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The effect of chicken essence on cognition and mood: A randomized controlled trial


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Young adults (n=147) were tested after consuming either BRAND'S Essence of Chicken (EOC) or a placebo for ten days. EOC resulted in feeling energetic, decision times (reaction time test) were quicker; reaction times on the focused attention task were also quicker; working memory imp roved, cortisol levels recovered more quickly after a stressor. The possibility that EOC might act via mechanisms associated with either serotonin or the metabolism of carnosine was considered by looking at various polymorphisms of enzymes associated with these neurochemicals. If those with genetic variations, associated with differences in the efficiency of these mechanisms, differentially responded to EOC then this would indicate the mechanism of action. In the event the alleles of 16 polymmphisms did not influence the response to EOC In the case of rs1050565, a polymorphism associated the serotonin transporter, a possible risk factor for dementia, EOC benefitted the decision times of those with the GG allele.
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ISSN 1540-7535 print, Copyright © 2015 by New Century Health Publishers, LLC
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D. Benton and H.A. Young
Department of Psychology, University of Swansea, Swansea SA2 8PP, Wales, United Kingdom
[Received August 6, 2014; Accepted December 29, 2014]
[Communicated by Prof. Chandan Prasad]
ABSTRACT: Young adults (n=147) were tested after
consuming either BRAND’S® Essence of Chicken (EOC) or
a placebo for ten days. EOC resulted in feeling energetic,
decision times (reaction time test) were quicker; reaction
times on the focused attention task were also quicker; working
memory improved; cortisol levels recovered more quickly after
a stressor. e possibility that EOC might act via mechanisms
associated with either serotonin or the metabolism of carnosine
was considered by looking at various polymorphisms of enzymes
associated with these neurochemicals. If those with genetic
variations, associated with differences in the efficiency of these
mechanisms, differentially responded to EOC then this would
indicate the mechanism of action. In the event the alleles of
16 polymorphisms did not influence the response to EOC. In
the case of rs1050565, a polymorphism associated the serotonin
transporter, a possible risk factor for dementia, EOC benefitted
the decision times of those with the GG allele.
KEY WORDS: Chicken extract, Essence of chicken, Mood,
Reaction times, Serotonin
Corresponding Author: Professor David Benton, Department of
Psychology, University of Swansea, Swansea SA2 8PP, Wales,
United Kingdom; Phone ++44 1792 295607; Fax ++44 1792
295679; Email:
Essence of chicken (EOC), a chicken meat extract, is a
popular supplement in Southeast Asia and is traditionally
consumed for a number of ailments, such as improving
cognition and reducing fatigue. EOC consists mainly of
proteins, amino acids and is high in the peptides carnosine
and anserine, that are also found in high concentrations in the
human brain (Kohen et al., 1988). Previous research has found
that drinking EOC reduced the fatigue that was associated
with a mental task (Nagai et al., 1996). After a stressor the
recovery of serum cortisol levels was also enhanced in those
who consumed EOC (Nagai et al., 1996). More recently it
has been reported that drinking EOC improved working and
episodic memory during times of stress (Azhar and Syed,
2003; Azhar et al., 2008). An aim of the present study was to
replicate and extend these ndings in a larger sample of young
adults. In particular, the study focuses on the ability of EOC to
improve cognition and reduce the subjective and physiological
stress associated with demanding mental eort. A second aim
was to consider the inuence of a range of polymorphisms
on the inuence of EOC and in this way consider the role of
possible mechanisms of action.
Inevitably there is a range of possible active ingredients
in EOC and hence various mechanisms by which it may
be inuential. Li et al. (2012) analysed EOC and found it
consisted of “proteins, dipeptides (such as carnosine and
anserine), polypeptides, minerals, trace elements, and multiple
amino acids”. Carnosine, homocarnosine, anserine and other
histidine derivatives, all have antioxidant activity that could
benet cognition. In addition, Tsuruoka et al. (2012) puried
a serotonin transporter inhibitor from EOC, that suppressed
serotonin uptake from rat brain synaptosomes, and identied it
as the diketopiperazine (DKP) cyclo (L-Phe-L-Phe). DKPs are
naturally-occurring cyclic dipeptides and this DKP increased
extracellular levels of the cerebral monoamines serotonin,
norepinephrine and dopamine in the medial prefrontal cortex,
and acetylcholine in the ventral hippocampus of freely moving
animals. Previously EOC had been reported to increase the
5-hydroxyindole acetic acid levels in the cerebrospinal uid of
the rat (breakdown product of serotonin), that was consistent
with increased brain serotonin activity (Xu and Sim, 1997).
It has been proposed that this peptide may act as an anti-
dementia agent and improves learning and memory (Tsuruoka
and Watanabe, 2012).
Two possibilities were therefore considered by looking at the
interactions between various single nucleotide polymorphisms
62 Chicken extract, mood and cognition
(SNP) and the eect of consuming EOC. In particular,
the possibilities that modifying serotonin activity may be a
mechanism, and that carnosine may play a role, were examined.
It was argued that if those with various polymorphisms of
enzymes associated with particular pathways dierentially
responded to EOC then this would be suggestive of the
mechanism of action.
e sample consisted of 152 subjects of whom 147 (96.7%)
completed the study and were paid £60. Of the ve subjects
that did not return for their second visit two were allocated
to the placebo and three to the active condition. ose
nishing the study were well matched. ose taking EOC
were on average 21.6 (3.7) years and the placebo 21.2 (2.7)
years. Similarly the BMI of the two groups did not dier
(EOC 23.1(3.6) and placebo 23.5(3.2)). 45 females and 28
males drank EOC whereas 44 females and 30 males consumed
the placebo. When the baseline data for the test battery
were examined there were no signicant dierences between
those who subsequently consumed EOC and those who
subsequently drank the placebo.
After giving informed consent, participants were randomly
allocated, under a double blind procedure, to one of two
groups who consumed either BRAND’S® Essence of Chicken
(EOC) or a placebo (caramel and gelatine) each day. e
Swansea University Psychology Ethics Committee approved
the procedure. At baseline and after ten days of consumption,
participants completed a cognitive test battery (in the order
presented below) and completed a number of questionnaires
about their recent mood and general health. Subjects were
told they could either take the supplement straight or add it to
a vegetable based soup to increase palatability. A bottle of EOC
(70 ml) contained 83 mg protein and peptide, 3.1 mg free
amino acids, 0.8 mg hexose, and 0.4 mg fat (Li et al. 2012). It
also contained b-alanyl- L-histidine (carnosine) and b-alanyl-
l-methyl-L-histidine (anserine) as active dipeptides (Li et al.
2012). e dose of EOC used in the present study was based
on previous human studies (Azhar and Syed, 2003; Azhar et
al., 2008; Yamano et al., 2013). A bottle of placebo (70 ml)
contained 83 mg milk casein and 3 mg caramel to produce a
protein content, caloric content and colour similar to EOC.
Casein is chosen as an ingredient in the placebo because it does
not include peptides reported to have eects on fatigue but
has a similar amino-acid composition as EOC. e EOC and
placebo samples were provided by Cerebos Pacic Ltd.
Episodic memory - Word list recall
Using the MRC Psycholinguistic Database two lists of
thirty words were constructed and matched for the number
of syllables, image-ability and the frequency with which they
occur in English. Using a recorder words were presented at
a rate of one word every two seconds. Immediately after
presentation participants wrote down as many words as they
could remember (immediate recall). Approximately 25 min
later, after completion of the other tasks, subjects were again
asked to recall as many words as possible (delayed recall).
Working memory – Serial sevens
A computerized version of the serial sevens task was used in
which subjects were required, from a starting number between
800 and 999, to say whether a second number was exactly
seven less. e test was scored and the total number of correct
subtractions and the average of the time taken in milliseconds
to perform each subtraction were reported.
Working memory – Letter number sequencing
Letter number sequencing is a sub-test of the Wechsler
Adult Intelligence Scale that measures working memory. An
example of the type of question was: repeat the sequence Q-1-
B-3-J-2 in numerical and alphabetical order.
Sustained attention - Rapid Information Processing Task
A computer generated a series of digits at the rate of 100 per
minute. Subjects pressed the space bar when they detected
three consecutive odd or consecutive even digits. Eight
target sequences were presented every minute. Following the
presentation of the third consecutive digit, 1500 milliseconds
were allowed for a correct response to be made. Responses
made at any other time were recorded as errors. A minimum
of 5 and a maximum of 30 digits separated any two target
sequences. e task was performed for ve minutes and any
change in performance over time was examined. e number
of correctly identied sequences and the time taken to respond
to a correct sequence (in milliseconds) were analysed.
Selective attention - Arrow Flankers Test
A modied version of the Eriksen and Eriksen (1974)
anker task was used to measure selective attention. e
Arrow Flankers test measures the ability to direct attention and
ignore peripheral information. e anking pairs of symbols
could be squares (□□<□□), crosses (xx<xx), congruent arrows
(pointing in the same direction (>>>>>)) or incongruent
arrows (pointing in the opposite direction (>><>>)). A stimulus
remained on screen until the key press was registered and there
was a randomly varying inter-stimulus interval of between 1
and 3seconds. e task was to indicate whether the middle
arrow is pointing to the right or left: the reaction times (in
milliseconds) and accuracy (number incorrect) were recorded.
Reaction times
e reaction time procedure was based on that of Jensen
(1987). On a panel eight lamps were arranged in a semicircle
5.5 inches from a central button (the home key). e index
nger was placed on the home key. Within one to two seconds
an auditory warning signal sounded and after a random interval
of one to four seconds one of the lamps illuminated. e subject
Chicken extract, mood and cognition 63
then extinguished the light by depressing a button directly below
that lamp, using the nger initially on the home key.
All subjects completed a practice session of 20 trials utilising
all eight lamps. Simple reaction times were measured for
20 trials using one lamp. Choice reaction times were then
measured over three sets of 20 trials when one of 2, 4 or 8
lamps could be potentially illuminated. Decision times, the
time taken to lift the nger from the home key, were analysed.
Prole of Mood States
e Prole of Mood States Bi-Polar Form (POMS; Lorr
and McNair, 1984) is a 72-item self-report questionnaire that
measures six dimensions of mood: (1) Composed - Anxious;
(2) Energetic - Tired; (3) Elated - Depressed; (4) Clear-headed
- Confused; (5) Agreeable - Hostile; (6) Condent-Unsure.
Participants were presented with a list of words or phrases and
had to rate on a scale of 0-3 (0 ‘not at all’, 3 ‘a lot like this’)
how much they had felt like this in the past week including
today. ere were twelve words for each mood dimension – six
positive and six negative. In addition, an overall mood score
was calculated by adding all six dimensions.
General Health Questionnaire (GHQ)
e GHQ is a 30-item self-report questionnaire that was
developed to detect, in a community sample, those who would
benet from seeing a psychiatrist (Goldberg and Williams,
1988). e participant responds to various statements
concerning mental health by rating themselves on a four point
scale that ranges from ‘better / healthier than normal’; ‘same
as usual’; ‘worse / more than usual’ to ‘much worse / more
than usual’. ese were scored using a scale 0-1-2-3, as the
responses varied from positive to negative, such that a higher
score indicated a greater incidence of psychiatric problems.
Perceived Stress Scale
e Perceived Stress Scale (Cohen et al. 1983) is a 10-item
self-report questionnaire that assesses the degree to which
situations in one’s life are perceived as stressful. e participants
were required to answer questions about the extent to which
they have had stressful thoughts and feeling during the last
week, for example, “In the last week, how often have you been
upset because of something that happened unexpectedly?”
e participant responds on a 5-point scale (ranging from 0 =
Never - 4 = Very Often). One overall score was produced by
summing all items.
Before and after completing the test battery, and after a 45
minute recovery period, a sample of saliva was collected and
used to assay cortisol levels. Testing was carried out in the
afternoon to avoid the high levels of cortisol that are found in
the rst ve hours after waking. Analysis was carried out using
an immunoassay supplied by Salimetrics Europe, Newmarket,
Suolk, UK.
Statistical Analyses
e data were examined using appropriate analysis of co-
variance designs with performance on day 2 as the dependant
variable and performance on day 1 as the covariate. EOC/
placebo and gender were entered as between-subjects factors.
Where applicable additional repeated measures factors were
also included, for example with mood the measures before
after testing were entered. When interactions were signicant,
appropriate post hoc tests were conducted to determine the
nature of the interaction. Unless otherwise stated the main
eect of the covariant was signicant. ere were no occasions
where gender interacted with treatment. e data reported are
adjusted means (SE).
When the baseline data for the test battery were examined
on no occasion was there a signicant dierence between those
who subsequently consumed EOC and those who subsequently
drank the placebo. To assess compliance to the experimental
protocol, subjects were also asked how many drinks they
actually consumed; they were informed that this would not
aect their payment. 76.2% (n=112) reported consuming all
ten drinks as instructed; the number of subjects who reported
consuming all ten drinks was similar in both conditions (Chi2
(1, n = 147) = 1.50, n.s.). Of those that did not consume all
ten drinks, 13.6% (n=20) consumed nine drinks, 5.4% (n=8)
consumed eight drinks, 3.4% (n=5) had drunk seven, 1 person
(0.7%) reported consuming only six and 1 person (0.7%) only
four drinks; again there were no dierences depending on the
type of drink consumed (Chi2 (4, n = 147) = 4.36, n.s.). To
exclude the possibility of bias an intention treat analysis was
carried out that included all subjects.
When asked if they thought they were taking an active
ingredient, a placebo, or were unsure, there were no signicant
dierences in responses depending on which drink they had
been taking (Chi2 (2, n = 143) = 1.24, n.s.); thus the blind was
successful. When asked about any side eects, 83.7% (n=123)
reported no side eects, 2% (n=3) reported changes in their
thirst/appetite, 0.7% (n=1) reported feeling calmer, 3.4%
(n=5) reported having experienced more headaches, 5.4%
(n=8) said they had either felt sick or vomited after taking
a drink, 4.1 (n=6) reported that they slept less or needed to
sleep less and 0.7% (n=1) reported that they had found it
harder to concentrate during the supplementation period.
e symptoms reported were similar for both the placebo and
active treatments (Chi2 (6, n = 147) = 6.29, n.s.).
Cortisol was measured when participants arrived at the
laboratory (Time 1), immediately following the test battery
(Time 2), and after a 45 minute recovery period (Time 3).
64 Chicken extract, mood and cognition
e interaction EOC/placebo X Time (1, 2, 3) was non-
signicant (F (2,258) = 1.45, n.s.). However, as Nagai et al.
(1996) reported that it was the recovery from a stressor that
was inuenced by EOC, the changes in cortisol from Time 2 to
Time 3 were calculated, a reection of the rate of recovery after
the stressor. e recovery measure just missed signicance (F
(1,134) = 3.49, p < 0.06; -0.47 for EOC, -0.27 for Placebo;
Figure 1): that is there was a trend for the cortisol levels of
participants who had drunk EOC to recover more quickly.
Working memory- Letter number task
ere was a signicant eect of EOC (F (1,141) =4.05,
p<0.04; Figure 2); participants who had drunk EOC gave
more correct responses than those who consumed the placebo.
Working memory – serial sevens
Neither the accuracy of performance (F (1,144) = 2.09, n.s.),
nor reaction times (F (1,144) = 0.60, n.s.), were inuenced by
the consumption of EOC.
Focused attention – arrow ankers
Although consuming EOC did not inuence the accuracy
of the task (F (1,142) = 0.32, n.s.) the speed of responding
diered (F (1,143) = 4.39, p<0.03; Figure 3). Participants
who had drunk EOC had faster reaction times.
With the vigilance task neither the accuracy of performance
(EOC/placebo X Minute of test; F (4, 552) = 0.86, n.s.) nor
the speed of responding (EOC/placebo X Minute of test; F
(4, 540) = 0.86, n.s.) achieved statistical signicance.
Reaction times
e interaction EOC/placebo X number of lamps was
signicant (F (3, 435) = 5.55, p<0.001; Figure 4). Follow up
FIGURE 1. The effect of EOC on cortisol recovery. Data are mean (SE) for the
number of correct responses. Time 2 – cortisol levels immediately after the 30minute test
battery. Time 3 – cortisol levels 45minutes after the test battery. The cortisol levels of
participants who had drunk EOC recovered more quickly
FIGURE 1. e eect of EOC on cortisol recovery. Data
are mean (SE) for the number of correct responses. Time 2 –
cortisol levels immediately after the 30minute test battery. Time
3 – cortisol levels 45minutes after the test battery. e cortisol
levels of participants who had drunk EOC recovered more quickly
FIGURE 2. e eect of EOC on letter number task
performance. Data are mean (SE) for the number of correct
responses. Participants who had drunk EOC performed signicantly
better than those who had consumed the placebo (p<0.04).
FIGURE 2. The effect of EOC on letter number task performance. Data are mean (SE)
for the number of correct responses. Participants who had drunk EOC performed
significantly better than those who had consumed the placebo (p<0.04).
FIGURE 4. The effect of EOC on simple and choice decision times.
Data are mean (SE) for decision times (ms). Subjects who had consumed EOC responded
more quickly to the 8 lamp task (p<0.04).
FIGURE 4. e eect of EOC on simple and choice
decision times. Data are mean (SE) for decision times (ms).
Subjects who had consumed EOC responded more quickly to
the 8 lamp task (p<0.04).
FIGURE 3. The effect of treatment on focused attention reaction times. Data are mean
(SE) for focused attention reaction times (ms). Participants who had consumed EOC had
significantly faster reaction times (p<0.002).
FIGURE 3. e eect of treatment on focused attention
reaction times. Data are mean (SE) for focused attention
reaction times (ms). Participants who had consumed EOC
had signicantly faster reaction times (p<0.002).
Chicken extract, mood and cognition 65
tests revealed that those who consumed EOC responded more
quickly to the most dicult 8 lamp task (p<0.04). ere were
no signicant dierences between those who had drunk the
placebo and those who had drunk EOC with 1, 2 or 4 lamps.
Episodic memory
e interaction EOC/placebo) X Immediate/delayed was
non-signicant (F (1, 144) =0.23, n.s.).
Perceived Stress Questionnaire.
e main eect of variant (EOC/Placebo) was non-
signicant (F (1,134)= 0.66, n.s.).
General Health Questionnaire
e main eect of the drink (EOC/placebo) was non-
signicant (F (1,144) = 0.26, n.s.).
Prole of Mood States
When the Energetic/tired dimension was considered the
eect of EOC approached signicance (F (1,141)=3.6.4,
p<0.06; Figure 5). Participants who consumed EOC
reported having more energy than those who had drunk the
placebo (Placebo -0.3(0.7): EOC 1.5(0.7)). ere were no
signicant eects with any of the other subscales: Agreeable/
Hostile, Clearheaded/Confused, Composed/Anxious, Elated/
Depressed or Condent/Unsure.
Where in the previous section a measure was inuenced
by the consumption of EOC the data were further analysed
depending on the alleles of a range of Single Nucleotide
Polymorphisms (SNPs). us the eect on ratings of energy,
decision times with eight lamps and the number letter task
were considered. e data were analysed as in the previous
section except that in addition the alleles of SNPs listed below
were added to the analysis of variance. Where fewer than ten
individuals had a particular allele a variant was not considered.
SNP analysis
Samples were taken using Isohelix Buccal Swabs (http:// from which DNA was extracted and
analysed by LGC Genomics (
using a proprietary competitive allele specic PCR system
(KASPar) for SNP analysis.
e approach taken was to consider various polymorphisms
of enzymes associated with the metabolisms of serotonin
and carnosine. e argument was if these substances played
a key role in the inuence of EOC then the response to its
consumption would dier in those with dierent SNPs.
e relevant metabolic pathways are therefore outlined
and the polymorphisms considered indicated. Tryptophan
hydroxylase (TPH) catalyzes the conversion of tryptophan
to 5-hydroxytryptophan (5-HTP), and is the rate limiting
step in the synthesis of serotonin. Until ten years ago it was
thought that there only was a single TPH gene (TPH1; SNP
rs1800532) but a second form was found in the human brain
(TPH2; rs1843809). After its release into the synapse the
serotonin transporter protein (5-HTT: rs1050565) removes
the neurotransmitter from the synapse to the presynaptic
neuron. An increasing number of receptors and sub-receptors
have been found including HT1A (rs6295), 5HT1B (rs6296),
5HTR2A (rs6314) and 5HTR2A (rs6311) amongst others.
Carnosine synthetase (CARNS 1) is a member of the ATP-
grasp family of ATPases and catalyzes the formation of carnosine
and homocarnosine, mainly in skeletal muscle and the central
nervous system (rs1626067). Carnosinase1 (CNDP1)
drives the reverse reaction and is the rate-limiting enzyme
in the hydrolysis of carnosine into β-alanine and L-histidine
(rs11151964; rs234601). Tissue carnosinase (CNDP2), or
peptidase A, is a nonspecic dipeptidase rather than a selective
carnosinase, that hydrolyzes a variety of dipeptides including
L-carnosine (rs7577; rs808885). Histidine decarboxylase
(HDC) is the key enzyme for histamine production from
histidine (rs854163; rs854158; rs854150). Histamine
N-methyltransferase (HNMT) activity is key to the rate of
histamine degradation in the brain (rs11558538).
To save journal space, and for brevity, only results that
achieved statistical signicance will be detailed. e three
measures that had been found to be inuenced by EOC were
considered; the letter number task, decision times with eight
lamps and ratings of energy. In the case of the various SNPs
associated with the metabolism of carnosine on no occasion
did a particular polymorphism inuence the response to EOC
with either decision times or the energy rating. With the
letter number task there was one signicant interaction. One
HDC SNP (rs854150; F (2,122)= 3.14, p<0.05), although
FIGURE 5. The effect of EOC on subjective energy levels. Data are mean (SE) for ratings
of energy (POMS). Participants who had consumed EOC reported having more energy than
those who had drunk the placebo (p<0.06).
FIGURE 5. e eect of EOC on subjective energy
levels. Data are mean (SE) for ratings of energy (POMS).
Participants who had consumed EOC reported having more
energy than those who had drunk the placebo (p<0.06).
66 Chicken extract, mood and cognition
not another SNP of this enzyme (rs854158, F (1,118) =
0.10, n.s.), inuenced the response to EOC. However, an
examination of the data found that the signicant interaction
reected baseline dierences in those with the same alleles and
therefore the nding was dismissed as a chance nding.
In no instance did a serotonin associated SNPs inuence
the EOC-induced eect on the number-letter task. With
the ratings of energy again with only one SNP was there
a signicant interaction: with one (rs6311; F (2.210) =
3.45, p<0.03), but not another, SNP (rs6314; F (1,124)
= 1.00, n.s.) of 5HTR2A. Again an examination of the
signicant interaction found dierences at baseline prior
to the consumption of the drinks that suggested a chance
nding. Finally when the decision times with eight lamps
was examined there was one signicant interaction, with the
5HTT polymorphism (rs1050565; F (2,132) = 3.84, p<0.02),
that is illustrated in Figure 6. When the changes in response
time from before to after the consumption of either EOC or a
placebo were considered there was a signicant EOC/placebo
X Before/after interaction (F (2,132) = 3.84, p<0.02). In those
with the GG allele there was a signicant dierence in decision
time after the consumption of the drinks (p<0.006) but not at
baseline. Whether rs1050565 inuenced changes in cortisol
was also examined although EOC did not interact with SNP
to aect the stress response (F (4,258) = 0.56, n.s.). ere was,
however, throughout the study a dierence in cortisol values
depending on the allele (F (2,129) = 2.99, p<0.05; AA 0.19
(0.01), GG 0.24 (0.03), GA 0.17 (0.01)) albeit they did not
inuence the eect of EOC.
e rst aim was to examine the inuence of EOC on
cognition. e letter – number task, used as a test of working
memory and performance, was better in those who had drunk
EOC (Figure 2), a nding similar to Azhar et al. (2008). It had
also been reported that EOC improved digit span performance
(Azhar et al., 2003), although as the lists of numbers forward
and backwards were added together it is unclear whether
this was a measure of working memory as such. Although,
an improvement in mental arithmetic, that relies heavily on
working memory, also occurred (Azhar and Syed, 2003, Azhar
et al., 2008), these eects did not reect a dierence between
EOC and the placebo but rather a change over time in those
who had consumed EOC, an eect that was not observed with
the placebo. Nagai et al. (1996) also reported fewer errors in
a test of mental arithmetic after supplementation with EOC;
however, the eect just missed statistical signicance. e
present ndings similarly did not support the view that EOC
beneted mental arithmetic. It is unclear why EOC would
improve performance on the letter –number task but not
serial sevens task, given that both involve working memory.
However, it has been suggested that serial sevens performance
is heavily inuenced by basic arithmetic skill (Karzmark, 2000)
and hence individual dierences in arithmetic ability may have
been more important.
Only a few studies have examined the inuence of EOC on
short term memory and the ndings are inconsistent. Azhar
and Syed (2003) reported an improvement in a ‘ree minute
memory test’ and recall of a paragraph. Azhar et al. (2008)
also found improvements in short term memory (digit span
forward) after consuming EOC. However, the present study
also found no eects of EOC on the recall of word lists. Given
these discrepancies there is a need for further research.
Performance of the focused attention task (arrow ankers)
was faster when EOC had been drunk (Figure 3). Similarly,
Yamano et al. (2013) studied the eect of consuming EOC
and found that it quickened reaction times on a modied
Stroop task. e Stroop task is similar to the arrow anker
task, as it requires focused attention while ignoring irrelevant
information. Consuming EOC was also related to faster
decision times on the reaction time task (Figure 4). Although
to our knowledge there is no previous literature that addresses
FIGURE 6. Changes in decision times after consuming
EOC depending the alleles of rs1050565 e data are mean
decision times for those with the three alleles of rs1050565:
AA n=77; AG n=51; GG n=10. In those with GG the
decision times of those consuming EOC were signicantly
quicker than after the placebo (p <0.006).
Chicken extract, mood and cognition 67
the inuence of EOC on choice reaction times, overall there
is an impression that drinking EOC resulted in a faster speed
of responding.
A second aim was to examine the eect on mood. ere
was no association between taking EOC and the subjective
response to testing. However, when asked to reect on how
they had been feeling during the ten day supplementation
period, participants who consumed EOC tended to report
having more energy (Figure 5). ese ndings are consistent
with recent studies by Yamano et al. (2013) and Young and
Benton (2015) who also reported that EOC improved mood.
EOC has also been associated with reduced fatigue when
facing a demanding mental task (Nagai et al., 1996; Yamano
et al., 2013).
In summary there is increasing evidence that consuming
EOC reduces fatigue and enhances energy. Young and Benton
(2015) found an increase in the Low / High Frequency ratio
(index of Heart Rate Variability that represents sympathetic/
parasympathetic balance). An increase in this ratio would
represent either an increase in sympathetic activity or vagal
withdrawal which may result in an increase in energy. e
mechanisms mediating the benecial eects of EOC on
energy levels are not, however, well understood. However, an
interesting hypothesis is that by virtue of histidine containing
peptides, it may inuence histaminergic system in the brain
(Li et al., 2012). Histidine is the precursor to histamine and
has a role in the maintenance of wakefulness (Panula and
Nuutinen, 2013), a possible mechanism for reducing fatigue.
It has been previously reported that after a mental workload
the speed of recovery of serum cortisol levels was enhanced in
those who consumed EOC (Nagai et al., 1996); the present
study tended to conrm these ndings (Figure 1; p<0.06).
Given that elevated cortisol levels are associated with poorer
cognition (Vedhara et al., 2000) and mood (Burke et al.,
2005), the enhanced cortisol recovery may partially explain
the benecial eects of EOC on cognition and mood.
Since EOC contains many dierent components it is dicult
to identify the active ingredient: it consists mainly of proteins,
peptides and free amino acids (Li et al., 2012). Among the
peptides carnosine and anserine are present at relatively high
concentrations in the human brain (Kohen et al., 1988) and
may contribute toward neuronal protection (Boldyrev et al.,
2004), possibly via their antioxidant (Kang et al. 2002; Kohen
et al. 1988) or antiglycation (Hipkiss 2005) actions. Although
it has been suggested that histidine containing peptides, such
as carnosine and anserine, may prevent cognitive decline
(Mong et al., 2011) and even Alzheimer’s disease (Corona et
al., 2011), to our knowledge only two studies have examined
the eects of carnosine in isolation on cognitive performance.
Baraniuk et al. (2013) studied the eects, in Gulf war
veterans, of consuming carnosine and found a signicant
dierence in digit symbol substitution test scores, a task
associated with activation of the fronto-parietal network
(Usui et al., 2009). However, taking carnosine produced no
dierences in fatigue, quality of life or accelerometer scores
although the fatigue experienced by Gulf war veterans is
greater than by a healthy population such that minor eects
might not be observed. Chez et al. (2002) studied the eects
of carnosine in children with autistic spectrum disorders who
showed signicant improvements on the Gilliam Autism
Rating Scale and the Receptive One-Word Picture Vocabulary
test. Although these nding cannot be generalised to healthy
populations they support the possibility that carnosine, and
perhaps anserine, may be the active components of EOC.
Future research should consider the cognitive/subjective
eects of carnosine or anserine in isolation to elucidate the
role, if any, played by these peptides.
Interestingly consuming chicken soup (also rich in
carnosine and anserine) not only improved mood but also
increased peripheral blood ow (Midoh and Noguchi, 2008).
Carnosine and anserine are powerful antioxidants and these
eects are consistent with antioxidant induced vasodilation
(Wray et al., 2012). e supply of blood to brain cells relies
upon neurovascular coupling, that is neuronal activity being
associated with increases in the diameter of blood vessels
resulting in greater blood ow (Kuschinsky, 1997). is
process is highly dependent on the ability of the endothelium
to vasodilate (Girovard and Ladecola, 2006). As dierences in
endothelial functioning have been related to brain activation
during a working memory task (Gonzales et al., 2010), you
can speculate that improvements in working memory after
consuming EOC may be mediated by increased cerebral blood
An examination of various polymorphisms oers a way of
examining potential mechanisms. For example carnosinase is
the rate limiting step involved in the metabolism of carnosine
and hence polymorphisms that inuence its activity might
be expected to inuence any benecial response to EOC,
should that is, carnosine be part of the underlying mechanism.
Although a case can be made for carnosine having a role in
the action of EOC, the results from the carnosine-related
SNPs presently examined gave no support for this suggestion.
An alternative is that EOC has an inuence on serotonergic
mechanisms. ere is also evidence that EOC modulates
cerebral levels of 5-HT as Xu and Sim (1997) found that
it increased the level of 5-hydroxyindoleacetic acid, the
metabolite of 5-HT, in cerebrospinal uid. A peptide has
also been identied in EOC that acts as a serotonin transport
inhibitor, indicating a possible mechanism (Tsuruoka et al.,
In this context the nding of an interaction between
rs1050565 and the response to EOC is of considerable interest.
Rs1050565 is often studied because of its association with
the transporter responsible for serotonin reuptake, although
its role is more complex. It occurs in the promoter region of
5HTT and is non-synonymous, that is it changes the protein
sequence. e 5HTT gene is of interest: it has been associated
with depression (Belzeaux et al., 2010) and may play in the
development of psychotic and aggressive tendencies in those
with Alzheimer’s disease (Pritchard et al., 2007).
68 Chicken extract, mood and cognition
Testicular cancer patients may be treated with the cytotoxic
drug bleomycin, that is broken down by the enzyme
Bleomycin hydrolase, a cysteine protease encoded by the
BLMH gene whose only known function is the inactivation
of bleomycin. e enzyme has been highly conserved by
evolution and is found throughout the body including the
hippocampus with its role in memory, and the amygdala
with its role in emotion. Rs1050565 is also a SNP in the
BLMH gene and those with testicular cancer, and the GG
rather than AA or GA genotype, are ve times more likely
to die when being treated with bleomycin (de Haas et al.,
2007). As it has been proposed that EOC may act as an anti-
dementia agent (Patent WO 2012160713 A8), it is relevant
that a possible association between BLMH and Alzheimer’s
disease has been discussed. e expression of this enzyme is
less in the brains of those with this disorder (Namba et al.,
1999; Malherbe et al., 2000). e polymorphism results
in the substitution of Adenine by Guanine at position 1450
resulting in the ineciency of the BLMH enyzyme (de Haas
et al., 2008; Altes et al., 2013). It has been reported that
those with the GG allele, who did not have the APOE 4
allele, were four times more likely to have Alzheimer’s disease
(Montoya et al., 1998; Farrer et al., 1998; Papassotiropoulos
et al., 2000; Ximenez et al., 2013), although not all studies
have reported this association (Prince et al., 2001; Smach et
al., 2010). It has also been suggested that the BLMH gene
inuences the production of the amyloid precursor protein
and hence the proteolytic fragment Amyloid-β that plays a
role in Alzheimer’s disease (Namba et al., 1999; Malherbe et
al., 2000).
Although it is easy to see an association between an
interaction between the rs1050565, EOC (Figure 6) and the
above discuss of the association between BLMH and dementia,
the present ndings must be viewed with caution. ere was
no a priori hypothesis, and as the sample size was small there
is a need for replication. e eect of rs1050565 was not on
memory as might be predicted if there was a direct inuence
of EOC on the mechanisms associated with dementia. Rather
the eect was on reaction times, however, if the BLMH gene
was important then the eect in Figure 6 might be a marker for
the later production of the amyloid plaques that characterize
Alzheimer’s disease. Clearly these are speculative suggestions
and the nding should be viewed as hypothesis generating
rather than hypothesis testing. However, if the nding is
replicated then an insight may have been given into the action
of EOC, with implications for the disease state.
In conclusion consuming EOC improved working memory
decision times and increased ratings of energy. Future research
should focus on isolating the active ingredients of EOC and
the mechanisms mediating its eects, including possible eects
on peripheral and cerebral blood ow. In particular the role of
the serotonin transporter should be examined.
We are grateful to thank and acknowledge Cerebros, Pacic,
Ltd, Singapore, for the supply of products and the funding of
this study.
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Reproduced with permission of the copyright owner. Further reproduction prohibited without
... In addition, the lack of standardized cognitive test classifications could prevent a meaningful conclusion from being drawn. Since the earlier reviews, several larger scale studies which assessed the impact of EC on more extensively represented cognitive domains have been published [11,17,18]. Hence, an updated evaluation with more clearly defined domains and more a powerful statistical analysis is both timely and necessary. ...
... A total of eight studies fulfilled the inclusion criteria and were shortlisted after a systematic review of the available literature with seven studies eligible for the meta-analysis [11,12,17,18,20,21,25,26]. The main characteristics of these eight studies are depicted in Table 2. Populationwise, there were 794 subjects altogether. ...
... This systematic review and meta-analysis provides an important update of earlier reviews [14,15] following the inclusion of three larger sampled studies which were published recently [11,17,18]. This increased the pooled sample to 794 subjects, which is more than double the 363 subjects in the earlier reviews. ...
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Essence of chicken (EC) is a dietary supplement with potential benefits on one's cognitive performance. The purpose of this meta-analysis is to evaluate the effects of consuming EC on cognitive function, applying extensively represented domains. Six databases were systematically searched to yield 1760 articles. These articles were independently screened to obtain 8 eligible articles with a pooled population of 794 subjects which is more than twice the population size considered in the previous meta-analyses. Largely, favorable effects on cognitive function were observed following daily EC intake, specifically in the working memory domain (standardized mean difference: 0.31, 95% CI: 0.16, 0.46), one of the core components in executive function which showed statistically significant results. Furthermore, the observed results were also robust to sensitivity analyses and subgroup analyses. This suggests that when consumed daily, EC may improve the mental processing aspect of cognitive function amongst the healthy population.
... These domains include attention (simple, sustained and selective), memory (short-term and working memory) and executive function, with heterogeneous findings reported across studies. Although individual studies have reported improvement in short-term memory [11,13,14], working memory [11,14,15], mental arithmetic [11,13,14] and reaction times [12] due to EC consumption, a systematic review and meta-analysis found large uncertainties on effect sizes and availability of only a small number of low quality trials. The authors concluded that more high-quality randomized control trials (RCTs) were needed to determine EC's effect on cognitive function [16]. ...
... The authors concluded that more high-quality randomized control trials (RCTs) were needed to determine EC's effect on cognitive function [16]. Two other recent studies have since been published [15,17]. Improvement in working memory, decision time and reaction time, but not episodic memory and sustained attention were found with EC consumption in one study [15]. ...
... Two other recent studies have since been published [15,17]. Improvement in working memory, decision time and reaction time, but not episodic memory and sustained attention were found with EC consumption in one study [15]. In the other study, no effect of EC on sustained attention, executive function, short-term or working memory was shown among young adults experiencing work stress. ...
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High-quality, adequately-powered clinical trials investigating the effect of Essence of Chicken (EC) on cognitive function are lacking. We conducted a randomized, double-blind, placebo-controlled clinical trial on healthy adult volunteers to determine the effect of EC on short-term memory, working memory, and selective and sustained attention. As a secondary objective, we evaluated baseline stress as a modifying factor by including treatment, stress and visit as main effects in a three-way ANOVA model. Cognitive function was evaluated at baseline, and Days 7 and 14. Data from 235 participants were analyzed on a per-protocol basis. The three-way interaction effect was significant (p = 0.020) in Digit Span Forward and further analyses showed EC improved test performance in moderate (p = 0.041) and severe stress (p = 0.065) but not in normal and mild stress subgroups. In Digit Span Backward, EC group showed greater improvement compared to placebo (p = 0.028), with 0.60 digits (8.50% improvement from baseline) more recalled on Day 7. No treatment or interaction effects were statistically significant in selective and sustained attention tests. Our findings support EC’s effect in improving mental processes used in working memory among healthy adults and short-term memory among healthy adults experiencing stress in daily life.
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Chicken extract, which is rich in anserine and carnosine, has been widely taken in Asian countries as a traditional remedy with various aims, including attenuation of psychological fatigue. The effects of consuming BRAND'S Essence of Chicken (EOC) or a placebo on 46 young adults' responses to a standard psychological "stressor" were considered. Heart rate variability (HRV), cortisol responses, mood and cognition were measured at baseline and after ten days supplementation. EOC resulted in feeling less anxious, depressed and confused and more agreeable and clearheaded. A decrease in HRV was observed after EOC but only in females. Cognition and cortisol levels were not influenced by EOC. Findings suggest that EOC may be a promising supplement to improve mood in a healthy population.
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Alzheimer disease (AD) is a progressive and irreversible neurodegenerative disorder that is characterized by cognitive decline, memory loss and confusion. The E4 allele of the apolipopro-tein E gene (APOE) is associated with AD and it is the main genetic risk factor for disease. Although the exact physiological function is unknown , bleomycin hydrolase (BLMH) may also be associated with AD development, although previous immunohistochemical findings have been inconsistent. Therefore, the purpose of this study was to evaluate the genotypic and allele frequencies of the APOE gene and BLMH 1450 G > A polymorphism and assess BLMH expression using PCR-RFLP and RT-qPCR analyses of blood samples from patients with Alzheimer disease (AD), healthy elderly adults (EC) and healthy young subjects (YC). BLMH expression was significantly different among groups (p = 0.015) and there was substantial reduction with age and with AD. The APOE and BLMH genotype frequency did not diverge from the Hardy-Wein-berg equilibrium. There was a higher frequency of genotype 3/3 in all subjects (61.1%) and the AD group demonstrated a higher frequency of allele 4; however, differences in genotype and allele distributions were statistically different among groups.
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Background Fatigue is a common symptom in modern society. There has been a recent resurgence of interest in traditional remedies for fatigue. Chicken essence, which is rich in anserine and carnosine, has been widely taken in Asian countries as a traditional remedy with various aims, including attenuation of physical and mental fatigue. However, the evidence for its efficacy specifically for mental fatigue remains unclear. We examined the effect of essence of chicken on mental fatigue in humans, using our established fatigue-inducing task and evaluation methods. Material/Methods In this placebo-controlled crossover study, 20 healthy male volunteers were randomized to receive daily oral administration of essence of chicken or placebo drink provided by Cerebos Pacific Ltd. via Suntory holdings Ltd. for 4 weeks. The participants performed 2-back test trials as a fatigue-inducing mental task and then had a rest session. Just before and after each session, they completed cognitive task trials focusing on selective attention to evaluate the level of mental fatigue. Results After essence of chicken intake for 1 and 4 weeks, the reaction times on the cognitive task trials after the rest session were significantly shorter than those at baseline, and significant changes were not observed with placebo intake. The reaction times before and after the fatigue-inducing session were not altered by either essence of chicken or placebo intake. Conclusions We showed that daily intake of essence of chicken could be effective for the recovery from mental fatigue and is a promising candidate for use as an anti-fatigue food.
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About 25% of 1990-1991 Persian Gulf War veterans experience disabling fatigue, widespread pain, and cognitive dysfunction termed Gulf War illness (GWI) or Chronic Multisymptom Illness (CMI). A leading theory proposes that wartime exposures initiated prolonged production of reactive oxygen species (ROS) and central nervous system injury. The endogenous antioxidant L-carnosine (B-alanyl-L-histidine) is a potential treatment since it is a free radical scavenger in nervous tissue. To determine if nutritional supplementation with L-carnosine would significantly improve pain, cognition and fatigue in GWI, a randomized double blind placebo controlled 12 week dose escalation study involving 25 GWI subjects was employed. L-carnosine was given as 500, 1000, and 1500 mg increasing at 4 week intervals. Outcomes included subjective fatigue, pain and psychosocial questionnaires, and instantaneous fatigue and activity levels recorded by ActiWatch Score devices. Cognitive function was evaluated by WAIS-R digit symbol substitution test. Carnosine had 2 potentially beneficial effects: WAIS-R scores increased significantly, and there was a decrease in diarrhea associated with irritable bowel syndrome. No other significant incremental changes were found. Therefore, 12 weeks of carnosine (1500 mg) may have beneficial cognitive effects in GWI. Fatigue, pain, hyperalgesia, activity and other outcomes were resistant to treatment.
Objective: This study evaluates the effect of a commercial brand of chicken essence (BEC) on the various parameters related to stress and cognition of human volunteers. BEC is produced by a hot-water extraction process from chicken meat under high pressure conditions. It contains concentrated amounts of proteins, amino acids and peptides such as carnosine compared to homemade traditional chicken soup. Due to the unique extraction process, it has been postulated that readily absorbed amino acids and bioactive peptides are present in BEC. Methods: In this study, we evaluated the effect of BEC in comparison with a placebo on a group of distressed medical students. Students were randomly divided into two groups and given either BEC or a placebo drink daily for two weeks. Before and after the two weeks, the Students were given a sedes of tests to assess their level of cognitive functioning and perceived stress level while being monitored for EEG recording. The combination of these tests, namely Digit span, Arithmetic and Letter-number sequencing, generally assessed the student's attention and working memory. Results: The Working memory performance of students who ingested essence of chicken was found to be significantly better than those who consumed placebo when data comparing baseline and after two weeks consumption were compared. Conclusion: This study seems to suggest that essence of chicken has positive effects on the subjects' cognitive functions.
The effect of oral feeding of a commercial preparation of essence of chicken (Brand's Essence of Chicken, BEC) on the level of 5-hydroxyindole acetic acid (5-HIAA) in the cerebrospinal fluid (CSF) of the rat was investigated. BEC, when fed to the rat for a period of 3 days, significantly increased the CSF level of 5-HIAA in seven out of 12 animals studied. As the level of CSF 5-HIAA is taken as an indication of 5-hydroxytryptamine (5-HT) activity in the brain, it is possible that BEC increased brain 5-HT activity. This increase was not due to the ingestion of tryptophan, the primary precursor of 5-HT, because BEC contains undetectable level of tryptophan. The data indicate that by causing an increase in brain 5-HT activity, consumption of BEC may lead to the activation of 5-HT-dependent physiological process like sleep improvement, mood elevation, analgesia, facilitation of motor output and regulation of circadian rhythm. However, such a possibility remains to be further investigated.
A battery of eight different reaction time (RT) tests, measuring the speed with which individuals perform various elementary cognitive processes, and a group test of scholastic aptitude (the Armed Services Vocational Aptitude Battery, ASVAB) were given to 50 black and 56 white male vocational college students. The regression of the general factor scores of the ASVAB on the RT measures yielded a shrunken multiple correlation of 0.465. Although discriminant analyses, when applied separately to the ASVAB subtests and to the RT variables, showed highly comparable overall discrimination (over 70% correct classification) between the black and white groups, factor scores derived from the general factor (labeled ‘speed of information processing’) of the RT battery show only about one-third as large a mean black-white difference as the mean group difference on the general factor scores derived from the ASVAB. Comparisons were also made between the 106 vocational college students and 100 university students of higher average academic aptitude who had previously been tested on the same RT battery (Vernon, 1983a). These groups showed marked differences on the RT variables, the largest differences occuring on the tests that required more complex cognitive processing. The more complex RT tests also correlate most highly with the psychometric measures of ability within each group. The results are consistent with the hypothesis that individual differences and the mean differences between groups in psychometric abilities and scholastic achievement are related to differences in the speed of information processing as measured in elementary cognitive tasks.
Histamine acts as a modulatory neurotransmitter in the mammalian brain. It has an important role in the maintenance of wakefulness, and dysfunction in the histaminergic system has been linked to narcolepsy. Recent evidence suggests that aberrant histamine signalling in the brain may also be a key factor in Gilles de la Tourette syndrome, Parkinson's disease and addictive behaviours. Furthermore, multiple sclerosis (MS) and experimental autoimmune encephalitis, which is an often-used model for MS, are associated with changes in the histaminergic system. This Review explores the possible roles of brain histamine in the mechanisms underlying these diseases.