Caffeine In Colas: "The Real Thing" Isn't The Taste
"The marketing parallels between nicotine and caffeine are pretty stunning"
The majority of people who drink colas can't tell whether a soda contains caffeine or
not, according to a new Johns Hopkins study. "This stands in sharp contrast to the
claim some soft drink manufacturers make that they add caffeine purely for taste,"
says psychopharmacologist Roland Griffiths, Ph.D., who directed the research.
In a study of 25 adult cola drinkers, the scientists found that only 8 percent of them
could detect caffeine in cola at a concentration of 0.1 milligram per milliliter, the
concentration in Coca-Cola Classic or Pepsi. The rest of the group couldn't taste
the difference between caffeine-containing and caffeine-free cola until caffeine levels
were raised to much higher levels beyond those approved by the U.S. Food and
Drug Administration (FDA).
The report appears in this month's Archives of Family Medicine.
"I'd like to see the soft drink industry come out of denial about the role of caffeine in
their products," says Griffiths. "They're adding a mildly addictive, mood-altering
drug, one which surely accounts for the fact that people drink far more sodas with
caffeine than without." About 70 percent of all soft drinks in this country contain
caffeine, he adds. The caffeine-free versions of Coca-Cola Classic and Pepsi, the
two most popular soft drinks, make up only 5 percent of sales of those sodas.
"Given that sodas are aggressively marketed to kids, manufacturers should openly
say why the caffeine is there. We should tell what the caffeine dose is. It's a case of
knowing what you're getting and why.
"The marketing parallels between nicotine and caffeine are pretty stunning," says
Griffiths. "Both are psychoactive drugs. Until recently, cigarette companies denied
that nicotine is addicting and said it was added merely as a flavor enhancer for
cigarettes. The same is being said for caffeine." In 1998, Americans guzzled 15
billion gallons of sodas, the equivalent of 585 cans for every man, woman and child.
Consumption of soft drinks has more than doubled since 1975 and more sodas are
consumed than water, says Griffiths. Soft drinks also represent the single largest
source of added sugar in the U.S. diet, according to sources cited in the study, and
increased soda drinking in children displaces eating more nutritious foods, possibly
increasing tooth decay, obesity and bone fracture.
"We know adults and children can become physiologically and psychologically
dependent on caffeinated soft drinks, experiencing a withdrawal syndrome if they
stop," says Griffiths. Earlier research at Hopkins shows that withdrawal symptoms
typically include headache and lethargy, and last a day or two.
"Most adults can become informed about, and cope with, withdrawal," says
Griffiths.
"But it is more problematic in children who are less well-informed and whose soft
drink consumption may be sporadic. Then children may go in and out of withdrawal
and have erratic periods of suboptimal feelings that could affect the way they
function."
In the study, the scientists first made sure that subjects could distinguish Diet Coke
from regular Coca-Cola a sign that they had reasonable taste sensitivity. Then,
during the actual test sessions, subjects sipped from 50 cups of soda, a pair at a
time, to see if they could distinguish between caffeine-free Coke and that with added
caffeine. Subjects were paid $10 per session and 25 cents for each correct answer.
The first five trials in each session were "warm-up" trials, in which participants were
told what they were drinking.
"We tried hard to design this study so it would be a fair test of whether caffeine
affects cola taste," says Griffiths. The scientists used cola from a single production
batch for each study session; subjects were required to rinse their mouths with water
after tasting each sample. The "warm up" trials were added to heighten the ability to
taste a difference. Subjects were chosen in part because they were regular cola
drinkers who believed they preferred caffeinated colas because of their taste. That
fact and the money reward helped ensure that they were motivated to participate,
says Griffiths.
Caffeine has long been added to colas, he adds. Early advertisements played up its
value as a stimulant until about 1920, when the U.S. government questioned its use
in soft drinks. "The objections, however, were countered by industry," says Griffiths,
"and sodas continued to contain caffeine. In 1981, the FDA again reviewed addition
of caffeine to soft drinks to see if they should maintain their GRAS (generally
recognized as safe) status.
"Nobody knew much then about caffeine's behavioral or mood-altering effects at
low doses. Industry scientists again countered queries, this time with studies that
appeared to show how important caffeine was to flavor.
"Since then, though, the picture has changed," says Griffiths. "Soft drink
consumption has gone through the roof. There's marketing of larger volumes of soda
drinks like the Big Gulp, and industry has now started targeting advertising to
children."
Ellen M. Vernotica, Ph.D., was a co-researcher in this study, which was funded by
the National Institute on Drug Abuse.
Related Web Sites:
* cspinet.org for a soft drink site from the Center for Science
in the Public Interest
*
med.jhu.edu
Editor's Note: The original news release can be found at
hopkins.med.jhu.edu |
