ArticlePDF Available

Effects of chronic consumption of energy drinks on liver and kidney of experimental rats

Authors:

Abstract and Figures

Purpose: To investigate the effects of chronic intake of a brand of energy drink (ED) on the liver and kidney of rats. Methods: Sixty male adult Sprague Dawley albino rats were randomly assigned to four groups (15 rats per group). Three groups received ED at different doses (0.4, 1.1 and 2.2 ml/100 g body weight/day) for 12 weeks. The fourth group (control) received distilled water. All treatments were administered by oral gavage. Blood samples were withdrawn at the start of the experiment, and at the 6th and 12th weeks for assay of hepatic and renal biochemical parameters. Histopathological studies were done at the end of the exposure period. Results: Exposure to ED doses of 1.1 and 2.2 ml/100g body weight/day for 12 weeks induced highly significant increases in serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), blood urea nitrogen (BUN), creatinine and uric acid, when compared with the control group (p < 0.001). On the other hand, the activities of the antioxidant enzymes, viz, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) significantly decreased (p < 0.001) by exposure to these two ED doses, relative to controls. Pronounced histopathological changes were observed in hepatic and renal tissues of the ED-treated rats. Conclusion: Oral exposure of rats to ED for 12 weeks produced noticeable hepatic and renal damage, probably due to increased free radical production and oxidative stress. This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest
Content may be subject to copyright.
Mansy et al
2849
Tropical Journal of Pharmaceutical Research December 2017; 16 (12): 2849-2856
ISSN: 1596-5996 (print); 1596-9827 (electronic)
© Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria.
Available online at http://www.tjpr.org
http://dx.doi.org/10.4314/tjpr.v16i12.8
Original Research Article
Effects of chronic consumption of energy drinks on liver
and kidney of experimental rats
Wael Mansy1,2*, Deema M Alogaiel3, Mona Hanafi4, Enas Zakaria5
1Clinical Pharmacy Department, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia, 2Pharmacology
Department, Faculty of Medicine, Cairo University, Cairo, Egypt, 3Health Sciences Department, College of Health and
Rehabilitation, Princess Nourah Bint Abdulrahman University, 4Department of Community Health Sciences. College of Applied
Medical Sciences, 5Pharmaceutics Department, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
*For correspondence: Email: whsayed@hotmail.com; Tel: +966567253275
Sent for review: 26 June 2017 Revised accepted: 19 November 2017
Abstract
Purpose: To investigate the effects of chronic intake of a brand of energy drink (ED) on the liver and
kidney of rats.
Methods: Sixty male adult Sprague Dawley albino rats were randomly assigned to four groups (15 rats
per group). Three groups received ED at different doses (0.4, 1.1 and 2.2 ml/100 g body weight/day) for
12 weeks. The fourth group (control) received distilled water. All treatments were administered by oral
gavage. Blood samples were withdrawn at the start of the experiment, and at the 6th and 12th weeks for
assay of hepatic and renal biochemical parameters. Histopathological studies were done at the end of
the exposure period.
Results: Exposure to ED doses of 1.1 and 2.2 ml/100g body weight/day for 12 weeks induced highly
significant increases in serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline
phosphatase (ALP), blood urea nitrogen (BUN), creatinine and uric acid, when compared with the
control group (p < 0.001). On the other hand, the activities of the antioxidant enzymes, viz, superoxide
dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) significantly decreased (p < 0.001)
by exposure to these two ED doses, relative to controls. Pronounced histopathological changes were
observed in hepatic and renal tissues of the ED-treated rats.
Conclusion: Oral exposure of rats to ED for 12 weeks produced noticeable hepatic and renal damage,
probably due to increased free radical production and oxidative stress.
Keywords: Energy drink, Reactive oxygen species, Liver function, Kidney function, Histopathological
changes
This is an Open Access article that uses a funding model which does not charge readers or their institutions
for access and distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative
(http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly credited.
Tropical Journal of Pharmaceutical Research is indexed by Science Citation Index (SciSearch), Scopus,
International Pharmaceutical Abstract, Chemical Abstracts, Embase, Index Copernicus, EBSCO, African
Index Medicus, JournalSeek, Journal Citation Reports/Science Edition, Directory of Open Access Journals
(DOAJ), African Journal Online, Bioline International, Open-J-Gate and Pharmacy Abstracts
INTRODUCTION
First appearance of energy drinks (EDs) was in
Europe and Asia in the 1960 as a result of
customer requirements for dietary supplements
that give energy [1]. Many Saudi studies found
that more than half of the consumers were
young (13 - 35 years old), more than half
consumed it for over a year, and over 40 %
used to drink more than 3 cans per week [2].
Centers for Disease Control and Prevention
reported that high school students consume
-----------------------------------------------------------------------------------------------------------------------------
------------------------
© 2017 The authors. This work is licensed under the Creative Commons Attribution 4.0 International License
Mansy et al
2850
EDs almost at the same rate as they consume
soda [1]. Indeed, the rate of ED consumption
might be higher than estimated levels in this
self-reporting survey, since such surveys
usually have high probability of under-
estimation.
It has been revealed that EDs contain mainly
taurine, glucuronolactone, caffeine, ginseng
and guarana [3]. These substances, most of
which act as stimulants, are not included in the
list of materials under regulation by the Food
and Drug Administration (FDA) of the United
States of America. The levels of these
stimulants vary amongst different brands of
EDs, and in most cases, are higher than values
allowable [4]. A study has shown that the
caffeine levels in EDs are between 50 and 505
mg/ can, which are much higher than the
caffeine content of one can of Coke (34 mg) [5].
Reports of significant, adverse health problems
due to ingestion of EDs have increased in
recent years. Indeed, in 2013, ED-associated
emergency interventions by the US Substance
Abuse and Mental Health Services
Administration doubled from 10,068 in 2017 to
over 20,000 in 2011 [6]. A major constraint in
understanding the link between EDs and the
adverse effects of their consumption is that very
little is known about the toxicity of the various
compounds present in them. However, based
on reported cases of ED-associated health
problems, and the well-established
physiological effects of the active ingredients of
EDs, it is very likely that the observed adverse
effects of EDs are linked to their compositions
[3]. Due to the aforementioned reasons we
purposed this study to explore the toxic effects
of prolonged intake of ED on hepatic and renal
tissues of rats.
EXPERIMENTAL
Energy drink
The brand of ED used in the present study was
“Red bull”, product of Rauch Trading AG,
Switzerland (manufactured for Red Bull GmbH,
Austria). It was purchased from a local store in
Riyadh, Saudi Arabia.
Animal feeding
Sixty (60) adult, male Sprague Dawley rats
(mean weight = 115.5g) were kept in the Animal
House of College of Pharmacy, King Saud
University. The rats were acclimatized under a
12h/12h light/dark photoperiod and under normal,
healthy laboratory conditions at a mean
temperature of 25 ± 2 °C. The experiments were
carried out in line with the recommendations of
International Laboratory Animal Use and Care
[7]. The study protocols and ethics were
approved by the Animal Research and Ethical
Committee of King Saud University (approval No.
CAMS24/3334, June 2013).
Experimental design
Four (4) groups of rats were used (15
rats/group). There was no bias in the allocation
of rats to any group. Rats in the control group
(G1) were maintained on the basal diet and
distilled water throughout the experiment. Three
levels of ED exposure were used: mild,
moderate and high ED. Rats in the mild ED
intake group (G2) was given low dose of ED
(0.4 ml / 100 g body weight / day) to simulate
low human consumption pattern (280 ml/ED
can), while the moderate ED group (G3)
received 1.1 ml /100g body weight / day, to
reflect moderate human consumption level of
770ml (about 3 cans of ED). The high ED intake
group (G4) was given 2.2 ml/100 g body
weight/day to mimic estimated high human
consumption level of 1540 ml (about six cans).
All treatments were given by gavage, and
lasted for 12 weeks.
Sample collection
Prior to the commencement of ED exposure,
blood samples were taken from the retrobulbar
venous plexus for the determination of various
basal biochemical parameters. Blood samples
were also drawn through the same route at the
6th week (mid-way) and at the end (12th week),
for similar assays. The samples were allowed to
coagulate and the sera were stored at -20 °C
prior to assay of AST, ALT, BUN and ALP.
Moreover, plasma samples from blood collected
in anticoagulant bottles were frozen at 20 °C
and used for assay of CAT activity. The pellet
(erythrocytes) was washed thrice in 3 mL of
physiological saline, and centrifuged for 10 min
at 3000 x g. The erythrocytes were thereafter
hemolyzed with 1.5 volume of distilled water,
and the hemolysate was clarified by
centrifugation for 15 min at 10,000 x g and 4 oC.
The resultant supernatant was used for the
assay of the activities of the antioxidant
enzymes GPx and SOD.
Histological examination
Blood samples were taken at the expiration of
week 12, and all rats were sacrificed by
decapitation. Liver and kidney samples were
immediately excised and processed for light
Mansy et al
2851
microscopy and histological investigation using
standard methods. Specimens were fixed in 10
% neutral formalin and stained with hematoxylin
and eosin.
Biochemical analysis
The activities of ALT, ALP and AST, and the
levels of creatinine, BUN and uric acid were
measured colorimetrically using Randox UV
kinetic method kits (Randox, USA) in line with
the manufacturer’s protocol [8]. Plasma
catalase (CAT) and erythrocyte SOD and GPx
activities were also assayed colorimetrically
using Randox assay kits (Randox, USA)
according to the procedures specified by the kit
manufacturer [9,10].
Statistical analysis
Data are presented as mean ± SE. One-way
analysis of variance (ANOVA) was used for
assessing differences among groups. This was
followed by Bonferroni post-hoc paired
comparison using Windows SPSS version 20.0
(SPSS Inc., Chicago IL, USA). P < 0.05 was
taken as indicating statistically significant
differences.
RESULTS
Liver function
Rats treated with either moderate or high doses
of ED had significant increases in serum AST,
ALT and ALP levels at weeks 6 and 12 of the
experimental period, when compared with their
baseline levels and corresponding levels in the
control group. These results are shown in
Tables 1, 2 and 3 below.
Kidney function
The effects of the three doses of ED on kidney
function of rats are presented in Tables 4, 5 and
6. Rats exposed to high doses of ED had
significant increases in serum creatinine, BUN
and uric acid levels at week 12 when compared
with the baseline levels of these parameters, and
the corresponding values in the control group.
Activity of antioxidant enzymes
The effect of the three doses of ED on levels of
some antioxidant enzymes in rats are
presented in Tables 7, 8 and 9. Exposure to
high dose of ED led to significant decreases in
SOD, GPx and CAT activities at 12 weeks of
the experimental period, relative to their
baseline levels and the corresponding levels in
the control group.
Histological features
The general architecture of the liver and the
kidneys in G4 were distorted with congestion of
central and portal veins and inflammation of
portal areas as shown in Figure 1 I. Proliferation
of bile ducts and starting fibrosis appears in
Figure 1 II.
Table 1: Serum AST (U/L) levels of rats treated daily by different concentrations of energy drinks for 12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
66.20±4.551
68.60±4.70
a1
67.77±3.81
a1
0.83
Group 2:(0.4 ml/100g/day) 78.21±4.76
ab12
91.21±4.76
b2
0.001
Group 3:(1.1 ml/100g/day) 93.43±6.91
b2
122.69±6.86
c3
0.001
Group 4:(2.2 ml/100g/day) 128.57±6.83
c2
190.62±3.61
d3
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 2: Serum ALT (U/L) levels of rats treated daily by different concentrations of energy drinks for 12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
45.27±2.471
54.27±4.62
a2
58.92±3.99
a2
0.04
Group 2:(0.4 ml/100g/day) 59.09±2.66
a2
66.27±3.45
a2
0.001
Group 3:(1.1 ml/100g/day) 61.94±4.23
a2
69.13±4.39
a2
0.001
Group 4:(2.2 ml/100g/day) 90.79±6.73
b2
107.80±7.90
b2
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Mansy et al
2852
Table 3: Serum ALP (U/L) levels of rats treated daily by different concentrations of energy drinks for 12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
137.27±18.201
142.40±11.37
a1
133.69±8.71
a1
0.91
Group 2:(0.4 ml/100g/day) 158.64±9.16
182.64±9.16
b1
0.06
Group 3:(1.1 ml/100g/day) 200.29±11.62
b2
237.00±12.41
c2
0.001
Group 4:(2.2 ml/100g/day) 300.86±15.70
c2
421.69±18.25
d3
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 4: Serum creatinine (mg/dL) levels of rats treated daily by different concentrations of energy drinks for 12
weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
0.33±0.021
0.43±0.03
0.45±0.03
a2
0.02
Group 2:(0.4 ml/100g/day) 0.45±0.02
a2
0.53±0.02
0.001
Group 3:(1.1 ml/100g/day) 0.47±0.02
0.58±0.05
b2
0.001
Group 4:(2.2 ml/100g/day) 0.57±0.04
b2
0.73±0.03
c3
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 5: Blood urea nitrogen (mg/dL) levels of rats treated daily by different concentrations of energy drinks for
12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
7.57±0.551
10.23±0.33
a2
8.68±0.44
0.84
Group 2:(0.4 ml/100g/day) 10.60±0.48
a2
11.54±0.48
b2
0.001
Group 3:(1.1 ml/100g/day) 18.70±0.60
b2
19.79±0.64
c2
0.001
Group 4:(2.2 ml/100g/day) 17.41±0.59
b2
23.48±0.63
d3
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 6: Serum uric acid (mg/dl) levels of rats treated daily by different concentrations of energy drinks for 12
weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
2.37±0.101
2.41±0.21
a1
2.31±0.19
a1
0.84
Group 2:(0.4 ml/100g/day) 2.57±0.10
a2
2.71±0.11
b3
0.001
Group 3:(1.1 ml/100g/day) 3.07±0.12
b2
3.28±0.13
c2
0.001
Group 4:(2.2 ml/100g/day) 3.46±0.15
b2
3.89±0.16
d3
0.001
P
-value 1.00
0.001
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Mansy et al
2853
Table 7: Superoxide dismutase (SODs, units/mL) level in erythrocytes of male rats orally and daily
administrated different concentration of energy drinks for 12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
0.20±0.021
0.22±0.02
a1
0.23±0.02
a1
0.75
Group 2:(0.4 ml/100g/day) 0.21±0.02
a1
0.21±0.02
a1
0.99
Group 3:(1.1 ml/100g/day) 0.20±0.01
a1
0.19±0.01
a1
0.77
Group 4:(2.2 ml/100g/day) 0.17±0.01
a1
0.09±0.01
b2
0.001
P
-value 1.00
0.26
0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 8: Glutathione Peroxidase (nmol/min/mL) level in erythrocyte of rats treated daily by different
concentrations of energy drinks for 12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
80.30±1.451
78.91±2.08
a1
77.30±1.45
a1
0.47
Group 2:(0.4 ml/100g/day) 76.07±1.98
73.92±0.85
a2
0.02
Group 3:(1.1 ml/100g/day) 56.31±3.19
b2
53.40±3.19
b2
0.001
Group 4:(2.2 ml/100g/day) 45.86±2.49
c2
42.69±2.41
c2
0.001
P
-value 1.00
0.001 0.001
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p<0.05); mean values not sharing a superscript digit in a row indicate significant difference at p
< 0.05
Table 9: Plasma catalase (nmol/min/mL) level of rats treated daily by different concentrations of energy drinks for
12 weeks
Group
Duration of consumption
P-value
Initial
Half-way (6 weeks) End (12 weeks)
Group 1:(control)
14.78±1.181
15.69±1.40
a1
14.82±1.37
a1
0.86
Group 2:(0.4 ml/100g/day) 14.46±1.31
a1
13.20±0.99
a1
0.61
Group 3:(1.1 ml/100g/day) 13.96±1.28
a1
12.97±1.29
a1
0.60
Group 4:(2.2 ml/100g/day) 12.74±0.83
10.17±0.73
a2
0.01
P
-value 1.00
0.45 0.07
Data are expressed as mean ± SE (n = 15); mean values with different alphabet superscripts within a column
differ significantly (p < 0.05); mean values not sharing a superscript digit in a row indicate significant difference
at p < 0.05
Marked dilatation and congestion of veins and
severe inflammation of the interstitial as shown
in Figure 1 III. Remnants of destroyed tubules
were seen within areas of inflammation with
signs of degeneration, necrosis, loss of cellular
details and cell boundaries as shown in Figure 1
IV.
DISCUSSION
This study has demonstrated that oral
administration of ED to rats for 12 weeks
resulted in varying degrees of liver and kidney
damage. This was evident in the ED-induced
significant elevations in serum AST, ALT and
ALP, creatinine, BUN and uric acid levels.
Increases in the blood levels of hepatic enzymes
serve as reliable indicators of liver damage by
toxic agents. Similar increases have been
reported in serum AST, ALT and ALP of rats
exposed to caffeinated EDs [11]. It has been
demonstrated that rats administered ED alone or
in combination with alcohol showed higher
serum total bilirubin, ALT, ALP and AST than
untreated controls [12].
In the present study, serum uric acid and
creatinine concentrations were significantly
increased in ED-treated rats. Increases in blood
levels of uric acid and creatinine are usually
associated with impaired kidney function [13].
These results are in agreement with the findings
of Khayyat and his colleagues who reported that
EDs induced elevations in serum urea, uric acid
and creatinine [14]. These researchers
suggested that caffeine induced the elevations
in urea, uric acid and creatinine through
inhibition of A2A adenosine receptors, resulting
in the development of interstitial inflammation,
increased proteinuria and deleterious changes in
renal function and structure [14].
Mansy et al
2854
Figure 1: Light micrographs of liver (I and II) and
kidney (III and IV) sections of rat in G 4 (highest ED-
exposed group). Specimens were fixed in 10%
neutral formalin and stained with H & E,
magnification 100 μm. I: Showing a markedly
dilated and congested portal vein (PV). The portal
area shows starting fibrosis (F), inflammatory
cellular infiltration (I), and bile duct proliferation
(asterisks). Hepatocytes at the periphery of the
lobules show undergoing degeneration and necrosis
with shrunken or disappearing nuclei (arrows). II:
Showing distorted general architecture of the liver,
congestion of a portal vein (PV) and inflammation (I)
in portal areas as well as between hepatocytes
which also show marked vacuolation mainly at the
peripheries of lobules (arrows). III: Showing
distorted general architecture, marked dilatation and
congestion of veins (V) and severe inflammation of
the interstitial tissue (I). Some renal corpuscles are
reduced in size with narrowing of the urinary space
(arrows). IV: Showing a markedly dilated vein (V), a
renal corpuscle with a markedly shrunken
glomerulus (G) and a markedly widened urinary
space (asterisk). The renal corpuscle is surrounded
by starting Fibrosis (F). The tubular cells show signs
of degeneration and necrosis with loss of cellular
details and cell boundaries (arrows)
However, some other ED-based studies
reported findings that are at variance with these
results. For example, it has been reported that
consumption of EDs was associated with higher
plasma total protein and lowered levels of
creatinine, albumin and uric acid [16]. Yet other
researchers found no significant association
between caffeine intake and the serum levels of
urea and creatinine in rats [17]. These
disparities on the effect of ED may be attributed
to lack of uniformity in the composition of these
energy beverages.
The present study also revealed that ED
exposure led to increased oxidative stress in the
rats. This was evident in the ED-induced
significant decreases in activities of SOD, CAT
and GPx. These enzymes are important
antioxidants which work in concert with the non-
enzymatic antioxidant system to protect cells
from oxidative damage by free radicals [18].
Indeed, the antioxidant enzymes are the first line
of defense which protects cells from oxidative
stress-induced damage. Superoxide dismutase
(SOD) neutralizes the highly reactive superoxide
anion by converting it to hydrogen peroxide,
which is in turn degraded to water by GPx and
CAT [19]. The significant reductions in blood
levels of these enzymes, especially in the rats
that received medium and high doses of ED,
might be due to ED-induced increases in
superoxide radical, thereby overwhelming the
neutralizing capacities of the antioxidant
enzymes.
Studies have shown that exposure of human
cells to high levels of caffeine induced a pro-
oxidant environment in the cells, leading to
increased protein oxidation, while low levels of
caffeine had no effect on the antioxidant
capacity of cells [20]. It has been demonstrated
that caffeine significantly increased BUN levels,
resulting in the activation of xanthine oxidase
which in turn, stimulated the oxidation of
xanthine to uric acid, and generation of
superoxide anion and H2O2 [21]. The interaction
between H2O2 with O2 produces free radicals.
On the other hand, several studies have
independently demonstrated the antioxidant
properties of many components of ED such as
taurine, ginseng, caffeine and guarana [21].
The pattern of variations seen in liver and kidney
function parameters of rats exposed to the
different doses of ED was in agreement with the
lesions in the photomicrographs of these
tissues. The observed lesions are most likely a
consequence of the deleterious effects of ED. It
can be reasonably suggested that the lesions
were brought about by tissue damage arising
from ED-induced oxidative stress. These results
are consistent with a previous report on
evidence of hepatotoxicity and alterations in liver
ultrastructure in rats treated with different types
of EDs [22]. In another study, the lesions in liver
and kidney tissues were attributed to potential
reaction of taurine with some other active ED
ingredient such as caffeine [23]. In addition,
Khayyat and his colleagues found that rats
treated with EDs had hepatic cytoplasmic
vacuolations due to presence of lipid droplets
which were attributed to deteriorative changes
within hepatocytes [22].
Many investigators are in agreement on the
adverse effects of ED as obtained in the present
Mansy et al
2855
study [11]. However, others reported that Power
Horse and Red Bull significantly influenced liver
enzyme activities but had no significant
influence liver histopathology [16]. Some
researchers reported irregular outlines and
pyknosis in the nuclei of hepatocytes, and
numerous mitotic figures [17].These changes
may be attributed to the toxic effects of caffeine,
and the harmful effects of preservative
substances added to EDs, such as sodium
benzoate [24]. However, it has been reported
that ED-induced hepatocyte damage was
reversible as indicated by blood chemistry
analysis and histopathological studies of the
organs of animals in the recovery group [19].
CONCLUSION
The results of this study demonstrate that
exposure of rats to high doses of Red bull for 12
weeks leads to liver and kidney damage. The
pronounced reduction in the blood levels of key
antioxidant enzymes suggests that the harmful
effects of Red bull are mediated through
increased ROS generation and oxidative stress.
If animal-to-man extrapolation is permitted, these
results call for restraint and caution in the
consumption of Red bull and other EDs. Thus,
the need for adequate public awareness cannot
be over-emphasized.
DECLARATIONS
Acknowledgement
The authors greatly appreciate the efforts of Dr
Mohammad Atteya, Assistant Professor of
Histology, Anatomy Department, College of
Medicine, King Saud University in preparing,
interpreting and writing reports for the
histopathological aspects of this work.
Conflict of Interest
No conflict of interest is associated with this
work.
Contribution of Authors
We declare that this work was done by the
authors named in this article and all liabilities
pertaining to claims relating to the content of this
article will be borne by the authors. Mansy and
Hanafi designed the study and drafted the
manuscript, Alogaiel participated in the whole
experimental work and statistical analysis.
Zakaria, Alogaiel and Mansy critically reviewed
the manuscript. All authors read and approved
the final manuscript.
REFERENCES
1. Reissig C, Strain EC, Griffiths RR. Caffeinated energy
drinks a growing problem. Drug Alcohol Depend 2009;
99: 1-10.
2. Elsoadaa S, Hejazi H, Sonbul A, Fayyadhah S, Al-Ahdal
S, Al-Turkistani S, Zarad R, AL- Harithy M. Prevalence
of Energy Drinks Consumption among Adolescents and
Young Adults in Makkah, KSA. J Health Med Nursing
2016; 33: 79-90.
3. Seifert SM, Schaechter JL, Hershorin ER, Lipshultz SE.
Health effects of energy drinks on children, adolescents,
and young adults. Pediatrics 2011; 127: 511–528
4. Tanne JH. New York attorney general investigates
energy drink makers. BMJ 2012; 345: e6108.
5. Burrows T, Pursey K, Neve M, Stanwell P. What are the
health implications associated with the consumption of
energy drinks? A systematic review. Nutr Rev 2013; 71:
135–148
6. Ali F, Rehman H, Babayan Z, Stapleton D. & Divya-Devi
J. Energy drinks and their adverse health effects: a
systematic review of the current evidence. Postgrad
Med J 2015; 127(3): 308-322
7. National Research Council. 2011. Guide for the Care and
Use of Laboratory Animals: Eighth Edition. Washington,
DC: The National Academies
8. Bergmeyer HV, Methods of Enzymatic analysis.
Weinheim Verlag Chemie 1984; 3: 92.
9. Aly NM, Abou-El-khear RK, El-Bakary AS.
Immunological, haematological studies on albino rats
treated with warfarin. Alex Sci Exch J 1997; 18: 265-
275.
10. Seven A, Guzel S, Seymen O, Civelek S, Bolayirli M,
Uncu M, Burcak G. Effects of vitamin E supplementation
on oxidative stress in streptozotocin induced diabetic
rats: investigation of liver and plasma. Yonsei Med J
2004; 45: 703-710.
11. Bukhari HM, El-Sawy NA, Header EA. Biological Effect of
High Energy Drink on Normal and Hyperglycemic Rats.
Pak J Nut 2012; 11(4): 301-309.
12. Ugwuja EI. Biochemical Effects of Energy Drinks Alone or
in Combination with Alcohol in Normal Albino Rats. Adv
Pharm Bull 2014; 4(1): 69-74.
13. Mossa AH & Abbassy MA, Adverse haematological and
biochemical effects of certain formulated insecticides in
male rats. Res J Environ Toxicol 2012; 6: 160-168.
14. Khayyat L, Essawy A, Sorour J, Al Rawi M. Impact of
Some Energy Drinks on the Structure and Function of
the Kidney in Wistar Albino Rats. Life Sci J 2014;
11(10): 1131-1138.
15. Tofovic S, Kost C, Jackson E, Bastacky A. Long term
caffeine consumption exacerbates renal failure in obese,
diabetic, ZSF1(fa-fa) rats. Kidney Int 2002; 61: 1433-
1444.
16. Ebuehi OA, Ajayl OE, Onyeulor AL, Awelimobor D.
Effects of oral administration of energy drinks on blood
chemistry, tissue histology and brain acetylcholine in
rabbits. Nig Q J Hosp Med 2011; 21(1):29-34.
Mansy et al
2856
17. Akande IS, Banjoko O A. Assessment of Biochemical
Effect of “Power Horse” Energy Drink on Hepatic, Renal
and Histological Functions in Sprague Dawley Rats.
Annu Res Rev Biol 2011; 1(3): 45-56.
18. Abdollahi M, Ranjbar A, Shadnia S, Nikfar S, Rezaie A.
Pesticides and oxidative stress: a review. Med Sci Monit
2004; 10: 141-147.
19. Sharma D, Sangha GK. Triazophos induced oxidative
stress and histomorphological changes in liver and
kidney of female albino rats. Pestic Biochem Physiol
2014; 110: 71-80.
20. Dias TR, Alves MG, Bernardino RL, Martins AD, Moreira
AC, Silva J, Barros A, Sousa M, Silva BM, Oliveira PF.
Dose-dependent effects of caffeine in human Sertoli
cells metabolism and oxidative profile: Relevance for
male fertility. Toxicology 2015; 328: 12-20.
21. Obochi GO, Amali OE, Ochalefu DO. Effect of Melatonin
and Caffeine Interaction on Caffeine Induced Oxidative
Stress and Sleep Disorders. Nig J Physiol Sci 2010; 25:
17-24.
22. Khayyat L, Sorour J, Al Rawi M, Essawy A. Histological,
Ultrastructural and Physiological Studies on the Effect of
Different Kinds of Energy Drinks on the Liver of Wistar
albino Rat. Am Sci J 2012; 8(8): 688-697.
23. Berger AJ & Alford K. Cardiac arrest in a young man
following excess consumption of caffeinated energy
drinks. Med J Aust 2009; 190: 41-43.
24. Mubarak R. Effect of Red Bull energy drink on Rats
Submandibular salivary glands (Light and Electron
microscopic Study). J Am Sci; 2012; 8(1): 366-372.
... The present investigation corroborated earlier findings since the energy drink-treated groups had increased AST and ALT values in comparison to the control group [32], where pregnant rats' ALT and AST enzyme levels increased in response to varying amounts of energy drinks consumed during the gestation stage. According to earlier research, energy drinks may produce too many reactive oxygen species (ROS), cause lipid peroxidation to tear down cell membranes, disrupt the plasma membrane, and cause excessive ALT and AST enzymes to leak into blood [32,33]. ...
... The present investigation corroborated earlier findings since the energy drink-treated groups had increased AST and ALT values in comparison to the control group [32], where pregnant rats' ALT and AST enzyme levels increased in response to varying amounts of energy drinks consumed during the gestation stage. According to earlier research, energy drinks may produce too many reactive oxygen species (ROS), cause lipid peroxidation to tear down cell membranes, disrupt the plasma membrane, and cause excessive ALT and AST enzymes to leak into blood [32,33]. Also, consuming beverages with added sugar increases the chance of increased ALT [34]. ...
... Pregnant Wistar rats that consumed energy drinks showed markedly elevated renal function (urea and uric acid). Similar findings in the past demonstrated that energy drinks, both at low and high dosages, harmed kidney function [32]. Caffeine is responsible for these changes because it inhibits the A2A adenosine receptor, causes proteinuria, speeds up the onset of interstitial inflammation, and modifies the structure and function of the kidneys [32,37]. ...
... These substances, most of which act as stimulants, are not included in the list of materials under regulation by the Food and Drug Administration (FDA) of the USA. The levels of these stimulants vary amongst different brands of energy drinks and, in most cases, are higher than the values allowable (Mansy et al., 2017). Usually, one can of an energy drink contains as much caffeine as three to five cans of Coke (34 mg) (Elbendary Frontiers A comprehensive literature review summarizes that a single dose of 200 mg of caffeine, or less, by healthy people without comorbidities and pharmacokinetic disturbances is usually not associated with toxic effects. ...
... The doses that caused the injuries varied, probably due to interactions with other ingredients. According to Mansy et al. (2017), chronic consumption of energy drinks for 12 weeks increases creatinine and uric acid levels. Besides alterations in liver function tests, the observed effects were due to free radical production and oxidative stress. ...
Article
Full-text available
Energy drinks containing significant quantities of caffeine, taurine, and sugar are increasingly consumed, particularly by adolescents and young adults. Excessive consumption of energy drinks and accumulation of the above ingredients, as well as their mutual interactions, can be hazardous to the health of young adults. This study aimed to assess the effect of acute consumption of energy drinks on body weight, blood glucose, insulin, leptin, and ghrelin hormones. The study involved 50 volunteers, healthy young adults (ages 19-22 years), who were divided into two groups: the first consumed energy drinks, and the second did not consume energy drinks. All participants had their serum glucose and insulin, leptin, and ghrelin hormones measured. In addition to calculating body mass index (BMI), the homeostasis model assessment estimated IR (HOMA-IR) and leptin/ghrelin ratio. In the above experiment, the consumers of energy drinks presented a significant increase in BMI, serum glucose, and insulin resistance (HOMA-IR) compared to those who did not consume energy drinks. No significant changes were noted in the insulin hormone and leptin/ghrelin ratio. Consumption of energy drinks caused a significant decrease (p < 0.001) in leptin and ghrelin levels. In conclusion, energy drink consumption significantly affects insulin resistance and leptin-ghrelin levels. More studies are needed to evaluate the effects of energy drink consumption in healthy, young, and normal-weight individuals.
... This may be similarity explained by the result of consuming energy drinks, which decreased the levels of antioxidant enzymes like SOD and GPX and elevated oxidative stress, These enzymes are important antioxidants that prevent oxidative damage from free radicals in cells by collaborating with the non-enzymatic antioxidant system, Antioxidant enzymes are the first line of defense against cell damage resulting from oxidative stress, By changing the extremely reactive superoxide anion into hydrogen peroxide, which is then broken down into water by GPX and CAT, SOD plays a significant role in neutralizing the anion 31 . ...
... Moreover, consuming energy drinks can lead to severe inflammation of the interstitial tissues, a reduction in the size of some renal corpuscles with a narrowing of the urinary space, a markedly shrunken glomerulus, and beginning fibrosis surrounding the renal corpuscle. Additionally, tubular cells exhibit signs of degradation and necrosis, losing cellular details and boundaries 31 According to Qassim 4 , energy drink consumption affects oxidative enzymes and lowers blood levels of antioxidant enzymes when given in high doses to rats. This causes reactive oxygen species and oxidative stress, which causes degeneration and desquamation in renal tissues. ...
... These results also came in line with Mansy et al., 2018, who compared three groups of rats given three different doses of ED with the control group. They found that serum levels of antioxidant enzymes were lowered markedly in rats with medium and high ED doses (Mansy et al., 2018). ...
... These results also came in line with Mansy et al., 2018, who compared three groups of rats given three different doses of ED with the control group. They found that serum levels of antioxidant enzymes were lowered markedly in rats with medium and high ED doses (Mansy et al., 2018). ...
... This change attributes these changes to oxidative stress and free radical production. [26] A 22-year-old lady presented with symptoms of a mild fever, abdomen pain, nausea, and vomiting. Upon investigation, it was discovered that she had been ingesting 10 cans of energy drinks per day for 2 weeks, resulting in abnormal liver test results. ...
Article
Full-text available
Beverages are non-alcoholic drinks designed to induce stimulation by the addition of active compounds, particularly high levels of caffeine. They are currently promoted as agents that boost energy (both mental and physical capabilities), This study aims to assess the side effects of energy drinks, such as Red Bull and Red Strong, on numerous physiological parameters and histological characteristics of the liver and kidney in male albino rats. Fifteen rats were allotted into three groups: group (1) consumed distilled water as the control group, group (2) drank Red Strong energy, and group (3) drank Red Bull energy, administered orally by gavage once a day for 8 weeks, with each group receiving 2.0 mL/100 g of body weight in the energy drink. The outcome shows that the body weight gain increased significantly induced in high long-term energy drinking groups and elevated the liver function enzymes, including alanine transaminase, aspartate transaminase, total serum bilirubin, and alkaline phosphatase. Furthermore, it adversely affects renal function through increased urea, creatinine, uric acid, and decreased glomerular filtration rates. Furthermore, adverse influences on reproduction organs by a decline in testosterone and sperm properties. Histological studies showed alteration structure in energy-drinking groups such as degenerative kidney tubules, hemorrhage, shrinkage of the glomerulus and the dilated sinusoid, degenerative hepatocyte, and inflammation in the liver. The presented study showed that the high consumption of beverages (Red Strong and Red Bull) have adverse effects on the liver and kidneys of male albino rats.
... While the elevation of free radical production along with a reduction of antioxidant enzymes was observed following the consumption of caffeine and taurine mixture which clarified the role of other EDs ingredients in modulating and reducing neurological oxidative damage. Also, [25] reported that exposure to a high dose of EDs led to significant decreases in SOD, GPX, and CAT activities, relative to their baseline levels and the corresponding levels in the control group. These results are similar to our findings. ...
Article
Full-text available
Energy drinks are cold caffeinated beverages commonly used by adolescents and young adults for increasing physical strength and mental alertness. The global market of EDs has grown dramatically, while the evidence and concern about the potential health risks are also increasing. This study explores the possible effect of two different energy drinks consumption on oxidative stress and neuroinflammation. Fifty adult male Sprague Dawley rats, weighing 120±5g divided into five groups, ten rats in each. Control group: healthy rats received distilled water only. RB-L and RB-H groups received Red Bull 5ml, 15ml/kg/day respectively, while ST-L and ST-H received Sting 5ml, 15ml/kg/day respectively for seven weeks. Our results concerning the effect of EDs on the oxidative stress biomarkers disclosed a significant decrease in SOD, GPX, CAT, and HO-1 in serum and brain tissue homogenate. Additionally, results showed a statistically significant reduction in Nrf-2 relative expression in all EDs-administrated groups. Stimulant neurotransmitters showed a significant increase in dopamine, noradrenaline, and acetylcholine in serum and brain tissue homogenate, which were consistent with findings of histopathological examination that showed severe degenerative changes and pyknosis of neural cells on the cerebral cortex and subiculum of the hippocampus, indicating the toxic effect of energy drinks on neurons of the brain. Both Sting and Red Bull consumption induced oxidative damage and neuroinflammation. Consumption of high dose of Sting showed the most dramatic effect. This work is licensed under a Creative Commons Attribution Non-Commercial 4.0 International License.
... Therefore, the reason for the increase in the activity of the two enzymes may be due to the metabolic imbalance resulting from giving an energy drink, which increased the hepatic cell metabolism and thus increased the leakage of liver enzymes. The activity increase of these two enzymes may also be due to hepatocyte enlargement and the stimulation of the endoplasmic reticulum to produce a larger amount of the enzyme proportional to the cell size (Mansy et al., 2017). Also, the increase in the fat percentage, especially cholesterol, in the liver creates what is known as liver steatosis, where the fatty acids accumulate due to the high glucose level in the blood, where the same enzymes increase as a result . ...
Article
Full-text available
The current study was designed to investigate the effect of pomegranate juice on some biochemical and histological variables resulting from dosing male rats with the energy drink Red Bull. In this study, 28 white male rats were used, divided into four groups, each involving seven animals, according to the following: G1 was given a physiological solution (5 ml/kg) and a standard diet for 120 days; G2 was given a dose of the energy drink Red Bull (volume 1 ml per 100 g); G3 was given pomegranate juice (5 ml/kg) first; then Red Bull; and G4 was given Red Bull first; and after six weeks, he was given pomegranate juice. The results showed that Red Bull consumption significantly elevated RBS, AST, ALT, TC, and TG levels. Pomegranate juice has the ability to reduce the concentration of RBS, AST, ALT, TC, and TG. Histological changes in the liver of animals that were given the Red Bull energy drink were represented by congestion of the central vein, degeneration, and necrosis of liver cells, with severe infiltration of inflammatory cells and a thick wall of the central vein (TW), as well as amyloid (AM) deposition, compared to the negative control group. The results of the histological examination showed that pomegranate juice could repair cellular tissue in the liver and make it similar to the tissue of a control normal group, denoting the possibility of using it in the diet and in treating atherosclerosis and heart disease
Article
Full-text available
Objective: The present research was carried out to observe withdrawal effects of energy drinks, whether these histomorphological changes are reversible or not. Study Design: Laboratory based experimental study. st th Place and Duration of Study: The research was carried out from 1 July to 30 August 2019 at national institute of health Islamabad. Materials and Methods: Total thirty adult male albino rats were divided into 3 groups by simple random sampling, with ten rats in each group. Group I was control group, while energy drink group II received 3.57ml/kg body weight red bull corresponding to one can of energy drink (250ml) in humans orally for eight weeks. Rats in withdrawal group III received energy drink for first four weeks followed by normal diet and water for last four weeks. After eight weeks, rats were sacrificed and their right kidneys were removed. Slides were prepared using hematoxylin eosin and Periodic Acid Schiff Stain, results were analyzed by SPSS. Results: The results showed that use of energy drink for 8 weeks resulted in increase in weight of kidneys along with histological alterations in renal cortex of rat kidneys. Grade 4 (severe) congestion, hemorrhage, loss of brush border and necrosis was observed in energy drink group II. Withdrawal of energy drink in group III resulted in weight of kidneys near to control group along with significant reduction in congestion, hemorrhage, loss of brush border and necrosis grades from grade 4 to grade 3 and 2 with P≤0.05. Conclusion: Caffeinated energy drinks are having damaging effects on kidneys of albino rats and these histological changes caused by caffeinated energy drinks in this duration of study and in low doses corresponding to one can of energy drink (250ml) in humans are reversible.
Article
Full-text available
Energy drink consumption, particularly among teenagers and young adults, has experienced a significant rise in recent years. However, mounting research points to the potential for chronic energy drink use to cause biochemical and histological abnormalities in vital organs such as the liver, kidneys, and reproductive system. To investigate whether pomegranate peel extract could offer protection against these toxic effects, this study was conducted on adult male albino rats divided into five groups: a control group, a pomegranate peel extract group, an energy drink group administered Red Bull ® , a group pre-treated with pomegranate peel extract before energy drink consumption, and a group given energy drink followed by pomegranate peel extract. Over a 12-week treatment period, serum and tissue samples were collected to analyze liver and kidney function markers, lipid profile, oxidative stress levels, and histological changes. Rats those consumed energy drinks for 12 weeks exhibited elevated liver enzymes, impaired kidney function, disrupted lipid profiles, increased oxidative stress, and noticeable morphological changes in liver, kidney, and testicular tissues. In contrast, rats those received pomegranate peel extract either before or after energy drink consumption showed significant improvements in these parameters, demonstrating the protective effects of pomegranate peel extract in attenuating biochemical abnormalities and restoring tissue histology. These findings suggest that pomegranate peel extract has both therapeutic and preventive potential against the toxicity induced by chronic energy drink consumption, offering valuable insights that could inform strategies to reduce the adverse health effects associated with the regular use of energy drinks.
Article
Full-text available
Several studies suggest that there was relationships between energy drink consumption and problem behaviors among adolescents and adults as it increase lipolysis glycogenolysis and catecholamine secretion. This study aimed to find out the potential effects of high energy drinks recommended intake and toxic dose on normal and hyperglycemic rats. Thirty-six (36) male adult Sprague-Dawley rats weighting 145±5.3 g each were used in this investigation. Non-diabetic rats [control-ve 6 rats feed on basal diet only and 12 Normal Rats (NR) divided into two groups consumed basal diet with 1 and 2 ml of High Energy Drink (HED) by gastric tube], while Diabetic Rats (DR) control+ve 6 rats received basal diet only and 12 rats divided into two groups consumed basal diet with 1 and 2 ml of HED after injected with alloxan for inducing diabetes mellitus. Body Weight Gain (BWG) and food intake were recorded weekly for 6 weeks. Blood samples were collected after 12 hours fasting at the end of experiment. Liver was removed and weighted. Blood serum was prepared for measurements of glucose, triglyceride, cholesterol, HDL-c, LDL-c, VLDL-c, AST, ALT and ALP. The BWG of NR groups received 2 ml only and DR groups received 1 and 2 ml of HED by oral injection recorded significant decrease (p<0.001) as compared to the control negative group. Blood glucose level was significantly higher (p<0.001) for DR fed on 1 and 2 ml compared with control (Serum rum AST, ALT and ALP were significantly higher (p<0.01 and p<0.001 resp.) for NR received the two doses of HED compared with normal rats control (As As for cholesterol, triglycerides and LDLc levels were significantly higher (p<0.01) in the hyperglycemic rats group fed on 2 ml of HED compared with control (Also lso LDLc/HDLc ratio increased gradually when the level of HED increased. Oral injection by HED cause histopathological changes in the liver for NR and DR like atrophy and cell damage also changes in the chemical and morphological structure.
Article
Full-text available
Purpose: To determine the biochemical effects of energy drink alone or in combination with alcohol in normal albino rats. Methods: Twenty male albino rats weighing 160-180g were assigned into groups A-E of four rats per group. Group A and B rats were given low and high doses of ED, respectively, groups C and D were administered low and high doses of EDmA, respectively while group E rats were given distilled water and served as control. The treatment lasted for 30 days after which the animals were killed and their blood collected for laboratory analyses using standard methods. Results: There were no significant differences in body weight, packed cell volume and haemoglobin concentration with either administration of ED or EDmA in comparison to the control. Energy drink alone or EDmA has significant effects on total white blood cell count, plasma potassium, calcium, renal functions, liver enzymes and plasma triglycerides, with EDmA having more effects than ED alone, except for body weight where the energy drink alone has higher effect. Conclusion: Consumption of energy drink alone or in combination with alcohol is associated with significant alterations in some biochemical parameters. Caution should be exercised while consuming either of them. Public health education is urgently needed to correct the wrong impression already formed by the unsuspecting consumers, especially the youths.
Article
Full-text available
Abstract: Three kinds of energy drinks (Power horse, Red bull and Code red) were used to study their histological, ultrastructural and physiological effects on Wistar albino rat liver. Forty male Wistar albino rats were divided into four groups. Group 1 was the control, while Groups 2, 3 and 4 were each orally administered with a type of the energy drinks daily for 4 weeks. After two and four weeks of treatment, five animals from each group were killed and dissected. The liver was removed, cut and fixed quickly to carry out light and electron microscopic preparations. Blood samples were collected from each rat via Cardiac puncture method for enzyme determination. The histopathological and ultrastructural results indicated mild hepatotoxicity of Power horse, Red bull and Code red. The alterations in liver ultrastructure were almost similar to each other; however the necrotic areas and the pyknotic nuclei were more obvious in Power horse and Red bull than that of Code red. Moreover, the present study showed that the energy drinks induced an elevation of liver enzymes AST, ALT and ALP after two and four weeks of treatment. The data illustrated that power horse was more effective in its action on liver enzymes, followed by red bull and to less extend code red. The different action of the energy drinks on liver function could be attributed to the different mixture of their ingredients.
Article
Purpose: With the rising consumption of so-called energy drinks over the last few years, there has been a growing body of literature describing significant adverse health events after the ingestion of these beverages. To gain further insight about the clinical spectrum of these adverse events, we conducted a literature review. Methods: Using PubMed and Google-Scholar, we searched the literature from January 1980 through May 2014 for articles on the adverse health effects of energy drinks. A total of 2097 publications were found. We then excluded molecular and industry-related studies, popular media reports, and case reports of isolated caffeine toxicity, yielding 43 reports. Conclusion: Energy drink consumption is a health issue primarily of the adolescent and young adult male population. It is linked to increased substance abuse and risk-taking behaviors. The most common adverse events affect the cardiovascular and neurological systems. The most common ingredient in energy drinks is caffeine, and it is believed that the adverse events are related to its effects, as well as potentiating effects of other stimulants in these drinks. Education, regulation, and further studies are required.
Article
There is increasing interest regarding the potential health effects of energy drink (ED) consumption. The aim of the present review was to investigate the existing evidence on health outcomes associated with ED consumption. Studies published between 1966 and February 2011 were retrieved and included if they met the following criteria: were randomized or pseudo randomized control trials; studied a human population; reported a health-related measure; and investigated a whole ED (as opposed to individual ingredients). Study quality was evaluated and data extracted using standardized tools. Fifteen studies were identified, the majority of which had less than 30 participants and included a short term of follow-up (range: 30 min-3 h). The following outcome measures were included: cardiorespiratory effects, physiological measures, pathological measures, and body composition. The mean dosage of ED was 390 mL (range: 250-750 mL). Commercial ED funding and/or study associations were identified in six studies. Studies investigating long-term consumption and follow-up were lacking. The findings from this review do not allow definitive dietary recommendations to be made regarding safe levels of ED consumption; caution should be exercised when consuming these drinks until further high-quality research is undertaken to substantiate findings.