Caffeine is a natural stimulant. It exists in more than 60 plants and is very popular all over the world. The coffee, chocolate and tea we often drink contain caffeine. It needs to be clear that the caffeine content in beverages varies with the ingredients and preparation methods. Although scientists believe that caffeine is safe, excessive consumption may always cause some concerns.
It is estimated that 80% of people in the world like to drink coffee every day. Because of its stimulating effect on the human body, scientists believe that caffeine has many benefits to human health, such as enhancing alertness, improving sports performance and mood, and promoting metabolism.
Both the United States Department of Agriculture (USDA) and the European Food Safety Agency (EFSA) define safe caffeine intake as no more than 400 mg per day, a single intake no more than 200 mg, or no more than 3 mg per kilogram of body weight. .
Having said that, a single intake of more than 500 mg of caffeine may cause some problems. Scientists point out that large amounts of caffeine can cause anxiety, restlessness and insomnia. Some studies have shown that even regular caffeine intake in moderate amounts can cause chronic headaches and migraines.
In addition, caffeine is considered to be mildly addictive, and some people may be more prone to dependence.
Caffeine is contained in tea or coffee, and its content varies greatly depending on the place of origin, type and production method.
Generally speaking, tea leaves contain 3.5% caffeine, while coffee beans contain 1.1% to 2.2% caffeine. Looking at it this way, it seems that the caffeine content in tea is higher. However, the process of brewing coffee uses hotter water, which will extract more caffeine from the coffee beans. Moreover, people use more coffee beans than tea leaves when they drink coffee. Therefore, a cup of brewed aromatic coffee usually contains more caffeine than a cup of tea.
Black tea, green tea and white tea are all made from tea tree leaves. The difference between them is the time of leaf picking and the degree of oxidation.
The leaves of black tea are oxidized during processing, while white tea and green tea are not. This makes the black tea have a unique and strong flavor, and also makes more coffee precipitate when the tea leaves are brewed with hot water.
A cup of 237 milliliters of black tea contains an average of 47 mg of caffeine, but it may also contain as much as 90 mg of caffeine. In other words, as far as an ordinary 500ml drink on the market is concerned, a full black tea will contain up to about 190 mg of caffeine. In contrast, the same cup of 237 milliliters of green tea contains only 20 to 45 milligrams of caffeine, while each cup of white tea contains 6 to 60 milligrams of caffeine.
The caffeine content in green tea powder tends to be higher, and about 1 gram of matcha powder for every half teaspoon usually contains 35 mg of caffeine.
The brewing method has a great influence on the caffeine content in tea. Tea with longer steeping time and higher water temperature tends to have more caffeine.
For example, a cup of Starbucks Taishu tea steeped in 177 milliliters of hot water for one minute and heated to 90 to 95 degrees Celsius will contain 40 milligrams of caffeine. After 3 minutes of soaking, the caffeine content will increase to 59 mg.
In contrast, green tea steeped for 1 minute under the same conditions contains 16 mg of caffeine. After 3 minutes of soaking, this value more than doubled to 36 mg.
Studies have shown that a cup of 237 milliliters of coffee contains an average of 95 milligrams of caffeine. And espresso contains more caffeine. For example, Starbucks contains 58 mg of caffeine in a 30 ml espresso. Specialty coffee beverages such as latte and cappuccino are made with double espresso, and a cup of coffee often contains 116 mg of caffeine.
Hot water will release more caffeine from the tea, as does coffee. The ideal brewing temperature for tea is 90 to 96°C, while coffee brewing problems are usually higher.
Of course, some people will soak ground coffee in filtered cold water for 8 to 24 hours to make cold brewed coffee. The amount of coffee brewed in this way is 1.5 times that of coffee brewed with ordinary hot water, so the caffeine content in the beverage may be higher.
The effect of caffeine is very fast, usually within 20 minutes to 1 hour after ingestion.
If you are sensitive to caffeine, consider drinking white tea or herbal tea with a lower caffeine content. You can also shorten the time for making tea. Or simply choose decaffeinated tea and coffee. On the contrary, if you like caffeine, you will like espresso, cold brewed coffee, and tea with higher caffeine content.
Even if you love caffeine again, the daily caffeine intake should not exceed 400 mg, and the single intake should not exceed 200 mg. This means that you can drink up to 3 to 5 cups of 237 milliliters of regular coffee, or 8 cups of 30 milliliters of espresso per day.
People suffering from heart disease, prone to migraines, and taking certain medications should limit their caffeine intake. Pregnant women or breastfeeding mothers should also insist that their daily caffeine intake does not exceed 200 mg. This is roughly equivalent to a cup of 355 milliliters of coffee or four cups of 237 milliliters of black tea.