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Journal of Analytical Toxicology, VoL 30, March 2(]06
[ TechnicalNote
Caffeine Content of Energy Drinks, Carbonated Sodas,
and Other Beverages
Rachel R. McCusker 1, Bruce A. Goldberger 1,2,*, and Edward J. Cone 3
I Department of l~atholog); hnmunology, and Laboratory Medicine and 2Department of Psychiatry, University of Florida
College of Medicino, P.O. Box 100275, Gainesville, Florida 32610-0275 and 3ConeChem Research, LLC, 441 Fairtree Drive,
Severna Park, Maryland 21146
i
Abstract
The caffeine content of 10 energy drinks, 19 carbonated sodas, and
7 other beverages was determined. In addition, the variability of
the caffeine content of Coca-Cola | fountain soda was evaluated.
Caffeine was isolated from the samples by liquid-liquid extraction
and analyzed by gas chromatography with nitrogen-phosphorus
detection. The caffeine concentration of the caffeinated energy
drinks ranged from none detected to 141.1 rag/serving. The
caffeine content of the carbonated sodas ranged from none
detected to 48.2 rag/serving, and the content of the other
beverages ranged from < 2.7 to 105.7 mg/serving. The intra-assay
mean, standard deviation, and % coefficient of variation for the
Coca-Cola fountain samples were 44.5, 2.95, and 6.64 rag/serving,
respectively.
Introduction
Recently there has been an increase in the popularity of caf-
feine-containing "energy drinks" or "functional beverages".
Functional beverages are also known as nutraceutical foods,
which are substances considered to be a food or part of a food
that may provide some health benefit (1). Because of their na-
ture, such beverages are touted as "highly vitalizing", leading to
an "improvement of performance" and a "stimulation of
metabolism". However, there are important health concerns
that cannot be ignored with regards to the amount of caffeine
contained in these drinks.
The American Dietetic Association takes the position that
women of childbearing potential should adopt a health-pro-
moting lifestyle. Their recommendation includes the avoid-
ance of the ingestion of > 300 rag/day of caffeine, citing studies
finding increased risk of spontaneous abortion and low birth
weight children born to women consuming more than 150
rag/day of caffeine (2). Although there are studies demon-
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strating no association between fetal growth retardation and
maternal caffeine consumption (3,4), there are a plethora of
other studies demonstrating a positive association between ma-
ternal caffeine consumption and fetal growth retardation or
decreased birth weight. One such study found that women
whose caffeine intake was 71-140 mg per day had infants
weighing 116 g less than those who consumed 0-10 mg per day
(5). Another study found mothers of small-for-gestational-age
(SGA) infants had a higher mean intake of caffeine in the third
trimester than mothers of non-SGA infants (6). Further, an-
other study linked caffeine consumption to the risk of miscar-
riage, finding that caffeine consumption > 300 rag/day doubled
the risk of miscarriage (7). Though the literature is inconsistent
on fetal growth and spontaneous abortion as it relates to caf-
feine ingestion, there remains a need for caution when caf-
feine is consumed by pregnant women.
Children are another group that should be considered vul-
nerable to excess caffeine. A nationwide caffeine consumption
survey conducted of children aged 5 to 18 years found that 98%
studied consumed caffeine on a weekly basis, derived mostly
from carbonated beverages (8). One study concluded that chil-
dren and adolescents consuming caffeine in high concentra-
tions suffered from caffeine-induced headaches (9). In that study,
36 children were evaluated. They ranged in age from 6 to 18
years and were soda consumers, ingesting on average 192 mg of
caffeine a day. When the subjects ceased drinking soda, 33 ex-
perienced complete cessation of all headaches. In a separate
study involving 191 youths aged 12-15 years, it was found that
an average of 52.7 mg of caffeine was consumed daily and 18.8%
of the total number of subjects consumed 100 mg or more daily
(10). The primary source of caffeine was from consumption of
soft drinks. The study found that the high caffeine consumers ex-
perienced more interrupted sleep during the night.
Materials and Methods
In Phase One of this study, we evaluated the caffeine content
of 10 energy drinks, 19 carbonated sodas, and 7 other beverages.
112
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Journal of Analytical Toxicology, Vol. 30, March 2006
The beverages were purchased from various convenience stores
located in Oainesville, FL. In Phase TWo of this study, we eval-
uated the caffeine content of nine samples of fountain Coca-
Cola which were purchased from various eating establishments
located in Gainesville, FL.
The extraction procedure and instrumental parameters were
previously reported (11). Caffeine was isolated from the bever-
ages by liquid-liquid extraction, and the final extracts were
subjected to a gas chromatographic analysis utilizing nitrogen-
phosphorus detection. Quantitation of caffeine was based on a
calibration curve prepared in a concentration range of 25-250
mg/L for the caffeinated samples and 10-100 mg/L for the de-
caffeinated samples, with the limit of quantitation arbitrarily set
Table I. Caffeine Content of Energy Drinks, Carbonated
Sodas, and Other Beverages
Serving Caffeine
Beverage Size (oz) (mg/serving)
Energy Drinks
Red Devil | 8,4 41.8
SoBe| Adrenaline Rush 8.3 76.7
SoBe| No Fear 16 141.1
Hair of the Dog | 8.4 none detected
Red Celeste
TM
8.3 75.2
E Maxx
TM
8.4 73.6
Amp
TM
8.4 69.6
Red Bull | Sugarfree 8.3 64.7
Red Bull | 8,3 66.7
KMX
TM
8.4 33.3
Carbonated Sodas
Coca-Cola | Classic 12 29,5
Diet Coke | 12 38,2
Diet Coke | wittl Lime 12 39,6
Caffeine Free Diet Coke | 12 none detected
Vanilla Coke | 12 29.5
Pepsi | 12 31.7
Diet Pepsi | 12 27.4
Mountain Dew | 12 45,4
Mountain Dew | Live Wire
TM
12 48.2
Dr Pepper ~ ] 2 36,0
Diet Dr Pepper ~ 12 33.8
Sierra Mist
TM
12 none detected
Celeste
TM
Cola 12 t9.4
Sprite | 12 none detected
Seagram's | Ginger Ale 12 none detected
garq's | Root Beer 12 18.0
Pibb| 12 34.6
A&W | Root Beer 12 none detected
7-UP | 12 none detected
Other Beverages
Nestea | Cool Lemon Iced Tea 12 11.5
Lipton | Brisk Lemon Iced Tea 12 6.5
Yoohoo | Chocolate Drink 9 < 2.7
Starbucks Doubleshot
TM
6.5 105,7
Starbucks Frappuccino ~"~ Mocha 9.5 71.8
Starbucks Frappuccino ~ Vanilla 9.5 63.8
Velda Farms | Chocolate Milk 16 < 3,8
at the concentration of the lowest standard. Control samples
were prepared at 75 mg/L for the caffeinated sample batches
and 50 mg/L for the decaffeinated sample batches.
Results
The results of the caffeine analyses of the energy drinks, car-
bonated sodas, and other beverages (Phase One) are listed in
Table I. Brand names, serving sizes, and measured concentra-
tions of caffeine per serving are provided. The results of the caf-
feine analyses of fountain Coca-Cola samples (Phase Two) are
listed in Table II. The names of the eating establishments where
the samples were purchased, serving sizes, and measured con-
centrations of caffeine per serving are provided.
In Phase One of the study, all beverages purported to be caf-
feine-free contained no caffeine. The caffeine concentration of
the caffeinated carbonated sodas ranged from 18.0 to 48.2
rag/serving. The caffeine concentration of the nine caffeinated
energy drinks ranged from 33.3 to 141.1 mg/serving. The caf-
feine concentration of the remaining seven beverages ranged
from < 2.7 to 105.7 rag/serving.
In Phase Two of the study, the caffeine concentration of the
nine Coca-Cola fountain samples were within the range of 40.9
to 48.4 mg per 16-oz serving. The intra-assay mean (N = 9),
standard deviation, and % coefficient of variation were 44.5
mg/serving, 2.95, and 6.64, respectively.
Discussion
The Food and Drug Administration (FDA) has included caf-
feine in the list of substances that are generally recognized as
safe and has set the maximum concentration of caffeine in
cola beverages at 32.4 mg of caffeine per 6-oz bottle or 65 mg
of caffeine per 12 oz (12). Of the carbonated sodas evaluated, the
caffeine concentrations were in the range of 0-48.2 mS/serving
(12 oz). Such findings are well below the maximum allowable
limits of caffeine concentration per serving as specified by the
FDA.
Table II. Caffeine Content of Fountain Coca-Cola
Serving Caffeine
Establishment Size (oz) (mg/serving)
Burger King | 16 41,5
Wendy's | 16 41.5
McDonald's | 16 44.0
Chick-fiI-A | 16 48.4
Fast Track ] 6 45.5
Steak N Shake | 16 43,5
Atlanta Bread Company | 16 40,9
Checkers | 16 46.9
Citgo | Food Mart 16 48.4
113
Journal of Analytical Toxicology, Vol. 30, March 2006
The caffeine content of energy drinks and cold coffee bever-
ages is not currently regulated by the FDA. Further, these bev-
erages do not fall under the same FDA regulation that limits caf-
feine content of cola beverages. Caffeine content for the
majority of energy drinks included in this study was higher
than the maximum allowed limit for cola beverages (45.3
rag/8.4 oz or 86.4 rag/16 oz). One of the energy drinks packaged
as a 16-oz can contained 141.1 mg of caffeine, well above the
maximum allowed limit for cola beverages. Six of the energy
drinks evaluated contained caffeine concentrations in the range
of 64.7 to 76.7 mg per serving (8.3 or 8.4 oz). The caffeine con-
tent of one of the cold coffee beverages was 105.7 mg per 6.5 oz,
which is approximately three times the maximum allowed limit
for cola beverages (32.4 rag/6 oz).
We decided to assess the variability of Coca-Cola fountain
samples because of potential variation in dispensing. For ex-
ample, some establishments may opt to mix their sodas much
"heavier",
that is, with less carbonated water and more syrup,
thus leading to a more concentrated drink with more caffeine
per serving, whereas some establishments may serve a more di-
lute drink with less caffeine per serving. Surprisingly, we found
little variability in concentration of caffeine in the fountain
samples evaluated.
Because of the previously mentioned health concerns arising
from the consumption of caffeine, it seems appropriate that
warning labels should accompany all caffeinated beverages.
None of the carbonated sodas evaluated in this study were so la-
beled. Of the 10 energy drinks studied, only 4 were labeled with
some form of warning. Three such labels (SoBe Adrenaline
Rush, SoBe No Fear, AMP) advise that the product is not rec-
ommended for children and pregnant women, and the fourth
label (Red Devil) advises that "kids, pregnant women, and caf-
feine-sensitive persons" should not use their product in "large"
amounts. The term "large" was not specified, leaving its inter-
pretation entirely up to the consumer. In addition to warning la-
bels, additional labeling, such as expanding the nutrition facts
panel to include the amount of caffeine per serving, would be
appropriate. The nutrients label currently contains substances
such as total fat, cholesterol, carbohydrates, and sodium rec-
ommended for limited consumption. The modification of the
product label to include caffeine content would be beneficial for
the caffeine-sensitive consumer. Considering the documented
effects of caffeine on children and pregnant women, it would be
prudent for the consumer product labeling of all caffeinated
beverages to indicate the maximum amount of caffeine rec-
ommended for such groups. Of particular concern are those
non-cola beverages that currently contain 150-300% of the
FDA regulated amount per serving for cola beverages. Although
the caffeine content of the energy drinks and cold coffee bever-
ages may seem alarmingly elevated as compared to the caffeine
content of the carbonated sodas, our previous caffeine study
found much higher caffeine concentrations in specialty coffees
with a mean caffeine content of 188 mg per 16-oz serving (11).
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114