Although it is true that the caffeine content in tea leaves is higher than that in coffee beans, when we compare a cup of tea and a cup of coffee, we are not talking about dry tea and coffee beans, but brewed tea soup and coffee. The ratio recommended by the Specialty Coffee Association of America (SCAA) is 8.25g of coffee beans per 150mL of water. However, the dry tea in tea bag products for single cup single brewing on the market is generally only about 2g. It can be seen that the amount of caffeine in coffee is much greater than that in tea.

In addition, Chinese people have another habit of drinking tea, which is to brew tea repeatedly. We will brew fresh green tea at least three times, and even black tea, oolong tea, and Pu'er tea can withstand repeated brewing for more than ten times. In other words, even if you drink many cups of tea a day, as long as you don't replace it with new tea leaves, it is just "one cup" from the perspective of caffeine intake.

There are other important components in tea that affect the stimulating and exciting effects of caffeine on the human body, the most important of which are theanine and tea polyphenols. Theanine is a unique water-soluble free amino acid in tea that can cross the blood-brain barrier and is effective in relieving stress and tension, relaxing the body and mind, improving cognitive ability, and improving sleep quality.

Moreover, some studies have found that theanine can produce an antagonistic effect on caffeine, which can partially offset the increase in blood pressure caused by caffeine and reduce physical discomfort. More importantly, other studies have found that theanine has a synergistic effect with caffeine, and that simultaneous intake can enhance attention and improve reaction agility and accuracy in behavioral tests. Therefore, the human body feels more awake and calm after drinking tea, rather than the excitement after a cup of coffee.

As for tea polyphenols, under certain conditions, they will react with part of the coffee and exist in a combined state, thereby delaying the absorption of caffeine and reducing the body's utilization efficiency of caffeine.

Studies have shown that the proportion of bound caffeine in deeply fermented Pu'er ripe tea and some dark teas that have also undergone microbial oxidation can reach about 20%, while the proportion of bound caffeine in green tea that has not been oxidized and fermented is only <2%, and other teas are in the middle. This also explains to a certain extent why some people think that green tea is refreshing and Pu'er tea is soothing.

　(Editor: Bonnie)

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