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Caffeine Myths and Facts

Caffeine myth or caffeine fact? It's not always easy to know. Chances are you have some real misperceptions about caffeine. For starters, do you know the most common sources of caffeine? Well, maybe two of the sources aren't too hard to name -- coffee and tea leaves. But did you know kola nuts and cocoa beans are also included among the most common caffeine sources? And do you know how much caffeine content can vary from food to food? Turns out it's quite a lot actually, depending on the type and serving size of a food or beverage and how it's prepared.

Caffeine content can range from as much as 160 milligrams in some energy drinks to as little as 4 milligrams in a 1-ounce serving of chocolate-flavored syrup. Even decaffeinated coffee isn't completely free of caffeine. Caffeine is also present in some over-the-counter pain relievers, cold medications, and diet pills. These products can contain as little as 16 milligrams or as much as 200 milligrams of caffeine. In fact, caffeine itself is a mild painkiller and increases the effectiveness of other pain relievers.

Want to know more? Read on. WebMD has examined some of the most common myths about caffeine and gathered the facts to shed some light on those myths.

Caffeine Myth No. 1: Caffeine Is Addictive

This one has some truth to it, depending on what you mean by "addictive." Caffeine is a stimulant to the central nervous system, and regular use of caffeine does cause mild physical dependence. But caffeine doesn't threaten your physical, social, or economic health the way addictive drugs do. (Although after seeing your monthly spending at the coffee shop, you might disagree!)

If you stop taking caffeine abruptly, you may have symptoms for a day or more, especially if you consume two or more cups of coffee a day. Symptoms of withdrawal from caffeine include:

  • headache
  • fatigue
  • anxiety
  • irritability
  • depressed mood
  • difficulty concentrating

No doubt, caffeine withdrawal can make for a few bad days. However, caffeine does not cause the severity of withdrawal or harmful drug-seeking behaviors as street drugs or alcohol. For this reason, most experts don't consider caffeine dependence a serious addiction.

Caffeine Myth No. 2: Caffeine Is Likely to Cause Insomnia

Your body quickly absorbs caffeine. But it also gets rid of it quickly. Processed mainly through the liver, caffeine has a relatively short half-life. This means it takes about five to seven hours, on average, to eliminate half of it from your body. After eight to 10 hours, 75% of the caffeine is gone. For most people, a cup of coffee or two in the morning won't interfere with sleep at night.

Consuming caffeine later in the day, however, can interfere with sleep. If you're like most people, your sleep won't be affected if you don't consume caffeine at least six hours before going to bed. Your sensitivity may vary, though, depending on your metabolism and the amount of caffeine you regularly consume. People who are more sensitive may not only experience insomnia but also have caffeine side effects of nervousness and gastrointestinal upset.

Caffeine Myth No. 3: Caffeine Increases the Risk of Osteoporosis, Heart Disease, and Cancer

Moderate amounts of daily caffeine -- about 300 milligrams, or three cups of coffee -- apparently cause no harm in most healthy adults. Some people are more vulnerable to its effects, however. That includes such people as those who have high blood pressure or are older. Here are the facts:

  • Osteoporosis and caffeine. At high levels (more than 744 milligrams/day), caffeine may increase calcium and magnesium loss in urine. But recent studies suggest it does not increase your risk for bone loss, especially if you get enough calcium. You can offset the calcium lost from drinking one cup of coffee by adding just two tablespoons of milk. However, research does show some links between caffeine and hip fracture risk in older adults. Older adults may be more sensitive to the effects of caffeine on calcium metabolism. If you're an older woman, discuss with your health care provider whether you should limit your daily caffeine intake to 300 milligrams or less.
  • Cardiovascular disease and caffeine. A slight, temporary rise in heart rate and blood pressure is common in those who are sensitive to caffeine. But several large studies do not link caffeine to higher cholesterol, irregular heartbeats, or an increased risk of cardiovascular disease. If you already have high blood pressure or heart problems, though, have a discussion with your doctor about your caffeine intake. You may be more sensitive to its effects. Also, more research is needed to tell whether caffeine increases the risk for stroke in people with high blood pressure.
  • Cancer and caffeine. Reviews of 13 studies involving 20,000 people revealed no relationship between cancer and caffeine. In fact, caffeine may even have a protective effect against certain cancers.

 

Caffeine Myth No. 4: Caffeine Is Harmful for Women Trying to Get Pregnant

Many studies show no links between low amounts of caffeine (a cup of coffee per day) and any of the following:

  • trouble conceiving
  • miscarriage
  • birth defects
  • premature birth
  • low birth rate

At the same time, for pregnant women or those attempting pregnancy, the March of Dimes suggests fewer than 200 milligrams of caffeine per day. That's largely because in limited studies, women consuming higher amounts of caffeine had an increased risk for miscarriage.

Caffeine Myth No. 5: Caffeine Has a Dehydrating Effect

Caffeine can make you need to urinate. However, the fluid you consume in caffeinated beverages tends to offset the effects of fluid loss when you urinate. The bottom line is that although caffeine does act as a mild diuretic, studies show drinking caffeinated drinks in moderation doesn't actually cause dehydration.

Caffeine Myth No. 6: Caffeine Harms Children, Who, Today, Consume Even More Than Adults

As of 2004, children ages 6 to 9 consumed about 22 milligrams of caffeine per day. This is well within the recommended limit. However, energy drinks that contain a lot of caffeine are becoming increasingly popular, so this number may go up.

Some kids are sensitive to caffeine, developing temporary anxiety or irritability, with a "crash" afterwards. Also, most caffeine that kids drink is in sodas, energy drinks, or sweetened teas, all of which have high sugar content. These empty calories put kids at higher risk for obesity.

Even if the caffeine itself isn't harmful, caffeinated drinks are generally not good for kids.

Caffeine Myth No. 7: Caffeine Can Help You Sober Up

Actually, research suggests that people only think caffeine helps them sober up. For example, people who drink caffeine along with alcohol think they're OK behind the wheel. But the truth is reaction time and judgment are still impaired. College kids who drink both alcohol and caffeine are actually more likely to have car accidents.

Caffeine Myth No. 8: Caffeine Has No Health Benefits

Caffeine has few proven health benefits. But the list of caffeine's potential benefits is interesting. Any regular coffee drinker may tell you that caffeine improves alertness, concentration, energy, clear-headedness, and feelings of sociability. You might even be the type who needs that first cup o' Joe each morning before you say a single word. Scientific studies support these subjective findings. One French study even showed a slower decline in cognitive ability among women who consumed caffeine.

Other possible benefits include helping certain types of headache pain. Some people's asthma also appears to benefit from caffeine. These research findings are intriguing, but still need to be proven.

Limited evidence suggests caffeine may also reduce the risk of the following:

  • Parkinson's disease
  • liver disease
  • colorectal cancer
  • type 2 diabetes
  • dementia

Despite its potential benefits, don't forget that high levels of caffeine may have adverse effects. More studies are needed to confirm both its benefits and potential risks.

WebMD Medical Reference

Reviewed by Melinda Ratini, DO, MS on March 20, 2013

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