The Perils of Caffeine

Some people should avoid caffeine, including those with certain heart problems or with insomnia or anxiety disorders. There are no life-threatening, long-term health risks associated with caffeine, but there are reasons to monitor your consumption.

It disturbs sleep.Caffeine can keep you from falling asleep, reduce the length of time you sleep, and alter the normal stages of sleep. "Caffeine-induced sleep disturbance is greatest among people who are not regular caffeine users," says Griffiths. The effects of caffeine can be felt for six hours or more after its consumption.

It increases jitteriness and anxiety. In some people, especially those prone to anxiety problems, just 200 milligrams of caffeine — about two cups of drip coffee — can increase anxiety and even cause panic attacks, says Griffiths. "If you have a stressful job or are experiencing stress in your life, you might want to cut out caffeine for a while," he says. Very high doses — 500 to 600 milligrams a day, or four to seven cups of coffee — can lead to caffeinism, a syndrome characterized by chronic restlessness, irritation, and stomach upset.

It is associated with fertility problems. One study suggests that women who consume more than two or three cups of coffee a day may decrease their odds of conception for as long as they use caffeine. Caffeine is metabolized differently during certain phases of a woman's menstrual cycle and can interfere with the implantation of an embryo in the uterus. Men who drink more than two cups of coffee a day may have more sluggish sperm than men who abstain, "Many doctors will tell you to give it up if you're trying to get pregnant," says Segall.

Going without it can lead to withdrawal symptoms. If you normally consume caffeine every day, going without it — for even one day — can lead to headaches, irritability, fatigue, difficulty concentrating, flulike symptoms, and impaired thinking. The more you consume, the more severe your withdrawal symptoms are likely to be.

It may affect bone health in women who don't get enough calcium. Researchers are not sure why, but some studies show that women who consume caffeine, a diuretic, may lose calcium in their urine. Other researchers theorize that women who drink a lot of caffeine in the form of coffee and diet drinks forgo milk, thus missing out on calcium. There is no evidence that women who take in the recommended daily amount of calcium risk their bones if they also consume caffeine. "If you drink coffee, drink at least one glass of milk a day, and the potential for (negative) effects is nil," Segall says.

It can aggravate heart problems. The cardiovascular responses are one reason that people with certain heart conditions might want to abstain from caffeine. "The amount of caffeine in one or two cups temporarily increases blood pressure and raises the heart rate a couple of points," says Segall. "It's not life-threatening, but I still wouldn't recommend using caffeine if you have heart problems."