Carbohydrate-Guide

Green tea contains a long list of compounds that appear to have all sorts of biological effects, from increasing metabolic rate, to being powerful anti oxidants and immune modulators.

What is it?

Green tea has been used in China, India, and other eastern countries-both as a beverage and medicinally-for centuries. In the west, black tea is by far the more common tea, but green tea is making great strides as a beverage in the west.

Green tea is prepared by steaming the leaves then allowing the leaves to dry, while black tea has an added step in that it is allowed to ferment. Because green tea is not allowed to ferment, green tea contains many compounds that would other wise be lost during the fermentation process. Both forms of tea contain caffeine. In recent years, companies have now been offering green tea extracts, which highly concentrate the active compounds in green tea.

What is it supposed to do?

Green tea contains a long list of compounds that appear to have all sorts of biological effects, from increasing metabolic rate, to being powerful anti oxidants and immune modulators. The major active compounds in green tea extracts are: polyphenols (catechins) and flavonols.

Some research green tea has up to 100 times greater antioxidant activity than vitamins C and E!

From a weight loss point of view

Green tea extracts offers some real benefits to the dieter. Green tea and green tea extracts do contain small amount of caffeine. Caffeine is known to increase energy levels, help the body to liberate stored body fat for energy, and other functions well known to most people.

Although caffeine alone has the above properties, recent studies have shown green tea may

Be superior to simple caffeine for liberating stored body fat as a fuel

And may be superior to simple caffeine for energy levels and enhance metabolic rate

Studies have found that the catachins in green tea inhibit the enzyme that breaks down norepinephrine, also, green tea extract may have a greater effect on thermogenesis. It should also be highly synergistic when combined with other thermogenic compounds.

Green tea has a wide range of potential health benefits. As mentioned above, various compounds in green tea extracts act as anti-oxidants,

- it may also reduce blood pressure
- prevents LDL cholesterol from oxidation
- may prevent certain forms of cancer
- improve immunity
- help prevent heart disease
- and control blood sugar.

Epidemiological studies suggest that people who drink green tea have significantly lower risks of many diseases, including cancer, heart disease and stroke. Laboratory studies show that green tea extract protects against, and may be an effective treatment for, many common degenerative diseases as listed above. Green tea catechins are potent anti-oxidants that provide health benefits beyond their ability to neutralize free radicals. Heart disease and stroke are associated with a number of risk factors, yet the surprising news is that green tea appears to mitigate many of these risk factors.

Green tea has been shown to lower LDL cholesterol and serum triglyceride levels. The potent anti-oxidant effects of green tea appear to inhibit the oxidation of LDL cholesterol in the arteries. The oxidation of LDL cholesterol plays a major contributory role in the formation of atherosclerosis. The formation of abnormal blood clots (thrombosis) is the leading cause of heart attack and stroke, and green tea has been shown to inhibit abnormal blood clot formation as effectively as aspirin. When looking at coagulation risk factors in the blood, green tea specifically inhibits platelet aggregation and adhesion via effects that differ from those of aspirin.

Green tea polyphenols are potent anti-oxidants, especially in the brain. Some studies show that the polyphenols most prevalent in green tea (the catechins) are far more potent in suppressing free radicals than vitamin C or E.

Green tea can kill bacteria and appears to promote the growth of friendly bifidobacteria in the intestine and prevents the growth of dangerous intestinal bacterial strains such as clostridia and E. coli. Green tea also appears to be protective to the immune system in cancer patients undergoing radiation or chemotherapy and white blood cell count appears to be maintained more effectively in cancer patients consuming green tea.

Interestingly, some research suggests green tea lowers leptin levels, a major hormone involved in metabolic rate and other important metabolic effects relating to weight gain or loss. One potential down side to green tea is a few animals studies found it reduced anabolic hormones such as testosterone and many other hormones in rats. The list of what green tea has been shown to do in the research is extensive and compelling.

What does the research have to say?

Because green tea has such a great deal of varied research behind it, this section will stick to research looking directly at weight loss or weight loss related effects.

Several compelling studies involving humans and animals exist for green tea extracts and its potential effects on metabolism. For example, a Dr. Abdul G. Dulloo, of the University of Geneva in Switzerland, and colleagues (Am J Clin Nutr 1999;70: 1 040-045 and fnt JObes Refat Metab Disord 2000 Feb;24(2):252-8) measured the 24-hour energy expenditure, respiratory quotient, and urinary excretion of nitrogen and catecholamines in 10 healthy men who received either placebo, caffeine alone, or green tea extract.

Compared with placebo,

- the green tea group had significantly increased 24-hour energy expenditure
- significantly decreased the 24-hour respiratory quotient
- and increased 24-hour urinary norepinephrine excretion

The effects did not appear to be due to the caffeine, since subjects receiving amounts of caffeine similar to that found in green tea (approx 50 mg) had no changes in any of the same measurements. No changes in urinary nitrogen were observed either.

What this translates into is this;

- The subjects getting the green tea extract had a higher metabolic rate and were using significantly more body fat (beta oxidation) for fuel which translated into an additional 800 calories burned over the 24 hour period without any change in urinary nitrogen.

- The group getting the caffeine alone did not experience these effects relative to the green tea group, which leads one to believe green tea has its own unique effects beyond that of its caffeine content.

- It also suggested that the green tea group burned fat without sacrificing lean body tissue (muscle), which is essential to the dieter.

In one animal study using mice, green tea was fed to the mice at between 1 and 4% of their diet for 4 months. The study found that the mice receiving the green tea at all levels ate far less food and gained less overall body weight and accumulated less body fat.

What does the real word have to say?

Most people report a definite added fat loss benefit to adding a green tea extract to their fat loss supplement regimen, but not everyone reports this effect. The reason may be the wide variation in green tea quality seen on the market.

Recommendations

As alluded to above, there is a wide range of quality in green tea extracts on the market. Also, manufacturers will often be extracting different compounds and or may concentrate different compounds in the green tea, which may not specifically be what a person wants for weight loss per se.

Truth is, high quality green tea extracts containing high levels of active compounds are expensive and rarely used in the cost conscious supplement industry. The few human studies done used a green tea extract containing approximately 90mg of EGCG.

People should look for a green tea extract standardized to at least 60% polyphenols with EGCG as a marker compound.

If people want to drink green tea, they will have to down about to 4-10 cups of strong brewed green tea to get those amounts of polyphenols..

As for any safety issues, studies have shown people drinking up to 20 cups per day failed to find any significant side effects. Of course, 20 cups of tea is a high dose of caffeine, and typical side effects of high caffeine intakes such as insomnia may occur.

People that combine green tea with other stimulants such as ephedrine and caffeine products need to also adjust for that. Also, because green tea can “thin” the blood, individuals taking aspirin or other anticoagulant medications should be aware blood clotting times (bleeding time) could be increased which has both positive or negative ramifications.