The Truth about Green Tea

A Health Powerhouse or Mostly Hype?

-- By Becky Hand, Licensed and Registered Dietitian

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Components of Tea: Catechins and Caffeine
Flavonoids are dietary compounds found in tea and other foods such as wine, cocoa, fruits and vegetables. Flavonoids determine the color and taste of food and may be involved in healthy body functions. The average U.S. adult consumes 189.7 milligrams of flavonoids each day, most of which (157 mg to be exact) come from tea. While there is currently no recommendation for flavonoid consumption, experts are in the initial stages of discussion regarding recommendations for these dietary components. Tea contains approximately 100-300 milligrams of flavonoids per serving, depending on the type of tea. The main type of flavonoids found in tea are catechins. Because the green tea variety is less processed, it contains more catechins than black tea does. Therefore green tea and green tea extracts have received the most research regarding possible health benefits and will be the focus of this particular article. Research has primarily investigated the health benefits of catechins such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

Green tea also contains 2% to 4% caffeine or about 10-80 milligrams per cup. (For reference, a cup of regular coffee contains 95 mg of caffeine, while 1 oz. of dark chocolate contains 23 mg.) Caffeine has also been the topic of many research studies regarding the health benefits of green tea.

Health Benefits of Green Tea: What the Research Really Shows

The research to date indicates that green tea is likely effective for:

Improving mental alertness. Because of the caffeine content, green tea and other caffeinated beverages can help maintain alertness and cognitive ability when used throughout the day.
Treating genital warts. An FDA prescription ointment that uses green tea extract heals genital and perianal warts in 24-60% of patients.

Research to date shows that green tea might be effective for:

Improving cholesterol levels. Green tea may help reduce elevated levels of LDL ("bad") cholesterol, total cholesterol, and triglycerides while increasing HDL ("healthy") cholesterol in the blood. However, more clinical studies are needed in this area.
Preventing low blood pressure upon standing and after eating (in the elderly population). This is likely due to the caffeine content of green tea.
Reducing the risk or preventing the onset of Parkinson's disease.This is also attributed to the caffeine content.
Preventing cancers of the bladder, esophagus, ovaries and pancreas. Most of these studies have been conducted on animals, but a few involved testing green tea extracts on people. More research is needed.

Currently, there is not enough evidence to say that green tea has the following health benefits: Continued ›

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About The Author

Becky Hand
Becky is a registered and licensed dietitian with almost 20 years of experience. Through her company, An Ounce of Prevention, she makes nutrition principles practical, easy to apply and fun. See all of Becky's articles.

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Member Comments

JGMARIE80

My hubby loves green tea; I like mine black. - 4/14/2013 5:18:19 AM
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FRAGMENTEDANGEL

I've been told that it's best to use boiled water that has been given time to cool slightly. Freshly boiled water can burn the leaves and causes the tea to become bitter. This is very likely why I've never been a fan. I've been doing it wrong all these years. Should give it another go and use that jasmine green that i have sitting in the tea cupboard. - 3/18/2013 11:50:54 PM
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DRATHKE

Love green tea! Used to drink it constantly, but have found that with my hyperthyroid, even the slightest bit of caffeine throws me way off track! It's really strange and makes me sad :( But I guess since green tea isn't as good for me as I though, oh well.... - 3/5/2013 9:26:37 PM
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HOLLYSNOWWOMAN

Green tea is contraindicated with people who take blood thinners like Coumadin. Thought I would throw that out. - 2/19/2013 11:12:09 PM
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NAOLEE

This is my favorite tea. - 1/26/2013 5:35:48 PM
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NAOLEE

THIS IS MY PREFERS TEA. GREAT - 1/26/2013 5:33:23 PM
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WALLOWA

PS... for those that don't like the flavor, you can cook with it. Therapeutic levels (from Japanese use) are 10 cups a day! That's why I use the ground leaf form - in baked goods, even on meat if you don't like the flavor). But I do like the flavor. And I like even more having no JOINT pain (I've been in a car wreck and a horse wreck - no joint pain at all!) - 1/24/2013 1:46:04 PM
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WALLOWA

I use a ground leaf green tea (about a tsp a day, equivalent of about 10 cups) and found that it directly correlates to relieving joint pain. I started when I had a cancer dx - took this and other measures for 3 months before - interestingly, no cancer found after the hysterectomy. - 1/24/2013 1:44:06 PM
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LUNELA

Just finished a workout on here, ate breakfast (light strawberry yogurt and nutrisystem double chocolate healthy bar) and drinking green tea. :) Cheers! - 1/23/2013 8:43:18 AM
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35BYMAY

in reference to MORVALTUR, who said that no tea should be steeped for 6-10 minutes, I am afraid I will have to correct you... green tea DOES need to be steeped for 6-10 minutes, this is verified by the package labels of any good, quality green tea vendor. - 1/22/2013 5:54:45 PM
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PATTISWIMMER

A great well searched and researched article. Becky... I am drinking it for breast cancer a couple of cups a day for prevention.... combined with mushroom eaten daily lowers the risk lots. - 1/14/2013 1:03:54 AM
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BLUEFAIRYTALE

Lots of interesting facts. I love tea. - 8/1/2012 8:39:29 PM
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DESIDERATA~GIRL

Wow, did not know that green tea may affect the absorbtion of iron! I must keep that in mind and not have it with meals then!! Other than that, I'm glad it does have some good effects and will keep on drinking it. - 8/1/2012 7:51:33 PM
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BB2352

Glad I read this as I tried drinking it a few times but I just don't care for it. Kind of felt I should drink it for the health benefits but looks like I really don't have to drink it if I don't like it. ;) - 8/1/2012 6:29:48 PM
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TEDDYBEAR662

I started drinking this last year, but I drink Decaf. Does that matter? Nothing was mentioned about decafinated green tea?!!??! - 8/1/2012 4:21:58 PM
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