Caffeinated: How Our Daily Habit Hooks, Helps and Hurts

Murray Carpenter approaches caffeine as a drug because most of us take it every day, it has predictable physiological effects and we are dependent on it. His new book Caffeinated: How Our Daily Habit Hooks, Helps and Hurts (Hudson Street Press) was launched on 13 March and sounds like it will make for a very interesting read:

  • Women on birth control metabolize caffeine twice as slowly—which means they get double the jolt from the same cup of coffee
  • Smokers metabolize it twice as fast so they needto up their intake to get the same buzz
  • Some people are genetically predisposed to metabolize caffeine slowly and they will be extremely sensitive to caffeine
  • 100 milligrams of caffeine daily is enough to get an adult dependent
  • 250ml of cola has ~24mg of caffeine but Coke used to contain ~80mg of caffeine (the same as Red Bull today)
  • Caffeine withdrawal-symptoms can include lethargy, irritability and headaches
  • Post-operative headaches are linked to caffeine withdrawal
  • Migraine, hangover and cold medicines often include caffeine and caffeine suppositories can be used medicinally
  • Extroverts get more cognitive enhancement from caffeine
  • A tablespoon of pure caffeine would kill you
Caffeinated Owls - Dave Mottram (Image Source)

Caffeinated Owls – Dave Mottram (Image Source)

 

As I previously wrote, there have been several papers written on the effect of caffeine on sleep disruption and even more papers written on the positive and negative effects of caffeine on other health issues. A major problem in this type of research is that the papers tend to use very different values for the caffeine content in beverages and foods  and most ignore the effects of other substances like theobromine, tanninic acid, caffeol etc.

For tea in particular it can be hard to pin down the precise caffeine content. Preparation plays a large role and differences in the time and temperature of steepings, the size of the tea leaf and the type of tea used will all influence the caffeine content of tea. The plant variety, soil, nutrients, picking season and the part of plant used will also play a role.

After a lot of searching, I eventually collected some reliable information on the caffeine content of tea.

[Note: moderate caffeine use is generally considered to be 200 – 300 milligrams per day]

 

Tea (~200ml after one steeping of three minutes)

Chinese white tea – 75mg

Darjeeling white – 56mg

Indian Green – 59mg

Kenyan Green – 58 mg

Chinese Oolong (Ti Kwan Yin) – 37mg

Assam (FTGFOP) – 86mg

Darjeeling Black (SFTGFOP1) – 54mg

 

For comparison here are some for coffee and other beverages:

Coffee (~200ml)

Coffee (ground roasted) – 115mg

Coffee (instant) – 80mg

Cola – 20mg

Decaffeinated coffee – 4mg

Espresso, single shot – 75mg

Espresso, double shot – 150mg

Red Bull (250ml can) – 80mg

 

Chocolate

70% Green and Black dark chocolate (30g) – 4.5mg

Green and Black milk chocolate (30g) – 2mg

White chocolate (30g) – 0mg

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