Vol.1, No.2, 83-87 (2009)
Copyright © 2009 Openly accessible at http://www.scirp.org/journal/HEALTH/
Serum homocysteine concentrations of Chinese
intellectuals and the influential factors concerned
Yue Hou*, Yan Hong, Wei-Qiang Chen, Dong-Lan Wang, Yi-Yong Cheng
*Institution of Hygiene and Environmental Medicine, Tianjin, China; Corresponding author: houy77@sohu.com
Received 23 July 2009; revised 6 August 2009; accepted 7 August 2009.
Objective: To observe the concentration of se-
rum homocysteine in intellectuals and the re-
lated influential factors. Methods: The concen-
trations serum homocysteine and saliva cortisol
were measured in 138 intellectuals from three
cities, Tianjin, Guangzhou and Chengdu in
China. All the subjects had senior titles of tech-
nical post, aged 40-69 years. Results: The mean
value of serum homocysteine concentration in
intellectuals was 20.6±0.8μmol/L, higher than
the reference value. With the increase of cortisol
levels the homocysteine concentrations rise (P
<0.05). The mean value of homocysteine con-
centration was highest in 40-49 years old group.
Men had higher homocysteine level than women
in this investigation. According to the mean
value of homocysteine concentration among
different cities, Tianjin was highest, Chengdu
medium, Guangzhou lowest. Conclusion: The
serum homocysteine concentration of intellec-
tuals is higher than the reference value. The
stress level, gender and resident cities might
contribute to the differences in serum homo-
cysteine concentration in Chinese intellectuals.
Keywords: Homocysteine; Psychological Stress;
Stress induces several physiological and behavioral al-
terations that increase cardiovascular morbidity and
mortality [1-3]. It is well known that total plasma ho-
mocysteine (tHcy) is now established as a clinical risk
factor for coronary artery disease, as well as other arte-
rial and venous occlusive disease in adult populations [4].
Nonetheless, only a few studies have evaluated the rela-
tionship between stress and tHcy level. In order to ex-
amine whether any acute effect on total plasma Homo-
cysteine (Hcy) concentrations in rats would occur four
distinct acute stressors in rats, i.e., swimming, restrain,
novelty and cold exposure were used. Plasma corticos-
terone and adrenocorticotropic hormone concentrations
were also measured to demonstrate the ability of the
chosen manipulations to activate the hypothalamic-pi-
tuitary-adrenal (HPA) axis. Three of the four stressors
activated the HPA axis and only restrain increased tHcy
concentrations [5]. Stoney et al.’s study was to test if
acute psychological stress could induce elevations in
plasma Hcy concentrations. Thirty-four healthy women
participated in this study. The results indicated signifi-
cant elevations in plasma Hcy during acute psychologi-
cal stress, with a return to baseline concentrations during
recovery [6]. The complexity of the physiological re-
sponses to stress, the peculiarities of stress responses and
the intricate regulatory systems involved in Hcy metabo-
lism must be taken into account in order to clarify the
increasing effect of restrain (mainly a psychological
stressor) on total plasma Hcy in rats and to evaluate its
meaning in human pathology.
Stress is one of the biggest problems faced by intel-
lectuals today. The increasingly demanding nature of
their jobs has also increased pressure levels dramatically.
Research shows that intellectuals are now facing greater
day-to-day problems with occupational stress than most
other employees. Psychological stressors and depressive
and anxiety disorders also are associated with psycho-
somatic disease such as heart disease, hypertension and
diabetes, which have become the main factors impairing
the intellectuals’ health [7-10]. The intellectuals were
selected from different resident cities in China as sub-
jects and their serum Hcy levels and some influential
factors were observed.
2.1. Subjects
One hundred and thirty-eight volunteers between the
ages of 40 and 69 years (mean age= 54.2 years) partici-
pated in the study after providing written informed con-
sent. The 138 intellectuals come from three cities, Tianjin,
Y. Hou et al. / HEALTH 1 (2009) 83-87
Openly accessible at
Table 1. The distribution of subjects by area, age and sex.
40-49(y) 50-59(y) 60-69(y)
Male Female Male Female Male Female
Tianjin 8 8 8 8 8 8 48
Guangzhou 5 5 5 5 5 5 30
Chengdu 10 10 10 10 10 10 60
Total 46 46 46 138
Guangzhou and Chengdu, and all the subjects had senior
titles of technical post in university or science research
institute or design institute. The distribution of partici-
pants is presented in Table 1.
2.2. Blood and Salivary Collection
The fasting blood samples were collected into chilled
tubes, and immediately immersed in ice. The serums
were separated by centrifugation within 30-min and
stored at -20 until analyses. The volunteers collected
the saliva samples in the morning. Firstly they gargled
three times, after 15 minutes they chaw on citric acid
slips for a few seconds to stimulate salivation (not use
gum or any other food-type product) and collected the
salivary with straw. The samples stored at -20 within
three hours and centrifuged before analysis [11,12].
2.3. Laboratory Analysis
Total Hcy was measured in serum by the Total-Homo-
cysteine Enzymatic Assay method [13]. The principle of
the assay is as follows. In reaction I, rHCYase specifi-
cally converts Hcy to α-ketobutyrate, ammonia, and H2S.
In reaction II, the H2S combines with DBPDA to form
3,7-bis (dibutyl amino) phenothiazine–5-ium chlorides,
which is highly fluorescent. For the reduction reaction,
flat-bottomed 96-well cell culture cluster plates with
low-evaporationlids were used (cat. no. 0720089; Corn-
ing). Twenty microliters of serum samples and 170 uL of
assay buffer [40mmol/L sodium phosphate buffer (pH
8.4), containing 2 mL/L Triton X- 100 and 0.25 mmol/L
DTT] were added to the wells. Two wells were used for
each sample. Reduction reaction was carried out at 37
°C for 30 min. It is necessary to break the disulfide
linkages in plasma proteins and to reduce the low mo-
lecular weight disulfides Hcy and homocysteine-cysteine
mixed disulfide in this reaction. For each sample, we
added 30 uL of rHCYase (0.05 g/L), the equivalent to 0.1
U, in 40mmol/L potassium phosphate buffer containing
20μmol/L pyridoxal phosphate. One unit of enzyme is
defined as the amount that catalyzes 1 μmol of H2S per
minute from Hcy. We added 30 uL of enzyme buffer to
the other well to serve as background. The enzymatic
reaction was carried out at room temperature for 5 min.
The lid was put on the dish to prevent possible loss of
H2S. The enzymatic reaction was stopped by the addition
of 30 uL of chromophore reagent (20 mmol/L DBPDA
in 3 mol/L H2SO4). The chromogenic reaction was car-
ried out at room temperature for 10 min. The resulting
fluorescence was measured at an excitation wavelength
of 665 nm and an emission wavelength of 690 nm in
Hcy special fluorescence spectral-photometer (JD Bio-
tech Co., Ltd.).
Cortisol level was measured with a RIA kit, a product
of Isotope Institute, Chinese Atomic Energy Science
Academy [14].
2.4. Statistical Analysis
Continuous variables were summarized as the mean ±
SE. One-way ANOVA were used to compare group
means. Statistical significance was defined as P < 0.05.
Subjects with missing data were dropped from the
129 saliva samples were collected. The Hcy concentra-
tions and the cortisol levels of all subjects were com-
pared (see Figure 1). A significant relation between Hcy
concentrations and the cortisol levels was observed
(r=0.21, P<0.05). With the increase of cortisol levels the
Hcy concentrations rise.
The average level of salivary cortisol was 10.3μg/L. The
subjects was divided into two groups, low cortisol group
(LCor, <10.3μg/L) and high cortisol group (HCor, 10.3
μg/L). As expected the HCor had signify cantly higher se-
rum concentrations of Hcy than the LCor (see Table 2).
Figure 1. The correlation plots of serum Hcy and cortisol
SciRes Copyright © 2009
Y. Hou et al. / HEALTH 1 (2009) 83-87
Openly accessible at
Table 2. Saliva cortisol and serum homocysteine concentra-
tions in LCor and HCor groups (
Group n Cortisolμg/L Hcyμmol/L
LCor 77 5.5±0.3 18.4±0.8
HCor 52 18.1±1.3 22.0±1.7
Total 129 10.3±0.7 20.3±0.9
Table 3. Comparison of serum homocysteine concentration by
Agey n Hcyμmol/L
40-49 46 23.2±1.6 a
50-59 46 19.0±1.4 b
60-69 46 19.5±1.2
Total 138 20.6±0.8
Values with different superscripts are significantly different (P<0.05)
Table 4. Differences of serum homocysteine concentrations
between male and female(
Sex n Hcyμmol/L
Male 69 24.0±1.5
Female 69 16.9±0.6
Table 5. Serum homocysteine concentrations of subjects in
three cities(
City n Hcyμmol/L
Tianjin 48 22.4±1.5a
Guangzhou 30 17.1±2.3b
Chengdu 60 20.5±1.0
Values with different superscripts are significantly different (P<0.05)
The mean value of serum Hcy concentration in intel-
lectuals was 20.6±0.8μmol/L. The mean value of Hcy
concentration was highest in 40-49 years old and lowest
in 50-59 years old. There was significant difference be-
tween 40-49 years group and 50-59 years group (see
Table 3).
Among the subjects the average Hcy level of men was
significant higher than women (see Table 4).
The average Hcy levels among the three cities were
compared. The average Hcy level of the volunteers in
Tianjin was highest, medium in Chengdu, lowest in
Guangzhou. But only significant difference was ob-
served between Tianjin and Guangzhou (see Table 5).
Hcy is a sulfur-containing amino acid generated through
the demethylation of methionine. The resulting Hcy is
either remethylated to methionine through methionine
synthase (MS), a process that utilizes folate and vitamin
B12 as cofactors, or catabolized by transsulfuration into
if excess Hcy is present, using vitamin B6 as cofactor
[15]. It is also controlled by individual genetic differ-
ences in how vitamins are utilized as cofactors in the
reactions controlling Hcy metabolism. In excess quanti-
ties, Hcy is thought to be thrombophilic and to damage
the vascular endothelium. Total plasma homocysteine
(tHcy) is now established as a independent risk factor for
coronary artery disease, as well as other arterial and ve-
nous occlusive disease in adult populations [4,16-18].
The third National Health Examination Surv
cystathionine through cystathionine-β-synthetase (CBS)
ical stress
owed the first data on Hcy concentration in a nation-
ally representative sample of Americans. The Survey
measured serum total Hcy concentrations for a nation-
ally representative samples of 3766 males and 4819 fe-
males aged 12 y. The normal total plasma Hcy concen-
trations of Americans was in the range of 5μmol/L to
15μmol/L and affected by age, sex and race [19]. Yan et
al. reported that Chinese average plasma Hcy level ref-
erence was (9.67±3.0) μmol/L, 95% confidence interval
was 3.79μmol/L to 15.55μmol/L. Zhang et al. investi-
gated 1226 middle- and old-age people and the average
plasma Hcy level was 9.1μmol/L [20]. The present study
reflected that the average serum Hcy level of the intel-
lectuals aged 40-69 in Tianjin, Guangzhou and Chengdu
was higher than the level other study showed.
It is now generally accepted that psycholog
a multi-dimensional and multi-level phenomenon that
is influenced by personal, situational or structural factors.
Studies of occupational stress indicate that workload and
communications are significant causes. Anticipation,
worry, helplessness and executive roles have all emerged
from laboratory studies as psychological factors induc-
ing stress. Several studies concur in finding that poor
working conditions, especially relationships with col-
leagues, overload, and poor school ethos are the major
causes of intellectual stress. There is considerable evi-
dence, mainly from self-reports, that intellectuals feel ill
as a consequence of excessive stress. However, available
absence and retirals statistics are not sufficiently specific
to support this connection [8]. Generally cortisol level
was recognized to be an index judging the degree of
stress [11,12]. Our study showed that the serum Hcy
concentration of high saliva cortisol concentration group
was significant higher than low saliva cortisol concen-
tration group. The result indicated that psychological
stress could be one of the reasons causing the increase of
serum Hcy level and the stress degree may connect with
the level of serum Hcy. Stoney et al.’s study was to test
the hypothesis that acute psychological stress induces
elevations in plasma Hcy concentrations. Thirty-four
healthy women participated in the study. The psycho-
logical stressors included standard mental arithmetic and
speech stressors and heat rate and blood samples were
also monitored. Results indicated significant elevations
in plasma Hcy during acute psychological stress, with a
SciRes Copyright © 2009
Y. Hou et al. / HEALTH 1 (2009) 83-87
ical variables influ-
onstrated that men had higher
onstrated that the average serum Hcy
Mental stress and its importance for
, R., Knickenberg, R.J., Schattenburg, L., and
and Dimsdale,
99) Homocysteine.
., Suchecki, D., Cohen, S., and Almeida, V.
e levels in-
le of stress in the health and
Openly accessible at
return to baseline concentrations during recovery. The
pattern of findings for blood pressure and heart rate was
similar, suggesting that the rise in Hcy concentrations
may have been sympathetically mediated [6]. But the
related mechanism remains unclear.
It is known that many physiolog
cing Hcy concentrations. Circulating tHcy increases
with age in both genders-an effect that is partly due to
decreasing renal function, partly due to increasing
prevalence of subclinical and clinically demonstrable
vitamin deficiency, or to other independent metabolic
factors. In particular, aging may be associated with de-
crease CBS activity [21]. However our study showed
that there is no trend of increase of Hcy concentrations
with the increase of age. On the contrary in the three age
group 40-49 years old group had highest level of serum
Hcy. That the intellectuals in 40-49 years group carried
more work, burden and stress may be the reason of their
high Hcy concentration.
This investigation dem
cy level than women and there are much epidemiol-
ogical evidence identifying the similar result [22-27] .In
a multicentre case-control study in Europe vascular dis-
ease of the coronary, cerebral, of peripheral vessels and
800 control subjects (570 men, 230 women) were en-
rolled. The tHcy comparison between the sexes was car-
ried out among control subjects only. The results showed
that fasting tHcy levels were lower in women than in
men [21]. The gender difference in fasting tHcy may be
caused by hormonal differences between men and
women. The hypothesized tHcy-lowering effect of oes-
trogens is derived from the observation that tHcy con-
centrations are lower in pregnant than in non-pregnant
women [28,29]. Strong evidence for the effects of hor-
mones on plasma tHcy levels is derived from a study in
which male to female transsexuals showed a decreased
geometric mean tHcy, and female to male transsexuals
an increase [30]. Dierkes et al.’s study comprised 336
men and women, aged 40 to 65 years, obtained from an
ongoing recruitment procedure. Plasma tHcy, folate,
vitamin B12, vitamin B6, fat-free mass, creatinine, tes-
tosterone and estradiol, protein, and hematocrit were
detected. From the gender-related variables, tHcy corre-
lated significantly with fat-free mass and testosterone
and inversely with estradiol. The difference between
genders with regard to tHcy was mainly explained by
differences in fat-free mass, but also by estrodiol con-
centration [23].
This study dem
ncentration of intellectuals in Tianjin was significant
higher than that in Guangzhou. Tianjin and Guangzhou
are located in north and south of china respectively and
there are many differences in diet habit, prandial struc-
ture and economic condition between these two cities.
Hao et al.’s study investigated 2545 subjects’ plasma
folate concentrations, sampled from the representative
rural and urban areas in the south and north of China
aged 35 to 64 years. Plasma concentrations of folate in
southern population were significant higher (16.9
nmol/L) than those in the north (8.3 nmol/L), and the
prevalence of folate deficiency in the south (5.8%) was
significantly lower than that in the north (37.1%) [31].
Folat level is one of the main nutrition factors that af-
fects the level of Hcy in body, so the Hcy concentration
difference between Tianjin and Guangzhou may due to
the difference of folate condition in this two cities.
In conclusion, the serum homocysteine concentration
intellectuals is higher than that of normal people. The
stress level, gender and resident cities might contribute
to the differences in serum homocysteine concentration
in Chinese intellectuals. The epidemiological study
showed that Hcy is not only pro-atherogenic and
pro-thrombotic, it is biologically plausible that high Hcy
levels may cause brain injury and neuropsychiatric dis-
orders. Cross-section and some longitudinal studies
support increased prevalence of stroke and vascular de-
mentia in hyper-homocysteinemic individuals. The evi-
dence of increased neurodegeneration caused by hy-
per-homocysteine is accumulating [17,32-34]. Thus to
study and control the serum Hcy level of intellectuals are
very important to handle and improve the health condi-
tion of intellectuals. To verify the exact relation between
psychological stress and the difference of Hcy level,
much more study and intervention experiment should be
conducted in the future.
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