Gail Zyla, MS, RD
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 intake is not a habit worth losing sleep over and advice for poeple who drink too much coffee and want to cut back.
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?
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 metabolic rate is the speed at which the body burns calories to fuel necessary functions like breathing. Anyone who cannot get going in the morning without a cup of coffee, tea, or a caffeine-containing soft drink knows all too well that caffeine can be habit-forming.
While most experts say addiction is too strong a word to be used with caffeine, researchers have identified a condition they call caffeine dependence syndrome. It is characterized by the following:
The idea of being dependent on caffeine can be unsettling. However, 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 did not 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 alone, they may go hand-in-hand with a lifestyle that does. One study, found that coffee drinkers were more likely to smoke, drink alcohol, and eat high-fat diets than those who do not drink coffee. So maybe it’s not the coffee, but rather the cream or cigarette with the coffee that contributes to health problems.
Recent studies have failed to link consumption of caffeine to heart disease or death. In fact, many observational studies have suggested that caffeine consumption may actually lower the risk of cardiovascular events and death.
Some people would clearly do well to limit their caffeine consumption or avoid it altogether. For example, people with dyspepsia or heartburn should stay away from caffeine. It stimulates the secretion of acid, which can irritate the lining of the gastrointestinal tract.
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. After 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 blood flow to the placenta, which may raise the risk of miscarriage. However, other research has not found a link between coffee consumption and pregnancy problems.
Women who breastfeed their babies should also avoid the substance. Although caffeine may make a new mother more alert, the caffeine passed to her child through breast milk may mean more time comforting a fussy child.
People with chronic headaches are strongly advised to limit all caffeinated products. While small amounts can help reduce a headache, regular use can cause headaches or make them worse.
Given the alert feeling that caffeine provides, those with anxiety or panic disorders should also avoid caffeine or limit its use. Caffeine has the ability to increase their anxiety and make symptoms worse.
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 can 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. This is 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. This can add to the jitteriness and irritability that goes with giving up nicotine. Smokers who quit cigarettes may want to cut back on caffeine at the same time.
Many manufacturers add caffeine to pain killers because it helps the drugs ease 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.
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Last reviewed February 2013 by Brian Randall, MD
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