Amounts of caffeine vary between teas, with black tea containing the most caffeine. Green and white teas contain the least, except for noncaffeinated 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 wilt and oxidize. A person can stop the oxidization process by heating the leaves.

The more tea leaves oxidize, the darker they become, which determines the type of tea:

  • Black tea leaves are bruised, wilted, rolled, and completely oxidized.
  • Green tea leaves are not wilted and are not oxidized.
  • Oolong tea leaves are bruised, wilted, and partially oxidized.
  • White tea consists of young leaves that are minimally oxidized.

Black tea is the most popular in the United States and Europe and accounts for about 75% of the world’s tea consumption. In Japan and China, green tea is the most popular. People consume oolong and white tea in lesser amounts worldwide.

In this article, we look at the most caffeinated teas, top healthy teas with no caffeine, and some of the risks involved in consuming too much caffeine.

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The amount of caffeine in a tea varies according to the type of tea.

The most caffeinated teas are black and oolong teas, with decaffeinated and herbal teas containing very little to trace amounts of caffeine.

Many teas offer various health benefits, as they contain:

  • Antioxidants: These delay or prevent oxidative damage, which helps lower the risk of diseases such as heart disease and cancer.
  • Phytochemicals: These plant compounds occur naturally. They may boost the immune system and play a role in lowering the risk of cancer and heart disease.
  • Flavonoids: These are a type of polyphenolic phytochemicals and are also antioxidants.
  • Flavonols: These are a type of flavonoids in tea that are powerful antioxidants.
  • Epigallocatechin gallate (EGCG): This is a catechin in black and green teas and a powerful antioxidant.
  • Theanine: This is an amino acid that may help reduce stress.

Black tea

Black contains the highest amount of caffeine, ranging between 64 and 112 milligrams (mg) per 8-fluid ounce (fl oz) serving.

Black tea does not contain calories, fats, protein, fiber, vitamins, or sugar. However, like other teas, it contains health-promoting flavonoids, phytochemicals, flavonols, theanine, and antioxidant properties. Research shows black tea may help with:

  • Increased mental alertness: A person may feel more alert and pay better attention if they drink black tea throughout the day due to its caffeine content.
  • Heart attack: People who drink black tea may be at lower risk of heart attack, while those who have been drinking black tea for at least 1 year may be less likely to die after having a heart attack.
  • Low blood pressure: Caffeinated beverages may help increase blood pressure in older adults who experience low blood pressure after eating.
  • Ovarian cancer: People who regularly drink tea seem to be at a lower risk of developing this type of cancer than those who never or rarely drink tea.

Oolong tea

Oolong tea contains between 29 and 53 mg of caffeine per 8-fl oz serving.

It contains no fats, sugars, protein, or fiber. Per 100 grams (g), oolong tea has:

  • 1 calorie
  • 1 mg calcium
  • 1 mg magnesium
  • 1 mg phosphorous
  • 12 mg potassium K
  • 3 mg sodium
  • 0.01 mg zinc
  • 0.06 mg niacin
  • 2 mg theobromine

Oolong tea may help with weight loss. Research from animal studies suggests that regularly drinking oolong tea and other types of tea may help with weight loss due to the antioxidant EGCG it contains.

It may also help with heart disease, as research shows that oolong tea may lower cholesterol, which can lower the risk of heart disease.

Green tea

The caffeine in green tea ranges between 24 and 39 mg per 8-fl oz serving.

According to the Department of Agriculture, per 100 g, green tea contains no fats, sugars, or fiber and contains:

  • 1 calorie
  • 0.22 g protein
  • 0.02 mg iron
  • 1 mg magnesium
  • 8 mg potassium K
  • 1 mg sodium
  • 0.01 mg zinc

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 help in the chemoprevention of UVB-induced skin cancer. This could be due to the tea’s 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 ability: Observational studies suggest a link between green tea and a decreased risk of cognitive impairment.

White tea

The caffeine in white tea ranges between 32 and 37 mg per 8-fl oz serving.

White tea is similar in nutrition to green tea and is less processed than black, oolong, and green tea, meaning it retains more antioxidants. It has many of the same benefits as these other teas and may also help with:

  • heart health
  • protecting against the effects of harmful UV rays
  • reducing inflammation
  • weight loss
  • improving cognitive ability

Decaffeinated teas

These contain less than 12 mg of caffeine per 8-fl oz serving, and many natural herbal teas that are caffeine-free contain no traceable amount of caffeine.

Many teas have zero to trace amounts of caffeine. A person can usually find a decaffeinated version of their favorite black, green, or white tea, including Earl Grey tea, but many herbal teas are naturally caffeine-free. Healthy caffeine-free teas with notable health benefits include the below.

This tea contains no caffeine. Research on animals suggests that rooibos supplements may help protect the liver from oxidative stress and may help lower blood pressure.

Research suggests that hibiscus leaf extracts may offer antitumoral and antioxidant properties and may promote cardiovascular health and healthy blood pressure.

Chamomile tea may help improve sleep in people who experience insomnia. It may also lower cholesterol, improve cardiovascular health, and provide antioxidant protection.

Research states that curcumin, which is in turmeric and gives it its distinct yellow color, improves immune function with antioxidant, anti-inflammatory, antiviral, and antibacterial properties.

Consuming too much caffeine can cause health problems. The Food and Drug Administration (FDA) has cited 400 milligrams — about 4 or 5 cups of coffee — as the maximum recommended amount per day. However, consuming more than this has links to dangerous, negative effects, including:

Some people should avoid or limit their intake of caffeine, including individuals who:

The most caffeinated teas include black, oolong, green, and white teas. These all have potential health benefits, as they contain antioxidants, polyphenols, flavonoids, flavonols, and other health-promoting compounds.

Health benefits of tea include:

  • cardiovascular health due to lower cholesterol
  • weight loss
  • antioxidant protection
  • protection from the effects of harmful UV rays
  • reduced inflammation

If a person wishes to avoid caffeine, which may overstimulate or interact with certain health conditions, decaffeinated varieties of popular teas are usually available. Some teas, including many herbal teas, are naturally caffeine-free. Healthy caffeine-free teas with health benefits include rooibos, hibiscus, and chamomile tea.