Cardiovascular Effects of Coffee: Is It a Risk Factor?

Chemical Characteristics

Caffeine (1,3,7-trimethylxanthine) belongs to the methylxanthines family. Theophylline, one of main remedies for bronchial asthma, and theobromine also belong to this family. Caffeine, theophylline and theobromine are three very similar alkaloids, present in different plants worldwide.^[1] They have similar effects but differ clearly in terms of potency—theophylline being stronger than caffeine, which is in turn stronger than theobromine. Coffee and decaffeinated coffee also contains a variety of other ingredients that have biologic activity. These include heterocyclic compounds with potent antioxidant effects and diterpenes such as cafestol and kahweol with chemoprotective properties.

More than 99% of orally ingested caffeine is absorbed.^[2] The maximal concentration of caffeine in plasma is reached after 60 minutes, but the interindividual differences are rather large. There is no correlation between time of intake and maximal plasma concentration of caffeine.^[3] Oral intake of caffeine (250 mg, comparable to two to three cups of coffee) results in plasma concentrations between 5 and 25 μg/mL, with 15% bound to plasma proteins.^[4] The plasma half-life of caffeine shows large interindividual variations and ranges between 3.0 and 7.5 hours.^[2,4] Between 0.5% and 3.5% of ingested caffeine is eliminated unmodified by the kidneys. There are many metabolites of caffeine. One of the most important is 1,7-dimethylxanthine. Caffeine clearance can be affected by various drugs, smoking, and pregnancy.

Prog Cardiovasc Nurs. 2005;20(2):65-69. © 2005 Le Jacq Communications, Inc.
© 2007 Prog Cardiovasc Nurs

Cite this: Cardiovascular Effects of Coffee: Is It a Risk Factor? - Medscape - May 01, 2005.