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Green Tea Supplements

Health Benefits, Uses, Side Effects & Tips

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Updated August 01, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Green tea supplements are often touted as a natural remedy for a number of health problems. The supplements contain green tea extract, a substance shown to be in rich in antioxidants. These antioxidants include epigallocatechin-3-gallate (EGCG), which is considered to be the active constituent of green tea extract. Many green tea supplements also contain theanine, an amino acid thought to produce a calming effect.

Uses for Green Tea Supplements

Green tea supplements are purported to offer a number of health benefits, including:

Health Benefits of Green Tea Supplements

Although research on green tea supplements is limited, studies suggest that green tea supplementation may offer the following health benefits:

1) Prostate Cancer Defense

In a 2009 study of 26 men diagnosed with prostate cancer, those who took four capsules of green tea extract daily had a significant decrease in certain markers that signal prostate cancer progression. Each four-capsule dose delivered the equivalent of about 12 cups of brewed green tea; the treatment period ranged from 12 days to 73 days, with a median time of 34.5 days.

Find out about other Natural Remedies For Prostate Cancer Prevention.

2) Cold and Flu Prevention

Green tea supplements may help stave off cold and flu, according to a study published in 2007. For three months, a group of healthy adults took either a proprietary formula of green tea extract or a placebo capsule twice a day. By the study's end, those taking green tea supplements had experienced fewer cold and flu symptoms and fewer days of illness compared to those taking the placebo.

See other remedies for colds and flu.

3) Lowering Cholesterol

A study published in 2003 suggests that, when paired with a low saturated fat diet, the use of green tea supplements may help keep cholesterol in check. The study involved 240 adults, all of whom had mildly to moderately elevated cholesterol levels at the study's start. Study results showed that those who took green tea extract in capsule form for 12 weeks had a greater decrease in LDL ("bad") cholesterol than participants who took a placebo capsule for the same length of time.

Find out about other natural strategies for lowering cholesterol.

Taking Supplements Vs. Drinking Green Tea

Available in capsule and liquid form, green tea supplements are often marketed as a means of increasing your antioxidant intake without having to drink multiple cups of green tea daily. However, most scientific studies to date have focused on the health effects of consuming green tea as a beverage (rather than in supplement form).

Are Green Tea Supplements Safe?

To date, little is known about the side effects and safety concerns associated with use of green supplements. Since many green tea supplements contain caffeine, it's important to take caution if you're concerned about caffeine-related adverse effects (such as anxiety, increased heart rate and blood pressure, and the worsening of ulcer symptoms).

It's also important to note that free-radical scavengers (antioxidants) are unwelcome during chemotherapy treatment, as they -- in theory -- may diminish the activity of the drugs.

Using Green Tea Supplements

The amount of green tea extract per capsule varies from supplement to supplement. However, there is no established recommended dose for green tea extract. If you're considering the use of green tea supplements, talk to your healthcare provider about which dose might be appropriate for you.

Sources:

Maron DJ, Lu GP, Cai NS, Wu ZG, Li YH, Chen H, Zhu JQ, Jin XJ, Wouters BC, Zhao J. "Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial." Arch Intern Med. 2003 23;163(12):1448-53.

McLarty J, Bigelow RL, Smith M, Elmajian D, Ankem M, Cardelli JA. "Tea polyphenols decrease serum levels of prostate-specific antigen, hepatocyte growth factor, and vascular endothelial growth factor in prostate cancer patients and inhibit production of hepatocyte growth factor and vascular endothelial growth factor in vitro." Cancer Prev Res (Phila Pa). 2009 2(7):673-82.

Rowe CA, Nantz MP, Bukowski JF, Percival SS. "Specific formulation of Camellia sinensis prevents cold and flu symptoms and enhances gamma,delta T cell function: a randomized, double-blind, placebo-controlled study." J Am Coll Nutr. 2007 Oct;26(5):445-52.

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