Caffeine in Tea

People often ask whether tea contains caffeine.  The simple answer is yes, there is caffeine in teas made from the tea plant, Camellia sinensis.  (Herbal infusions and rooibos are not produced from Camellia sinensis, and they generally do not contain caffeine.)  Regardless of your relationship with caffeine, most experts agree that tea would have never become such an important beverage in the world were it not for its caffeine content.

Some History and Background...

Caffeine is classified as an alkaloid and was first isolated in coffee in 1820.  Less than a decade later, theine was discovered in tea.  Scientists soon realized that caffeine and theine were essentially the same substance, and the term theine fell out of use. Caffeine is found in more than 60 different kinds of plants, the most well-known being coffee, tea, and cocoa.  

Even though caffeine and theine are the same substance, there's a difference in how they behave in our systems.  The caffeine in coffee is absorbed in the body very quickly and has a very rapid outward effect often referred to as a caffeine "rush."  While coffee's caffeine spike occurs very quickly, it's largely dissipated within five hours.

The caffeine in tea has an extra component called "theanine" which appears to moderate its effect.   As a result, tea's caffeine is released into our systems more slowly and lasts up to 10 hours.  You are unlikely to notice either a quick rush soon after drinking it or a sudden letdown when it wears off.  Instead you get a longer, more subtle stimulation. 

"Tea is consumed for its lightness of touch and weight; for its easy digestibility under normal circumstances; for its warmth, yet a warmth which produces a subsequent coolness due to free perspiration, when humidity and temperature are high; for its piquant palatability and aroma; and chiefly for its stimulation of the nervous and muscular system, which induces a state of consciousness midway between gentle excitement and easy repose."

  - William E. Ukers

The Caffeine in Tea Plants

Plants are capable of producing caffeine; animals are not.  Caffeine serves a couple different purposes in tea plants.  First, it acts as a pesticide that deters critters from nibbling on the plant.  Secondly, the tea plant's flowers also contain some caffeine, and perhaps because of it insects seem to have some memory of the flowers and make repeat visits, thereby ensuring pollination. 

All parts of the tea plant contain at least some caffeine with the exception of the seed.  The buds have the highest concentration of caffeine at about 4.7 percent.  The first leaves have slightly less than this with about 4.2 percent.  Each leaf further down the stem has less caffeine.  The stems of the plant also have small amounts of caffeine with the sections near the bud containing higher amounts than the older, lower stem parts.  Even the hairs on young leaves contain caffeine, as do the tea plant's flowers and shells of its fruit.

Which Has More Caffeine, Tea or Coffee?

Surprisingly, in dry form coffee has less than half the amount of caffeine as tea.  But since we don't drink either of these beverages in dry form, this piece of trivia is interesting but not terribly significant.  When brewed, the same size serving of coffee has from one-half to two-thirds more caffeine than a cup of tea. 

How Much Caffeine is In a Cup of Tea?

It's difficult to say.  Many factors contribute to variation in the amount of caffeine in tea, and short of chemical analysis, it's impossible to know precisely how much caffeine is in your freshly brewed cup.

As consumers, we have no control over some of these factors since they are determined long before the tea is shipped to our local shop.  For example…

  • The part of the plant harvested.  Buds, along with the uppermost and young leaves contain more caffeine than older leaves and those lower on the stem. 
  • Harvest time.  The leaves plucked during the first harvest in the spring have a bit more caffeine than those later in the season.
  • Cultivation practices.  Some practices, such as hard pruning of tea plants, cause a higher concentration of caffeine in leaves when they re-sprout.  Growing tea plants in the shade (as is done with some Japanese green teas) also increases the amount of caffeine.  Other practices, such as fertilizing or applying manure, don't seem to have any significant impact. 
  • Type of plant.  Camellia sinensis var. assamica is said to contain higher levels of caffeine than Camelliasinensis var. sinensis.  Some tea plant cultivars also contain higher or lower amounts of caffeine and other beneficial substances found in tea.

A few of the factors influencing caffeine content can be controlled by a tea drinker.

  • Type of tea.  The type of tea you select has some bearing on the amount of caffeine it contains.  While there are overlapping ranges and plenty of variation, green teas contain lower amounts of caffeine than oolongs; oolongs have lower amounts than most black teas.
  • Water temperature used for brewing.  Higher water temperatures generally cause more caffeine to be released in your cup than cooler temperatures.  If you use cool water to brew tea in the sun or the refrigerator (as is commonly practiced when making iced tea), less caffeine is released.
  • Infusion time.  About 75 percent of the caffeine in tea is released during a 5-minute steeping.  A shorter infusion will have less caffeine.
  • Number of infusions.   The first cup of tea you steep with fresh leaves contains the most caffeine.  Less caffeine will be extracted during each subsequent infusion.

Minimizing the Effects of Caffeine in Tea

Our bodies have different metabolisms and, as a result, we are all affected differently by caffeine.  Some people have difficulty handling caffeine of any sort while others make it a habit to have a cup of tea or coffee before bedtime.  Body weight, medications, and countless other factors enter the equation.  There have been periods of my life when caffeine has affected me more negatively than others, and even I can't guess the reason(s).

If you have problems with the caffeine in tea, here are some tips to help lessen its effects. 

  • Don’t drink tea on an empty stomach.  Only drink it with or after a meal.  Your body will have a slower absorption rate on a full stomach, and the effect of the caffeine will be lessened.
  • If you find that caffeine keeps you awake at night, you might want to limit your tea drinking to mornings.  Since its caffeine is released over a 10-hour period, you should be able to sleep by 10 p.m. if you stop drinking tea by noon.
  • You can lessen the amount of caffeine in your cup if you don't drink the first infusion of the tea leaves or teabag.  Sources vary as to how much of an effect this has, but depending upon how long you steep it, it may reduce the amount of caffeine in your cup by 60 percent or more.  If you use teabags, the effect may be even more dramatic since the leaves are usually cut into smaller pieces, and the compounds are released more quickly.  In either case, share the first infusion with your partner or housemate, or pour it down the drain if you must.  But be sure to enjoy the next infusion for yourself. 
  • Buy decaffeinated tea.  It will still will have a little bit of caffeine in it, but at least 97 percent of it will have been removed in order to carry the decaf label.
  • If decaffeinated tea still has too much caffeine for you, then your alternative is to imbibe in herbal infusions. There are many flavorful herbals on the market, and they are widely available.  But beware—sometimes teas advertised as herbals are blended with green or white teas and contain caffeine as a result.  Read the packaging to be sure it suits your needs.

Is Tea Healthy to Drink Every Day?

It’s generally considered safe to drink about 5 cups of tea per day.  If you drink more than that, you're probably overdoing it.  Like anything else in life, tea drinking is best done in moderation.

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