Whether in a cup or capsule, few herbs rank higher in beneficial properties than
. In fact, Camellia sinensis, more commonly known as tea, ranks behind only water as the most popular beverage worldwide. Over three-fourths of tea produced is black, and the rest is green and oolong. Although each variation offers proven benefits, it is green tea that contains the most remarkable beneficial compounds, and that is due primarily to the fact that unlike black and oolong, green tea is not roasted, thus preserving more of the active constituents. In recent years there's been well-justified excitement over the potential of
green tea to promote health, burn fat and help prevent disease
, based on a large number of scientific studies. A Medline search on "green tea" reveals more than 1600 publications since 1980, the bulk of them in just the last few years. Cell culture, animal and human studies have all shown green tea to produce a very impressive range of health-promoting effects.
Green Tea for Fat Loss
Both human and animal studies have shown that green tea has great potential for increasing calorie-burning and fat-burning. These studies clearly show that
green tea increases thermogenesis (the wasting of calories as excess body heat), directly promotes fat-burning, cuts fat production (in the body), reduces appetite, and even promotes insulin action!
This is a remarkable array of desirable effects from a single dietary substance. For example, a landmark 1999 human study assessed the ability of
to stimulate thermogenesis and fat-burning.1
In this study, ten healthy men spent 24-hour periods in a metabolic testing chamber. During the sessions, they consumed either, 1) green tea extract containing 150 mg of caffeine and 270 mg of epigallocatechin gallate (EGCG--the key active component of green tea), 2) 150 mg of caffeine, or 3) a placebo. The study results documented that there were no effects of caffeine compared to placebo, but green tea extract was shown to increase 24-hour metabolism and calorie-burning by 4% compared to placebo--amounting to 80 calories per day.
Now, 80 calories may not sound like much, but the calorie/weight game is one that is played over months and years, and the small numbers add up to big results over time. In this case, 80 calories per day translates to about 2/3 pound of fat loss over just one month, or over 7 pounds in a year --without moving a muscle. (Do you need to lose 7 pounds of fat? Most of us do. And it is much better done gradually, over the course of a year, than rapidly.) Also, imagine how much the better the results could be when combined with training or exercise. And also imagine how many more calories could be burned using higher levels of EGCG. Further, this study showed that
caused a shift to fat over carbohydrate oxidation--that is, that fat was burned in preference to carbohydrate. This is of great significance for athletes, fitness enthusiasts and generally active people, since the name of the game is precisely that: burning fat, not the precious energy-enhancing glycogen (carbohydrate) reserves. This study also found that the green tea caused a greater urinary excretion of norepinephrine over 24 hours, which is one of the chemical "markers" of the metabolism- and thermogenesis-enhancing effects of the extract. Also, there were no adverse side effects, including no differences between treatments in heart rate. These findings clearly indicate that components of
green tea extract
(with caffeine) significantly stimulate thermogenesis and fat-burning. These results were further confirmed in a study published earlier this year done with Japanese men (Nagao et al. 2005). The men were provided with tea containing 690 mg catechins (including EGCG) per day or a placebo tea for 12 weeks. The men taking the green tea extract lost two-fold more body weight and body fat than the placebo group. The amount of fat lost in the abdominal area was also measured using computed tomography. It was found that green tea resulted in significant reductions in both the subcutaneous and visceral fat stores of the mid-section. Fat in this region is associated with higher risk for many chronic diseases. Cell culture ("test tube") and animal studies provide clues to green tea's remarkable mode of action. Green tea contains flavonoids (a type of polyphenols) such as catechins. Catechins (especially EGCG) have a range of effects, including inhibition of a key enzyme (catechol O-methyltransferase, COMT) that breaks down norepinephrine.2
Norepinephrine is a hormone that increases cellular levels of cyclic AMP (cAMP), which in turn increases metabolic rate and breakdown of fat. Thermogenesis depends on it. Green tea also contains caffeine, which inhibits the enzyme phosphodiesterase. Phosphodiesterase is a "bad guy" in the fat wars, because it breaks down cAMP in cells and can thus reduce the stimulatory effects of norepinephrine. This amazing herb works through both catechins and caffeine, which synergistically inhibit COMT (thus allowing norepinephrine to work longer) and phosphodiesterase (thus allowing cAMP to work longer in the cell).3
Inhibition of COMT as a mechanism is supported by the findings in the study by Dulloo 1 showing that green tea extract resulted in significantly greater urine norepinephrine levels, probably reflecting less degradation. Catechins and caffeine, however, are not the only active agents in green tea. A recent study (Shizuoka University, Japan) has identified an additional compound--the neuroactive glutamine derivative L-theanine--which may participate with caffeine and EGCG (catechins) in reducing body weight. These researchers demonstrated that catechins and caffeine are synergistic in their fat-busting activity. But they found that the L-theanine exerted an additive effect, as well. The researchers concluded that: "These results indicate that...caffeine and theanine were responsible for the suppressive effect of green tea powder on body-weight increase and fat accumulation." 4
Recent studies at the USDA (United States Department of Agriculture) have shown that green tea also enhances insulin action.5
Insulin resistance (blocked insulin action) is an important component of a very common metabolic syndrome that accompanies abdominal adiposity, or "beer gut." Blocked insulin does all the wrong things, including promoting fat production and storage (particularly around the abdomen), and shunting calories away from lean tissue where they can be burned instead of stored as fat. Anything that promotes normal insulin action (chromium, vanadium, glucomannan, lipoic acid) is going to be a great help--and
has just emerged as one of those helpers. According to the USDA's Dr. Richard Anderson, the insulin activity boost from green tea can be dramatic: as much as 15-fold! It seems that the EGCG or catechin component of the tea is responsible for this effect. In addition to Dr. Anderson's work, other recent studies have shown that green tea ameliorates insulin resistance,6
possibly by increasing the glucose transporter IV content.7
Researchers have shown that EGCG alone causes fast weight loss in animals, and that EGCG prevented further weight gain,8,9
by a mechanism involving a decrease in food intake. This and other studies show that in addition to all of its other benefits, green tea also cuts appetite as well. What more could you ask for? And to top it all off, cell culture ("test tube") studies show that EGCG inhibits acetyl-CoA carboxylase (ACC) and fatty acid synthase, which are rate-limiting enzymes in the biosynthesis of fatty acids.10,11
In other words, green tea cuts down fat production in the body. In one of those studies, green tea extract resulted in significant weight loss compared to controls. In yet another study, the fat-suppressive effects of green tea involved a reduced digestibility of fat along with thermogenic stimulation.12
Frankly, it is hard not to get excited about all of these remarkable findings. Collectively, these studies provide very strong evidence that green tea contains bioactive and bioavailable substances that can help reduce fat gain, increase thermogenic calorie-burning, enhance fat-burning specifically (while sparing carbohydrate), suppress endogenous fat synthesis, reduce appetite, promote normal insulin action, and generally be a fantastic aid for body-weight and body-fat control. It's also important to note that, while green tea appears to work primarily through the hormone norepinephrine, it is distinct from similar substances (e.g., ephedrine) that act through the same receptors, in that green tea does not have adverse cardiovascular effects (e.g., increased heart rate, blood pressure, etc.). Lastly, since one mechanism of action of green tea is to prolong the action of norepinephrine by inhibiting COMT (the enzyme that degrades norepinephrine), there might be additive effects when using it with other dietary supplements that can enhance norepinephrine levels. Tyrosine, for example, is the amino acid that is the precursor of norepinephrine. Tyrosine increases norepinephrine levels in humans,13
and a recent study showed that tyrosine enhanced cognitive task performance during a demanding combat training course designed to deplete norepinephrine.14
The combination of tyrosine (increases the amount of norepinephrine) and green tea EGCG (prevents breakdown of norepinephrine) and caffeine (prolongs the action of cAMP in cells), could have powerful synergistic effects on thermogenesis and fat breakdown. Clearly, green tea is a perfectly safe and phenomenally broad-acting adjunct to your body-weight and fat-control program.
In addition to its extraordinary fat-loss benefits, a recent study in Japan showed that consumption of green tea was also associated with a lower incidence of coronary artery disease.15
Other studies have also shown that
people who consume higher amounts of green tea have a lower incidence of cardiovascular disease.16, 17
Several cell culture and animal studies have shown that
green tea can help prevent a variety of different cancers
Some, but not all, human population-based studies also support an association between increased tea consumption and decreased risk of cancer. Ongoing studies are underway to determine the mechanisms of action and further test the anticancer effects in Phase II clinical trials. Most studies have focused on EGCG and have shown this compound inhibits the growth and induces cell cycle arrest and apoptosis (cell death) in different cancer lines.
may protect against cancer due to its potent antioxidant activity. Several human studies have shown that consumption of green tea leads to substantial increases in the antioxidant capacity of blood which peaks about one hour after ingestion.27
These studies clearly show that the polyphenols in green tea are absorbed and bioavailable because oxidative damage to important molecules such as DNA and lipids are reduced after green tea consumption.20
There is even evidence that green tea may have beneficial affects for dental carries,21
and cognitive function.23
The active polyphenolic compounds in green tea account for a third of the dry weight of the leaves. The predominant polyphenols are the catechins and include epicatechin, epicatechin-3-gallate, epigallocatechin, and epigallocatechin-3-gallate (EGCG). Although green tea does contain a variety of compounds, most research has focused on EGCG as the active ingredient in green tea responsible for the antioxidant and anticarcinogenic effects (as well as the thermogenic and other anti-fat effects). All that being said, there is a great deal of variability among different green tea products. For example, the bioactive contents in green tea are dependent upon how the tea leaves were processed prior to drying, the geographic location and growing conditions, the tea type (decaffeinated, instant, etc.), and preparation method (amount used, brew time, temperature).
Supplements Are Better Than Liquid Teas
In order to get the benefits of green tea, the active compounds need to be present in the product and get absorbed into the blood. A recent study from UCLA compared the effects of green tea, black tea, and a
green tea extract in pill form
that all contained the same amount of the flavanol EGCG (Henning et al. 2004)24
. Despite containing the same amount of EGCG, the absorption of total plasma flavanols into the blood after ingestion of the
green tea extract supplement
was far superior to the liquid teas. The green tea extract also led to higher antioxidant activity in the blood. This clearly shows the benefit of green tea extract supplements over liquid tea.
Seek Out a Premium-Quality Green Tea Supplement
Altogether, it is just simply impossible to go wrong with green tea. From its remarkable effects on body weight and fat, to its heart-protective actions and potential anti-cancer effects, to its antioxidant and cell-protective benefits, this is a common, safe, and extraordinary herb that does it all. In addition to drinking green tea, you can also look for
supplements that contain green tea for fat loss and weight management
, though it is critically important to choose one that is standardized in order to ensure the highest quality and optimum effects. If you're considering using a green tea supplement to support fat loss, amp up your workout, or for its antioxidant benefits, it's important to know that the quality of green-tea-containing supplements in the marketplace varies widely. Many products simply contain far too little bioactive EGCG to ever provide any measurable metabolic or antioxidant benefit.
However, new products that incorporate the latest research breakthroughs into green-tea-derived health benefits are just starting to appear. These products stand out for the fact that their green tea sources are all standardized to contain efficacious levels of EGCG and other key active ingredients necessary to promote significant results, (and their manufacturers lab test them to ensure this). Each of these products also contain other ingredients that further support thermogenesis and fat-loss such as L-tyrosine. There is however one green tea product that belongs in a category of its own and that is
ProSource's Ultra GTX
, an all-new, super-potency, pure green tea product which contains nothing but a
superior-grade green tea
. What sets this product apart is that it's the first to contain an all-new form of super green tea that yields an unprecedented 45% EGCG, plus higher levels of key polyphenols and a complete spectrum of other beneficial catechins. As a result of this superior high potency, Ultra GTX may take the extraordinary benefits of green tea to the next level. And another plus to this product is that it contains only a modest level of naturally occurring caffeine which makes it ideal for use virtually any time of day. In essence,
represents this wonder nutrient in its purest, most potent form. In short, once you've made the wise decision to include a
green tea supplement
in your nutritional regimen, it's equally important to know exactly what you're buying. Beware substandard green tea formulations. Go with a premium-quality green-tea-based supplement like
. It will make all the difference in the world.
With so many health related benefits associated with green tea, it's no wonder that this amazing compound's enormous popularity has made it the supplement of choice in so many diverse circles of the population--from people sipping cups of it at coffee shops to fitness enthusiasts at your local gym or health club. Also, elite athletes and celebrities, like model and actress
Estelle Warren, call green tea their supplement of choice for the long list of health benefits and metabolic properties it delivers.
References 1. Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999 Dec;70(6):1040-5. Nagao T, Komine Y, Soga S, Meguro S, Hase T, Tanaka Y, Tokimitsu I. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am J Clin Nutr. 2005 Jan;81(1):122-9. 2. Borchardt RT, Huber JA. Catechol O-methyltransferase. 5. Structure-activity relationships for inhibition by flavonoids. J Med Chem. 1975 Jan;18(1):120-2. 3. Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J. Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity. Int J Obes Relat Metab Disord. 2000 Feb;24(2):252-8. 4. Zheng G, Sayama K, Okubo T, Juneja LR, Oguni I. Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice. In Vivo. 2004 Jan-Feb;18(1):55-62 5. Anderson RA, Polansky MM. Tea enhances insulin activity. J Agric Food Chem. 2002 Nov 20;50(24):7182-6 6. Wu LY, Juan CC, Ho LT, Hsu YP, Hwang LS. Effect of green tea supplementation on insulin sensitivity in Sprague-Dawley rats. J Agric Food Chem. 2004 Feb 11;52(3):643-8. 7. Wu LY, Juan CC, Hwang LS, Hsu YP, Ho PH, Ho LT. Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model. Eur J Nutr. 2004 Apr;43(2):116-24. Epub 2004 Jan 06. 8. Kao YH, Hiipakka RA, Liao S. Modulation of endocrine systems and food intake by green tea epigallocatechin gallate. Endocrinology. 2000 Mar;141(3):980-7. 9. Kao YH, Hiipakka RA, Liao S. Modulation of obesity by a green tea catechin. Am J Clin Nutr. 2000 Nov;72(5):1232-4. 10. Watanabe J, Kawabata J, Niki R. Isolation and identification of acetyl-CoA carboxylase inhibitors from green tea (Camellia sinensis). Biosci Biotechnol Biochem. 1998 Mar;62(3):532-4. 11. Tian WX, Li LC, Wu XD, Chen CC. Weight reduction by Chinese medicinal herbs may be related to inhibition of fatty acid synthase. Life Sci. 2004 Mar 26;74(19):2389-99. 12. Choo JJ. Green tea reduces body fat accretion caused by high-fat diet in rats through beta-adrenoceptor activation of thermogenesis in brown adipose tissue. J Nutr Biochem. 2003 Nov;14(11):671-6 13. Agharanya JC, Alonso R, Wurtman RJ. Changes in catecholamine excretion after short-term tyrosine ingestion in normally fed human subjects. Am J Clin Nutr. 1981 Jan;34(1):82-7. 14. Deijen, J.B., C.J.E. Wientjes, H.F.M. Vullinghs, P.A. Cloin, and J.J. Langefeld. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Research Bull. 48:203-209, 1999. 15. Sano J, Inami S, Seimiya K, Ohba T, Sakai S, Takano T, Mizuno K. Effects of green tea intake on the development of coronary artery disease. Circ J. 2004 Jul;68(7):665-70. 16. Sesso HD, Gaziano JM, Buring JE, Hennekens CH. Coffee and tea intake and the risk of myocardial infarction. Am J Epidemiol. 1999 Jan 15;149(2):162-7. 17. Geleijnse JM, Launer LJ, Van der Kuip DA, Hofman A, Witteman JC. Inverse association of tea and flavonoid intakes with incident myocardial infarction: the Rotterdam Study. Am J Clin Nutr. 2002 May;75(5):880-6. 18. Chung FL, Schwartz J, Herzog CR, Yang YM. Tea and cancer prevention: studies in animals and humans. J Nutr. 2003 Oct;133(10):3268S-3274S. 20. Shim JS, Kang MH, Kim YH, Roh JK, Roberts C, Lee IP. Chemopreventive effect of green tea (Camellia sinensis) among cigarette smokers. Cancer Epidemiol Biomarkers Prev. 1995 Jun;4(4):387-91. 21. Wu CD, Wei GX. Tea as a functional food for oral health. Nutrition. 2002 May;18(5):443-4. 22. Hegarty VM, May HM, Khaw KT. Tea drinking and bone mineral density in older women. Am J Clin Nutr. 2000 Apr;71(4):1003-7. 23. Hindmarch I, Rigney U, Stanley N, Quinlan P, Rycroft J, Lane J. A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology (Berl). 2000 Apr;149(3):203-16. 24. 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 Dec;80(6):1558-64.