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Caffeine is the world's most popular natural stimulant, and tea is one of its most common sources. Because caffeine can affect heart rate and blood pressure, people interested in heart health often ask whether the caffeine in tea is something to worry about. For most healthy adults, moderate tea drinking appears to be compatible with a healthy heart, but it helps to understand how caffeine works.
How much caffeine is in tea?
The caffeine in a cup of tea varies a great deal. It depends on the type of tea, the size of the cup, the amount of leaf used and how long it steeps. As a general guide:
- Black tea usually contains less caffeine than a similar cup of brewed coffee, often around half as much.
- Green and white teas usually contain a little less than black tea, although some contain just as much.
- Matcha contains more than regular green tea because you consume the whole powdered leaf.
- Decaffeinated tea contains only small traces.
- Most herbal teas, such as rooibos, chamomile and hibiscus, are naturally caffeine-free.
What caffeine does in the body
Caffeine blocks a brain chemical called adenosine, which normally builds up during the day and makes us feel tired. This is why caffeine increases alertness. It can also cause a short-term rise in heart rate and blood pressure, particularly in people who are not used to it.
Regular caffeine users tend to develop some tolerance, so the effect on blood pressure is usually smaller in habitual tea drinkers. Tea also contains an amino acid called L-theanine, which many people find gives a calmer, more focused feeling than coffee.
Caffeine and heart rhythm
People sometimes worry that caffeine causes irregular heartbeats. Research in recent years suggests that moderate caffeine intake does not increase the risk of heart rhythm problems in most people. However, some individuals are more sensitive and notice palpitations after caffeinated drinks. If that applies to you, it makes sense to cut back or choose decaffeinated tea.
Who should be more careful
Some people may need to limit caffeine more strictly:
- People who are pregnant or breastfeeding
- People with certain heart rhythm conditions or uncontrolled high blood pressure
- People with anxiety or sleep problems
- People taking medications that interact with caffeine
Tips for managing caffeine from tea
- Steep your tea for a shorter time if you want a milder cup.
- Enjoy caffeinated tea earlier in the day and switch to herbal tea in the evening.
- Keep track of all your caffeine sources, including coffee, cola, energy drinks and chocolate.
- Try decaffeinated black or green tea if you love the taste but want less stimulation.
Putting it in perspective
For most healthy adults, a few cups of tea a day provide a moderate amount of caffeine that fits well within commonly recommended limits. The natural flavonoids in tea, and the chance to replace sugary drinks, are bonuses for heart health.
If you have a heart condition, notice symptoms such as palpitations or chest discomfort, or are unsure how much caffeine is right for you, speak with your doctor. Chest pain should always be checked by a medical professional promptly.
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