Caffeine is probably the best-known ingredient in coffee, tea, energy drinks, soft drinks and cocoa. While many people enjoy the taste of these drinks or use them to satisfy thirst, they may not be thinking about the effect of the caffeine they are ingesting along with that mocha latte or cappuccino. Too much caffeine can cause some problems.
How Much Caffeine?
Drugs.com notes that caffeine is a central nervous system stimulant and a diuretic. Generic brewed coffee can contain variable amounts of caffeine, depending on how long it brewed and the amount of coffee used. According to the Mayo Clinic, generic brewed coffee ranges from 95 to 200 mg of caffeine per cup. In the same way, caffeine in tea can vary depending on how long it steeps. Eight oz. of black tea ranges from 40 to 120 mg. The soft drink Mountain Dew has 54 mg of caffeine in 12 oz. A moderate intake is up to three 8-oz. cups of coffee a day or about 250 mg of caffeine. But if you reach 10 cups a day -- over 830 mg of caffeine -- Drugs.com says your intake is excessive.
Caffeine, Hallucinations and Incontinence
High caffeine intake -- seven or more cups a day of instant coffee -- increases the chances of people having visual and auditory hallucinations. Writing in the Durham University News, Simon Jones and co-author Dr. Charles Fernyhough reported on 200 students whose caffeine intake from all sources was assessed and then correlated with seeing things or hearing voices. Reuters Health writer Amy Norton reported that Dr. Mary K. Townsend completed a study that found that women who drank four or more cups of coffee a day were more likely to have urinary incontinence.
Caffeine Intoxication
The most dangerous consequence of a high caffeine intake is a serious syndrome called caffeine intoxication. In people sensitive to caffeine, poison control specialist Holly Pohler reports, even 250 mg can cause nausea and vomiting, nervousness, agitation, headache, tremor and sleep disturbances. Caffeine intoxication can even cause seizures, she notes in the January 2010 "Journal for Nurse Practitioners."
Final Words
Coffee is popular in many beverages and harmless when consumed in moderation. But serious side effects can occur with the equivalent of three cups of coffee. If you think you may be having symptoms related to excess caffeine, don't just stop abruptly -- it can result in withdrawal symptoms such as headaches. To taper off, Drugs.com suggests you cut your consumption in half each day.
References
- National institutes of Health; Medline Plus; Caffeine; June 2011
- Caffeine in the Diet; David C. Dugdale, III, M.D., David Zieve, M.D., M.H.A.; May 2009
- Mayo Clinic; Nutrition and Healthy Eating; Caffeine Content for Coffee, Tea, Soda and More; Mayo Clinic Staff; October 2009
- Durham University; News; High Caffeine Intake Linked to Hallucination Proneness; May 2011
- Reuters Health; Very High Caffeine Intake Linked to Leaky Bladder; Amy Norton; April 2011
- "Journal of Nurse Practitioners; Caffeine Intoxication and Addiction; Holly Pohler; January 2010
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