo retired from drug discovery research in 2009 and, since 2010, has covered fitness and well-being for various online publications. DiPardo holds a Master of Science in organic chemistry from Yale University.