Green tea has been associated with mythology and mystery, including a litany of miraculous health benefits, since its “discovery” nearly 5,000 years ago. The story begins with an incident of serendipity when in 2737 B.C. the second emperor of China stumbled upon this magical brew when green tea leaves blew compliantly into his cup of hot water. Perhaps it was this act of nature, or his intense need to cure all ills and become hero as well as emperor, but from that day forward green tea has been touted as a preventative and cure for everything from heart disease to cancer.
The health benefits of green tea have been subject to clinical studies only in the last few years, and there is evidently an eastern bias. Studies conducted on human subjects in the Far East do not appear to take into account the difference in diet; people in, for example China and Japan, may drink more green tea than in western nations, but they also eat more fish and soy, affecting the results. Researchers at Yale University, in a 2006 study entitled, “The Asian Paradox”, examined 100 other studies concerning the health benefits of green tea, including lower cancer and heart disease rates despite a high percentage of cigarette smokers in China. Their conclusion was that the Chinese tend to consume, on average, 1-1/4 quarts of green tea daily and the antioxidant properties showed some benefits. More can be found on this study at www.medical.yale.edu.
Odds are these people got very little sleep with that much caffeine in their systems. Caffeine is one of the beneficial properties contained in green tea. For example, in weight studies, it was found that caffeinated green tea helped participants lose weight, but decaffeinated green tea was far less effective. Caffeine is a stimulant, whether it’s in coffee or black tea or green, and stimulants can interfere with sleep. Decaffeinating green tea has proved to reduce the effectiveness of one of its main beneficial elements by three times, rendering it relatively ineffective.
The Good, the Bad and the Contradictory
Given that tea is the most popular beverage (after water) in the world, and has been consumed for many millenniums, you would think there would have been a lot of research done to weigh its potential benefits. Curiously, the word “potential” is found in most studies conducted on the health benefits of green tea. The vast majority of research has been performed in the Far East and the results of studies there and in the west show conflicting results. Here is what research tells us is good (for humans, not just laboratory rats…) about green tea:
- It is high in antioxidants (so are grapes, berry fruits, red wine and 70% cocoa (or higher) dark chocolate).
- It contains catechins, a type of which is specifically contained in green tea and not black, white, red or orange teas. The catechin sub-type is known as epigallocatechin-3-gallate (EGCG).
- It contains vitamin C in the form of ascorbic acid, another type of antioxidant.
Can green tea be bad for you? Like anything else you might ingest, its benefits and drawbacks have something to do with individual constitutions and existing health conditions. People with liver problems such as sclerosis and hepatitis (to mention just two) should avoid green tea. Other drawbacks to the consumption of green tea include:
- It contains fluoride, which increases risk of bone fracture from conditions such as osteoporosis. A bone density scan will help to ascertain if you have or are at risk for this bone-weakening condition.
- It contains caffeine. Contrary to popular belief, green tea is not a “herbal” tea, or “tisane” as the French refer to teas steeped from leaves, flowers, fruits or other natural foodstuffs that do not contain caffeine. Caffeine is an addictive substance and consumption of beverages containing it can cause sleep disorders.
- It contains oxalates. Over-consumption of green tea (which happens when people stricken with illnesses grasp at straws to cure their ills) can cause kidney stones.
- Its properties can create an increased risk of rheumatoid arthritis.
- It is a diuretic. In simple terms, diuretics (including other types of tea and coffee) pass through your system quickly, taking with them precious fluids. It is always appropriate to drink a glass of water each time you consume a diuretic beverage. And it’s well known that too much ingestion of water and other fluids can place unnecessary pressure on your bladder.
Green tea’s claims of miraculous health benefits can be summed up simply, if rather harshly: people who drink green tea still die. And its claims are rich with more than antioxidants… For example, one health benefit of green tea is supposedly mental acuity, its ability to stave off dementia in older age. But green tea contains aluminum, a mineral known to contribute to the onslaught of Alzheimer’s Disease.
Contradictions abound not just between clinical studies on the health benefits of green tea between east and west, but on specific claims. Another example is cancer prevention and cancer cell control. Green tea contains tannins; these have shown an inclination to promote esophageal cancer. Hot beverages also possess this tendency, so the two combined may be even more detrimental.
Proven and Suspected Health Benefits of Green Tea
Green tea has so many claimed health benefits that, if all were true, we’d need nothing but green tea, and perhaps a small amount of food, to live disease-free for a very long life. Is this a marketing ploy? In modern times, perhaps, but green tea has been enjoyed and demonstrated certain benefits for thousands of years. There must be something to it.
Those catechins are believed to be the primary beneficial components of green tea. What they do is search for free radicals (although they sound like fun, they’re detrimental in the healthy-human scheme of things) that can, among other things, cause or contribute to some cancers, atherosclerosis, blood clots and DNA damage. Green tea has proven its effectiveness in preventing blood clots such that some doctors now advise patients about to undergo surgery to cease drinking green tea in advance of their operation.
Because green tea is processed differently from black teas, the catechins, our “good guys”, are more concentrated. Green tea is simply the tealeaf that has been withered through a light steaming process; black tea is fermented, harming or reducing the concentration and effectiveness of the catechins. This is pivotal to the medicinal value and properties of green tea.
There have been significant weight-loss results cited from drinking caffeinated green tea. A widely reported Japanese study of 240 women and men showed greater weight loss in the subjects who drank larger quantities of green tea. Not only did this group have the highest amount of lost fat, weight and inches, it also tested as having lower blood pressure and LDL cholesterol levels.
What western researchers find curious about this study is that the Japanese are not known for their obesity (except, perhaps, for sumo wrestlers!), and their overall diets boast significantly less fat and a lot more fish and legumes than most North American diets. There may be a bias in place; Japan is a seller of green tea. One thing for certain in this and all other studies regarding green tea and weight loss is that the tea must not have been decaffeinated; caffeine is known to assist in fat oxidation and is a common ingredient in diet pills.
The benefits of green tea relating to general heart health are more available than detailed components and issues such as cholesterol levels. Green tea’s antioxidants are known as “dilators”. They dilate, just like the pupils of your eyes, widening and thereby increasing the flexibility of blood vessels; this results in less clogging. But the studies have, by and large, been conducted on laboratory rats. Heart specialists insist that there is insufficient evidence to prescribe green tea as a preventative or curative relative to heart disease, and that overall lifestyle and diet, which may or may not include drinking green tea, has a far more profound effect.
Then there are the cancer claims. Cancer has become ubiquitous in western civilization, and toying with its seriousness is not only a dangerous game, it’s unkind. Researchers have concluded that you would have to have drunk a lot of green tea every day all your life in order to achieve any level of cancer prevention. And this is based on laboratory studies, not human control groups. What is known, clinically and chemically, is that EGCG has the ability to regulate the incidence of cancer and may inhibit the growth of cancer cells. Apple co-founder, Steve Jobs, tried numerous natural curatives, but still died of cancer. An article published in the Journal of the American Medical Association on September 13, 2006, reported the results of a study that demonstrated green tea’s benefits in some areas, but concluded definitively that green tea did not help in the curing of cancer. More can be found on this subject at: https://jama.ama-assn.org/.
General health benefits are, overall, unsubstantiated, but a Chinese study undertaken at the Hong Kong Polytechnic University concluded with this rather ambiguous statement: “The results indicate that green tea has significant genoprotective effects and provide evidence for green tea as a ‘functional food’.” The definition of a so-called functional food escapes the medical vernacular. This study, at least, shows less of an eastern bias and can be read at www.ncbi.nlm.nih.gov/pubmed/20807462.
Green Tea and Cholesterol: Effective or Not?
The lowering of LDL (bad) cholesterol by the ingestion of green tea is one of the least studied aspects of the beverage. Its claims to prevent or retard cancer cell growth and clean out arteries have been far more the subject of research and experiments. This suggests a limited benefit; otherwise studies would have been far more frequent.
One Dutch study confirmed definitively that decaffeinated green tea loses whatever health benefits it might otherwise have.
Another research project found that anticoagulant properties in green tea help to prevent blood platelets from adhering to one another, thereby also making improvements in cholesterol levels. The results, published in the “Journal of the American College of Surgeons”, included the conclusion that, “green tea may prevent the oxidation of LDL cholesterol (the “bad” type), which, in turn, can reduce the buildup of plaque in arteries”. More on this study can be read at: www.journalacs.org.
Green tea extract may offer a more concentrated dose of what is beneficial about green tea. The August 22, 2006, edition of “Biological Psychology” reported the results of a study conducted at the Division of Cardiovascular Medicine, Vanderbilt University Medical Center in Nashville, Tennessee. It took particular focus on a chemical that exists in green tea; “L-Theanine”, as it is called, seems to modify stress in some individuals, and that happens by inhibiting levels of stress activity in certain neurons. In the controlled research group, 240 adults ingested either a placebo or an extract of green tea (in pill form) that was enriched with L-Theanine. Twelve weeks later the green tea extract group demonstrated a significant reduction in LDL cholesterol, but the authors of the research and study concluded it was not a solo solution to high LDL cholesterol levels; other dietary measures, such as a reduction of fat intake, would need to be included for full effectiveness. The complete study can be found at: www.ncbi.nlm.nih.gov/pubmed/12824094.
How Much is Enough?
Consumption of green tea in high quantities carries certain health risks, as previously outlined, so what is the minimum for general heath benefits? It depends. If you have a genetic or other predisposition to liver disease or ailments, you should not drink green tea at all. If you are otherwise healthy and want to drink green tea to maintain your good health, then 2 cups a day has been suggested as the minimum quantity to enforce that goal. If the stimulant effects of caffeine bother you, nutritionists recommend that you drink green tea only in the morning so as not to interrupt precious sleep.
Here’s a great tip: It’s the catechins in green tea that are really beneficial. The ingestion of citric acid boosts the properties of catechins, allowing more of them to be absorbed. So, take your green tea with a wedge of fresh lemon and enhance the good stuff!
Tea for Two for Good Health
The drinking of green tea, like any other food or fluid we ingest, should be done in moderation. The aforementioned study at Vanderbilt University concluded, as part of its results reporting, that green tea is “well tolerated” by most people. In that sense, they mean in a medical capacity. But what about the taste? The British, who are famous for loving their tea, mostly find green tea “oily” and “acrid”. Those from the Far East who were raised on green tea and drink it as much as we drink water and soda pop, find sweetened black and orange pekoe teas distasteful.
If you opt to drink green tea for its health benefits, not so much its unusual flavor, then be sure to limit your intake so as not to interrupt your sleep, be certain your liver is up to snuff, don’t waste your time or money on decaffeinated green tea, and drink a glass of water for each cup of green tea you take. And don’t expect too much. Until further detailed studies are done in more western universities, the health benefits of green tea are thus far fairly unsubstantiated. Regard green tea as a pleasant beverage that will likely do you a little good if sipped in moderation.