Taking more than 500 to 600 milligrams of caffeine daily has been associated with adverse effects such as stomach upset and arrhythmia, MayoClinic.com says. Moderate caffeine doses of 200 to 300 milligrams, roughly equal to between two and four cups of coffee, daily is generally not considered harmful. However, regularly taking excessive caffeine will potentially damage organs such as your heart, according to a study featured in a 1993 issue of “Comparative Biochemistry and Physiology.”
Heart
Rat hearts exposed to 10 millimolars of caffeine sustained severe cellular damage, according to a study published in a 1993 issue of “Comparative Biochemistry and Physiology.” Further research is needed to determine whether exposure to high levels of caffeine injures human hearts. Moreover, factors that affect the degree of potential damage sustained also require more study.
Kidneys
A study featured in a 2007 issue of “Renal Failure” found that caffeine intake damaged the kidneys of obese rats. Although the study showed that caffeine initially had beneficial effects such as reduced body weight and improved glucose tolerance, adverse effects such as increased renal vascular resistance and heart occurred two weeks after caffeine intake was initiated. The study determined that chronic caffeine consumption eventually damaged the kidneys and induced adverse effects such as renal inflammation and fibrosis. While more research is needed to establish whether the same holds true for humans, the study’s results suggest that chronic consumption of even a small amount of caffeine is potentially harmful to the kidneys in the long run.
Stomach
Stomach ulcers are open sores or lesions found on the lining of the stomach as a result of hydrochloric or pepsin damage, the University of Maryland Medical Center notes. Factors such as the level of stomach acid and pepsin secretion as well as diet contribute to ulcer formation. Caffeine seems to contribute to factors that cause your stomach to secrete excessive amounts of stomach acid. However, other factors such as diet and health conditions also affect stomach acid secretion. So it is not possible to attribute ulcer formation to excessive caffeine consumption alone.
Other Side Effects
Other side effects associated with caffeine include insomnia, increased urination, depression and tremors, Medline Plus, a service of the National Institutes of Health, says. Other adverse effects associated with caffeine consumption include decreased bone density, because caffeine impairs your ability to absorb calcium. Sudden cessation of caffeine consumption often induces withdrawal symptoms. Reduce your level of consumption gradually.
References
- "Comparative Biochemistry and Physiology"; Cellular Damage in the Rat Heart Caused by Caffeine or Dinitrophenol; Daniels S., et al.; June 1993
- Mayo Clinic; Caffeine: How Much is Too Much; March 2011
- Medline Plus; Caffeine; Alison Evert; May 2011
- "Renal Failure"; Early Renal Injury Induced by Caffeine Consumption in Obese, Diabetic ZSF1 Rats; Tofovic S.P., et al.; 2007
- University of Maryland Medical Center; Stomach and Duodenal Ulcers (Peptic Ulcer); January 2008
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