Function

Caffeine is absorbed and passes quickly into the brain. It does not collect in the bloodstream or get stored in the body. It leaves the body in the urine many hours after it has been consumed.

There is no nutritional need for caffeine. It can be avoided in the diet.

Caffeine stimulates, or excites, the brain and nervous system. It will not reduce the effects of alcohol, although many people still believe a cup of coffee will help a person "sober-up."

Caffeine may be used for the short-term relief of fatigue or drowsiness.

Food Sources

Caffeine is widely consumed. It is found naturally in the leaves, seeds, and fruits of more than 60 plants, including:

• Tea leaves
• Kola nuts
• Coffee
• Cocoa beans

It is in:

• Coffee
• Tea
• Chocolate
• Most colas (unless they are labeled "caffeine-free")

Caffeine is often added to over-the-counter medications such as pain relievers, over-the-counter diet pills, and cold medicines. Caffeine has no flavor and it can be removed from a food by a chemical process called decaffeination.

Side Effects

Caffeine can lead to:

• A fast heart rate
• Anxiety
• Depression
• Difficulty sleeping
• Nausea
• Restlessness
• Tremors
• Urinating more often
• Vomiting

Stopping caffeine abruptly may cause withdrawal symptoms, such as:

• Drowsiness
• Headaches
• Irritability
• Nausea
• Vomiting

Reduce caffeine gradually to prevent any symptoms of withdrawal.

The effect of caffeine on health has been widely studied.

• Large amounts of caffeine may decrease bone mass density, most likely by interfering with the body's ability to absorb calcium. This may lead to osteoporosis.
• Caffeine may cause or worsen painful, lumpy breasts (fibrocystic disease).

Caffeine may have a negative effect on a child's nutrition if caffeinated drinks replace healthy drinks, such as milk. A child who consumes caffeine may also eat less, because caffeine reduces the appetite.

Recommendations

The American Medical Association Council on Scientific Affairs states that moderate tea or coffee drinking likely has no negative effect on health, as long as you live an otherwise healthy lifestyle.

• Three 8 oz. cups of coffee (about 250 milligrams of caffeine) per day and 5 servings of caffeinated soft drinks or tea is considered an average or moderate amount of caffeine.
• Ten 8 oz. cups of coffee per day is considered excessive intake of caffeine.

People who may want to avoid caffeine or only drink small amounts of it include:

• People who are prone to stress, anxiety, or sleep problems
• Women with painful, lumpy breasts
• People with acid reflux or stomach ulcers
• People with high blood pressure that does not respond to treatment
• People who have problems with fast or irregular heart rhythms
• People who have chronic headaches

Carefully watch how much caffeine a child gets. Even though caffeine is safe in moderate amounts, it is a stimulant. A hyperactive child may need to avoid caffeine.

Small amounts of caffeine during pregnancy are safe, but large amounts are strongly discouraged.

• Caffeine, like alcohol, travels through your bloodstream to the placenta and can have a negative affect on your baby. Because caffeine is a stimulant, it increases your heart rate and metabolism -- both of which directly affect the baby.
• It is okay to have one or two cups of coffee, tea, or cola a week, but try to give them up completely if you can.

Many drugs will interact with caffeine. Talk to your health care provider or pharmacist about possible interactions with caffeine whenever you take medications.

Alternative Names

Diet - caffeine

References

National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis -- 2008. Washington, DC.

Escott-Stump S. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.

Update Date: 5/5/2012

Reviewed by: Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.