All teas contain these principle constituents: vitamins, essential oils, polyphenols and caffeine.
vitamins
> All teas contain antioxidants (vitamins that are anti-aging).
> All teas contain vitamins b and k, and traces of minerals like potassium and calcium.
> Black tea contains vitamin a.
> Green tea contains vitamin c.
calories
> All teas contain approx. 4 calories per cup.
essential oils
> Essential oils contribute to the flavour, fragrance and digestive qualities of a tea.
polyphenols
> Polyphenols are responsible for the tea’s pungency and flavour.
> Together with the essential oils, they play a role in stimulating the digestive tract.
> Research indicates that polyphenols increase the number of white blood cells in the body and boost immunity to disease. They inhibit absorption of cholesterol in the digestive tract and seem to inhibit DNA mutation in rats (anti-carcinogenic). Scientists think that teas may have the same effect on us.
> Polyphenols were once known as tannins, but recent evidence indicates that polyphenols resemble tannins chemically but are not actually tannins.
caffeine
> Caffeine accounts for tea’s energizing/uplifting qualities and isn’t necessarily bad for you!
> Studies are beginning to indicate that caffeine in small doses can be beneficial. A study about the health benefits of green tea found that the caffeine is an active ingredient in helping your system assimilate the antioxidants.
> Caffeine stimulates the central nervous system, promotes circulation and assists the release of waste products.
approximate caffeine content of coffee and teas (milligrams per cup):
> drip coffee 60-90mg
> black tea 25-110mg
> semi-green/oolong tea 12-55mg
> white tea 8-16mg
> green tea* 8-16mg
The range above depends on the variety of tea and how long you steep it for. A shorter steeping time equals less caffeine. If you like strong flavour, but want to avoid caffeine, use more tea leaves and steep for a shorter time. Caffeine starts to release after about a minute.
*Matcha is an exception to this range because it can be prepared in two ways, and can contain as much caffeine as black tea, depending on how much powder is used.
Researchers have discovered that white tea contains marginally higher levels of caffeine compared to green tea brewed under the same conditions. They suggested that this could occur because white tea oxidizes slightly during withering; whereas, the oxidation process is stopped early in the manufacture of green tea by the steaming or pan firing of the leaves.
Since the term "antioxidant" is similar to "oxidation", it's important to clarify further what each represents. Both have a relationship to oxygen. Oxidation describes the process of combining a substance with oxygen. Black, semi-green and white teas are "oxidized" because they are exposed to air immediately after picking, prior to being dried. An "antioxidant" is a substance such as vitamin e, c or beta carotene which inhibits oxidation. They are believed to have health benefits because they protect the body's cells from the damaging effects of oxidation.
Tea naturally contains antioxidants, and the level of antioxidants found in tea is not as a result of the oxidation process. "Oxidation" is just a way to describe how black, semi-green and white teas are processed. Exposure to air is what causes changes to occur in the leaf, making it look and taste different, as well as increasing the caffeine content.
the caffeine in tea affects you differently than the caffeine in coffee:
> Coffee gives you a very fast lift, but an equally sharp decline in your energy is felt later.
> Tea gives you a slower, more delayed lift, which leads to a plateau, and then a secondary lift.
> Tea does not give you a sharp decline, rather it very gradually decreases so you don’t feel the negative effects of the decrease in the way it is felt with coffee.
> Black and semi-green teas are a good way to wean yourself off of coffee; you can start out by continuing to drink a cup of coffee in the morning and following it up with a black or semi-green tea in the afternoon.
a note about the caffeine and nutritional value of teabags:
> Teabags release up to twice as much caffeine as loose teas because they are made with low grade leaves that are powdered and crushed up.
> As soon as a tea leaf is crushed, the surface area of the leaf is exposed to more air, which causes the tea to lose nutrient value, go stale and lose flavour rapidly.*
> To counteract loss of flavour, more crushed leaves are used, which equals more caffeine.
> Teabags are generally made with low-grade leaves (the twigs, leaves, stems that are located lower on the tea bush) as opposed to the “top” leaves and bud that are used for high quality loose teas. The lower grade leaves contain less nutrient value, not solely because they are crushed, but also because they are poorer quality to start out with.
> Many estates produce their entire low-grade tea yield solely for teabag production, and some teabag manufacturers also use leftovers from high-grade tea production (crushed and broken leaves).
> Teabags are made with glue to hold the bag together when it hits the water.
*Matcha is the only tea that does not lose flavour or health benefits when the leaves are crushed. Matcha is powdered under very stringent controls, which are designed to keep it fresh and nutrient rich. Its exposure time to air is deliberately very minimal. The same attention is not paid to crushed leaves used for teabag teas.
digestive system
> Essential oils and polyphenols aid digestion by stimulating peristalsis
and the production of digestive juices.
cardiovascular system
> All teas promote the circulation.
> All teas may lower blood pressure.
cholesterol
> All types of tea may help reduce blood triglycerides and cholesterol, but studies done so far indicate that semi-greens appear to be the best.
teeth
> All teas contain fluoride, a mineral that helps prevent the development of bacterial plaque (which leads to tooth decay), but green teas have the most fluoride.
nervous system
> All teas increase alertness.
> All teas reduce fatigue.
> All teas improve concentration.
immune system
> Vitamins and other constituents in tea are thought to be responsible for its ability to prevent colds and flu.
> A recent study suggests that drinking 5 cups of black tea daily could boost the body’s ability to fight infection fivefold. Researchers from Brigham and Women’s Hospital in Boston and Harvard Medical School claim to have isolated a chemical in tea that protects humans against germs. In the study, Dr. Jack F. Bukowski and his co-authors isolated from ordinary black tea a substance called L-theanine. He said the substance is also found in green and oolong tea, which also are processed from traditional tea leaves. The L-theanine is broken down in the liver to ethylamine, a molecule that primes the response of an immune blood.
> Gargling with green, semi-green or black tea may reduce likelihood of sore throats or may soothe and calm irritation and assist faster recovery.
caution! sore throats may indicate a serious medical condition. always consult your doctor before use.
skincare
> All teas have anti-bacterial/antiseptic properties that may help skin heal faster.
> Moist tea leaves and tea infusions were traditionally used as soothing salves for sunburn and insect bites.
> Antioxidant properties of tea make for excellent skincare properties (anti-aging, soothing and calming, minimise sun damage). caution! sunburns may require medical attention. always consult your doctor before use.
cancer
> Polyphenols in green teas have been identified as antioxidants and have shown
they may reduce the incidents of skin, lung, liver, stomach cancers.
> In a study for the American Health Foundation, mice were given green tea and then
exposed to a cancer causing agent (MNK). The mice that were given green tea developed
12.2 lung tumours each, and the mice that weren’t given green tea developed 22.5 tumours
each. This reveals a possible correlation in humans.
> Cigarette smokers in Japanese tea producing districts have a lower incidence of lung cancer than other Japanese smokers.
to get maximum benefits from green tea it must be fresh and steeped 1-3 minutes:
> Green teas lose their freshness and nutrient value relatively quickly.
> Their maximum shelf life for health benefits and flavour is approximately 1 year, if they are stored properly (no clear jars, plastic bags, paper bags, heat or cardboard boxes, because all of these will affect the tea’s freshness).
> Studies have indicated that the health benefits of green teas can reverse (i.e. become potentially harmful) if steeped too long.*
> For optimum flavour (no bitterness) and maximum health benefits green teas should be steeped for no more than about 3 minutes.
* To clarify, if you over steep green tea by a short margin (i.e. 15 minutes instead of 3 minutes), you are losing anti-oxidants and nutrient value, but not necessarily causing the properties to become harmful. However, if you drink green tea that has been over steeped by a long margin (over 24 hours), the properties may have become carcinogenic.
There have been a number of studies done which have indicated that green tea is anti-carcinogenic. There have also been a number of studies that have indicated that the beneficial properties of green tea deteriorate if the tea is steeped for too long. A good analogy for this is vegetables. If fresh veggies are overcooked, their nutrient value diminishes. In addition, there was a study done which found that if green tea is steeped for 24 hours, the anti-carcinogenic properties reverse, and the resulting beverage can become somewhat carcinogenic. The exact reason for this is unknown at this time, but it appears that some of the beneficial properties of tea are very biologically active, and that this may be linked to the reversal. It is not uncommon for foods that may have some beneficial properties to become altered (and become potentially hazardous) when prepared in different ways, or allowed to oxidize. Black pepper is an example of this: it is believed to have a wide variety of potentially healthful benefits, but when oxidized it may become somewhat carcinogenic.
Green tea contains a naturally occurring substance that is believed to have the effect of normalizing and slightly lowering blood pressure. This accounts for the general perception that drinking a cup of tea has a relaxing effect, despite the slight caffeine content. A number of studies have indicated that all teas may have a beneficial effect on overall cardiovascular health, but so far the studies have indicated that semi-green tea appears to be the most effective.
It's important to note that while tea may have some positive benefits, it should not be considered a treatment for medical conditions, and it is important for you to seek appropriate medical advice and treatment from your doctor.
White teas are becoming increasingly valued for their health benefits. As a result of the type
of leaves used (the youngest leaves and buds) and the method of manufacture (very little heat), white teas appear to have more antioxidants and nutrient value than any other type of tea. The caffeine content of white teas is slightly above or comparable to that of green teas. White tea is especially potent in that it has up to three times as many antioxidant polyphenols as green or
black tea.
skincare
> Studies have indicated that white tea is twice as effective in neutralizing free radicals than green or black tea.
cancer
> Researchers at the Linus Pauling Institute in Oregon tested white teas on selected rats to test for the ability of white teas to inhibit natural mutations in bacteria and to protect the rats from colon cancer. Interestingly, white teas were found to be more effective than green tea in inhibiting the early stages of cancer, but researchers were quick to point out that their study was on rats and the effects should not be extrapolated to humans, without further study.
digestive system and weight loss
> In China, semi-green teas are traditionally known as “slimming teas”.
> They are considered excellent for assisting the digestion, especially when one is eating fatty foods.
> Chinese studies cite cases where weight loss occurred as a result of drinking just 2 to 3 cups of oolong tea per day.
cardiovascular system
> In Fuzhou (China), researchers found that in patients with hypertension or coronary heart disease, drinking oolong tea helped decrease blood viscosity, improved micro-circulation (circulation within the blood) and prevented blood clotting. Where blood clotting (thrombosis) did occur, it took longer to form and was of a shorter duration.
> In 1980, Japanese studies indicated that regular drinking of semi-greens may reduce hypertension and assist in cases of coronary heart disease.
cholesterol
> Studies have indicated that all teas may help reduce cholesterol, but semi-greens have so far demonstrated the fastest results.
> In Fuzhou (China), researchers found that in patients with atherosclerosis or a high lipid (fat) viscosity, drinking oolong tea helped decrease blood viscosity, improved micro-circulation (circulation within the blood) and prevented blood clotting. Where blood clotting (thrombosis) did occur, it took longer to form and was of a shorter duration.
> In 1980, Japanese studies indicated that regular drinking of semi-greens may reduce cholesterol and neutral.
> In a California study, there was less atherosclerosis among tea drinkers than coffee drinkers.
immune system
> Chinese researchers found that a 1% solution of oolong tea doubled the lifespan of fruit flies.
black tea
cardiovascular system
Many of black tea’s health benefits are geared to the cardiovascular system (this can be especially helpful in hot climates or in the summer when hot weather puts added stress
on the heart).
> Black tea may lower blood pressure.
> Black tea may reduce cholesterol.
> Black tea may assist in stabilising blood sugar.
> Black tea is high in potassium, which helps the heart perform its functions better.
diabetes
> Long term black tea drinkers have a lower incidence of diabetes.
skincare
> Black tea contains vitamin a, which helps combat sun damage and improve the suppleness of skin with both internal and external use.
> lemongrass (found in alchemist's brew, philosopher's brew, seamist, sublime) - avoid in large quantities during pregnancy. Moderate amounts may be fine.
> red clover (found in angelwater) - avoid in large quantities during pregnancy. Moderate amounts may be fine.
> peppermint (found in seamist, westcoast peppermint, green dragon) - should be avoided while nursing. It is believed to have the potential to lessen milk flow (however, this has not been conclusively proven).
Please note that there are many herbs that are contraindicated during pregnancy. The above is only a list of ingredients found in our teas. It is not a list of all herbs contraindicated during pregnancy.
As a general rule, teas consumed during pregnancy should be made at about 1/2 the strength of what we normally recommend (use 1/2 tsp. for every 2 cups, instead of 1 tsp. for every 2 cups).
Many healthcare professionals are currently recommending that women avoid caffeine during pregnancy. We recommend you discuss this with your healthcare provider and arrive at an approach that is best for you.
Our research is based on a number of different sources, including data that is released to the public, as well as tea industry studies that are not always widely released or available to the public. Many tea-related studies are ongoing and are being continually released. The internet can be a good way to access the information, but it's important to check to see if the sources are reputable (i.e. scientific journals and publications).
the collection of information in this document is the intellectual property of silk road aromatherapy and tea co. copyright 2001 by silk road aromatherapy and tea co. all rights reserved. no part of this document may be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from silk road aromatherapy and tea co.
silk road aromatherapy and tea co. cannot be held responsible for misadventure resulting from the misuse or the use of any of the teas or methods mentioned in this document. this document is intended as an informational guide. the information outlined should not be used to treat any ailment or imply in any way that tea or its use is a treatment or prevention for any health or medical condition. individuals with health conditions or use medication should consult their doctor if they intend to start drinking tea. see health benefits section for contraindications.
© 2008 SR