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41 cases of caffeine intoxication were reported in the United States from 2002 to 2004. This fact could indicate an increase in caffeine dependence as well as withdrawal symptoms. A moderate amount of caffeine intake, which is around 300mg or the equivalent of 4 cups of coffee per day, is regarded as a safe amount of caffeine to be consumed.
Caffeine is readily absorbed by the gastrointestinal tract of the human body and up to 99% of the chemical is absorbed within 45 minutes. Caffeine penetrates through biological membranes such as the blood-brain barrier (BBB) and the placenta, which is why it causes neurological affects as well as affecting a fetus. Caffeine does not accumulate in tissues or organs.
Effects of caffeine on the body
Caffeine can affect many other systems of the body and they include the following:
- Cardiovascular system - caffeine can cause arterial wall stiffness as well as vasodilatation which results in an increased blood pressure. It should therefore be consumed with caution in people who are hypertensive and who are experiencing high stress levels.
- Respiratory system - the respiratory rate is increased here.
- Gastrointestinal system - the small intestine becomes stimulated which results in the release of water and sodium from this organ. Caffeine can also lead to an upset stomach and result in symptoms such as abdominal cramps, nausea and vomiting.
- Urinary system - increased urinary frequency occurs due to the release of water from the gastrointestinal tract.
- Endocrine system - caffeine stimulates the release of catecholamines which results in an increase in the basal metabolic rate. This process includes lipolysis which releases free fatty acids.
Interactions with certain medications or supplements
It's very important to take note of interactions that caffeine may have with certain medications. Some of the more important interactions include the following:
- Antibiotics - Ciprofloxacin and norfloxacin can interfere with the breakdown of caffeine which can result in an increased length of time of caffeine in the body. This can then lead to unwanted effects of caffeine.
- Theophylline - taking this medication with caffeine containing products can increase the effect of theophylline. This can then result in symptoms such as nausea, vomiting and heart palpitations.
- Echinacea - this is a natural supplement used to prevent infections such as the common cold. This supplement can increase the concentration of caffeine when taken together, and can then increase the effects of caffeine on the body.