The health consequences of caffeine.

Acutely administered caffeine modestly increases blood pressure, plasma catecholamine levels, plasma renin activity, serum free fatty acid levels, urine production, and gastric acid secretion. It alters the electroencephalographic spectrum, mood, and sleep patterns of normal volunteers. Chronic caffeine consumption has no effect on blood pressure, plasma catecholamine levels, plasma renin activity, serum cholesterol concentration, blood glucose levels, or urine production. Caffeine does not appear to be useful for increasing the motility of hypomotile sperm in artificial insemination or in the therapy of minimal brain dysfunction, cancer, or Parkinson's syndrome, but it may be effective as a topical treatment of atopic dermatitis and as systemic therapy for neonatal apnea. Caffeine does not seem to be associated with myocardial infarction; lower urinary tract, renal, or pancreatic cancer; teratogenicity; or fibrocystic breast disease. The role of caffeine in the production of cardiac arrhythmias or gastric or duodenal ulcers remains uncertain.