Added fat and calories Watch out for added fats and calories in your caffeinated drinks. Sodas can be loaded with sugar, and coffee and tea drinks can be loaded with fats and calories. Irregular heart beat, anxiety or insomnia Reduce caffeine intake if you experience irregular heart beats, anxiety or insomnia. People who experience an irregular heart beat when they consume caffeine, feel like their hearts are beating too fast, or are "skipping beats." For some, any caffeine is too much. Decaffeinated coffee, tea and cola drinks may be safe, since the amount of caffeine in these products is minimal. Many people experience feelings of stress and anxiety when they consume caffeine. This is because caffeine causes a version of the stress response in your body. And to add insult to injury, people are more likely to overindulge in caffeine when they are stressed, and end up feeling more stressed than before. Caffeine is a long-acting drug, so some of the caffeine consumed early in the day is still circulating in your bloodstream at night. If insomnia is a problem, giving up caffeine may be the answer. Limit consumption Consume no more than two to five caffeinated beverages a day. Even if you do not experience negative caffeine effects, health risks begin to appear in people consuming more than two cups of coffee a day, or somewhat larger amounts of tea or cola.

Also, switch from coffee to tea if you experience ulcers or heartburn. Coffee, not caffeine, is the culprit, since it increases stomach acid production, so decaf is no solution. People with digestive complaints should reduce or eliminate coffee. Tea is not as likely to provoke stomach problems.

Women should avoid caffeine when pregnant or nursing. High caffeine intake during pregnancy increases risk of miscarriage and low birth weight. Caffeine gets into breast milk, so nursing moms who consume caffeine may end up with irritable, fussy babies who have trouble sleeping.

The jury is still out on caffeine and heart disease risk, but it is probably a good idea to limit caffeine anyway, especially coffee. Two substances in unfiltered coffee raise blood cholesterol levels. Coffee may also raise the level of another marker of heart disease risk, homocysteine, in some people.

People concerned about anemia or bone density should keep an eye on tea and coffee. The polyphenols in tea and coffee interfere with iron absorption, so if you are taking iron supplements, drink your tea or coffee one hour before meals, and take the iron after the meal. Caffeine increases risk for osteoporosis, but only if calcium consumption is low.

Barbara A. Brehm, Ed.D., is professor of exercise and sport studies at Smith College, Northampton, Mass.