Tea and Caffeine...
What is a safe intake of caffeine?
The safety of caffeine consumption remains a topic of major debate in the research literature. To our knowledge, no studies have shown problems with caffeine consumption of less than 75 milligrams per day. Most studies showing potentially problematic effects of caffeine consumption have focused on intakes above 200 milligrams. In addition, there appears to be a significant difference in people’s sensitivity to caffeine.
Tea contains the stimulant caffeine at about 3% of its dry weight, translating to between 30mg and 90mg per 250mg cup depending on type and brewing method.
Caffeine, in extremely high doses, can dehydrate the body but even if you brew a cup strong enough to have that effect, which is almost impossible, it wouldn't be palatable. According to the review, even a really super strong cup of tea would have a net gain of fluid. The reviewers went on to suggest that any possible risk related to excess caffeine intake, if that is a concern for you, can be avoided by limiting your tea intake to 8 cups per day.
Other ingredients in Tea slow absorption of caffeine
At least two beneficial components in green tea—its catechins and the amino acid L-theanine—lessen the impact of its caffeine.
When green tea is brewed, its caffeine combines with catechins in the water, reducing the caffeine's activity compared to coffee or cocoa.
- Decaffeinated tea is not caffeine free – it still contains up to 0.4% by dry weight of caffeine.
- The longer the leaves have fermented, the greater their caffeine content. A 4 minute infusion of black tea will produce 40-100 milligrams of caffeine, a 3 minute infusion only about 20-40 milligrams of caffeine.
- The smaller the leaf, the stronger the extraction of caffeine. A tea bag filled with cut leaf will release nearly twice as much caffeine per cup as full leaf loose tea.
- Green tea, which is unfermented, has 1/3 the caffeine per cup as black tea, which is fully fermented.
- Oolong tea, which is semi fermented, has about half as much caffeine as black tea.
- Guarana contains 50mg of caffeine per 2 grams of dry herb.
- Coffee contains 100- 180mgs of caffeine per cup
- Black tea contains 25- 60 mgs of caffeine per cup
- Green tea contains 8-16 mgs of caffeine per cup
Tea vs Coffee
While coffee and tea are both sources of caffeine, the amounts of caffeine in any single serving varies significantly. An average serving of coffee contains the most caffeine – the equivalent serving of tea contains ½ to 1/3 as much.
One of the confusing aspects of caffeine content is the fact that coffee contains less caffeine than tea when measured in its dry form. But the caffeine content of a prepared cup of coffee is significantly higher than the caffeine content of a prepared cup of tea.