Coffee and other caffeinated beverages are among the most popular in the world. People everywhere on this planet can’t seem to get enough of the stuff. But, can you have too much of a good thing?

With regard to caffeine, no-one seems to know.

Under current Commission regulations, the former Scientific Committee on Food (SCF), ruled back in 1999 that with the exception of pregnant women and children, caffeine consumption in ‘energy drinks’ when replacing other forms of the stimulant is not a ’cause for concern’.

The U.S. Food and Drug Administration lists caffeine as a “Multiple Purpose Generally Recognized as Safe Food Substance” – a listing reserved only for the more benign substances.

An acute “overdose” of caffeine is documented to be in excess of 300 milligrams, but this can depend on body weight and level of caffeine tolerance. This “overdose” has been termed caffeine intoxification which is simply a short-term central nervous system over-stimulation or the “caffeine jitters”.

Caffeine is completely absorbed by the stomach and small intestine within 45 minutes of ingestion. After ingestion it is distributed throughout all tissues of the body. Like alcohol and nicotine, caffeine readily crosses the blood–brain barrier that separates the bloodstream from the interior of the brain. Once in the brain, the principal mode of action is as an antagonist of adenosine receptors which promotes its stimulating effect.

The half-life of caffeine (the time required for the body to eliminate one-half of the total amount) varies widely among individuals according to such factors as age, body size and liver function. In healthy adults, caffeine’s half-life is approximately 3 to 4 hours.

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In cases of extreme overdose, death can result from caffeine consumption. The median lethal dose given orally, is 192 milligrams per kilogram in rats. In humans, this is estimated to be about 150 to 200 milligrams per kilogram of body mass, roughly 80 to 100 cups of coffee consumed over a few hours. As good as he is, even Paul Deila has trouble achieving that sort of mile-stone. The rest of us caffeine-fiends should feel pretty safe.

The other side of the coin…..

A regular cup of normally brewed coffee contains around 50-75milligrams of caffeine. As much as 4 to 5 cups of caffeinated coffee a day is a research documented prescription to enhance carbohydrate metabolism and reduce the risk of insulin resistance in tissues. A fairly high dose of caffeine improves health. It is interesting to note that many sports science studies suggest that the 300 milligrams dose classified as “intoxification” is the dose required to improve athletic performance.

Therefore, regarding safety and efficiency of caffeine, the bottom line recommendation appears to be somewhere between the equivalent of 5 but no more than 100 cups of coffee.

For the most socially accepted drug in the world, that’s the best science can come up with!

    References
    1. Forensic Sci Int 153 (1): 67–69, 2005.
    2. Cancer Lett. Sep 30, 2008.
    3. Crit Rev Food Sci Nutr. 46(2):101-23, 2006.
    4. Crit Rev Food Sci Nutr. 48(5):464-86, 2008.
    5. Curr Opin Clin Nutr Metab Care. 10(6):745-51, 2007.
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How much caffeine is too much?

by Paul Cribb Ph.D. CSCS. time to read: 2 min