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Caffeine and Tea

What is caffeine and what effects does it have on the body?

Chemically, caffeine is a member of the xanthine family. Caffeine is odorless, has a bitter taste and is highly soluble in hot water. Caffeine occurs naturally in coffee, tea, cocoa, kola nuts and a variety of other plants.

The relief from fatigue that tea provides is due to caffeine, and caffeine has been a matter of controversy. It is a stimulant that has been shown to speed reaction time, increase alertness, and improve concentration. The physical effects include stimulation of digestive juice, the kidneys, and the metabolism in ways that possibly help eliminate toxins. An increasing of mental alertness, shortening of reaction time, and improving efficiency of muscle action is brought about by caffeine's stimulation of the heart and respiratory system, bringing more oxygen to the brain.

In general, consumption of higher doses of caffeine (less than 600 mg/day) has been reported to have lead to caffeinism. Caffeinism is a syndrome characterized by anxiety, restlessness, and sleep disorders (similar to anxiety states). It has also been reported that chronic, heavy caffeine ingestion may be associated with depression. Caffeine may cause anxiety and panic in panic disorder patients and may aggravate premenstrual syndrome (PMS).

Caffeine tolerance varies greatly among individuals, and an excess of it is toxic. Some research has shown a possibility that caffeine can interfere with fetal development, including lowering birth weight and contributing to skeletal and other abnormalities. Until they reach the age of seven or eight months, babies cannot get rid of caffeine metabolites, and traces of caffeine can appear in breast milk too. Due to these concerns, pregnant and nursing mothers should limit or avoid any beverage with caffeine, including tea.

Two studies have shown that caffeine consumption is associated with a lower serum uric acid level and a lower risk of incident gout.

How much caffeine does a cup of tea contain?

The simple answer is: it depends. There are two main variables that influence the caffeine content of a cup of brewed tea: the type of leaf and the tea preparation method.

First, let's examine the type of leaf. On average, tea leaves contain 3% caffeine by weight, although this can range from 1.4% to 4.5%. Many factors determine the caffeine content in the dry leaf, such as soil chemistry, altitude, type of tea plant, position of the leaf on the tea bush and cultivation practices. For example, the young bud and first leaf generally have slightly more caffeine than leaves picked from the lower part of the tea bush. The leaves from the small leaf China tea plant (camellia sinensis) tend to have lower caffeine levels than the leaves from the large leaf Assam tea plant (camellia assamica). One factor that does not impact caffeine level is the level of oxidation. Green, oolong, dark and white teas all contain caffeine. No one category of tea has more or less caffeine than another. Again, it all depends on the particular tea in question.

Next, let's take a look at the tea preparation method. There are many parameters that affect caffeine content such as the amount of leaf, the leaf particle size, water temperature and steeping time. For example, tea steeped in hot water for a longer time will release more of its caffeine than tea steeped with cooler water for a shorter period. A smaller leaf tea will release more of its caffeine than a larger leaf tea.

A Department of Nutritional Services report provides the following ranges of caffeine content for a cup of tea made with loose leaves:

Black Tea: 23 - 110 mg
Oolong Tea: 12 - 55 mg
Green Tea: 8 - 36 mg
White Tea: 6 - 25 mg

How can I lower the amount of caffeine in my cup?

For those who are sensitive to caffeine, we recommend using a little less leaf and brewing your teas with slightly cooler water for a shorter period of time. Green tea, white tea and lightly oxidized oolong tea are good choices, as they tend to benefit from lower water temperatures and shorter steeping times.

Here are some simple and effective measures to enjoy green tea without suffering from its caffeine side effects.

Know your tea.The younger the tea leaves, the more caffeine will be produced in the tea. The most prized part of tea is the terminal bud and the adjacent two leaves, also called the tea flush. They are the sweetest, but also contain the most caffeine.
Color is a poor indicator of caffeine levels - Gyokuro, a top level Japanese green tea, contains more caffeine than a black tea such as Lapsang Souchong. High grade teas are made from the bud and two adjacent leaves (the tea flush), where the caffeine content is highly concentrated. On the plus side, these are the sweetest part of the tea and also contain the catechins and the theanine (mentioned below).
Become familiar with your level of tolerance. Many experts recommend consuming no more than 300 milligrams of caffeine a day. When compared to black teas, coffee and soft drinks, green tea has been found to provide a gentle and steady source of stimulation and there are few reports of common caffeine side effects, such as nervousness or headaches. To realize the cancer-fighting benefits of green tea, researchers generally agree that drinking 14-16 ounces (415-475 mL) per day is reasonable. If there's an average of 30-60 mg of caffeine per a 6-8 oz cup of green tea, drinking the recommended amount translates into 90-105 mg of caffeine per day (much less than 300 mg), and even that caffeine level can be reduced by following these instructions.
Avoid tea bags. Tea bags contain a lot more caffeine - and you will suffer some loss of quality as the teabags are poorer in flavor than the loose green tea leaves. Try to buy loose green tea leaves. You can use the same high-quality leaves three times before throwing them away, so after you've thrown out the first infusion (as described below), you still have two more cups of green tea to enjoy.
Start slowly. One cup of tea can contain anywhere from 15 to 75 milligrams of caffeine. The best thing that you can do is to try it in small doses and monitor your own reactions. Start with a half of a cup per day and increase the amount gradually, observing your reaction to the increase and adjusting accordingly. If you feel calmly stimulated and content, you will know that tea works for you.
Brew your tea half strength. This can be a helpful solution if you are suffering from caffeine intolerance. Purchasing loose leaf tea will allow you to adjust how many leaves are brewed in your tea. Most people brew approximately one to two teaspoons of loose leaf tea per cup, you can try cutting that in half. If the resulted brew is too weak, increase it little by little.
Throw away the first infusion. Caffeine is quicker to dissolve than the other tea compounds. Throw away the first infusion, as it soaks up 70% of the caffeine within the first five minutes. The length of the first infusion can affect the strength of the second infusion--the longer the infusion, the blander the next, but also the lower the caffeine presence. Try to find the longest first infusion time that still preserves enough tea flavor for your liking.
Drink it hot. Green tea contains catechins (location of the antioxidants) and theanine (provides sweetness and freshness) that reduce caffeine activity. Brewing green tea allows these molecules to combine with caffeine in hot water, rendering the caffeine less effective. If you let it cool off too much after brewing, the catechins break down and more caffeine is released.

Other things you'd better know

1. If you are pregnant or have a medical condition and have been advised to reduce your caffeine intake, consult with your doctor before consuming tea on a regular basis.
2. Don't go overboard. The caffeine in tea isn't the only thing that might be bad in large quantities. Tea polyphenols, when consumed excessively, can cause liver and kidney damage. Don't drink more than 10 cups per day, and be careful with green tea supplements, which can contain 50 times the polyphenol found in one cup of green tea.