This Facts About reviews teas and provides a guide for selecting and incorporating healthy changes into your diet.

What are the recommended servings per day?

• 2-4 cups per day

Why should you drink tea?

Teas are rich in antioxidants called polyphenols which are plant chemicals that may help prevent cancer, heart disease, and other diseases by:

• Inhibiting growth of cancer cells
• Reducing high blood pressure
• Protecting against stroke
• Improving blood flow to the heart
• Reducing total and LDL (bad) cholesterol
• Inhibiting the formation of blood clots in artery walls
• Steadying blood sugar levels
• Lowering the risk for osteoporosis
• Acting as an anti-inflammatory agent
• Enhancing immune function and helping fight infections
• Protecting against viral infections and liver disease
• Inhibiting the growth of bacteria that can cause gum disease, cavities, and bad breath

Selected Food Sources with Serving Sizes

White and green teas are less processed and contain higher levels of antioxidants than black or oolong teas. Caffeine content varies in teas - more processed often is linked to higher caffeine levels.

Special Considerations

What are antioxidants?

Antioxidants are substances that allow the human body to neutralize unstable molecules, commonly called free radicals. They may also target and repair DNA mutations caused by oxidation. Like other antioxidants, catechins found in green tea and theaflavins found in black tea selectively prevent enzyme activities that lead to cancer or heart disease.

What are the different types of tea?

• All true tea comes from the tea plant, Camellia sinensis, and differences between each tea type come from variations in the processing of the tea leaves.  In addition, there are natural differences within each tea type resulting from as portion of the plant harvested, time of year the leaves and buds are harvested, soil type and climate the tea plants are grown.
• White tea is a form of tea in which the young leaves and buds are rolled and dried. It is the least processed form of tea.
• Green tea is an unfermented tea which is withered and steamed before drying to prevent oxidation/fermentation and retain the leaves’ green color.  This method preserves the polyphenol content of green tea.
• Oolong tea is a lightly fermented tea, between green and black tea on a continuum
• Black tea is the most common form of tea worldwide and has a stronger color and flavor than green tea. It is prepared from tea leaves that have been allowed to ferment/oxidize before being fully dried, and due to the oxidation process the polyphenol content is less than that of unfermented green tea.
• Herbal teas, technically called tisanes, are not true teas in the strict sense but are popular for their medicinal and calming qualities, unique flavors and are all caffeine-free. They contain a blend of dried plant flowers, stems, roots, or leaves.  Due to the diverse nature of herbal teas, they are not reviewed here in detail.  

Caffeine

• Tea contains varying amounts
• An addictive stimulant that may negatively impact health by contributing to headaches, anxiety, insomnia, heart palpitations, high blood pressure, digestive and urinary tract disorders
• Has a diuretic effect, causing the body to lose water
• Acidic beverages and caffeine increase stomach acid. Avoiding these substances may be beneficial to people who have digestive concerns
• Even modest amounts of caffeine may increase symptoms of hypoglycemia. For this reason, people with blood sugar concerns may consider avoiding caffeine
• Avoidance of caffeine reduces symptoms of fibrocystic breasts in some women
• Black tea contains an average of 60 mg caffeine per cup, while green tea contains 36 mg per cup
• All teas contains less caffeine than an 8 oz. cup of coffee, which has about 95 mg

Decaffeination Process

The process of decaffeinating tea may involve the use of chemicals and traces of solvents may remain in the tea. To avoid chemical residues from this process, purchase tea that is decaffeinated by more natural means such as water or carbon dioxide.

How do you brew a pot of tea?

For best results, start with a ceramic teapot with a lid. Warm the teapot with hot water and pour it out.  Also begin with good-tasting water, such as filtered or spring water.  Tap water contains chemicals which will affect the taste of the tea.  Brew times and temperatures vary depending on type of tea used and personal preference.  We offer recommendations below for brewing black, oolong, green and white teas.

To make black or oolong tea add one teaspoon of tea or one tea bag for each 8 oz. cup of water to the warmed teapot. In a separate tea kettle, bring water to a full boil-water at a bubbling boil agitates the tea leaves and causes them to open, for the full extraction of flavor. Pour boiling water over the tea bags or tea leaves in the warmed teapot, and steep for a full three to five minutes. After steeping, remove tea bags or strain tea through a fine mesh tea strainer.

For green tea remove water from heat just prior to boiling or allow water to stand for a few minutes after boiling and steep one teaspoon of tea or one tea bag per 8 oz water for only 1-3 minutes in a covered teapot.

White tea is prepared similarly to green tea, though a longer steep time is necessary to allow the leaves enclosing the bud to open up and release their flavor to the cup.  Steep 3-10 minutes for the first steep, adding a minute or two to each subsequent steep.  White tea will stand up to 3 or more steeps.  White tea is extremely light weight so to be sure to add enough leaf to the cup or pot.

Tea Selection

The more space tea leaves have available during brewing, the better they are able to release all of their flavor.  For this reason, loose tea is preferred over a small tea ball, infuser or teabag.

To maintain freshness, tea must be stored in a dark, odor-free and moisture-free environment.  An airtight container stored at room temperature is fine for most types of tea.  Green tea can be stored in an air-tight container in the refrigerator as long as no moisture is in the storage container.

Ideas to Increase Tea Consumption

1. Keep a pitcher of brewed iced tea in the refrigerator.
2. Replace part or all of the coffee or sodapop you consume during the day with tea, either hot or iced.
3. Take tea breaks instead of coffee breaks.
4. Carry teabags in your handbag or car.
5. Add fresh squeezed citrus juice or pureed berries to a pitcher of iced tea.
6. Try an herbal tea blended with green or white tea.

This Facts About document is published by Monica Myklebust, MD, and Jenna Wunder, MPH, RD, at University of Michigan Integrative Medicine Clinical Services. Our mission is to care for people using an Integrative Medicine model that reaffirms the importance of relationship between practitioner and patient, focuses on the whole person, is informed by evidence, and makes use of all appropriate therapeutic approaches to achieve optimal health and healing.

Resources

Brewing Guide
In Pursuit of Tea
www.inpursuitoftea.com
Accessed May 30, 2006

Caffeine Content of Common Beverages
Mayo Clinic
www.mayoclinic.com
Accessed May 17, 2006

Caffeine:  How Does it Affect Blood Pressure?
Mayo Clinic
www.mayoclinic.com
Accessed May 17, 2006

NCI Fact Sheet: Tea and Cancer Prevention
National Cancer Institute
www.cancer.gov
Accessed May 17, 2006

Tea-Making Tools and Techniques
Real Simple
www.realsimple.com
Accessed May 30, 2006

Tea Storage and Packaging
In Pursuit of Tea
www.inpursuitoftea.com
Accessed May 17, 2006

Teas, Black, Green and Now White
Cancer Decisions Newsletter Archives
www.cancerdecisions.com
Accessed May 17, 2006

A White Tea Overview
A Green Tea Overview
An Oolong Tea Overview
A Black Tea Overview
Salada Tea
www.greentea.com
Accessed May 17, 2006

Original Research and Review Articles

Boekema PJ, et al.  Coffee and gastrointestinal function:  facts and fiction.  Scandinavian Journal of Gastroenterology.  1999;34suppl(230):35-39.

Cooper R, et al.  Medicinal benefits of green tea:  part I.  Review of noncancer health benefits.  The Journal of Alternative and Complementary Medicine.  2005;11(3):521-528.

Cooper R, et al.  Medicinal benefits of green tea:  part II.  Review of anticancer properties.  The Journal of Alternative and Complementary Medicine.  2005;11(4):639-652.

Davies MJ, et al.  Black tea consumption reduces total and LDL cholesterol in mildly hypercholestrolemic adults.  Journal of Nutrition.  2003;133:3298s-3302s.

Geleijnse JM, et al.  Inverse association of tea and flavonoid intakes with incident myocardial infarction:  the Rotterdam study.  American Journal of Clinical Nutrition.  2002;75:880-886.

Hirata K, et al.  Black tea increases coronary flow velocity reserve in healthy male subjects.  The American Journal of Cardiology.  2004;93:1384-1388.

Horner NK et al.  Potential mechanisms of diet therapy for fibrocystic breast conditions show inadequate evidence of effectiveness.  Journal of the American Dietetic Association.  2000;100(11):1368-1380.

Manach C, et al.  Polyphenols:  food sources and bioavailability.  American Journal of Clinical Nutrition.  2004;79:727-747.

Mukhtar H, et al.  Tea polyphenols:  prevention of cancer and optimizing health.  American Journal of Clinical Nutrition.  2000;71(suppl):1698s-1702s.

Richardson T, et al.  Influence of caffeine on frequency of hypoglycemia detected by continuous interstitial glucose monitoring system in patients with long-standing type 1 diabetes.  Diabetes Care.  2005;28(6):1316-1320.

Stensvold I, et al.  Tea consumption.  Relationship to cholesterol, blood pressure and coronary and total mortality.  Preventative Medicine.  1992;21:546-553.