|Tea Extract Helps
Reduce Cholesterol Levels
Green tea/black tea hybrid formulation shows clear benefit in clinical trial
By Will Block
hat’s in a color? Red is good—bold and sexy. Yellow is more cheerful, blue is more serene, purple more elegant. But perhaps none of those colors is your favorite. Perhaps green is your cup of tea. Aha! By sheer coincidence, green is the color of tea—at least when it’s young and sassy. Green tea—the kind that’s famous for its health-giving properties—is made from the tenderest young tea leaves that have not been allowed to undergo oxidative fermentation.
Green tea (unfermented), with catechins
Black tea (fermented), with theaflavins
When those same leaves are fermented, however, the result is black tea. Now, black means the absence of color, and that’s clearly not the case with “black” tea (at least not when it’s been brewed for drinking), but let’s not quibble.
What makes black tea different from green tea? The flavor, for starters. Most tea drinkers in the Occident seem to prefer the strongly flavored black tea. The more subtly flavored (but also more astringent) green tea is gaining in popularity, however, and it has always been a favorite in the Orient, especially in Japan, where it’s the centerpiece of the traditional tea ceremony. The difference in flavor between green tea and black tea comes about, of course, because of chemical transformations occurring in the fermentation process that changes the tea leaves from green to black.*
Fermentation Destroys Catechins (Bad) . . .
In those chemical transformations lie some health consequences of great importance to human beings—who, by the way, drink more tea than any other beverage on earth except water. Most of the health benefits attributed to tea are found predominantly in green tea, which is why you’ve heard so much about that color of tea in the pages of Life Enhancement and elsewhere.
In a nutshell, here’s what happens: when green tea is fermented, some of the most beneficial chemical compounds it contains are partially or completely destroyed (in the sense that they’re converted to other compounds). The most notable of these health-giving compounds is EGCG (epigallocatechin gallate), a remarkable, multifaceted substance that scientists regard as among the most promising natural anticancer compounds yet discovered.
EGCG is one of a class of potent antioxidant molecules called catechins, which are members of a larger class of antioxidant compounds called flavonoids (see the sidebar on this topic), which are members of a still larger class of antioxidant compounds called polyphenols.
Those Colorful Flavonoids
You see flavonoids every time you look at brightly colored fruits, vegetables, or berries, because that’s where those foods’ vivid colors come from, by and large. There are at least 4000 flavonoids known to biochemists. All are antioxidants, and at least 50 of them are present in plant-based foods and beverages, notably berries, tea, and red wine. Flavonoids are found most commonly in the pigments of rinds, seeds, flowers, leaves, and barks.
Flavonoids—or, more accurately, plant extracts that are rich in flavonoids—have been used medicinally for thousands of years, but it is only in the last few decades that scientists have begun to discover exactly what they are and how they work. We now know that various flavonoids are helpful in promoting good circulation, treating impotence, boosting brain function, fighting inflammation, strengthening immune function, alleviating chronic fatigue syndrome, and preventing cancer and heart disease.
These effects are attributed to the flavonoids’ antioxidant properties to varying degrees. In some cases, antioxidant activity may be the primary factor; in other cases, it many be a minor factor—we don’t always know. It’s worth remembering that any antioxidant compound may provide health benefits that are unrelated to its antioxidant capacity.
- Packer L, Colman C. The Antioxidant Miracle. John Wiley & Sons, New York, 1999.
. . . But It Creates Theaflavins (Good)
In terms of EGCG and other catechins, therefore, fermenting green tea to black tea is a bad thing (the antioxidant power of black tea is only about one-sixth that of green tea). But wait—while one hand of the fermentation taketh, the other hand giveth. That same process causes some of the catechins in green tea to become polymerized (converted to chainlike molecular structures), resulting in polyphenolic pigments in black tea called theaflavins and thearubigins, which have some significant health benefits of their own. The former are of particular interest, as we’ll see in a moment.
Thus, as catechin levels in tea go down in the progression from green to oolong to black, theaflavin and thearubigin levels go up. (Another category of antioxidant molecules in tea, called flavonols, is relatively unaffected by the fermentation process and thus remains constant.)
The Paradox of Tea and Cholesterol Levels
Recently, researchers in China and the United States decided to investigate the potential benefits of mixing the two colors of tea, so to speak, by using a green tea extract that was enriched with theaflavins from black tea. They were motivated by a paradox that has vexed scientists for some time. On the one hand, it is well known from epidemiological studies that drinking tea is inversely correlated with cholesterol levels and heart disease, i.e., higher tea consumption correlates with lower cholesterol levels and a reduced risk for heart disease.
On the other hand, clinical trials designed to demonstrate the presumed effect of tea drinking in reducing cholesterol levels have, by and large, failed to do so, leaving uncertainty over the mechanism by which tea undeniably works to improve our cardiac health. (There has been some recent progress, however. For a report on a new study that does demonstrate the effect in question, see the sidebar “Black Tea Lowers Cholesterol.”)
Black Tea Lowers Cholesterol
A new study has shown a cholesterol-lowering effect from drinking tea—in this case, black tea. Researchers at the U.S. Department of Agriculture conducted a small trial on patients with mild hypercholesterolemia to determine the effects of black tea on cholesterol levels, oxidative stress (the degree of oxidation of LDL-cholesterol in the bloodstream), and antioxidant status (the capacity for antioxidant activity in the blood plasma) in a controlled dietary setting.
Unlike most similar studies, in which the patients consumed their own normal diet, this study required all the patients to eat the same carefully designed diet of foods and beverages prepared by staff nutritionists. Thus, dietary factors that might obscure the results of interest could be eliminated, leaving a “clean field” in which to observe the effects of the tea.
In the randomized, placebo-controlled, double-blind trial, 15 men and women on this diet drank 5 cups per day of either black tea or a placebo beverage for 3 weeks. (Artificial fruit flavorings, sweeteners, and coloring were used to mask the appearance and distinctive taste of black tea so that it could not be distinguished from the placebo.) Two placebos were used in two separate 3-week trials: one contained no caffeine, and the other contained caffeine equivalent to that in the black tea.
The results were gratifying: compared with the caffeine-containing placebo, black tea reduced total cholesterol by 6.5% and LDL-cholesterol (“bad cholesterol”) by 11.1%. Lesser reductions—3.8% and 7.5%, respectively—were observed versus the caffeine-free placebo. There was no effect on HDL-cholesterol (“good cholesterol”), nor were any effects observed on oxidative stress or antioxidant status from any of the three beverages.
The authors speculate that tea polyphenols may limit the absorption of cholesterol in the intestine, thus reducing the blood levels. This idea is consistent with the results of animal studies in which this effect has been seen and in which an inhibition of cholesterol synthesis in the liver has not been seen. Nonetheless, one cannot say whether this is true in humans—only hard evidence will tell the tale.
- Davies MJ, Judd JT, Baer DJ, et al. Black tea consumption reduces total and LDL cholesterol in mildly hypercholesterolemic adults. J Nutr 2003;133:3298S-3302S.
To compound the confusion, various studies have shown that tea extracts do reduce cholesterol levels in hypercholesterolemic (high-cholesterol) laboratory animals. In separate studies, the effect has been seen with green tea, black tea, green tea catechins, and black tea polyphenols. Other animal studies have shown additional positive effects of teas or tea extracts, such as reducing the intestinal absorption of cholesterol and increasing the excretion of cholesterol and related lipids (fatty compounds).
Green/Black Tea Formulation Reduces Cholesterol
To shed some new light on this situation, the Chinese and American researchers formulated a green tea extract containing 150 mg of catechins and 150 mg of other polyphenols, augmenting it with 75 mg of theaflavins from black tea. They tested this hybrid formulation (in capsule form) on 240 Chinese men and women (average age 55) with mild to moderate hypercholesterolemia who were on a low-fat diet but were not taking any lipid-lowering drugs or other drugs that might interfere with their lipid metabolism. The patients were asked to maintain their habitual, traditional Chinese diet, including their customary daily intake of tea. Surprisingly, only about half the subjects were regular tea drinkers, most of them consuming 1 to 4 cups per day, and the rest 5 to 10 cups per day.
The 12-week study was randomized, placebo-controlled, and double-blind. When the 12 weeks were up, it was found that the control group (placebo) showed no reductions in total cholesterol or LDL-cholesterol (“bad cholesterol”) levels. In the treatment group, however, total cholesterol dropped by 11.3%, and LDL-cholesterol dropped by 16.4%. At the same time, the levels of HDL-cholesterol (“good cholesterol”) increased by 2.3% in the treatment group, whereas in the control group they dropped by 0.7%. In both groups, the levels of triglycerides (fats) increased somewhat—by 2.6% in the treatment group and by 5.6% in the control group.
Two Interesting Facets of the Study
Interestingly, the researchers found that whether the patients in the treatment group did or did not drink tea regularly made no difference in the observed reductions in LDL-cholesterol levels (no indication was given as to whether this was also true of the other parameters measured). This indicates, perhaps, that 1 to 4 cups of tea per day is insufficient to deliver enough of the most potent tea flavonoids to make much of a difference in cholesterol levels.
Drinking tea is inversely correlated
with cholesterol levels and heart
disease, i.e., higher tea
consumption correlates with
lower cholesterol levels and a
reduced risk for heart disease.
Also interesting was that the patients in the upper half of LDL-cholesterol levels (160–190 mg/dL) at baseline (the outset of the study) showed only a slightly greater percentage reduction in these levels than the patients in the lower half (130–159 mg/dL): the two figures were 17.6% and 15.3%, respectively, and the difference was determined not to be statistically significant. Thus, all patients benefited about equally from the hybrid tea extract, regardless of their baseline cholesterol levels.
Long-Term Tea Use Could Reduce Cardiovascular Risk
The researchers believe that theirs is the first human placebo-controlled trial that demonstrates an LDL-cholesterol-reducing action of tea flavonoids. They state:
While it is possible that the addition of theaflavins to catechins was responsible for the reduction in cholesterol seen in our study, it is not possible to conclude what role theaflavins, catechins, other tea polyphenols, or even the method of extract preparation may have had in the reduction of LDL-cholesterol.
In other words, whether the benefits of tea compounds in reducing cholesterol levels are attributable to their antioxidant properties or to some other mechanism(s) of action is not known. It would be interesting to know this, of course, but what is more important is that there is an undeniable correlation between tea consumption and a reduced risk for heart disease. In this regard, the researchers state:
In observational studies as well as clinical trials with statin drugs, each 1% reduction in LDL-cholesterol results in approximately a 1.0% to 1.5% reduction in the relative risk of major cardiovascular events. By extrapolation, if the long-term use of the tea extract produced a persistent 16% reduction of LDL-cholesterol, this could reduce the risk of major cardiovascular events by 16% to 24%.
They go on to claim that their study represents “the first step in establishing the practicality, safety, and LDL-cholesterol-lowering efficacy of a tea product.” They caution, however, that more research is needed to determine whether results similar to theirs would be obtained in people of other ethnic groups eating a diet with a different amount of fat or cholesterol.
All patients benefited about equally
from the hybrid tea extract,
regardless of their baseline
Statin drugs, by the way, are very popular in the medical community because of their ability to reduce cholesterol levels dramatically. Also dramatic, but not as well known to the general public, is the ability of a natural supplement called policosanol, a nonsugar substance extracted from sugar cane, to reduce cholesterol levels—at lower cost and with a higher safety profile than the statin drugs, and with equivalent or even better efficacy.
To Tea, or Not to Tea—That Is Not the Question
It seems safe to say that consuming tea—green tea especially, but black tea as well—is a good thing to do if you wish to lower your cholesterol levels and reduce your risk of heart attack or stroke. To obtain the full benefits of green tea, some physicians recommend 4–6 cups/day, but others recommend 8–10 cups/day (the average in Far Eastern societies where green tea is a staple is about 5–10 cups/day).
Or, you can supplement with a tea extract, which gives you the benefit of a constant, optimal amount of tea’s most beneficial compounds, every day. And whether your favorite color (of tea) is green or black or grack or bleen, you can have it.
- Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract. Arch Intern Med 2003;163:1448-53.
- Janikula M. Policosanol: a new treatment for cardiovascular disease? Alt Med Rev 2002;7(3):203-17.
Will Block is the publisher and editorial director of Life Enhancement magazine.