Journalist Murray Carpenter enjoys a cup of coffee and the caffeine buzz that goes with it.

(Photo: Courtesy of Bangor Daily News/Kathleen Pierce)
University of Colorado undergraduate student Murray Carpenter was a regular at coffee shops around Boulder, Colo., in the 1980s. The coffee he drank around Boulder got him to thinking about the effects of caffeine. 
 
Carpenter wondered how caffeine worked and why people like it so much. Is it good or bad for you? Does it make you quicker, stronger and more responsive or does it spoil your sleep and make you jittery? 
 
What began as a research paper for his senior year eventually turned into a full journalistic investigation that took Carpenter to tea shops in China, Colombian coffee plantations and Mexican cacao farms.
 
Carpenter’s new book "Caffeinated: How Our Daily Habit Helps, Hurts and Hooks Us" tries to answer some of these questions.
 
Caffeine's health effects
 
According to Carpenter, long-term studies have found no association between drinking caffeinated coffee and increased cardiovascular disease. He also notes that coffee consumption is associated with a lower risk of Type 2 diabetes and a lower risk of basal cell carcinoma, the most common type of skin cancer.
 
Carpenter says, however, that caffeine can also bring on anxiety and even trigger panic attacks in some people.
 
“Most people understand that too much caffeine late in the day can affect sleep but researchers have also found that a moderate dose of caffeine in the morning can decrease sleep quality the following night,” Carpenter says.  “Although it’s [caffeine] long been thought that high-altitude climbers and skiers should avoid caffeine, it seems to be safe and maybe even beneficial.
 
How much caffeine is in your cup?
 
Carpenter also examined how much caffeine is in some popular products and cautions that caffeine content in coffee and tea can vary tremendously depending on a variety of factors.
 
A Starbucks Grande, for example, ranged from 260 to 564 milligrams of caffeine while another analysis shows espresso ranging from 56 milligrams to 196 milligrams per ounce.
 
Other caffeine findings by Carpenter: 
 
Coffee drinks
  • Single shot espresso—approx. 75 mg (per Starbucks website)
  • Mocha—approx 175 mg per 16-ounce (grande), (per Starbucks website)
  • Starbucks Bold Pick of the day—approx. 330 mg per 16 ounces (grande) (per Starbucks website)
 
Soda
  • Coca Cola —34 mg per 12 ounce can
  • Dr. Pepper—41 mg per 12 ounces
  • Diet Coke—45 mg per 12 ounces
  • Starbucks Refreshers—50 mg per 12 ounce can
  • Mountain Dew—54 mg per 12 ounces
  • Pepsi Max—69 mg per 12 ounces
 
Energy drinks
  • Red Bull can—80 mg per 8.4 ounce can
  • Mountain Dew Kickstart—92 mg per 16 ounces 
  • Monster—184 mg per 16 ounces (per Consumer Reports)
  • 5-hour Energy—215 mg per 1.9 oz shot (per Consumer Reports)
  • Kraft Mio Energy (concentrate, 12 servings)—720 mg per 1.08 oz (labeled amount)
  
Tea
  • Stash Premium Green Tea—36 mg per six ounces
  • Twining's English Breakfast Tea—25 mg per six ounces
  • Lipton tea—47 mg per six ounces
  • (All teas were made with with 5-minute steep)
  • Chai Tea Latte—approx. 95 mg per 16 ounce (grande) size, according to Starbucks
 
Chocolate milk
  • Hershey’s Milk Chocolate—9 mg per 43 grams
  • Scharrfen Berger 82% Cacao Extra Dark Chocolate—42 mg per 43 gram serving
 
Tablet
  • Vivarin—200 mg per tablet