Are you drinking a safe amount of caffeine? Tea Edition

Are you a tea drinker who has ever wondered if you're consuming a safe amount of caffeine? If so, you're not alone. A recent MakeoverMonday challenge (2023 week 9) on caffeine levels in coffee prompted me to explore what the data looks like for some common types of tea. I suspected many of us tea lovers - with our 5+ cups a day - may be unknowingly exceeding the recommended daily limit for caffeine: 400mg.

Check out the visualization I created below:

And here is a summary of what I found interesting from the research process and from my visualization:

• Caffeine is a naturally occurring compound found in up to 28 plants, which use it as a pesticide to protect themselves from insects and other pests. [1]
• I was surprised to learn that tea leaves actually contain more caffeine than coffee beans on a dry weight basis. However, when preparing a cup of tea, less dry leaf is needed than the amount of coffee beans required to make a coffee, which means the caffeine content in tea is lower per cup. [2]
• The caffeine content in a cup of tea can vary depending on several factors: [3]
  • The type of tea leaf used - Generally, broken down tea leaves, like the ones found in tea bags, yield more caffeine compared to whole leaves.
  • The amount of tea used - The more tea leaves used in brewing, the higher the amount of caffeine.
  • Brewing time - The caffeine content in tea increases as the leaves are left to steep in hot water for a longer period of time. [4]
  • Brewing temperature - The caffeine content in tea also increases with higher water temperatures because the hotter water accelerates the process of caffeine extraction from the leaves.
• Finally, I found that it takes only about two cups of black tea to obtain about the same amount of caffeine as in a cup of coffee — I thought black tea had significantly less caffeine!

Notes

[1] Source: Caffeine: Facts, Usage, and Side Effects

[2] Source: How Much Caffeine is there in a Cup of Tea? | Good & Proper Tea

[3] Source: How Much Caffeine is in Tea? | BBC Good Food

[3] Find a breakdown of the effects of a longer brew here: Caffeine compared: from coke and coffee to aspirin and chocolate