Vol.2, No.7, 769-772 (2010)
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Alternations in salivary glucose during ramadan fasting
Reyhaneh Sariri1*, Abdolali V arasteh1, Ali Erfani2
1Department of Biochemistry, The University of Guilan, Rasht, Iran; *Corresponding Author: sariri@guilan.ac.ir
2Department of Interna l Medicine, Iran University of Medical Sciences, Tehran, Iran
Received. 21 October 2009; revised 7 December 2009; accepted 9 December 2009.
During the holly month of Ramadan, Muslims
fast every day from dawn to sunset. Although
the effect of Ramadan fasting on general health
has been widely studied, the impact of fasting
on oral health and possible changes in salivary
biochemicals, such as glucose, has not re-
ceived much attentiom. The aim of our study
was to evaluate the influence of fasting on the
level of glucose in the saliva of healthy indi-
viduals. Salivary glucose was measured using
an enzymatic method based on oxidation of
glucose by glucoseoxidase followed by deter-
mination of resulting H2O2 in the presence of
peroxidase. A reduction in mean concentration
of glucose was observed in the saliva of all
fasting subjects as compared to the control
group. It was concluded that reduction in
salivary glucose is mostly due to reduced food
intake and may be beneficial to dental health.
Keywords: Saliva; Glucose Level; Diabetes;
Several of the world’s great religions recommend a pe-
riod of fasting or abstinence from certain foods. Of these,
the Islamic fast during the Muslim month of Ramadan is
strictly observed every year. During the month of
Ramadan, Muslims fast every day from dawn to sunset.
Muslims observing the fast are required to abstain not
only from eating and drinking, but also from consuming
oral medications and in travenous nutritional fluids.
It has been found that, in the healthy subject, Rama-
dan fasting does not appreciably affect one’s health.
However, it may induce some complications in patients
with important metabo lic disorders su ch as diabetes. Th e
effect of experimental short-term fasting on carbohy-
drate metabolism has been extensively studied [1,2].
Mean normal blood glucose levels in humans are about
90 mg/dl, equivalent to 5 mM (mmol/l). It has been
found that a slight decrease in serum glucose (60-70
mg/dl, 3.3-3.9 mM) occurs in normal adults a few hours
after fasting has begun. However, the reduction in serum
glucose ceases due to increased gluconeogenesis in the
liver [3].
Saliva is the first biological fluid to encounter any
change in eating habits as well as any environmental or
physical changes. Saliva influences oral health both
through its non-specific physico-chemical properties, as
well as through more specific effects [4]. Saliva is well
known for its highly protective functions against deterious
agents such as microorganisms, toxines and various
oxidants [5,6]. The antioxidant capacity and reducing
power of saliva may diminish to a high degree due to
various factors [7]. It has been shown that in vitro
exposure to cigarette smoke could significantly decrease
some enzymatic activities, both in plasma and in saliva
The research reports in this area are few and almost
limited to the changes of glucose concentrations in
plasma. This study reports alternations in glucose con-
tent of saliva during one month fasting in Ramadan 1428
(Sept. 22nd-Oct 12th 2007).
2.1. Materials
The level of glucose in saliva was measured using an
enzymatic method based on oxidation of glucose by
glucoseoxidase followed by determination of resulting
H2O2 in the presence of peroxidase. An enzymatic assay
glucose kit was purchased from Pars Azmoon™. The kit
consisted of a standard glucose and a colour reagent. The
concentration of standard glucose was 100 mg/dl and the
colour reagent was a mixture of the following chemicals:
250 mmol/l phosphate buffer pH 7.5, 5.0 mmol/l phenol,
0.5 mmol/l 4-aminoantipyrine 10 ku/l glucose oxidase
and 1 ku/l peroxidase.
R. Sariri et al. / HEALTH 2 (2010) 769-772
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
2.2. Volenteers
30 healthy male students (mean age 24.21 years, sx =
2.34), who intended to fast the whole Ramadan. 30 sam-
ples for control and comparison were also collected from
the same students who donated their saliva in the month
before Ramadan when they performed normal eating
pattern. A precise consent was obtained from each indi-
vidual and a dentist examined their mouth and teeth be-
fore sample collection.
2.3. Collection of Saliva Samples
The subjects were examined by a dentist for the absence
of infection and other symptoms of oral/and or dental
disorders. A few volunteers with severe infections were
excluded from the research. After gaggling their mouth
with about 5.0 ml of distilled water for abou t 2 minutes,
timed un-stimulated whole saliva samples (3 ml) were
collected in clean, dry in sterile pre-weighted tubes. The
duration of saliva sampling was altered among individu-
als depending on their flow rate (2.0-5.0 minutes). The
flow rate was calculated by measuring the time required
to collect one ml of saliva in minutes. During the holly
month of Ramadan, saliva samples were donated mid-day
(after about 6 hours fasting) and three samples collected
from each volunteer during one month of Ramadan
(days 1-9, 10-19 and 21-29). Three control samples from
each volunteer were also collected at the same time of
the day during a non-fasting period, i.e. one week after
Ramadan. All of the saliva samples were immediately
centrifuged at 800 × g for 10 min at 4°C to remove
squamous cells and cell debr is. Th e resu lting supern atan t
was stored at 18°C until used for determination glucose
content. They were analyzed within 48-72 hours of col-
lection. Each assay was repe ated th ree ti mes and th e data
obtained were expressed as mean ± SD of the three de-
terminations. To test the effect of freezing on the glucose
content of saliva, random measurements on fresh sam-
ples were also performed. No significant difference was
observed between thawed and fresh samples. Therefore,
only the frozen samples were used for continuing stud-
2.4. Glucose Assay
Glucose concentration was determined in supernatant of
saliva samples collected from volunteers. The level of
glucose in saliva was measured using an enzymatic
method based on oxidation of glucose by glucose oxi-
dase (GOD) followed by determination of resulting
H2O2 in the presence of peroxidase (POD).
Glucose + O2 GOD Gluconic acid + H2O2
2 H2O2 + 4-Aminoantopyrine + Phenol POD Quin-
oneimini + 4 H2O
1000 ml of reagent was mixed with 30 ml of each saliva
sample. The mixture was incubated in a 37°C water bath
and the intensity of resu lting colour was measured spec-
trophotometrically at 546 nm against a blank of contain-
ing 1000 ml reagent and 30 ml distilled water.
Glucose concentration (CG) in whole saliva was cal-
culated using the Beer-Lambert’s equation and absorb-
ances of standards solution (AS), each sample (AT) and
concentration of standar d (C S).
CG (mg/ml) = AT/AS × CS (100 mg/100 ml)
2.5. Statistics
Each assay was repeated triplicate and the results were
presented as mean ± SD values. Statistical difference
between groups was compared by un-paired t-test, p
values less than 0.5 were retained as significant.
The saliva flow rate ranged from 0.08 to 1.40 ml/min at
rest and showed about 10% decrease in response to fast-
ing. Concentration of glucose was calculated in mg/100
ml using the absorbance and standard concentration.
Figure 1 compares content of glucose in saliva of some
selected volenteers during fasting and non-fasting period.
The data presented in this figure are a random selection
from saliva samples of 30 volenteers. It should be em-
phasized that the results of other samples were similar to
the randomly selected ones. The mean values together
with p values are shown in Table 1.
The effect of experimental short-term and Ramadan
fasting on carbohydrate metabolism has been extensively
Figure 1. Comparison of glucose level in saliva samples of
non-fast (control) with fasting group during different days of
R. Sariri et al. / HEALTH 2 (2010) 769-772
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Ta bl e 1 . Mean ± SD salivary glucose (mg/100 ml) of subjects
during fasting nad non-fasting period.
Sample collected during Salivary glucose concen-
tration (mg/100 ml ) P values*
First 10 days of Ramadan 54.5 ± 0.74 0.5
Second 10 days of Ramad an 58.8 ± 1.25 0.6
Third 10 days of Ramadan 63.6 ± 9.43 0.5
First week after Ramadan 68.5 ± 1.22 NS
Values presented as Mean ± SD.
* P values were compared by t-test; NS – not significant
studied [10-13]. It has been found that a slight decrease
in serum glucose to 60 mg/dl to 70 mg/dl occurs in nor-
mal adults a few hours after fasting has begun. However,
the reduction in serum glucose ceases due to increased
gluconeogenesis in the liver. In this study, some blood
samples from the same subjects were also taken exactly
the same day of saliva collection in order to compare the
pattern of change in saliva and blood (results are not
included in this report).
It can be seen from data given in Figure 1, that a
mean 20-25% reduction in salivary glucose has occurred
during the first 10 days of Ramadan fasting followed by
a less reduction in the next ten days and, finally, another
rise by the 29th day of Ramadan fasting. Rise in salivary
glucose during the last 10 days of Ramadan did not,
however, reach the normal glucose level as compared to
the non-fast volenteers. Examination of blood samples of
each volenteer showed some similar alternations. How-
ever, the results need more investig ations and, therefore,
are not presented in this paper. There are only a few re-
ports about blood glucose variations due to fasting dur-
ing Ramadan [12,13]. In the case of blood glucose, re-
duction during the first 10 days of Ramadan could al-
most be compensated by the middle of the month due to
gluconeogenesis. In saliva, however, maintenance of
glucose concentration in low level compared to blood
glucose, suggests that gluconeogensis provides glucose
mostly for leveling the blood glucose. This is an inter-
esting phenomema bearing in mind that the function of
glucose in saliva is not as critical as it is in blood.
Normal salivary function is considered to be critical for
the maintenance of healthy oral mucosa [4-6]. Oral flu-
ids provide an easily available non-invasive for the di-
agnosis of a wide range of diseases and clinical situa-
tions. The effect of Ramadan fasting on some b lood fac-
tors such as thyroid hormons [14,15], plasma lipopro-
teins [16], serum glucose and many other laboratory
findings [11-13] have been reported. However, accord-
ing to our literature survey, saliva has received less at-
tention in this regard . The labo ratory findings repo rted in
this research, indicate that the glucose concentration in
saliva is decreased during fasting, mainly at the begin-
ning of the month.
It was shown that about 25 ± 2% reduction in the fir st
10 days was follo wed by a r ise (17 ± 2% reduction co m-
pared to the non-fasting state) in the next ten days and
finally another rise in the last 10 days of the month. Ac-
cording to these results, it was concluded that although
fasting during Ramadan affected salivary glucose con-
centration, it had no impact on the glucose function in
saliva of healthy people. As concentration of glucose in
saliva is highly dependent on the food intake and does
not play a crucial role in carbohydrate metabolism [17,
18], we concluded that reduction in salivary glucose dur-
ing fasting is not accompanied by serious health risks.
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