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The Highs and Lows of Caffeine

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What's New? | Can You Be Addicted to Caffeine? | Is It a Habit Worth Breaking? | Who Should Keep Caffeine in Check? | Are You Contemplating Quitting?

caffeine Many Americans regularly consume caffeine, the most widely used behaviorally active drug in the world. But does caffeine cause more than just a morning boost?

Over the years, caffeine has been singled out as a possible factor in cancer, and birth defects, among others. Here is a look at why most experts say that moderate caffeine consumption is not a habit worth losing sleep over and some advice for "addicts" who want to cut back.

What's New?

Energy drinks are the latest entry into the beverage market and perhaps the most potent way to get a caffeine fix. The popularity of these carbonated, caffeine loaded drinks has skyrocketed since they first appeared on the market in 1997. They are particularly popular among the younger generation, including teenagers. Does the entry of another caffeine-containing concoction into the marketplace prove yet again that we are a nation of addicts?

Can You Be Addicted to Caffeine?

In a manner of speaking, yes. The majority of Americans regularly consume caffeine, a drug that acts as a central nervous system stimulant. It increases heart rate, boosts urine production, and raises the metabolic rate (the speed at which the body burns calories to fuel necessary functions such as breathing). And as anyone who cannot get going in the morning without a cup of coffee, tea, or a caffeine-containing soft drink knows all too well, caffeine can be habit-forming.

While most experts say "addiction" is too strong a word to be used in conjunction with caffeine, researchers at Johns Hopkins University have identified a condition they call "caffeine dependence syndrome," characterized by at least three of the following four criteria:

  • Withdrawal symptoms, such as headache, fatigue, and depression
  • Caffeine consumption despite causing physical problems, such as irritating an ulcer
  • Unsuccessful attempts to cut back on caffeine
  • Tolerance to caffeine (for example, the ability to drink an extra cup of coffee and still fall asleep)

Is It a Habit Worth Breaking?

Although the idea of being "dependent" on caffeine is unsettling, most healthy people who drink a cup or two of coffee, tea, or soda every day suffer no more serious physical symptoms than jitteriness, irritability, and minor gastrointestinal upsets. Why, then, have scientists long suspected that caffeine might contribute to heart disease, cancer, birth defects, and other problems?

The snag here is that much of the early research linking caffeine to various conditions was clouded by a number of issues. When questioning people about their caffeine-consuming habits, for example, many researchers failed to ask about caffeine sources other than coffee or tea, such as soft drinks, chocolate, and certain medicines (see chart).

In addition, most early studies neglected to account for differences in methods of preparing coffee. For example, some research has suggested that coffee drinking raises blood cholesterol levels. Yet most of that evidence comes from Scandinavia, where coffee is boiled rather than brewed.

Another confounding issue is that even though caffeine and coffee drinking may not contribute to disease in and of themselves, they seem to go hand-in-hand with a lifestyle that does. One study conducted by researchers at the University of California, San Diego, found that coffee drinkers were more likely to smoke, drink alcohol, and eat high-fat diets than abstainers.So maybe it’s not the coffee, but rather the cream or cigarette accompanying the coffee that contributes to health problems.

Recent studies have failed to link consumption of caffeine to heart disease. In fact, many observational studies have suggested that caffeine consumption may actually lower the risk of cardiovascular events and death.

Who Should Keep Caffeine in Check?

Some people would clearly do well to limit their caffeine consumption or avoid it altogether. For example, people with ulcers or heartburn should stay away from caffeine because it stimulates the secretion of acid, which can irritate the lining of the gastrointestinal tract. (The chemicals in decaf coffee also boost acid secretion.)

Pregnant women should watch the amount of caffeine they consume, as well. While moderate amounts (a cup or two of coffee a day) have not been proven to cause birth defects, caffeine does cross the placenta. Once caffeine enters the fetal bloodstream, large amounts can alter the unborn baby's normal heart rate and breathing. Some research also suggests that large amounts of caffeine may decrease bloodflow to the placenta, which in turn may raise the risk of miscarriage. However, other research has not found a link between coffee consumption and pregnancy problems.

People with chronic headaches are strongly advised to quit all caffeinated products. Many headache specialists link caffeine intake with tension headaches.

On the other hand, there is some data that suggest caffeine intake my lower the risk of diabetes. Coffee may work by improving the body’s sensitivity to insulin.

Are You Contemplating Quitting?

Even if you only drink a cup or two of coffee, tea, or soda each day, try to cut back on caffeine gradually. Moderate caffeine users who stop cold turkey often suffer from withdrawal symptoms such as headaches, fatigue, moodiness, and nausea. Instead of switching over completely to decaffeinated coffee, substitute decaf for half your regular blend for a couple days and gradually wean yourself. Or, alternate decaf sodas with the regular version throughout the day until you feel comfortable weaning yourself from the caffeinated version completely.

Smokers need more caffeine to get a kick than their nonsmoking counterparts because smoking causes caffeine to be metabolized more quickly—one reason so many smokers get caught up in the coffee-and-cigarette habit. When a smoker kicks the cigarette habit, however, caffeine lingers in the bloodstream longer, which can add to the jitteriness and irritability that goes with giving up nicotine. To avoid frazzled nerves, smokers who quit cigarettes may want to cut back on caffeine at the same time.

Beverages, Food, and Over-the-Counter Medicine Caffeine
(Milligrams)
Coffee
Coffee (8 oz cup), brewed133
Coffee (8 oz cup), instant93
Starbucks brewed coffee (16 oz)320
Dunkin’ Donuts regular coffee (16 oz)206
Einstein Bros. regular coffee (16 oz)300
Starbucks Latte (16 oz, 2 shots of espresso)150
Starbucks Espresso, solo (1 oz)75
Decaffeinated coffee (8 oz cup), brewed or instant5
Tea
Tea (8 oz cup), brewed, black, steeped for 3 minutes53
Instant iced tea (12 oz glass)26
Starbucks Tazo Chai Tea Latte (16 oz)100
Snapple Iced Tea (16 oz)42
Arizona Iced Tea (16 oz)32
Soft Drinks (12 oz)
Dr Pepper42
Jolt Cola72
Vault71
Regular Coke35
Diet Coke47
Caffeine free0
Mountain Dew, Mello Yello53-54
Mountain Dew MDX71
Energy Drinks
Spike Shooter (8.4 oz) 300
Monster Energy (16 oz)160
Rip It, all varieties (8 oz)100
Enviga (12 oz)100
Red Bull (8.3 oz)80
SoBe Adrenaline Rush (8.3 oz)79
Amp (8.4 oz)74
Chocolate Drinks
Cocoa beverage (8 oz cup)9
Chocolate milk beverage (8 oz carton)5-8
Chocolate
Hershey's Chocolate Bar (1.55 oz)31
Hershey's Special Dark Bar (1.45 oz)31
Hershey's Kisses (9 pieces)9
Over-the-Counter Medicine
Anacin64
Extra Strength Excedrin130
No-Doz, Vivarin200

Many manufacturers add caffeine to pain killers because it helps the drugs alleviate muscular aches and other discomforts more effectively. Some research also suggests that caffeine acts independently to relieve pain. The caffeine content of products may change, so contact the manufacturer for information on products you use frequently.

RESOURCES:

International Food Information Council

http://www.ific.org/

National Coffee Association of USA

http://www.ncausa.org/

CANADIAN RESOURCES:

Canada's Food Guide

http://www.hc-sc.gc.ca/

Dietitians of Canada

http://www.dietitians.ca/

References:

Agardh EE, Carlsson S, Ahlbom A, et al. Coffee consumption, type 2 diabetes and impaired glucose tolerance in Swedish men and women. J Intern Med. 2004;255(6):645-652

Benowitz NL, Hall SM, Modin G. Persistent increase in caffeine concentrations in people who stop smoking, BMJ. 1989;298:1075-1076.

Caffeine content of food and drugs. Center for Science in the Public Interest. Available at: http://www.cspinet.org/new/cafchart.htm. Accessed February 8, 2011.

DynaMed Editors. Dietary recommendations for cardiovascular disease prevention. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated February 12, 2011. Accessed February 24, 2011.

DynaMed Editors. Drug use in pregnancy. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated February 22, 2011. Accessed February 24, 2011.

Energy Drinks: The Fads and the Facts. International Food Information Center website. Available at: http://www.ific.org/foodinsight/2008/jf/energydrinksfi108.cfm. Accessed February 19, 2009.

Eskenazi B. Caffeine during pregnancy: grounds for concern? JAMA. 1993; 270:2973-2974.

Jahanfar S, Sharifah H. Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcome. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD006965.

Leviton A, Allred EN. Correlates of decaffeinated coffee choice. Epidemiology. 1994;5:537-540.

Oei SG, Vosters RP, van der Hagen NL. Fetal arrhythmia caused by excessive intake of caffeine by pregnant women. BMJ.1989;298:1075-1076.

Pennington J. Bowes & Church's Food Values of Portions Commonly Used. 16th ed. Philadelphia, PA: JB Lippincott Company; 1994:381-383.

Physicians' Desk Reference for Nonprescription Drugs [end chart]. 15th ed. Montvale, NJ: Medical Economics Data Production Company; 1994.

Schwartz, BS, Stewart, WF, Simon D, Lipton, RB. Epidemiology of tension-type headache. JAMA. 1998;279:381-383.

Smith B, Wingard DL, Smith TC, Kritz-Silverstein D, Barrett-Connor E. Does coffee consumption reduce the risk of type 2 diabetes in individuals with impaired glucose? Diabetes Care. 2006;29(11):2385-2390.

Strain EC, Mumford GK, Silverman K, Griffiths RR. Caffeine dependence syndrome. JAMA. 1994;272:1043-1048.

Willett WC, Stampfer MJ, Manson JE, et al. Coffee consumption and coronary heart disease in women: a ten-year follow-up. JAMA. 1996;275:458-462.

Last reviewed February 2011 by Brian Randall, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.