One of the questions we are often asked is whether green tea contains caffeine. The answer is yes. The amount of caffeine in an average-sized cup of green tea (around 230 ml) varies between 30 mg and 50 mg. A 200 ml cup of filter coffee contains around 90 mg of caffeine, and an energy drink contains around 160 mg of caffeine.
How caffeine works in tea
Both tea and coffee contain caffeine. But drinking coffee has a different effect on your body and mind than drinking tea.
Coffee gives you an instant energy boost and acts quickly. Tea works more slowly and gently, it doesn’t just give you energy, it helps you concentrate. The reason for the difference between the effects of tea and coffee on the body is a chemical compound called L-Theanine. This amino acid, found naturally in tea leaves, affects the way caffeine interacts with your body and brain, slowing down the onset of caffeine’s effects and providing a steady release of energy that can last for several hours.
This combined effect of caffeine and L-Theanine in tea was first discovered over three thousand years ago by Buddhist monks who drank tea to help them stay focused yet relaxed during long periods of meditation.
How much green tea is it safe to drink in a single day?
One cup of green tea contains an average of 35 mg of caffeine. According to the European Food Safety Authority (EFSA), the maximum safe daily intake of caffeine should be 400 mg (or 3 mg per kg of body weight). So while you could theoretically drink more, drinking three to five cups of green tea should allow you to reap all the health benefits without exposing yourself to the potential risks of too much caffeine.
What are the effects of too much green tea?
Too much caffeine can cause symptoms such as anxiety, restlessness, headache, nausea or increased heart rate. Therefore, drinking too much green tea or too late in the day could lead to sleep problems.
Although the effects of caffeine vary from person to person, drinking green tea may help to maintain alertness and concentration for up to five hours. It is therefore ideal to drink in the morning or early afternoon.
Caffeine levels in different types of green tea
The amount of caffeine in each tea depends on the variety of tea plant used, its growing conditions, the time of year it was harvested, the way it was processed and how it is prepared. Premium quality teas from the first plucking of the year will have more caffeine than teas from later harvests.
Examples of low caffeine green teas
Houjicha is a Japanese green tea also made from leaves and stems taken from the new growth after the summer and roasted. During the roasting process, the tea loses some of its caffeine content and develops a sweet, caramel and nutty flavour, very different from most Japanese green teas.
Genmaicha is a Japanese green tea, typically Sencha, mixed with roasted rice. As the rice doesn’t contain caffeine, it lowers the overall caffeine content.
Examples of medium caffeine green teas
Sencha is the most famous type of Japanese green tea. The amount of caffeine in a cup of Sencha depends on the time of year the tea is produced, how much tea is used and how it is prepared. A Sencha from the second harvest of the year will have less caffeine than a Sencha from the spring harvest.
Dragon Well (Long Jing) is a wonderfully smooth, sweet Chinese green tea, popular for its antioxidant properties. In addition to a moderate amount of caffeine, it also contains a high amount of L-Theanine, making it a wonderful tea to enjoy throughout the day.
Green teas with the highest caffeine levels
Kabusecha, Gyokuro and Matcha are Japanese green teas made from plants that were shaded before harvest. This shading results in high levels of L-Theanine and amino acids, which reduces the bitterness in the tea and enhances the sweet and savoury flavours. The shading process also affects the caffeine content in the tea plants, making it more concentrated. An average cup of shaded green tea contains around 35 mg of caffeine.
Matcha is a powdered green tea. Rather than being infused like other green teas, matcha powder is mixed directly into water and dissolved. The amount of caffeine in a cup of matcha would vary depending on the age and quality of the matcha and whether it was prepared as thin matcha (usacha) or thick matcha (koicha). While a cup of usacha would contain about 2 g of powder and about 80 mg of caffeine, a cup of koicha would contain 4 g of matcha powder and about 140 mg of caffeine.
The health benefits of green tea
As well as being a pleasant and gentle stimulant, green tea has many health benefits. Studies show that regular consumption of green tea can help:
- Lower cholesterol
- Boost the immune system
- Reduce the risk of Alzheimer’s disease
- Reduce the risk of cancer
- Neutralise free radicals
- Have a protective effect on the cardiovascular system
- Improve athletic performance.
If you suffer from any of the conditions listed above please consult your doctor for advice on whether green tea would be appropriate for you.