Comparison Of The Amount Of Caffeine In Coffee & Green Tea

Bitter-tasting caffeine is consumed by a large number of the world's population each day. If you need a daily cup of coffee, tea, or cola to help get you going, you probably know all about caffeine's effects: alertness, enhanced focus and occasionally a few heart palpitations. But if you are trying to avoid caffeine, you might be reaching for green tea instead. Unfortunately, green tea does contain caffeine, although a great deal less than most coffees.

Effects of Caffeine

Caffeine, unlike many other drugs, can easily cross the barrier into your brain that generally filters out harmful substances, bacteria, viruses and other drugs. Because of this, caffeine reaches your cerebral cortex and is thought to block the slow-down receptors in your brain, leading to a state of heightened awareness and focus. Caffeine is also reported to have an impact on physical performance capabilities -- in fact, "New York Magazine" reports that its use was once limited by the International Olympic Committee because of these effects.

Of course, not all of caffeine's effects are positive. It can also interfere with both regular and dream-state REM sleep, and large daily doses have been linked to an increase in miscarriage and female infertility.

If you are in a situation in which you have been told to limit caffeine by your healthcare provider, you should be cautious about what beverages you select. A study published in the October 2006 issue of the "Journal of Analytical Toxicology" found that many beverages touted as "decaffeinated" actually contained as much as 14 milligrams of caffeine in a 16-ounce serving. (ref. 4)

Caffeine in Coffee

The problem with attempting to measure the caffeine in drip beverages like coffee is that the amount of caffeine in a cup depends. It depends on the method you used to brew the coffee, the strength of the brew and the coffee grinds themselves. Mayo Clinic offers a few estimates for the amount of coffee in cups you will commonly see. For example, they suggest that a 16-ounce cup of Dunkin' Donuts brewed coffee contains between 143 and 208 milligrams. A standard 8-ounce cup of coffee you brew at home might have less caffeine on average, measuring about between 95 and 200 milligrams. A regular-sized 1-ounce espresso from Starbucks has between 58 and 75 milligrams of caffeine, while ordering a 16-ounce Vanilla Latte instead will get you about 150 milligrams of caffeine.

Instant coffee packs a caffeine punch as well, with a standard 8-ounce cup providing between 27 and 173 milligrams of caffeine. Even "decaffeinated" coffee still contains some caffeine: An 8-ounce cup of brewed decaf has between 2 and 12 milligrams of caffeine, and a cup of instant coffee the same size has the same amount of caffeine.

Caffeine in Tea

Many people have the idea that in order to cut back on caffeine they will switch from coffee to tea in the morning. Unfortunately, most teas contain caffeine as well. The Mayo Clinic, which provides the caffeine content of common tea drinks, estimates that an 8-ounce cup of black tea provides between 40 and 100 milligrams of caffeine. That is less caffeine on average than the 95 to 200 milligrams of caffeine in an 8-ounce cup of coffee, but it is far from "low" in caffeine.

Green tea, on the other hand, is estimated by the Mayo Clinic to contain around 26 milligrams of caffeine in a 6-ounce serving, less than half of the caffeine found in a standard cup of brewed coffee. To further decrease the caffeine in a cup of tea you should allow it to steep for less time.

Green Tea Explained

Green tea and black tea are both purported to have health benefits, and both contain some caffeine. According to the University of Maryland Medical Center, green tea is made from unfermented leaves, while the leaves used to make black tea are fermented for different lengths of time depending on the variety of tea. Longer fermentation time means a higher caffeine content and a reduced polyphenol -- the antioxidant found in green tea -- content in black tea. Conversely, no fermentation means that green tea is rich in polyphenols and has less caffeine.

Polyphenols are the reason that green tea is touted as having health benefits. These antioxidants help to neutralize harmful substances called free radicals in your body and may even prevent free radical damage from occurring in the first place. Scientific evidence has been presented linking green tea consumption to fighting diseases such as hardening of the arteries, high cholesterol, some kinds of cancer, irritable bowel syndrome, liver disease and diabetes. Talk with your healthcare provider before beginning any supplement regimen, even one that consists of something normally edible like green tea.