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Sunday
May292011

Nutrient Spotlight: Green Tea

Written by: Cindi Lockhart, RD, LD, Weight Loss Coaching Program Manager

Green tea comes from the leaves of the Camellia sinensis plant.  It is not fermented or processed as others, such as oolong or black tea, so it retains natural polyphenols, potent antioxidants that protect our cells from the damaging effects of various lifestyle exposures.  Although oxygen is essential to life, it can create unstable compounds in our body, called free radicals. These damaging compounds are created in response to normal cellular metabolism, exposure to pollution, radiation and chemicals such as cigarette smoke or exhaust, and even from something as healthful as exercise. Green tea’s polyphenols “neutralize” these free radicals and protect our cells against disease. The most potent polyphenols are called catechins with epigallocatechin 3-gallate (EGCG) responsible for cancer-fighting benefits.  In fact, it has been found that the antioxidant activity of EGCG is at least 20 times as potent as the antioxidant vitamins C and E.

Polyphenols

The health benefits of green tea relate to its polyphenol content.  Not only are these catechins strong antioxidants, but they are also antiviral, anti-inflammatory, and immunity-boosting agents.  Regular intake of green tea has been found to positively impact one’s risk for cancer, hypertension, cataracts, sun-induced skin aging and, possibly, obesity. 

Three recent studies also showed a positive relationship between green tea consumption and the risk for cancer of the ovaries, endometrium, prostate, esophagus, and lungs.[i],[ii]  The polyphenols helped decrease blood flow to the cancer cells, prevented cancer cells from replicating and, ultimately, led to cancer cell death. Due to this strong anticancer evidence, the Chemoprevention Branch of the National Cancer Institute initiated a plan to develop tea compounds as cancer-chemopreventive agents in human studies.[iii]

On another note related to weight loss, a study in the American Journal of Clinical Nutrition found that while green tea does not increase metabolism, green tea extract does — a derivative that can be purchased as a supplement. The research showed that polyphenol, along with the caffeine content, promoted thermogenesis and stimulated fat oxidation so that metabolism increased 4 percent without an increase in heart rate.[iv]

Making green tea part of your life

So now you know the health perks of green tea, what’s the best way to incorporate it into your lifestyle?  First, opt for the actual tea bags. When considering hot versus cold beverage options, remember that bottled or prepared cold tea mixes are high in sugar, high fructose corn syrup and/or artificial sweeteners.  If you desire cold tea, brew your own, pour over ice with lemon slices and add natural stevia or truvia sweeteners. 

An average cup of green tea contains 10-40 milligrams of polyphenol — and antioxidant effects greater than one serving of most vegetables. Tip:  The longer you steep the tea and squeeze the bag, the stronger the polyphenol content.  If you’re new to drinking tea and/or caffeine, start with one to two cups a day and build to three to five for optimal health benefits. 

There are also many green tea extract supplements on the market – so do your research regarding product quality first.  Supplements are not standardized and thus carry no guarantee to potency or polyphenol content. Life Time Fitness carries a thermogenic product called LeanSource, which contains 400 milligrams of green tea extract plus 20 milligrams of green tea leaf. 

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

Share thoughts and post questions below.


 

[i] Butler, LM, et al. “Green and black tea in relation to gynecologic cancers” Mol Nutr Food Res 2011 May 19.

[ii] Yuan, JM. “Green tea and prevention of esophageal and lung cancers” Mol Nutr Food Res 2011 April 29.

[iii] The 150  Healthiest Foods on Earth, Johnny Bowden, PhD, Fair Winds, Beverly Mass, 2007, pgs. 264-268.

[iv] Dulloo, AG, et al. “Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24 hour energy expenditure and fat oxidation in humans”. Am J Clin Nutr 70 (6): 1040-5.

Vi SuperFoods HealthStyle, Steven G. Pratt, MD and Kathy Matthews, Harper, New York, 2007, pgs. 161-164.

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Reader Comments (4)

Lean Source----How does 400 milligrams of extract and 20 milligrams of green tea leaf compare to 3 to 5 cups of green tea a day??

May 30, 2011 | Unregistered CommenterNewby

Is decaffeinated green tea still rich in polyphenols? Some of us have circulatory issues that prevent consumption of caffeine without dizziness and pressure headaches.

June 2, 2011 | Unregistered CommenterTara

Well the article says each cup has between 10 and 40 milligrams - so if we assume 40 milligrams and 5 cups, the article is recommending 200 milligrams a day versus the 400 milligrams in the supplement. There is bound to be a decreasing return to the extract, so it probably doesn't matter much which format you go with.

June 2, 2011 | Unregistered Commenterjoe

Is there a website available that compares tea brand names?

June 7, 2011 | Unregistered CommenterB.J. Staley

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