What is caffeine?
Before we tell you about tea and caffeine, let us first quickly go over what caffeine is.
Caffeine is an organic compound found in plants. It forms part of the alkaloid group that includes morphine, strychnine, quinine, ephedrine, and nicotine many of which are used to make drugs. These plant compounds have both beneficial and harmful physiological effects on the human body when ingested.
Although the role of caffeine, or for that matter other alkaloids, in the plant world is not quite clear, it is thought to have survival and reproductive functions. Caffeine is odorless but has a bitter taste. In everyday life it is found in tea, coffee, soft drinks, chocolate and used in many drugs for cold, allergy and pain relief.
Effects of caffeine on the body
Caffeine stimulates our central nervous system, heart, blood vessels, and kidneys. It also acts as a mild diuretic. The positive effects of caffeine include improved motor performance, decreased fatigue, enhanced sensory activity, and increased alertness. However, it can be addictive. (Coffee drinkers especially seem to have it bad.)
According to Mayo Clinic, up to 400 milligrams (mg) of caffeine a day is supposed to be safe for healthy adults. This translates to around 9 cups of tea, or about 3 cups of coffee. (On average an 8 oz cup has about 45 mg of caffeine for tea and 142 mg for coffee. More of this later.) As undesirable side effects, Mayo Clinic lists the following for caffeine: insomnia, nervousness, restlessness, irritability, stomach upset, fast heartbeat, muscle tremors.
The lethal dose is said to be 12.5 g -14.6 g for an adult male, which is 360 cups of tea or about 140 cups of coffee that needs to be consumed in a short period of time. Rest assured, we cannot possibly kill ourselves with caffeine.
Caffeine in Tea
Although it is now given that tea has less caffeine than coffee, the levels of caffeine in different kinds of tea is still a matter of great debate. A lot of people believe that caffeine levels in tea are determined by the type of tea. True, but not always. Generally, people believe that tea with robust flavors have more caffeine than ones that are delicate. You often hear from this group of tea enthusiasts that black tea has more caffeine than green and green has more than white tea.
The other widely circulated belief in the tea community is that a quick rinse of the tea leaves before the actual steeping will get rid of most of the caffeine. Not true. You can read another blog post of ours to find out why.
There a many factors that determine caffeine content in a tea. The place and manner of cultivation, the leaf size and production processes all have an impact. Caffeine levels in tea seem to vary widely within and across different types of tea. Some green tea can have as much caffeine as black tea or, in some cases even more.
The current belief in the tea community is that caffeine is most concentrated in the leaf buds, the kind that goes into making the finest of teas. In fact, white tea is entirely made up of just the buds, which makes it the most caffeine rich of all teas! This totally upends the traditional belief that white tea, being the most delicate of all teas, was thought to be the lowest in caffeine content.
The idea of tender leaves having more caffeine than older ones would make all high quality tea relatively richer in caffeine. The finest teas are made from tender most sprigs on the tea bush, comprising two leaves and a bud. On the other hand “coarser” plucking for making lower grade tea takes in older leaves and no buds. Such teas, therefore, are lower in caffeine.
Some people are more sensitive to caffeine than others. Even the slightest amount can cause jitteriness and anxiety. According to Mayo Clinic, caffeine sensitivity may be determined by how much caffeine you are used to drinking. “People who don't regularly drink caffeine tend to be more sensitive to its negative effects. Other factors may include body mass, age, medication use and health conditions such as anxiety disorders. Research also suggests that men may be more susceptible to the effects of caffeine than are women.”
Caffeine and pregnancy
Because caffeine as a stimulant raises the heartbeat and blood pressure levels, pregnant women are advised to cut back on their consumption of caffeinated beverages. Also since caffeine is a diuretic, pregnant women need to be careful not to get dehydrated.
However, in spite of many studies there is no agreement on how much caffeine intake is safe during pregnancy. Various studies have drawn different results. Given the conflicting conclusions, March of Dimes advises pregnant women to limit caffeine intake to 200 mg per day, which would translate to around four 6oz cups of tea.