Dr. Tim Ziegenfuss

The Miraculous Green Tea

The Science of Curvelle, Part I

Interview with Dr. Tim Ziegenfuss

There are some natural ingredients that catch us by surprise. They're so powerful, so amazing, we can hardly believe they've been part of our natural world for, well... forever.

Green tea is one such ingredient. Completely natural. Completely powerful. Sure, it had a reputation for being able to do some pretty cool stuff—like give you an energy lift while making you feel calm at the same time.

But now the science is showing that it does more. Far more. For instance, just some of the claims you'll find in the scientific literature: pound your fat cells to oblivion. Stop viruses in their tracks. Improve brain functioning. Lower cholesterol. Even prevent cancer.

No wonder this unique ingredient found its way into iSatori's new natural fat-burning supplement, Curvelle.

But in case you're still in doubt about this strange dried leaf that's been thrown into water and brewed for thousands of year, Dr. Tim Ziegenfuss—or Dr. Z. as we fondly call him—fills us in on the full story for our first installment of our Science Behind Curvelle series.

So please, brew up a cup, sit back, and prepare to be amazed! Even if Curvelle isn't your cup of tea, you'll still learn an amazing amount of useful information about green tea.

RS: Dr. Z, what does the research tell us about green tea?

TZ: When looking in the research, you'll find green tea has some significant benefits for those of us interested in losing fat:

• Increases fat burning
• Increases resting energy expenditure
• Increases fat loss during dieting
• Supports a healthy cardiovascular system

Tea is currently the second most widely consumed beverage in the world, next to water.¹ Of the three forms available—black, green, and oolong—green undergoes the least amount of processing.

It's also been used for medicinal purposes for literally thousands of years and has recently gained greater recognition for its antioxidant and anticarcinogenic effects. However, it's also shown promise for fighting cardiovascular disease, diabetes, skin problems, obesity, and even oral health problems.²

RS: Impressive!

TZ: We can gain a deeper understanding of green tea by breaking down its various constituents and the benefits they have to offer:

Catechins: Known as "polyphenols," these are generally considered to be the most beneficial elements found in green tea. They include EC, EGC, ECG, and EGCG, with EGCG [(-)-epigallocatechin-3-gallate] being by far the most active, individually, though there appear to be synergistic effects of all of these catechins in green tea.^{3, 4}

Pheophytins, Chlorophylls, and Carotenoids: Some studies have found that catechins are dependant on other components and are not even the major players in some of the key benefits of green tea—such as its anti-genotoxic and antioxidant effects.^5,6

Other components, such as chlorophylls a and b, pheophytins a and b, lutein, and beta-carotene are more powerful antioxidants and have a great many health benefits.⁷ Lutein and beta-carotene, for example, have been shown to help prevent macular degeneration. But that's beyond the scope of this conversation.^8,9

Theanine: There are high concentrations of L-theanine, an amino acid, in a cup of tea—30 mg or more. This amino acid has been shown to decrease blood pressure^10,11 and increase the anti-tumor activity of certain anti-cancer drugs,^12,13 but its most important properties have to do with the brain.

See, it has a similar structure to glutamic acid and therefore competes with it for binding to the glutamate receptors, offering protection against neurotoxity.

Because of its binding capacity¹¹ and the cascade of chemical events that follows in the brain, it's been shown to promote a state of "alert relaxation."^14,15 It also interrupts the stimulating and anxiety-promoting effects of caffeine, which may be why green tea has a calming effect, despite its caffeine content.^11,16

Caffeine: Although the amounts of caffeine found in green tea are pretty low—just 20 mg in a typical cup (or a tenth of that found in a cup of coffee)—this component is still one of the most important when it comes to burning calories and fat.

Interestingly, the caffeine in green tea also appears to help prevent UV-induced skin cancer. ^17,18

RS: So now we know how green tea may help improve our health. But how about with how we look? Has the research shown any benefits when it comes to body composition?

TZ: Recent research has confirmed that green tea can help with weight loss in multiple ways. It's a potent appetite suppressant, it increases thermogenesis [calorie burning], and perhaps most importantly, it burns fat over protein.

Green tea has even been shown to be as or more effective than some prescription weight-loss medications and may even rival the potent and popular ephedrine, caffeine, aspirin [ECA] stack when it comes to fat loss. In addition, green tea is one of the few weight-loss aides that has not been associated with negative effects on the cardiovascular system [such as increased heart rate and blood pressure] or central nervous system side effects [such as over-stimulation and irritability]. More research is needed before the level of effectiveness of green tea can be more conclusively determined, but the present data show a clear benefit.

RS: Going back to green teas thermogenic effect, is that just due to its caffeine content?

TZ: Green tea has been known to be a thermogenic agent for quite some time, and the thermogenesis was usually attributed to the caffeine content. But it's since been found in an in vitro [test tube] experiment with brown adipose tissue that the thermogenic effect of green tea was "much greater than can be attributed to its caffeine content."¹⁹ Other in vitro experiments also demonstrate that green tea inhibits the creation of fat [lipogenesis].^{20, 21} In rodents, studies with both green tea and green tea powder have shown that it decreases bodyweight and food intake^22,23 and inhibits lipogenesis.²⁴

Two important studies have been done assessing the thermogenic effect of green tea in humans. The first was a preliminary study that compared the effects of green tea extract [containing 150 mg caffeine and 270 mg EGCG], caffeine [150 mg], and placebo on 24-hour energy expenditure.

While caffeine alone increased energy expenditure by about .6% over placebo [which was not considered statistically significant], the green tea extract increased it by 3.5%. Additionally, while the oxidation of fat contributed to 31.6% of energy expenditure in the placebo group, it contributed 41.5% in the green tea extract group, indicating that the increase in energy expenditure was due to the breakdown of fat, not protein. Measurements of urinary nitrogen excretion, which were significantly different between treatments, further supported this contention.

It is also interesting to note that thermogenic response was not correlated with body mass index (BMI), implying that green tea may be equally as effective in relatively lean individuals. Finally, the increased thermogenesis was not accompanied by an increase in heart rate, which makes green tea distinct from other thermogenic drugs.²⁵

The second study was a three-month open trial with 70 subjects using the same dosage of the same extract as in the above study [150 mg caffeine, 375 mg total catechins, 270 mg EGCG per day]. Treatment with green tea was well tolerated and associated with a bodyweight reduction of 4.6% and a reduction of waist circumference of 4.5%.¹ Similar promising results have been reported in larger placebo-controlled studies.

RS: So, Dr. Z., how exactly does green tea work?

TZ: Green tea has many mechanisms of action [i.e., works in different ways] to stimulate weight loss. The most important is probably the inhibition of catechol-O-methyl-transferase [COMT] by EGCG.^1,19,25 COMT is the enzyme that breaks down norepinephrine [NE], one of the body's most important lipolytic hormones.

Caffeine also plays a synergistic role by inhibiting phosophdiesterases [enzymes that break down cAMP, which is further down the lipolytic pathway].^19,25

Although EGCG is the most responsible, some flavanoids found in small amounts in green tea such as quercetin and myricetin also inhibit COMT and may play a minor role.²⁵

Secondly, green tea appears to decrease the digestibility of dietary fat.^{1, 26} The proposed mechanism of action is inhibition of both gastric and pancreatic lipase, which has been demonstrated in vitro.¹ These enzymes both play major roles in the digestion of fat, so when they are inhibited, a smaller proportion of fat is absorbed and a greater proportion excreted.

Green tea is also a potent appetite suppressant. This can be partly explained by the fact that it increases both NE and dopamine,^{14, 25} but further mechanisms of action have been theorized. Specifically, tea polyphenols have been known to elevate levels of cholecystokinin (CCK),² a hormone which depresses food intake.^{2, 22} It is not yet known whether this plays a significant role in the action of green tea, and one of the effects of elevated CCK is an increase in pancreatic lipase, which is actually inhibited by green tea. It could be that green tea simultaneously elevates CCK and decreases pancreatic lipase, conferring the benefits of both appetite suppression and decreased fat digestibility.

Finally, the antioxidant properties of green tea may play a role in the fat-burning effect.^20-22 One cell culture study suggested that green tea inhibited lipogenesis by increasing superoxide dismutase activity and subsequently decreasing the formation of free radicals,²⁰ while another suggests that vitamin C from green tea plays a role in its lipolytic activity.²¹ Even if the antioxidant activity turns out to have little to do with the breakdown of fat, it leads to many health benefits that will be discussed in greater detail in following sections.

RS: I think we've probably all heard about green tea's power as an antioxidant. Can you share some of the research that supports this claim?

TZ: Green tea's enhanced protection against oxidative stress offers a variety of health benefits. As discussed earlier, drinking green tea may delay death from cardiovascular disease by one to two years with a greater increase seen in men.³¹ A study on 14,000 Japanese workers found that green tea drinkers had significantly lower cholesterol levels⁶² while a smaller study on 500 Japanese subjects found a statistically significant reduced risk of atherosclerosis in men, though not in women.⁶³

Due to its ability to increase superoxide dismutase and glutathione levels, green tea also may aid in the prevention of insulin resistance and type II diabetes,⁶⁵ which is often closely interrelated with other cardiovascular conditions. In normal rats, green tea significantly increases glucose tolerance, while in diabetic rats, it significantly reduces serum glucose.⁶⁵

Another area in which the activity of green tea is particularly important is in the brain. It goes without saying that green tea may protect against the development of brain tumors.⁶⁷ It also protects against oxidative damage in the brain⁵⁷ and improves brain recovery.⁶⁸ Green tea may also be useful in preventing Parkinson's disease through a fairly specific mechanism, and this has been an area of much study as of late.⁶⁹

Finally, recent cell culture studies have found that green tea may have strong antiviral activity. It has been tested successfully against influenza A and B and has been found to inhibit their growth,⁷⁸ and it may also decrease the chance of HIV infection.⁷⁹ As of yet, it is unknown whether these observations are relevant in humans, in which the concentrations of the active ingredients would be much smaller.

RS: Thanks so much for your insights into green tea. It's been exceptionally interesting.

TZ: You're welcome. I hope the information is also applicable.

Science can be boring to some people at some times. But in this case, we hope you'll agree that Dr. Z's explainations have been enlightening and even stimulating.

Makes you want to have another cup of tea, doesn't it? Or perhaps take a little, easy-to-swallow pill.

In future installments, you'll learn about some of the other inspiring ingredients in our new all-natural weight-loss supplement, Curvelle. So stay tuned.

Editor's Note: For a full list of references, please email us at Editors at RealSOLUTIONSmag.com with Green Tea References in the subject line.

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