Caffeine in the Diet

Caffeine Intoxication and Overdose
Anyone who’s ever had too much coffee can tell you that caffeine intoxication is no fun. Medical experts agree that ingesting more than 250 mg of caffeine in a short period of time can cause restlessness, insomnia, muscle twitching, gastrointestinal disturbance, cardiac arrhythmia and a host of other problems. These symptoms can cause significant social and occupational disturbances [source: Johns Hopkins University -- Bayview Medical Center]. Caffeine intoxication is rarely fatal, although 5,000-10,000 mg of caffeine can actually kill you [source: Dance]. Fortunately, most people won’t ever ingest this much caffeine accidentally - it would take between 30 and 60 cups of coffee in one morning.

Caffeine occurs naturally in many plants, including coffee beans, tea leaves and cocoa beans, so it’s found in a wide range of food products. What most people don’t know is that caffeine is added artificially to many others, including a variety of beverages like colas. Coca-Cola was originally made with kola nut extract, which naturally contains caffeine and was mostly responsible for the flavor and buzz that early fans of the beverage craved (although the cocaine contained in early formulas of the drink certainly helped increase that craving). Now, colas are made with artificial flavors, and caffeine from another source is added in the production process. Energy drinks are a new trend in caffeinated beverages. They contain an abundance of sugar and other chemicals that help provide that sought-after boost. Caffeine can also be found in many weight loss pills and some over-the-counter pain medicines.

Here are the most common sources of caffeine for Americans:

  • Typical drip-brewed coffee contains about 100 mg per 8-ounce cup [source: MayoClinic.com]. If you are buying your coffee at Starbucks or a convenience store or drinking it at home or the office out of a mug, you are consuming it in 12-, 14- or 20-ounce containers. You can calculate the number of milligrams based on your normal serving size.
  • Typical brewed black tea contains 50 mg per 8-ounce cup.
  • Typical caffeinated sodas (Coke, Pepsi, Mountain Dew, etc.) contain 40-50 mg per 12-ounce can.
  • Super-caffeinated colas like Jolt contain 70 mg per 12-ounce can [source: Center for Science in the Public Interest].  
  • Typical milk chocolate contains 6 mg per ounce [source: March of Dimes].
  • Maximum Strength Anacin contains 32 mg per tablet. NoDoz and Vivarin each contain 200 mg per tablet. Extra Strength Excedrin contains 65 mg per tablet [source: Center for Science in the Public Interest].
  • Energy drinks like Red Bull (8.3 oz-sized can) and Rock Star (8.4 oz-sized can) contain about 80 mg per can.

By looking at these numbers and by knowing how widespread coffee, chocolate, tea, cola and energy drinks are in our society, you can see why half of all American adults consume more than 300 mg of caffeine per day. Two mugs of coffee or a mug of coffee and a couple of Cokes during the day are all you need to get there. If you sit down and calculate your caffeine consumption during a typical day, you may be surprised. Many people consume a gram or more every single day and don't even realize it.

In the next section, we’ll learn exactly what effects caffeine has on the body.