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The Buzz on Caffeine
Caffeine is found in coffee, soda, tea, energy drinks, and some medicines. Are you getting too much?

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Picture of cup of coffee The Buzz on Caffeine

There's no doubt about it. Americans have a collective caffeine habit. From our morning "cup of joe" to tea, soda, and energy drinks, this common stimulant can be found in some form in almost every home, supermarket, coffee shop, and pharmacy in the United States.

So it begs the question: is there really any harm?

Moderate consumption of caffeine is generally safe for most people. That is the equivalent of about 200 to 400 mg a day, or the amount in 2 to 3 cups of coffee. Some people can tolerate more. But caffeine is a drug. Classified as a stimulant, it speeds up the brain and nervous system, and can:

  • increase heart rate
  • interfere with sleep
  • cause heartburn or upset stomach
  • increase anxiety and nervousness
  • interfere with concentration

There has been recent concern about energy drinks. These products contain high amounts of caffeine as well as other ingredients that some researchers have questioned. Energy drinks have been linked to serious side effects, especially in children and young adults. As a result, several countries and states have restricted the selling or advertising of energy drinks.

Caffeine and certain health considerations
For any of the following health conditions, it is vitally important to check with your doctor before you consume caffeine.

  • Pregnancy. Drinking 5 or more cups of coffee a day may increase the risk of miscarriage and may cause low birth weight. Doctors recommend limiting caffeine to 200 mg a day during pregnancy.
  • Breast-feeding. Caffeine passes into breast milk. Nursing mothers who drink the equivalent of 2 cups of coffee a day may find that their babies have trouble sleeping.
  • Dehydration or urinary problems. You may need to reduce your intake of caffeine or avoid it completely. Talk to your doctor.
  • Chronic medical conditions. Ask your doctor if caffeine is safe for you if you:
    • Take any medications
    • Have a thyroid, gastrointestinal, cardiovascular, or anxiety disorder
    • Have any other chronic medical condition
  • High blood pressure. Besides getting caffeine from other sources, be especially careful with energy drinks. They may cause a temporary increase in blood pressure and interfere with blood pressure medications.

Are there health benefits?
Coffee has been in the news for its potential health benefits, including the possible prevention of heart disease, Alzheimer's, and some types of cancer. These studies have mainly been linked to moderate consumption of coffee, and not other sources of caffeine. It is not clear whether these effects are due to the caffeine or other properties in the coffee, such as antioxidants. Research is ongoing.

No one should use caffeine all the time as a crutch to enhance alertness or fight fatigue. This could mask an underlying disorder.

If you think you are getting too much caffeine, though, don't quit "cold turkey." If you do, you're likely to get headaches, or feel irritable or nauseated. Cut back slowly to make the transition easier.

By Jane Harrison, RD, Staff Nutritionist
Created on 03/06/2008
Updated on 05/09/2011
  • NSW Department of Health. Caffeine fact sheet.
  • American Academy of Pediatrics. Health effects of energy drinks on children,adolescents, and young adults.
  • American Dietetic Association. Caffeine for energy.
  • National Toxicology Program. Caffeine.
  • Echeverri D, Montes FR, Cabrera M, Galan A, Prieto A. Caffeine's vascular mechanisms of action. International Journal of Vascular Medicine. Online publication:2010.
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