Alternations in salivary glucose during ramadan fasting

doi:10.4236/health.2010.27116

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Vol.2, No.7, 769-772 (2010)

doi:10.4236/health.2010.27116

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.

ABSTRACT

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;

Fasting

1. INTRODUCTION

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

[8,9].

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. MATERIALS AND METHODS

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

770

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-

ies.

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.

3. RESULTS

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.

4. DISCUSSION

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

Ramada.

R. Sariri et al. / HEALTH 2 (2010) 769-772

771

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.

5. CONCLUSIONS

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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