Date: Fri Oct 1 08:51:54 1999
Posted By: Mary Hadley, Faculty, Food and Nutrition, North Dakota State University
Area of science: Chemistry
One of my colleagues found this web site:
You might like to check it out.
Caffeine belongs to a group of compounds called methylxanthines. Another
compound in this class of chemicals is theophylline which is found in tea.
I will define metabolism before answering your question. Scientists define
'metabolism' as all the chemical reactions that occur in a living organism.
We do know that both caffeine and theophylline inhibit an enzyme
(phosphodiesterase) that inactivates c-AMP. Through several steps, the
inhibition of phosphodiesterase leads to increased blood glucose and fatty
acid levels along with increased oxygen consumption and for so for short
periods of time we feel more alert. So, although caffeine inhibits only one
enzyme, the consequences of that inhibition are far reaching and many many
enzymatic reactions are influenced.
Effects of caffeine
Lastly, there are many studies in which caffeine has been SUGGESTED to play a
role in several diseases. For instance, there are reports in the literature in
which very high caffeine intake has been related to:
However, there is no definitive answer as to the role of caffeine in these
conditions or in different forms of human
- High caffeine (3-5 cups of coffee a dayor 200-400 mg caffeine/day) or
theophylline intake increase excreation of calcium in the urine and may have
some role in osteoporosis. How it does this is not clear. Tea has a little
less caffeine per cup than coffee. Remember too that many cola drinks have
- Heart rate increases and so does the amount of blood pumped each time the
heart pumps. Very large doses of caffeine can cause very fast irregular
- Scientist think the effects of caffeine are most likely due to caffeine
competing with adenosine for a receptor on nervous tissue. Adenosine
inhibits neuronal activity so when caffeine gets into the receptor there is
- Prolonged large intakes of caffeine may lead to flu like-symptoms. The jolt
one gets from a given amount of coffee decreases with time so one must
drink more and more to get the same effect.
Hope that helps.
Reference: pp. 619 - 630
The Pharmacological Basis of Medical Therapeutics, 8th ed.
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