The amounts of caffeine vary between teas, with black tea being the one that contains the most. Green and white teas contain the least, with the exception of non-caffeinated teas.
Tea is one of the most popular beverages in the world. It consists of the leaves of the Camellia sinensis plant which, after harvesting, begin to wither and oxidize. The oxidation process can be stopped by heating the leaves.
The more the tea leaves oxidize, the darker they become, which determines the type of tea:
Black tea leaves are withered, rolled and completely oxidized.
Green tea leaves are not withered and oxidized.
Oolong tea leaves are withered and partially oxidized.
White tea is composed of young leaves which are very little oxidized.
Black tea is most popular in Europe and accounts for around 75% of global tea consumption. In Japan and China, green tea is the most popular. Oolong tea and white tea are less consumed in the world.
The amount of caffeine in a tea varies depending on the type of tea. The most caffeinated teas are black teas and oolong teas, decaffeinated teas and herbal teas containing very little or traces of caffeine.
Many teas offer various health benefits, as they contain:
- Antioxidants: They delay or prevent oxidative damage, which helps reduce the risk of diseases such as heart disease and cancer.
- Phytochemicals: These plant compounds occur naturally. They can boost the immune system and play a role in reducing the risk of cancer and heart disease.
- Flavonoids: These are a type of polyphenol phytochemicals and are also antioxidants.
- Flavonols: These are a type of flavonoids found in tea that are powerful antioxidants.
- Epigallocatechin gallate (EGCG): This is a catechin found in black and green teas and a powerful antioxidant.
Theanine: This is an amino acid that can help reduce stress.
Black tea contains the highest amount of caffeine, between 64 and 112 milligrams (mg) per 200g serving.
Black tea contains no calories, fat, protein, fiber, vitamins or sugar. However, like other teas, it contains flavonoids, phytochemicals, flavonols, theanine, and health-promoting antioxidant properties. Black tea can help:
Increase Mental Alertness: A person may feel more alert and be more attentive if they drink black tea throughout the day due to its caffeine content.
Heart attack: People who drink black tea may have a lower risk of heart attack, while those who have been drinking black tea for at least a year may be less likely to die from a heart attack.
Low blood pressure: Caffeinated beverages may contribute to increased blood pressure in older people who experience low blood pressure after eating.
Ovarian cancer: People who regularly drink tea seem to have a lower risk of developing this type of cancer than those who never or rarely drink it.
Oolong tea contains between 29 and 53 mg of caffeine per 2.5 liter serving.
It contains no fats, sugars, proteins or fibers. Per 100 grams (g), oolong tea has:
1 mg of phosphorus
12mg Potassium K
2 mg of theobromine
Oolong tea can help with weight loss. Animal studies suggest that regular consumption of oolong tea and other types of tea can help with weight loss thanks to the antioxidant EGCG it contains. It may also help fight heart disease, as research shows that oolong tea can lower cholesterol, which may reduce the risk of heart disease.
The caffeine in green tea ranges between 24-39mg per 200g serving.
Per 100 g, green tea contains no fats, sugars or fibers and contains:
8mg Potassium K
Green tea may have health benefits, including
Anti-carcinogenic properties for skin cancer: Human, in vivo and in vitro research has found that green tea may aid in the chemoprevention of UVB-induced skin cancer. This could be due to tea polyphenols, micronutrients found in plants.
Inflammatory skin conditions: Studies have found that green tea and the EGCG it contains appear to help reduce inflammation.
Cognitive abilities: Observational studies suggest a link between green tea and a reduced risk of cognitive impairment.
The caffeine in white tea ranges between 32-37mg per 200g serving:
White tea is nutritionally similar to green tea and is less processed than black tea, Oolong tea and green tea, which means it retains more antioxidants. It has many of the same benefits as these other teas and may also help:
protection against the effects of harmful UV rays
reduction of inflammation
improve cognitive abilities
These teas contain less than 12 mg of caffeine per 8 ounce serving, and many natural caffeine-free herbal teas contain no trace of caffeine.
The best healthy caffeine-free teas
Many teas contain no trace of caffeine. You can usually find a decaffeinated version of your favorite black, green, or white tea, including Earl Gray tea, but many herbal teas are naturally caffeine-free. Some caffeine-free teas with notable health benefits include the following.
This tea does not contain caffeine. Animal research suggests that rooibos supplements may help protect the liver from oxidative stress and lower blood pressure.
Research suggests that hibiscus leaf extracts may offer antitumor and antioxidant properties and may support cardiovascular health and healthy blood pressure.
Chamomile tea may help improve sleep in people with insomnia. It may also lower cholesterol levels, improve cardiovascular health, and provide antioxidant protection.
Curcumin, which is found in turmeric and gives it its distinct yellow color, improves immune function with antioxidant, anti-inflammatory, antiviral, and antibacterial properties.
The risks of caffeine
Consuming too much caffeine can lead to health problems. The research cited 400 milligrams, or about 4 or 5 cups of coffee, as the maximum recommended amount per day. However, consuming more than this figure is linked to dangerous negative effects, including:
increased heart rate
Some people need to avoid or limit their caffeine intake, including people who:
are pregnant or breastfeeding
have trouble sleeping
have high blood pressure
have ulcers or gastroesophageal reflux disease
you are taking medications, such as stimulants.
The most caffeinated teas are black tea, Oolong tea, green tea and white tea. They all have potential health benefits because they contain antioxidants, polyphenols, flavonoids, flavonols, and other health-promoting compounds.
The health benefits of tea include:
– cardiovascular health thanks to the reduction of cholesterol
– weight loss
– protection against antioxidants
– protection against the effects of harmful UV rays
– reduction of inflammation
If a person wishes to avoid caffeine, which can cause overstimulation or interact with certain health conditions, decaffeinated varieties of popular teas are commonly available. Some teas, including many herbal teas, are naturally caffeine-free. Some health-promoting caffeine-free teas include rooibos, hibiscus, and chamomile.
- Canda, BD, et al. (2014). Effects of consumption of rooibos (aspalathus linearis) and a rooibos-derived commercial supplement on hepatic tissue injury by tert-butyl hydroperoxide in wistar rats.
- Chang, S.-M., et al. (2015). Effects of an intervention with drinking chamomile tea on sleep quality and depression in sleep disturbed postnatal women: A randomized controlled trial.
- Chin, JM, et al. (2008). Caffeine content of brewed teas.
- Chitpan, M., et al. (2015). Chemistry and health beneficial effects of oolong tea and theasinensins.
- Ohishi, T., et al. (2016). Anti-inflammatory action of green tea [Abstract].
- Pastoriza, S., et al. (2017). Healthy properties of green and white teas: An update [Abstract].
- Rasheed. Z. (2019). Molecular evidence of health benefits of drinking black tea.