Caffeine is a bitter substance found in coffee, tea, soft drinks, chocolate, some nuts and certain medicines. It has many effects on the body's metabolism, including stimulating the central nervous system. This can make you more alert and give you a boost of energy.
For most people, the amount of caffeine in two to four cups of coffee a day is not harmful. However, too much caffeine can make you restless, anxious and irritable. It may also keep you from sleeping well and cause headaches, abnormal heart rhythms or other problems. If you stop using caffeine, you could get withdrawal symptoms.
Some people are more sensitive to the effects of caffeine than others. They should limit their use of caffeine. So should pregnant and nursing women. Certain drugs and supplements may interact with caffeine. If you have questions about whether caffeine is safe for you, talk with your health care provider.
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Caffeine(American Heart Association) - http://www.americanheart.org/presenter.jhtml?identifier=4445
Also available in Spanish http://www.americanheart.org/presenter.jhtml?identifier=3041028
- Caffeine(National Sleep Foundation) - http://www.sleepfoundation.org/site/c.huIXKjM0IxF/b.2465369/apps/nl/content3.asp?content_id={5B9531C4-FAC0-48D9-B46C-B24F705A04CC}¬oc=1
- How Much Caffeine Is in Your Daily Habit?(Mayo Foundation for Medical Education and Research) - http://www.mayoclinic.com/print/caffeine/AN01211/METHOD=print
- Caffeine in Pregnancy Associated with Low Birth Weight Risk(11/03/2008, HealthDay) - http://www.nlm.nih.gov/medlineplus/news/fullstory_71181.html
- Caffeine Consumption Doesn't Raise Overall Breast Cancer Risk(10/14/2008, HealthDay) - http://www.nlm.nih.gov/medlineplus/news/fullstory_70381.html
- Caffeine for Athletes(Iowa State University, University Extension) - http://www.extension.iastate.edu/nutrition/supplements/caffeine.php
- Caffeine: How Does It Affect Blood Pressure?(Mayo Foundation for Medical Education and Research) - http://www.mayoclinic.com/print/blood-pressure/AN00792/METHOD=print
- Caffeine: How Much Is Too Much?(Mayo Foundation for Medical Education and Research) - http://www.mayoclinic.com/print/caffeine/NU00600/METHOD=print
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ClinicalTrials.gov: Caffeine
(National Institutes of Health) - http://clinicaltrials.gov/search/open/intervention=caffeine
- Relationship of Coffee Drinking and Death(American College of Physicians) - http://www.annals.org/cgi/content/full/148/12/I-40
- Article: Caffeine consumption and the risk of breast cancer in a... - http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=18852405&tool=MedlinePlus
- Article: Restoration of risk-propensity during sleep deprivation: caffeine, dextroamphetamine, and modafinil. - http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=18785355&tool=MedlinePlus
- Article: A summer caffeine rush. - http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=18763325&tool=MedlinePlus
- Caffeine -- see more articles - http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&db=pubmed&term=caffeine[majr]+AND+humans[mh]+AND+english[la]+AND+(review[pt]+OR+guideline[pt]+OR+clinical+trial[pt]+OR+jsubsetk[text]+OR+jsubsetaim[text]+OR+jsubsetn[text]+OR+patient+education+handout[pt])+NOT+(letter[pt]+OR+editorial[pt])&doptcmdl=summary&cmd_current=Limits&pmfilter_EDatLimit=last+1+Year&tool=MedlinePlus
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National Institute of Environmental Health Sciences - http://www.niehs.nih.gov/
Also available in Spanish http://www.niehs.nih.gov/about/community/espanol/
- Caffeine and Your Child(Nemours Foundation) - http://kidshealth.org/parent/food/general/caffeine.html
- Caffeine Confusion(Nemours Foundation) - http://kidshealth.org/kid/stay_healthy/food/caffeine.html
- Caffeine(Nemours Foundation) - http://kidshealth.org/teen/food_fitness/nutrition/caffeine.html
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Caffeine(Center for the Evaluation of Risks to Human Reproduction) - http://cerhr.niehs.nih.gov/common/caffeine.html
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Caffeine in Pregnancy(March of Dimes Birth Defects Foundation) - http://www.marchofdimes.com/professionals/14332_1148.asp
Also available in Spanish http://www.nacersano.org/centro/9246_9631.asp
- Food and Nutrition - http://www.nlm.nih.gov/medlineplus/foodandnutrition.html
The primary NIH organization for research on Caffeine is the National Institute of Environmental Health Sciences - http://www.niehs.nih.gov/