When consumed in moderation, caffeine has many beneficial effects. Over-consumption, however, can contribute to a variety of health problems. For optimal health benefit, the National Institutes of Health website MedlinePlus recommends limiting your caffeine intake to 250 mg per day, which is equivalent to three 8-oz. cups of coffee. Consult your doctor about caffeine consumption if you are pregnant or if you have ulcers or heart disease.
Energy and Focus
Because caffeine stimulates the central nervous system, it is classified as a stimulant. This leads to increased focus, alertness and energy. It also delays the onset of fatigue during exercise, according to a study published in the "American Journal of Physiology." These effects can last up to six hours after caffeine intake. When it is consumed in excessive amounts, however, these effects are amplified, which may result in anxiety and rapid heartbeat.
Cardiovascular Effects
Whether or not caffeine consumption contributes to an increased rate of heart disease is still under examination, according to the American Heart Association. Caffeine does raise blood pressure temporarily after it is consumed, which may be caused by interactions with hormones. According to hypertension specialist Sheldon G. Sheps of MayoClinic.com, you should limit your caffeine intake if you have high blood pressure or eliminate caffeine from your diet altogether. If you are at high risk for developing hypertension, consider limiting your caffeine intake to 200 mg per day.
Headaches
Caffeine is often added to pain relievers, due to its ability to fight headaches. According to BBC News Health, caffeine has been shown to be especially effective against tension headaches. Regular, excessive caffeine consumption, however, can also cause headaches, as noted by Drugs.com. In a 2009 study by researchers at Norwegian University of Science and Technology, people who consumed 500 mg. or more of caffeine each day were 18 percent more likely to experience non-migraine headaches than those who consumed it in moderate amounts.
Effects on Metabolism
Caffeine consumption has a variety of effects on metabolism. It acts as a diuretic, which means it causes you to urinate more frequently, and also stimulates digestion. Caffeine may also cause decreased appetite. Because of these metabolic effects, caffeine is sometimes promoted as a weight loss aid. According to Katherine Zeratsky of MayoClinic.com, however, caffeine does not cause long-term, sustained weight loss, although it may contribute to short-term weight loss and weight gain prevention.
References
- MedlinePlus: Caffeine in the Diet
- American Journal of Physiology; "Central Nervous System Effects of Caffeine and Adenosine on Fatigue"; J. Mark Davis et al.; 2002
- American Heart Associarion: Caffeine
- MayoClinic.com; Caffeine: How Does it Affect Blood Pressure?; Sheldon G. Sheps
- BBC News Health; Caffeine 'Can Ease Headaches'; October 2001
- Drugs.com: High-Octane Caffeine May Trigger Headaches
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