According to the Taiwan Food and Drug Administration (TFDA) under the Ministry of Health and Welfare, it is recommended that daily caffeine intake should not exceed 300 milligrams (mg) to avoid potential health effects.
The caffeine content in tea leaves is influenced by factors such as the tea plant variety, the part of the leaf harvested, the season, climate, and cultivation conditions. Additionally, brewing conditions—such as water-to-tea ratio, temperature, steeping time, and number of infusions—also significantly affect the amount of caffeine in the tea infusion.
Experiments have shown that caffeine extraction decreases with lower water temperatures. For example, using the standard green tea brewing method (3 grams of tea leaves with 150 ml of water), the caffeine content extracted at different water temperatures was:
| Temperature | Steeping Time | Caffeine Content |
|---|---|---|
| 4°C (cold brew) | 4 hours | 100 mg/L |
| 80°C | 5 minutes | 180 mg/L |
| 100°C | 5 minutes | 390 mg/L |
Many factors influence caffeine release from tea leaves, but water temperature is the most controllable. For tea lovers concerned about caffeine intake, lower temperature brewing or cold brewing is a recommended way to enjoy tea with reduced caffeine.
Source: Tea Research and Extension Station – Tea Bulletin Issue No. 97
https://www.tbrs.gov.tw/ws.php?id=2655
