He who enjoys good health is rich, though he knows it not. – Italian proverb
|Harvesting green tea. Photo: markb120, Flickr ccl|
This post is about green tea. Do not solely rely on any of the information contained in this post to be definitive. It is only what I have found in searches.
It’s funny how a post can take on a life of its own. The one a few days about margarine did, and this one did today. I was prepared to do a short piece about green tea and how healthy it was (yada yada yada), but when I started to research…wow. It was like a floodgate opened.
|Photo: bkajino, Flickr ccl|
I found all kinds of purported health benefits as well as concerns. Please don’t take my word on any of the scientific benefits or constraints listed here. This is only what I found and I thought you may like to know. You may find different information.
Green tea is held up by some as a panacea and poster child health product. The more I read the more I alternated between somewhat agreeing and somewhat not. I doubt that any of the listed health drawbacks would occur in the consumption of an occasional cup (or the benefits for that matter) but if you are considering switching, are on medications or have a specific condition you may just want to keep reading…and talk to your doctor.
What is green tea?
Green tea is made from Camellia sinensis leaves that have undergone little to no oxidation during processing. Green tea originates in China but has become associated with many Eastern cultures. As you would imagine, each country grows their own variety so differences do exist between green teas.
Green tea is dried, but not fermented. This gives green tea its colour and a lighter flavour than traditional teas. It also helps keep all the beneficial chemicals preserved in the finished product.
In the last few decades there has been a huge surge in interest regarding the health benefits of drinking green tea in Western nations. Many claims have been tested, or are being tested, in scientific research studies.
Support has been found to suggest that regular consumption lowers the chance of heart disease. Green tea contains more flavioids than fruits, vegetable juices or wine. Flavinoids are phytochemicals that are responsible for anti-oxidative and anti-carcinogenic health benefits. So links have been established there as well.
|Photo: KOREA.NET, Official Page of the |
Republic of Korea, Flickr ccl
A recent study by Charité Hospital (Berlin) showed that casein in milk blocks many of the healthful benefits of drinking tea. Other studies have shown little to no effect. What do you believe? Soy and nut milks contain no casein by the way.
A Purdue University study found that most antioxidants were not absorbed when tea was drunk by itself. Adding citrus lowered the pH in the small intestine which caused more to be absorbed by the body.
As I told someone recently, you can find anything on the Web to back up what you already think, but it doesn't make it true. Green tea sites list an amazingly wide range of proven—and supposed—health benefits. I think I’m going to start including some green tea in my diet. It can't hurt, can it?
Read on to see why you should, or shouldn't, include it in your daily life as well.
If you are on any medications or have a specific condition you should discuss with your doctor any decision to drink green tea in quantity. Although the positive health benefits seem amazing, and are being backed up by science, there are some scary negative ones as well. Both are listed here. You can Google any potential interactions for conditions you have or medications you may be taking. But for goodness sake, talk to your doc as well.
Good news health benefits
Much of this information is condensed from http://www.wikidoc.org/index.php/Potential_effects_of_tea_on_health. Please go there to read much more information on all of these topics.
|Green tea KitKat. Photo: agelalcantara, Flickr ccl|
Studies suggest green tea protects against a range of cancers, including lung, prostate and breast. It is suggested it is due to the presence of epigallocatechin gallate (EGCG) in green tea. Google “EGCG and green tea” to learn more.
Increased metabolic rate
Clinical trials at the University of Geneva, Switzerland indicate green tea raises the metabolic rate and speeds up fat oxidation.
In 2003 a Brigham and Women's Hospital research project indicated that theanine in green tea may help the body's immune system fight infection, by boosting the disease-fighting capacity of gamma delta “T cells.” The study included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 2.5 cups (600ml) of coffee or black tea daily.
Blood sample analysis found that the production of anti-bacterial proteins was up to five times higher in the tea-drinkers, an indicator of a stronger immune response. That’s after only four weeks! Most of the same chemicals are present in green tea as black.
|Photo: KateMonkey, Flickr ccl|
Human trial results released in 2007 found L-theanine (in green tea) is absorbed by the small intestine and crosses the brain-blood barrier where it affects neurotransmitters and increases alpha brain-wave activity. The result is a calmer, yet more alert, state of mind.
A 2006 study showed that elderly Japanese people who consumed more than 2 cups of green tea a day had a 50% lower chance of having cognitive impairment, in comparison to those who drank fewer than 2 cups a day, or who consumed other tested beverages.
Lower stress hormone levels
UCL researchers published results finding that drinking black tea has an effect on stress hormone levels in the body and thus helps in recovering more quickly from life's stresses.
Effects on HIV
A recent study appearing in the Journal of Allergy and Clinical Immunology stating that EGCG can help to boost the immune system. The study said, "Our research shows that drinking green tea could reduce the risk of becoming infected by HIV, and could also slow down the spread of HIV…we suggest that it should be used in combination with conventional medicines to improve quality of life for those infected.” Black tea also showed this same benefit.
Inflammatory Bowel Disease (IBD)
Polyphenols in green tea show ability to inhibit intestinal inflammation.
Oxalates, including those found in all teas are a mixed bag (see problems below), oxalates help with HIV and in general infections by mopping up free iron, one less thing for the immune system to do. Oxalates chelate zinc as well, a crucial nutrient for HIV to hijack a cell, as it has zinc fingers. (see “bad news” below, as well)
|Green tea frozen yogurt. Photo: Brandon Shigeta, Flcikr ccl|
Effects on bad breath
Research has shown that polyphenols help inhibit the growth of bacteria that cause bad breath.
Iron overload disorders
A daily cup of black tea was shown in a German study to stop excess iron damaging the bodies of people who suffer from haemochromatosis, due to its high content of tannin which limits iron absorption.
I have to admit, the “bad news” sections when researched seemed less definitive in statements than the benefits section. Take it as you will. For more inidepth information about drawbacks about tea in general go to http://en.wikipedia.org/wiki/Health_effects_of_tea#Potential_drawbacks
A 2009 USC study using mouse models found that EGCG can bind to a common anti-cancer drug called bortezomib. In doing so it can render the drug therapeutically useless.
|Green tea sweet bread made with powdered green tea.|
Photo: vlxyz, Flickr ccl
The overconsumption of tea can cause kidney stones as well as make calcium less available to the body. This is due to oxalates. Its bioavailability in tea is low, so only in large consumptive volumes is this supposedly a problem.
One study showed tannins in tea may increase the risk of esophageal cancer. Another study in 2009 drew the conclusion that hot tea may be linked more closely than lukewarm tea. Since other studies seem to tout tea’s anti-cancer attributes, the effect of tea consumption on cancer is likely to depend on the specific cancer.
Green tea extract may be linked to the potential of liver damage. The company Hydroxycut actually withdrew two products and resulted in a class action lawsuit. 9 million bottles bottles were sold and resulted in 23 severe cases of liver damage, including one fatality and three requiring liver transplants. It is thought that the toxicity may be due to a genetic predisposition.
Drinking green tea shouldn’t have the same result. Hydroxycut contained 415 mg of a mixture of green, white, and oolong tea extracts, and several other herbal extracts—per dose.
So there you have it. Cup of tea, anyone?
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