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Objective: To examine
the effect of purple
sweet potato (PSP)
beverage rich in
acylated anthocyanins on
serum hepatic
biomarkers in healthy
Japanese men.
Design: A randomized,
double-blind,
placebo-controlled,
parallel study.
Setting: Kumamoto in
Japan.
Subjects: Healthy adult
men (30–60 years) with
borderline hepatitis who
had one or more of serum
g-glutamyl transferase
(GGT), aspertate
aminotransferase (AST)
and alanine
aminotransferase (ALT)
levels over normal
ranges, and who were
negative
for hepatitis virus were
openly recruited by an
advertisement. Of the 48
persons enrolled, 38
(mean age 43.0 years
(30–54years) completed the
study.
Methods: The subjects
were randomly assigned
to the PSP group and the
placebo group. During
the 8-week intervention,
the
subjects in the PSP
group consumed two
bottles of the PSP
beverage with acylated
anthocyanins (200.3mg
anthocyanins per
125 ml per bottle) per
day, and the subjects in
the placebo group, two
bottles of a placebo
beverage (1.7mg
anthocyanins per
125 ml per bottle). All
of the data measured
were analyzed by two-way
repeated measures
analysis of variance
(ANOVA) with
groups and times. The
data of the hepatic
markers were analyzed
using the Dunnett
multiple comparison
among the time
points and t-test
between groups at the
same time point.
Two-sided Po0.05 were
defined as the level of
significance.
Results: Serum GGT, AST
and ALT levels showed
interactions (Po0.05)
between the beverage
groups and time; the
others were
not affected. The PSP
beverage group showed
lower hepatic marker
levels than the placebo
group during the
ingestion period,
particularly the GGT
level ( 14.1 IU/l, 95%
Confidence intervel (CI)
25.4 to 2.7, P¼0.017 at
2 weeks; 16.8 IU/l, 95%
CI
36.2 to 2.5, P¼0.081 at
4 weeks; 26.7 IU/l, 95%
CI 47.6 to 5.7, P¼0.014
at 6 weeks and 27.9
IU/l, 95% CI 49.9 to
5.9; P¼0.014 at 8
weeks). No correlation
between alcohol
consumption and each
hepatic biomarker level
before and after the
ingestion was observed.
Conclusion: The intake
of the PSP beverage
significantly decreased
the serum levels of
hepatic biomarkers,
particularly the GGT
level, in healthy men
with borderline
hepatitis.
European Journal of
Clinical Nutrition
(2008) 62, 60–67;
doi:10.1038/sj.ejcn.1602674;
published online 14
February 2007
Epidemiological studies
indicate an inverse
correlation
between the intake of
polyphenols and the
incidence of
chronic diseases, such
as cardiovascular
disease (CVD) and
cancer (Negri et al.,
1991; Hertog et al.,
1993; Keli et al.,
1996). Fruits and
vegetables rich in
polyphenols have been
expected to be important
materials for the
maintenance of
health.
Polyphenols are
non-nutritive
components; however,
they
have various biological
functions, such as
antioxidative,
anti-inflammatory and
antimutagenic
activities.
Anthocyanins of purple
sweet potato (PSP),
Ipomoea
batatas cultivar
Ayamurasaki (Yamakawa et
al., 1998), which
are mono- and
di-acylated forms of
cyanidin (YGM-1a, -1b,
-2 and -3) and peonidin
(YGM-4b, -5a, -5b and
-6) (Figure 1),
have a higher
antioxidative activity
than other anthocyanins.
Despite the complex
chemical structure of
PSP
anthocyanins, they are
rapidly absorbed into
the body,
detected in blood and
rapidly excreted in the
urine of rats
and humans (Suda et al.,
2002; Harada et al.,
2004).
Oral feeding of PSP
anthocyanins increased
the 1,1-
diphenyl-2-picrylhydrazyl
radical-scavenging
activity in the
urine of rats and
humans, increased the
resistance of lowdensity
lipoprotein (LDL) to
oxidation in rats and
the
suppressed carbon
tetrachloride
(CCl4)-induced liver
injury
in rats (Suda et al.,
1997; Kano et al.,
2005).
Liver injury is induced
by oxidative stress. For
example,
experimental acute liver
injury with CCl4 is
characterized by
centrilobular necrosis
resulting from the
formation of free
radicals and reactive
oxygen species during
the metabolism
of CCl4 by cytochrome
P450 and the activation
of Kupffer
cells by free radicals
(Recknagel and Glende
1973; Edwards
et al., 1993). The
damage of liver cells
accompanies the
release of liver
function enzymes, such
as g-glutamyl
transferase (GGT; EC
2.3.2.2), alanine
aminotransferase
(ALT; EC 2.6.1.1), and
aspartate
aminotransferase (AST;
EC
2.6.1.2) into the blood
(Skinner et al., 1984;
Shaper et al.,
1985). Clinically, these
enzymes are often used
as biomarkers
for liver injury or
liver diseases.
Recently, several
epidemiological
reports have shown that
serum GGT is associated
with risk factors of
CVD, suggesting the
possibility of the
close relationship
between oxidative stress
and chronic
diseases (Perry et al.,
1998; Lee et al., 2003;
Nakanishi et al.,
2003; Yamada et al.,
2003).
We have previously
reported in a
preliminary open study,
that the serum levels of
hepatic biomarkers in
healthy
volunteers were
depressed after
ingesting a PSP beverage
rich
in the acylated
anthocyanins (Suda et
al., 1998). The
ameliorative effect due
to PSP beverage intake
is clearly
exerted in men who had
one or more of GGT, AST
and ALT
over the normal range in
their medical checkup,
and who
had a need to recover
their liver function.
In light of these
findings, we have
examined the effect of
the intake of a PSP
beverage on the
biomarkers of healthy
men with the above
conditions in this
double-blind
placebocontrolled
study.
Methods
Test beverages
We used the fleshed PSP
beverage (trade name
‘AYAMURASAKI’)
obtained from Yakult
Honsha Co, Ltd (Tokyo,
Japan)
as the test beverage.
The PSP beverage was a
mixture of the
concentrated PSP extract
prepared from the tuber
of I.
batatas (Suda et al.,
2002) and taste
adjusting materials
(lemon juice and
flavors); one bottle of
beverage (125 ml)
contained 0.7 g protein,
no lipid, 14.8 g
carbohydrates, 0.4 g
dietary fiber, 5mg
sodium, and 200.3mg
anthocyanins (see
below on analysis
method). Using the same
manufacturing method,
the placebo beverage was
made from a PSP extract
equivalent to 1/100 the
volume of the PSP
beverage, lemon
juice, flavors and
glucose solution to
adjust to the same Brix
value; the anthocyanin
content was 1.7 mg/125
ml. Each of
the PSP and the placebo
beverage was packed in a
similar
white vessel, so as to
be indistinguishable by
their outward
appearance.
To measure the
anthocyanin content of
the PSP and the
placebo beverages
according to the
previous report (Suda
et al., 2002), each
beverage was evaporated
to dryness under
reduced pressure at
351C, and the dried
extract was redissolved
into a 1.0%
trifluoroacetic acid
(TFA) aqueous
solution. The absorbance
of the sample solution
was
measured at 530 nm. The
anthocyanin content was
calculated
from a calibration curve
for YGM-5b and expressed
as
the YGM-5b equivalent
per 1ml of beverage. To
determine
the composition of
anthocyanins in the PSP
beverage, highpressure
liquid chromatatography
(HPLC) analysis was
performed under the same
conditions, which could
detect the eight major
peaks of the
anthocyanins (YGM-1a
to YGM-6) in PSP (Figure
1).
Subjects
Healthy adult male
volunteers were
recruited from Kumamoto
city and the surrounding
area by an advertisement
of
SAKURA Inc. (Kumamoto,
Japan). The content and
methods
of the study were fully
explained to all
participants, and their
written informed consent
was obtained in writing
before
enrollment. The study
was carried out in
accordance to the
Declaration of Helsinki,
and was approved by the
Kumamoto
Clinical Examination
Ethics Committee.
Forty-eight candidates
were selected from
applicants
satisfying the following
eligibility criteria:
men between 30
and 60 years old; those
with borderline levels
of one or more
hepatic function markers
(over 80 IU/l of GGT,
42–99 IU/l of
AST and 42–99 IU/l of
ALT) excluding those
with a more than
6-year history of
impaired hepatic
function according to
medical diagnosis in
those negative for
hepatitis virus; those
not taking abundant
medication or dietary
supplements that
may affect hepatic
function, such as those
made from PSP,
turmeric, a soft-shelled
turtle, sesame or
oyster; those
without a history of
food allergies,
diabetes,
cardiovascular,
gastrointestinal or
renal disease; and those
who did not
donate more than 200 ml
of blood during the 4
weeks before
the start of the study;
those willing to
complete a complex
diet diary and to
maintain their
conventional lifestyle
with
regard to dietary and
physical habits.
Study design
A double-blinded
comparative study with
two parallel
groups was performed to
test the effect of the
PSP beverage
in subjects with
borderline hepatitis.
Following the entry
period, the study was
carried out for a
period of 15 weeks,
which included a 3-week
pre ingestion
period, an 8-week
beverage-ingestion
period and a 4-week
postingestion period. In
the entry period and
preingestion
period, a pre-clinical
examination and a
dietary survey were
carried out to screen
the qualified subjects
as mentioned
above. After the
clinical examination,
twice (at week 2 ( 2
weeks) and 0 (0 weeks))
during the preingestion
period, the
48 subjects were
randomly assigned to
either the PSP
beverage-ingestion group
(PSP group) or the
placebo beverage-
ingestion group (placebo
group) with
stratification
according to age, body
mass index (BMI), and
serum GGT,
AST and ALT levels, and
subjected to
beverage-ingestion
examination. The men in
each group were
instructed to
drink two bottles of the
beverage (125 ml/bottle)
daily, every
1072 h. The total number
of beverages ingested
during this
study period was 112
bottles per subject.
After the
beverageingestion
period, the
post-ingestion period
immediately
followed.
The subjects were
advised not to change
their current
dietary habits or
lifestyle during the
study period. The
subject was instructed
to keep a diary about
items as follows:
(1) the number of
bottles and time of
ingesting the
beverages, to obtain
information as to
whether the beverage
was drunk at regular
intervals; (2) the type,
volume, alcohol
content and beginning
and finish time of
ingesting alcoholic
drinks, to calculate the
amount of alcohol intake
and (3) the
lack of sleep, feelings
of fatigue during the
hour of rising, loss
of appetite, feelings of
nausea, diarrhea, bowel
movements
and so on to observe the
changes in physical
condition.
Furthermore, the
subjects were instructed
to record the
contents of all foods
consumed for 7
consecutive days in
every preingestion
period,
beverage-ingestion
period and
post-ingestion period.
These were filled out
referring to the
Standard Tables of Food
Composition in Japan
(5th edition).
Clinical examination for
physical, blood and
urine parameters
was performed every 2
weeks. Blood was drawn
between 08:00 and
11:00hours. after the
subjects had fasted
for at least 10 h. The
first spontaneous urine
was collected at
home of the each
subject. Systolic and
diastolic blood
pressures were measured
on the left arm using a
standard
mercury sphygmomanometer
while the subjects were
seated.
BMIs were calculated
using the body weight
and height.
During the 15-week study
period, the 38 subjects
(mean
age 43.0 years (30–54
years)) completed the
study according
to the protocol.
However, 10 subjects who
were forced to
discontinue the study
due to the job transfer,
who neglected
the conditions of
clinical examination,
who had been
forgetting to drink the
test beverages and who
did not
maintain a regular
dietary lifestyle were
excluded from the
final study analysis.
Biochemical analysis of
blood and urine
Blood and urine samples
were transported to the
Clinical
Research Center of the
Kumamoto City Medical
Association
(Kumamoto, Japan). Blood
samples were used for
the
analysis of total
protein, albumin,
globulin, albumin/
globulin ratio, total
bilirubin, direct
bilirubin, indirect
bilirubin, ALT, AST,
GGT, alkaline
phosphatase,
cholinesterase,
lactate dehydrogenase,
total cholesterol,
HDL-cholesterol,
LDL-cholesterol,
triglyceride, urea
nitrogen, creatinine,
uric
acid, sodium, chloride,
potassium, magnesium,
calcium,
glucose, hemoglobin A1C,
red blood cell count,
white blood
cell count, hemoglobin,
hematocrit, mean
corpuscular
volume, mean corpuscular
hemoglobin, mean
corpuscular
hemoglobin
concentration, platelet
count, neutrophil,
eosinophil, basophil,
lymphocyte and monocyte.
Urine was
used for the analysis of
glucose, protein and
creatinine.
Dietary survey
Nutrient intake (energy,
protein, fat,
carbohydrate, ash,
sodium, potassium,
calcium, magnesium,
phosphorus, iron,
zinc, vitamin A (retinal
equivalent), vitamin E,
vitamin C,
cholesterol, total
dietary fiber, salt (as
NaCl), protein ratio,
fat ratio, carbohydrate
ratio and alcohol
intake) was
calculated on the basis
of the dietary record
for 7 consecutive
days in three periods
for this study, using
nutritional
software (The
Eiyoushidou PRO ver1.0,.
Access Intelligent,
Ltd, Kumamoto, Japan)
based on the Standard
Tables of Food
Composition in Japan
(5th edition).
Statistical analysis
The average of the
clinical data at –2 and
0 weeks was
calculated and used as a
baseline value in the
preingestion
period before the
beginning of the
beverage ingestion. Data
were expressed as the
means7standard error of
mean
(s.e.m.). Variations in
the clinical parameters
and food
intake in the study were
analyzed by two-way
repeated
measures analysis of
variance (ANOVA) for two
groups (PSP
and placebo) 7 time
points (baseline, 2, 4,
6, 8, 10 and 12
weeks) using SPSS
software for Windows
(version 12.0J, SPSS
Japan, Tokyo, Japan).
For the changes in the
GGT, AST and
ALT levels in the study
period, differences
between the
baseline value and the
following time points
within the
group, and differences
between the PSP and the
placebo
groups for the same
period, were analyzed
using the Dunnett
multiple comparison
among the times for the
paired data
and with the unpaired
t-test using the
software of the SAS
Preclinical Package for
Windows (version 5.0,
SAS Japan,
Tokyo, Japan). The
correlation between both
distances of
each hepatic parameter
level and the amount of
alcohol
consumed before and
after the ingestion of
the beverages
was analyzed by linear
correlation using Kyplot
software for
Windows (Kyence Inc,
Tokyo, Japan). Two-sided
P-values
o0.05 were considered to
be significant.
Results
Baseline characteristics
of the subjects
The baseline clinical
characteristics of the
subjects are shown
in Table 1. Overall,
there was no difference
between the PSP
and placebo groups in
any of the parameters of
age, height,
weight, BMI, GGT, AST
and ALT.
Changes in physical,
urine and blood
parameters, and dietary
status
Physical and urine
parameters were not
changed during the
study period within the
same group, and there
was no
difference between both
the PSP and placebo
groups for the
same period.
Most of the blood
parameters were also
unchanged.
However, in the serum
GGT, AST and ALT levels,
the
interactions between the
groups and times were
observed
by two-way repeated
measures ANOVA. These
parameters
were further analyzed as
described below. The
dietary status,
such as nutrition and
alcohol consumption, was
not
changed throughout the
pre-observation,
beverage-ingestion
and post-observation
periods within the same
group,
and there was no
difference between the
PSP and placebo
groups.
Changes in GGT, AST and
ALT
The PSP group (n¼20)
constituted 11 subjects
with hyper
GGT over the normal
range (480 IU/l), five
with hyper-AST
(442 IU/l), and 13 with
hyper-ALT (442 IU/l) at
the start
point (Figure 2). The
placebo group (n¼18)
contained 12-
hyper GGT subjects, 4
hyper-AST, and 10
hyper-ALT subjects.
The changes in the GGT,
AST and ALT value after
ingesting
PSP and placebo
beverages are shown in
Figures 3–5. GGT
values against the
baseline value in the
PSP group were
decreased at 4 weeks
(mean difference, 19.0
IU/l; CI95,
35.3 to 2.7; P¼0.016), 6
weeks ( 19.9 IU/l; CI95,
36.2 to
3.6; P¼0.010), 8 weeks (
20.9 IU/l; CI95, 37.2 to
4.6;
P¼0.006) and 12 weeks (
20.12 IU/l; CI95, 36.4
to 3.8;
P¼0.009) in all subjects
(Figure 3a) and at 4
weeks ( 37.0 IU/
l; CI95, 64.8 to 9.3;
P¼0.004), 6 weeks ( 37.7
IU/l; CI95,
65.4 to 10.0; P¼0.004),
8 weeks ( 37.3 IU/l;
CI95, 65.0
to 9.6; P¼0.004), 10
weeks ( 30.0 IU/l; CI95,
57.8 to 2.3; P¼0.029)
and 12 weeks ( 35.1
IU/l; CI95, 62.9 to
7.4; P¼0.007) the
hyper-subjects (Figure
3b). GGT values
in the placebo group,
however, were not
changed throughout
the entire period. A
significant difference
of the GGT
values between both PSP
and placebo groups are
seen at 2
weeks ( 14.1 IU/l; CI95,
25.4 to 2.7; P¼0.017), 4
weeks
( 16.8 IU/l; CI95, 36.2
to 2.5; P¼0.081), 6
weeks ( 26.7 IU/
l; CI95, 47.6 to 5.7;
P¼0.014) and 8 weeks (
27.9 IU/l;
CI95, 49.9 to 5.9;
P¼0.014) in all
subjects, and at 2 weeks
( 23.5 IU/l; CI95, 40.4
to 6.6; P¼0.009), 4
weeks
( 31.8 IU/l; CI95, 59.3
to 4.4; P¼0.025), 6
weeks
( 46.3 IU/l; CI95, 77.7
to 14.9; P¼0.006) and 8
weeks
( 43.8 IU/l; CI95, 77.9
to 9.6; P¼0.014) in the
hypersubjects.
AST values against the
baseline value in the
PSP group were
decreased at 2 weeks (
4.9 IU/l; CI95, 9.0 to
0.8;
P¼0.012), 4 weeks ( 5.4
IU/l; CI95, 9.4 to 1.3;
P¼0.005), 6 weeks ( 5.7
IU/l; CI95, 9.7 to 1.6;
P¼0.003), 10 weeks ( 5.9
IU/l; CI95, 9.9 to 1.8;
P¼0.002)
and 12 weeks ( 6.7 IU/l;
CI95, 10.8 to 2.6;
Po0.001) in all
subjects, and at 6 weeks
( 13.7 IU/l; CI95, 25.5
to 1.9;
P¼0.019), 8 weeks ( 12.5
IU/l; CI95, 24.3 to 0.7;
P¼0.035), and 12 weeks (
13.7 IU/l; CI95, 25.5 to
1.9;
P¼0.019) in the
hyper-subjects (Figure
4). AST values in the
placebo group were not
changed throughout the
entire
period, except for a
decrease at 10 weeks (
4.8 IU/l; CI95,
9.3 to 0.3; P¼0.033) in
all subjects, and were
not
changed in the
hyper-subjects.
Significant differences
in
the AST values between
both the PSP and placebo
groups
were seen at 2 weeks (
5.4 IU/l; CI95, 10.0 to
0.8;
P¼0.024), 4 weeks ( 6.3
IU/l; CI95, 11.3 to 1.4;
P¼0.014), 6 weeks ( 5.8
IU/l; CI95, 9.8 to 1.8;
P¼0.005) and 12 weeks (
6.2 IU/l; CI95, 11.5 to
0.8;
P¼0.025) in all
subjects, and were not
observed in the
hyper-subjects.
ALT values against the
baseline value in the
PSP group
were decreased at 10
weeks ( 8.2 IU/l; CI95,
15.0 to 1.4;
P¼0.011) and 12 weeks (
8.5 IU/l; CI95, 15.3 to
1.7;
P¼0.008) in all subjects
and at 12w ( 10.7 IU/l;
CI95, 20.6
to 0.9; P¼0.027) in the
hyper-subjects (Figure
5). The ALT
values in the placebo
group were not changed
during whole
period. A significant
difference of the ALT
value between
both the PSP and placebo
groups was seen at 2
weeks
( 9.9 IU/l; CI95, 15.9
to 4.0; P¼0.002), 4
weeks ( 8.7 IU/l;
CI95, 15.3 to 2.0;
P¼0.012), 6 weeks ( 9.8
IU/l; CI95,
17.6 to 1.9; P¼0.016)
and 8 weeks ( 8.4 IU/l;
CI95, 16.2
to 0.5; P¼0.037) in all
subjects, and at 2 weeks
( 14.5 IU/l;
CI95, 23.1 to 5.9;
P¼0.002) in the
hyper-subjects. The
differences of the
change in the ALT might
be explained by
the tendency to decrease
in the PSP group and to
increase in
the placebo group during
the intake period.
Correlation between
hepatic biomarkers and
alcohol intake
Hepatic marker levels
are affected by the
intake of alcohol as
well as liver diseases
(Skinner et al., 1984;
Shaper et al., 1985).
In particular, the GGT
levels rise with alcohol
consumption,
even in the absence of
chronic liver diseases
(Whitehead
et al., 1978; Chick et
al., 1981). We analyzed
the correlation
between alcohol
consumption and each
marker level before
and after the ingestion
of the beverages. The
difference of the
GGT level was not
associated with that of
alcohol consumption
in the PSP group
(r¼0.195, P¼0.411) or
the placebo
group (r¼ 0.126,
P¼0.617) in all
subjects. It was
irrelevant
in the case of the hyper
GGT subjects (r¼0.146,
P¼0.668 in
the PSP group and r¼
0.157, P¼0.646 in the
placebo
group). Furthermore,
there was no association
between the
difference of the serum
AST and ALT levels with
that of
alcohol consumption
before and after the
ingestion of the
beverages (data not
shown).
Discussion
The PSP beverage
contains at least eight
anthocyanins, each
of which has a high
radical scavenging
activity (Kano et al.,
2005). In the case of
ingesting the beverage,
two major
components, YGM-2
(cyanidin
3-O-(2-O-(6-O-(E)-caffeoylb-
D-glucopyranosyl)-b-D-glucopyranoside)-5-O-b-D-glucopyranosyl)-
b-D-glucopyaranoside))
and YGM-5b (peonidin
3-O-(2-O-(6-O-(E)-caffeoyl-b-D-glucopyranosyl)-b-D-glucopyranoside)-
5-O-b-D-glucopyranosyl)-b-D-glucopyranoside)),
are
selectively detected in
the blood and rapidly
excreted in the
urine of rats and humans
(Suda et al., 2002;
Harada et al.,
2004; Kano et al.,
2005). The urinary
recovery rate of PSP
anthocyanins is very low
(0.01% in humans and
0.11% in
rats); however, the
radical-scavenging
activity in the urine is
elevated after the
ingestion of the PSP
beverage (Kano et al.,
2005). These facts imply
that even if the
absorbability is low,
the PSP anthocyanins in
the body are sufficient
to exert some
physiological effects.
Since serum GGT, AST and
ALT activities reflect
damage to
the cells, particularly
liver cells, they are
clinically used as
biomarkers for liver
injury or liver
diseases. In rats, the
oral
feeding of PSP
anthocyanins suppressed
the increase in
serum hepatic enzyme
levels in rats due to
CCl4 administration
(Suda et al., 1998; Kano
et al., 2005), showing
the
efficacy of PSP
anthocyanins against
chemical-induced
hepatotoxicity. In this
human study, the
ingestion of the
PSP beverage decreased
the serum levels of
these hepatic
markers in healthy men
with these borderline
levels. This
was the case in subjects
whose levels exceeded
the normal
range of each marker.
The previous animal
experiments and
this human study
indicate that acylated
anthocyanins rich in PSP
beverages possess the
potential capacity for
hepatoprotection.
In this study, we
instructed the subjects
not to change
their current dietary
habits and conventional
lifestyle,
including alcohol
intake. Consequently,
alcohol consumption
was not statistically
different during the
whole period or
between the groups. As
the hepatic marker
levels are
probably affected by
alcohol consumption on
an individual
basis, the association
between those factors
was analyzed
using the differences of
alcohol consumption and
of each
marker level before and
after the ingestion of
the beverages.
We observed no
correlation between
alcohol consumption
and the marker levels,
indicating that the
intake of PSP
beverage, but not
alcohol, was closely
related to the
decreases in these
marker levels.
A recent cohort study
showed that GGT was
inversely
associated with fruit
intake, but directly so
with alcohol and
meat consumption (Lee et
al., 2004). GGT, widely
distributed
in the human body, plays
a key role in
antioxidation
systems, while
maintaining
intracellular
glutathione recycling
in the cells (Kugelman
et al., 1994, Takahashi
et al.,
1997, Karp et al.,
2001). The elevation of
the serum GGT level
is induced by an
increase in the
production of reactive
oxidative species after
ethanol treatment
(Cederbaum,
2002). Furthermore,
serum GGT, AST and ALT
levels might
be a marker of the
progression of
lifestyle-related
diseases
due to oxidative stress
(Perry et al., 1998;
Falck-Ytter et al.,
2001; Lee et al., 2003).
Our observation that
serum hepatic
marker levels,
particularly the GGT
level, were reduced by
the ingestion of PSP
beverage might indicate
the contribution
of PSP anthocyanins to
the alleviation of
oxidative
stress.
In conclusion, the
ingestion of PSP
beverage decreased the
serum levels of the
hepatic markers in
healthy men with
borderline hepatitis in
this double-blind
placebo-controlled
study. There was no
correlation between the
alcohol intake
and each marker level.
This study suggested
that the PSP
beverage may have a
potential capacity for
hepatoprotection
against oxidative
stress.
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