Does Caffeine Cause Deyhdration?

For years, many in the health field have claimed that caffeine is a diuretic and that consuming excessive amounts can lead to dehydration. This long-held belief is now being challenged. Caffeine does have some definite side effects. If caffeine is not a regular part of your diet, make sure you consult a health care provider before trying caffeinated drinks or supplements.

No Simple Answer

A few conditions contribute to dehydration -- excessive sweating, vomiting, diarrhea, fever and increased urination. However, caffeine intake does not appear to directly cause any one of these conditions. It is not a true diuretic, nor does it cause fever, vomiting or diarrhea. Registered dietitian Katherine Zeratsky of Mayo Clinic notes that caffeine might have adverse effects, including diuretic effects, but only in large quantities -- more than 500 to 600 mg, or 5 to 7 cups of coffee per day. So, the short answer is no, caffeine is not dehydrating, unless you consume it in large doses.

Caffeine

Caffeine is part of a group of compounds classified as stimulants. It is naturally present in many plants, such as coffee, cocoa, tea and herbs like guarana and kola nut. If you consume caffeine in excessive amounts, potential adverse effects include jitteriness, anxiety, insomnia and gastrointestinal upset. You might develop a caffeine addiction, so only consume it in moderation. In addition to coffee, tea and some colas, many diet supplements contain caffeine. Because of their potential side effects, always consult your health care provider before taking supplements or other products containing caffeine.

What the Research Says

For many years, scientists have supported the idea that caffeine is a diuretic. In a review of recent scientific literature on the subject, published in the "Journal of Human Nutrition and Dietetics" in 2002, researchers found that low to moderate caffeine consumption did not increase fluid output or directly cause dehydration. However, in cases where more than 2 to 3 cups of coffee or 5 to 8 cups of tea were consumed over the course of a day, there was a short-term diuretic effect in test subjects. However, researchers concluded there was not enough evidence to state that caffeine intake causes dehydration or fluid imbalance.

Some Considerations

Make sure you get plenty of water each day. The general rule is to drink eight 8-oz. glasses of water daily. Experts from Mayo Clinic now recommend different amounts for men and women. Women should consume around 9 cups of water, and men as much as 13 cups each day. Try to consume at least as much fluid as you put out -- more if you exercise or are sick -- and avoid taking excessive amounts of caffeine.