Caffeine is a substance that is found in certain plants. It can also be man-made and added to foods. It is a central nervous system stimulant and a diuretic (substance that helps rid your body of fluids).
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.
Caffeine is widely consumed. It is found naturally in the leaves, seeds, and fruits of more than 60 plants, including:
- Tea leaves
- Kola nuts
- Cocoa beans
It is also found in processed foods:
- Coffee – 100 mg per cup
- Tea – 14 mg to 60 mg per cup
- Chocolate – 45 mg in 1.5 oz. bar
- Most colas (unless they are labeled "caffeine-free") – 45 mg in 12 oz. drink
- Candies, energy drinks, snacks, gum – 40 - 100 mg per serving
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. It can be removed from a food by a chemical process called decaffeination.
Caffeine can lead to:
- A fast heart rate
- Difficulty sleeping
- Urinating more often
Stopping caffeine suddenly may cause withdrawal symptoms. These may include:
There has been much research on the health effects of caffeine.
- Large amounts of caffeine may stop the absorption of calcium and cause lead to thinning bones (osteoporosis).
- Caffeine may lead to painful, lumpy breasts (fibrocystic disease).
Caffeine may harm a child's nutrition if drinks with caffeine replace healthy drinks such as milk. Caffeine cuts down on appetite so a child who consumes caffeine may eat less. The United States has not developed guidelines for caffeine intake and children.
The American Medical Association Council on Scientific Affairs states that moderate tea or coffee drinking is not likely to be harmful as to your health as long as you have other good health habits.
- Two to three 8 oz. cups of brewed or drip coffee (about 200 to 300 mg of caffeine) per day and 5 servings of caffeinated soft drinks or tea is an average or moderate amount of caffeine for most people. (However, it should be noted that 5 servings of regular soft drinks is over 700 calories and can contribute to obesity.)
- Ten 8 oz. cups of coffee per day is considered excessive intake of caffeine.
You may want to limit your caffeine intake if:
- You are prone to stress, anxiety, or sleep problems.
- You are woman with painful, lumpy breasts.
- You have acid reflux or stomach ulcers
- Have high blood pressure that does get lower with medicine.
- You have problems with fast or irregular heart rhythms.
- You have chronic headaches.
Watch how much caffeine a child gets. Caffeine is a stimulant and a hyperactive child may need to avoid it. Small amounts of caffeine during pregnancy are safe. Avoid large amounts.
- Caffeine, like alcohol, travels through your bloodstream to the placenta. It can have a negative effect on a developing baby. Caffeine is a stimulant, so it increases your heart rate and metabolism. Both of these can affect the baby.
- It is okay to have one or two cups of coffee, tea, or cola a week.
- Try to give up caffeine completely if you can.
Many drugs will interact with caffeine. Talk to your health care provider about possible interactions with the medicines you take.
If you are trying to cut back on caffeine, reduce you intake slowly to prevent withdrawal symptoms.
Diet - caffeine
Chin JM et al. Caffeine content of brewed teas. J Anal Toxicol.
Gagne L, Maizes V. Osteoporosis. In: Rakel D, ed. Integrative Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 37.
Update Date 4/30/2013
Updated by: Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.