Well, but what about the health benefits of tea?
[I]But surely the main reason for drinking tea is its health benefits, right?[/I]
Yes and no. There are those that drink tea merely because they find doing so to be a pleasurable act. And that in itself might be considered a health benefit, but we'll get to that. There are those that chug down tea bags just because of its supposed health benefits and being a terrific source of antioxidants. Nothing wrong with that either. And there are those that recognize and understand both aspects of tea and drink it for the combination of reasons.
[I]Wait, how is drinking tea for pleasure already some sort of health benefit?[/I]
Well, even if tea had no supposed health benefits at all (but it does, trust me on this) there is a certain zen in the way the Asians approach tea drinking. They take pride in serving a quality beverage. They take their time to select the proper brewing vessel for each type of tea in question. They are careful to make sure the water is at the proper temperature for each type of tea so as not to scorch the leaf or draw out too much bitterness in the brew. They make sure to brew the tea for the proper amount of time so as not to overbrew the leaves and draw out too much flavor or to under few the leaves and make for a weak cup with no flavor. They savor the aroma of the unbrewed leaves, check for quality of the leaves. They noisily slurp at the tea to draw the aroma into their nostrils and they drink their tea slowly. This whole process takes time. In the Asian view, brewing a good cup of tea is akin to a form of meditation. You must concentrate on the leaves, making the tea. It removes you from your thoughts, your troubles, your stress. In Asian thought, brewing a good cup of tea is time away from the world, time to spend relaxing and focusing in on yourself and your senses, your body, your mind.
In essence, taking in a good cup of properly brewed tea is a time to destress, relax, and be at one with the world, to appreciate that which nature has given you by producing the proper cup of tea. Why do you think the Chinese can spend hours a day in tea houses enjoying tea? Why do you think the Japanese have multiple, elaborate ceremonies around the making of matcha tea (which is almost an art in itself)?
[I]Oh, so tea then, is often about the simply taking time to unwind and appreciate things in a way you can't in our hectic, modern lives?[/I]
Many Asians see it that way and sometimes all you need to dramatically improve your health is to learn to take a little time for yourself.
[I]Wow, ok, that is a little bit of a zen experience then! But what about the sciencey and nutritional stuff?[/I]
Well, the research around tea has mostly investigated the role of the antioxidants in tea and how they effect the body in various ways.
[I]I'd heard it was a good source of them! Just like berries and herbs and veggies, right?[/I]
Precisely. In fact, depending on the tea beverage, even more so in many cases. Right now, green tea has the most research regarding its potential health effects, but it is not the only tea that has benefits. All tea does. In fact, depending on your specific health concerns you may want to consider different types of tea. Here is a list providing a general background of tea benefits, though I will go into a little bit more detail following this:
Green and white teas have been reviewed and studied for their high levels of antioxidants, the potential to reduce chronic inflammation markers, and the role they may play in preventing or helping treat various diseases such as cancer, diabetes, and arthritis.
Oolong tea has been shown to greatly increase insulin sensitivity and seems to increase metabolism (the ability to burn calories) greater than other types of tea.
Black tea has two remarkable benefits. The first is, of all the tea types it seems to be the most cardio protective. The second is, for whatever reason, black tea lowers cortisol despite the caffeine in it which might often be speculated to raise cortisol levels.
Pu'erh tea research is relatively new. It is being investigated as a great way to reduce elevated cholesterol. Preliminary evidence shows that it may be even more effective than statins for reducing cholesterol levels. Let's hear it for natural remedies! Pu'erh tea has also been shown to increase the body's ability to efficiently digest fats. It is also thought that even though it contains relatively few antioxidants compared to other types of tea, the fermentation process the leaves undergo instigate radical changes to the make-up of these antioxidants which might actually make it the most effective of the teas at reducing free radical damage in the body.
Note: Yellow tea is very similar to green tea in terms of chemical make-up so it is theorized that these teas would have similar health effects as the greens do.
[I]So, what do I do if I want all of these great benefits to drinking tea?[/I]
Keep your consumption of tea varied and learn to enjoy teas from all of the different categories we've talked about. Rotation also keeps the tea pallet from getting stale. ;)
[I]What can you tell me about green and white teas?[/I]
Green and white teas have been investigated largely for their role in reducing chronic diseases such as cancer because of the high levels of antioxidants they contain. For example: [url]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2946098/[/url]
Of particular note is the high levels of epigallocatchen-3-gallate (EGCG) in tea which is the main antioxidant that seems to provide the majority of the health benefits from these types of tea. The more oxidized a tea is, the less the EGCG levels contained in the tea will be.
[I]So as teas change in oxidation levels the more their antioxidant make-up changes?[/I]
Absolutely! Green tea and white tea are mostly catechin antioxidants such as EGCG and black tea (depending on if it is given a slow oxidation or rapid oxidation) are a various combination of antioxidants known as thearubigans and theaflavins ([url]http://www.biriz.biz/cay/literatur/malditof.pdf[/url]). Oolong teas, which are anywhere from 10-90% oxidized, vary a bit in their antioxidant make-up. Since they are never fully oxidized, they contain a mix of the various tea polyphenols. The less oxidized they are the more they will contain green tea catechins. The more oxidized, the more thearubigins and theaflavins they will have.
[I]What about the pu'erh teas then? Where do they fall on this spectrum?[/I]
Pu'erh teas are a different beast altogether since they are fermented and not simply oxidized ([url]http://www.mdpi.com/1420-3049/17/12/14037/pdf[/url] and maxwellsci.com/print/ajas/(2)48-54.pdf). Depending on whether it is sheng (raw or unoxidized) or shou (cooked or oxidized) pu'erh it can have antioxidants similar to either black or green teas or even completely different from either. However, it seems that regardless of the tea type, the fermentation seems to increase the effectiveness of these polyphenols found in the tea although why this is is still being studied.
[I]So this difference I oxidation level and antioxidant type is what determines the specific health benefits of differing types of tea?[/I]
Science has not conformed this 100% just yet but it seems to be the most common explanation for the differences in the benefits of various teas.
For example, black tea consumption, as I mentioned before, is often associated with a reduction in cardio vascular disease risk: [url]http://circ.ahajournals.org/content/104/2/151.full[/url] and [url]http://www.clinsciusa.org/cs/102/0195/1020195.pdf[/url] and [url]http://teaadvisorypanel.com/files/research/ARUOMA_TOXICOLOGY.pdf[/url]
Black tea was also shown to reduce cortisol levels after stressful events: [url]http://www.ncbi.nlm.nih.gov/pubmed/17013636[/url]
Another good example of this is oolong tea. While all types of tea have been show to raise metabolism somewhat, it is oolong teas unique combination of EGCG, theaflavins, thearubigans, and caffeine together that likely produce it's increased metabolic enhancing effect as compared to other types of tea: [url]http://jn.nutrition.org/content/131/11/2848.full.pdf[/url] and [url]http://medical.med.tokushima-u.ac.jp/jmi/vol50/pdf/v50_n3-4_p170.pdf?q=tea[/url]
Of course, one would expect less oxidized oolongs to be more similar in benefits to green tea and more oxidized oolongs similar to black tea in benefits, but really, they do form a unique middle ground combining the benefits of their unique mixture of tea polyphenols in ways that black tea and green tea cannot do on their own.
Lastly, we come to the strange, but fascinating pu'erh tea. As I said before, little is known about its antioxidant make-up, which depends partly on how the tea is processed (unoxidized or oxidized) and how the fermentation of both forms of the tea impacts their respective antioxidants, especially the aging process which can be dozens of years for particularly high quality pu'erh teas. A few generalizations about pu'erh teas can be made however.
Pu'erh teas are increasingly being shown more effective than statin drugs for lowering cholesterol: [url]http://www.aseanfood.info/Articles/11022086.pdf[/url] and [url]http://drinktealike.com/web/pdf/TP_content_of_Pu-erh_effects.pdf[/url] and [url]http://www.ncbi.nlm.nih.gov/pubmed/19348878[/url]
Pu'erh tea might even be a more potent free radical fighter than the famed green and white teas: [url]http://www.aseanfood.info/Articles/11018334.pdf[/url] and [url]http://www.ncbi.nlm.nih.gov/pubmed/15612813[/url]
One final note that seems to apply to almost all types of tea is that tea in general seems to increase bone density and reduce risk of osteoporosis: [url]http://archinte.jamanetwork.com/data/Journals/InteMed/5322/ioi10300.pdf[/url] and [url]http://ajcn.nutrition.org/content/86/4/1243.full.pdf[/url] and [url]http://ajcn.nutrition.org/content/71/4/1003.full.pdf[/url]