(NaturalNews) Coffee no longer boosts energy or alertness levels above baseline in regular drinkers of the beverage, according to a study conducted by researchers from Bristol University and published in the journal Neuropsychopharmacology.
"Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee or other caffeine-containing drink, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute caffeine withdrawal," the researchers wrote.
Scientists assigned 379 volunteers to drink either a beverage containing the caffeine found in a 100-milligram shot of espresso, or a placebo containing no caffeine. Prior to beginning the study, all participants had abstained from caffeine consumption for 16 hours.
The researchers found that among participants who drank less than one cup of coffee per day, drinking the caffeinated beverage resulted in enhanced performance on tests of alertness, while the placebo had no noticeable effect.
In contrast, participants who regularly drank between one and six cups of coffee a day self-reported a decrease in alertness and an increase in headache following consumption of the placebo, in contrast to the low-coffee-drinkers who reported no such effects. Regular coffee drinkers who received the placebo also scored lower on objective tests of alertness than members of all other groups.
Regular coffee drinkers who had received real caffeine, by comparison, scored the same on alertness test as infrequent drinkers who had received the placebo.
The study supports the theory that the body quickly develops a dependence on caffeine, soon requiring it just for normal levels of alertness. Thus, regular coffee drinkers actually become less alert when they stop drinking it, not more alert when they consume it.
A spokesperson for the British Coffee Association disputed the findings, stating that caffeine increases alertness levels and is safe to consume in moderation. He also said that pregnant women should avoid consuming more than 200 milligrams of caffeine per day.