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How Do the Phytonutrients in Green Tea Benefit Health?

Published on June 4, 2010 in green tea and healthy aging spotlight. 0 Comments Tags: , .

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
How Do the Phytonutrients in Tea Benefit Health?

In general, the catechins act throughout the body as very efficient antioxidants. The ability of these beneficial phytonutrients to detoxify free radicals and other harmful chemicals has been demonstrated beyond any doubt. In fact, the results of a study published recently in the Journal of Agricultural and Food Chemistry proved that the greater the catechin content of a dietary supplement, the greater its antioxidant capacity (measured in units of its “oxygen radical absorbance capacity” or “ORAC value”, which is a standard measure of in vitro antioxidant capacity).2

Other research has shown that the catechins and the theaflavins all possess about the same capacity to act as antioxidants.3 However, the total catechin content of green tea is about 2 to 3 times the total catechin plus theaflavin content of black tea (because some of the catechins are destroyed during the fermentation process). Therefore, when consumed in equal amounts, green tea should be 2 to 3 times more effective than black tea as an antioxidant (though black tea has unique benefits all its own). This has been confirmed in experiments on hamsters that were fed diets containing very high levels of cholesterol – adding green tea to the diet of these hamsters was about twice as effective in preventing the oxidation of the cholesterol in their blood as was adding black tea.4 Furthermore, men and women who smoke cigarettes typically exhibit a vastly accelerated rate of oxidative damage to the DNA in their bodies; when they drink 4 cups of green tea daily, they experience a large decrease in DNA free radical damage.5,6

Next Best Kept Secrets to Healthy Aging topic:
Healthy Blood Pressure with Tea

References:
2. Seeram NP, Henning SM, Niu Y, Lee R, Scheuller HS, Heber D. Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity. J Agric Food Chem 2006;54:1599-1603.
3. Leung LK, Su Y, Chen R, Zhang Z, Huang Y, Chen ZY. Theaflavins in black tea and catechins in green tea are equally effective antioxidants. J Nutr 2001;131:2248-2251.
4. Vinson JA, Dabbagh YA. Effect of green and black tea supplementation on lipids, lipid oxidation and fibrinogen in the hamster: Mechanisms for the epidemiological benefits of tea drinking. FEBS Lett 1998;433:44-46.
5. Hakim IA, Harris RB, Brown S, Chow HH, Wiseman S, Agarwal S, Talbot W. Effect of increased tea consumption on oxidative DNA damage among smokers: A randomized controlled study. J Nutr 2003;133:3303S-3309S.
6. Hakim IA, Harris RB, Chow HH, Dean M, Brown S, Ali IU. Effect of a 4-month tea intervention on oxidative DNA damage among heavy smokers: Role of glutathione S-transferase genotypes. Cancer Epidemiol Biomarkers Prev 2004;13:242-249.

Does the Source of Green Tea Matter?

Published on June 3, 2010 in green tea and healthy aging spotlight. 0 Comments Tags: , .

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Does the Source of the Tea Matter?

The exact amounts of the catechins and theaflavins that are present in any sample of tea, (green, black or oolong) depends on where the leaves are grown and just how the leaves are processed prior to drying. Of course, factors such as the soil the tea is grown in can influence the content of polyphenols. In addition, whether the tea is decaffeinated, blended or freeze-dried (“instant”) and the specifics of its preparation (how much tea is used per cup or glass, how long the tea is left to steep, brew or dissolve, and at what temperature) all affect the resulting beverage’s phytonutrient content. The process of decaffeination removes some of the phytonutrients along with the caffeine (an unavoidable consequence of the chemistry of decaffeination).

Brewed hot tea contains the largest amount of phytonutrients, “instant” teas have lost about 80% of their phytonutrients and “iced” and other ready-to-drink tea products contain even less. Diluting tea with milk, water or ice obviously reduces the amount of phytonutrients contained in each cup or glass. Interestingly, recent studies have found that taking tea with milk may reduce its ability to enhance blood circulation and hinder some of its antioxidant benefits. It’s also important to realize that so-called “herbal teas” really are not “teas” but are boiled decoctions of the herbs used to make them – and they contain none of the beneficial tea catechins or theaflavins, although they certainly do contain beneficial compounds present in the particular herbs.

Tea as a Dietary Supplement

Why is all this important to you? It is important for you to remember that even though drinking tea is an extremely healthy practice, hot or cold teas prepared from either loose dried leaves, powdered leaves or “bags” are less reliable sources of tea phytonutrients than are the standardized powders used in the highest-quality dietary supplements. Standardized extracts control for the level of collective and individual tea polyphenols, and research shows that in order to receive optimal benefits from tea intake, an optimal amount of polyphenols needs to be consumed on a daily basis. This could mean drinking cups and cups of tea per day. In addition, the catechins in high-quality standardized powders are absorbed about twice as readily as they are from teas.1

Of course, when it comes to drinking tea, sometimes enough can be enough! And some days you’d just rather drink something else. Not to worry – combining tea (or even replacing tea as a beverage) with a top-of-the-line dietary supplement high in catechin content is the perfect answer. Make sure to look for products that contain the multiple polyphenols present in tea as each polyphenol has unique benefits and together they create synergistic effects.

Next Best Kept Secrets to Healthy Aging topic:
How Do the Phytonutrients in Tea Benefit Health?

References:
1. Henning SM, Niu Y, Lee NH, Thames GD, Minutti RR, Wang H, Go VL, Heber D. Bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement. Am J Clin Nutr 2004;80:1558-1564.

Green Tea: Drinking Your Way to Health and Longevity

Published on June 2, 2010 in green tea and healthy aging spotlight. 0 Comments Tags: , .

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Green Tea – Drinking Your Way to Health and Longevity

Tea made from the leaves of the Camellia sinensis plant has been consumed for over 5000 years. After water, tea is the most popularly consumed beverage worldwide. Europeans, North Americans and North Africans drink mainly black tea, Asians seem to prefer green tea, and oolong tea is popular in China and Taiwan.

Tea is tasty, soothing and either warming or cooling (depending on whether you drink it hot or cold). But tea is so much more than that – it is a well-recognized enhancer of the health and performance of your heart, your cardiovascular system, your muscles, your teeth and your bones – just to name a few reasons why this natural food is so beneficial.

What Difference Does the Color of Tea Make?
Whatever its color or name, all true “teas” are produced from the leaves of the tropical evergreen plant, Camellia sinensis. When tea leaves are converted into black tea, the harvested leaves are allowed to ferment before and while drying – an oxidation process that changes both the color of the leaves and the nature of their phytochemical contents. In contrast, the leaves for green tea are steamed to prevent oxidation and phytonutrient change during drying. Oolong tea is produced by allowing a partial oxidation of the leaves, making oolong tea equivalent to “half-green and halfblack” tea. About 20% of the tea produced worldwide is green tea. Essentially, then, with changes in the phytonutrient profiles, drinkers of the different types of tea can experience differing beneficial effects. Each phytochemical has unique healthful properties and, as antioxidants, has affinities for different types of free radicals.

What Does Green Tea have that is missing from Other Beverages?
Tea is a rich source of “polyphenolic phytonutrients.” While this class of phytonutrients is huge, with over 4000 known members, tea leaves become heavily loaded with one particular class of phytonutrient during their growth. In unoxidized, unfermented green tea leaves, this class, the catechins, includes epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG). During the oxidation process of converting green tea to black tea, the catechins also are oxidized, changing into a class called the theaflavins: EC becomes theaflavin, ECG becomes theaflavin-3- gallate, EGC becomes theaflavin-3í-gallate and EGCG becomes theaflavin-3,3í-digallate.

It has been estimated that one cup of brewed green tea contains between 100 and 150 mg of catechins, of which about half is EGCG and a little less than half is EGC. The other catechins are present but in much smaller amounts. Hot water extraction (brewing) maintains these relative proportions; EGCG comprises about half of the dissolved solids in brewed green tea.

Next Best Kept Secrets to Healthy Aging topic:
Green Tea – Does the Source of the Tea Matter?