Differential effect of honey on selected variables in alloxan-induced and fructose- induced diabetic rats

Abstract

Honey contains a high concentration of fructose, a monosaccharide, capable of raising blood sugar level after oral ingestion. It is thus a paradox that nutritional experts have advocated its use as a nutrition supplement in patients with diabetes mellitus. It has also been used, over the years, as a sweetener by those who wish to avoid the use of sugar. The effective use of sugar in diabetes may be due to its other constituents, especially the various antioxidants that are abundant in honey. Glycemic effect of honey on alloxaninduced diabetes and with concomitant administration of fructose was studied in male rats of the Wistar strain. Alloxan was injected into the rats through a tail artery and three days later, a confirmation of successful induction of diabetes was made by demonstration of hyperglycemia in the rats. Another group of rats received daily oral ingestion of fructose. At the end of three weeks it was found that daily ingestion of honey for three weeks progressively and effectively reduced blood glucose level in rats with alloxaninduced diabetes. Honey also caused a reduction in hyperglycemia induced by long-term ingestion of fructose, albeit to a lesser degree than its effect on alloxan-induced hyperglycemia. Honey could not reduce blood glucose in controlled rats that received neither alloxan treatment nor fructose ingestion, even though it caused an increase in body weight, irrespective of other substances concomitantly administered to the rats. It is thus apparent that honey may be a useful adjunct in the management of diabetes, while serving as a sweetener, especially if taken in moderate quantities. (Afr. J. Biomed. Res. 11: 191 - 196) Key Words: Honey, Alloxan-induced diabetes, Fructose-induced diabetes, Rats

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African Journal of Biomedical Research, Vol. 11 (2008); 191-196
ISSN 1119 – 5096 © Ibadan Biomedical Communications Group
Abstracted by:
African Index Medicus (WHO), CAB Abstracts, Index Copernicus, Global Health Abstracts, Asian Science Index, Index
Veterinarius, Bioline International , African Journals online
Full-text available at
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Received:
August, 2007
Accepted (Revised):
March 2008
Published
May 2008
Full Length Research Article
Differential Effect of Honey on Selected
Variables in Alloxan-Induced and Fructose-
Induced Diabetic Rats
*Adesoji A Fasanmade and Oluwakemi T Alabi
Departments of Physiology and Medicine
College of Medicine, University of Ibadan
Ibadan, Nigeria
ABSTRACT
Honey contains a high concentration of fructose, a monosaccharide, capable
of raising blood sugar level after oral ingestion. It is thus a paradox that
nutritional experts have advocated its use as a nutrition supplement in patients
with diabetes mellitus. It has also been used, over the years, as a sweetener by
those who wish to avoid the use of sugar. The effective use of sugar in
diabetes may be due to its other constituents, especially the various
antioxidants that are abundant in honey. Glycemic effect of honey on alloxan-
induced diabetes and with concomitant administration of fructose was studied
in male rats of the Wistar strain. Alloxan was injected into the rats through a
tail artery and three days later, a confirmation of successful induction of
diabetes was made by demonstration of hyperglycemia in the rats. Another
group of rats received daily oral ingestion of fructose. At the end of three
weeks it was found that daily ingestion of honey for three weeks
progressively and effectively reduced blood glucose level in rats with alloxan-
induced diabetes. Honey also caused a reduction in hyperglycemia induced by
long-term ingestion of fructose, albeit to a lesser degree than its effect on
alloxan-induced hyperglycemia. Honey could not reduce blood glucose in
controlled rats that received neither alloxan treatment nor fructose ingestion,
even though it caused an increase in body weight, irrespective of other
substances concomitantly administered to the rats. It is thus apparent that
honey may be a useful adjunct in the management of diabetes, while serving
as a sweetener, especially if taken in moderate quantities.
(Afr. J. Biomed. Res. 11: 191 - 196)
Key Words: Honey, Alloxan-induced diabetes, Fructose-induced diabetes, Rats
*Corresponding Author: E-mail: adesojif@yahoo.com

African Journal of Biomedical Research 2008 (Vol. 11) / Fasanmade and Alabi
Glycemic effect of honey on alloxan-induced diabetes
192
INTRODUCTION
The non-communicable chronic diseases prevalent
in the developing countries of Tropical Africa
include sickle cell disease, hypertension and
diabetes mellitus. There is an increasing advocacy
of alternate therapy in the management of these
and other diseases, as the use of Western
medicines are costly and at best are useful only for
control of these diseases. Several alternate
therapies include honey as an important
component in the management of diabetes but the
mechanism for its hypoglycaemic effect has not
been clearly understood. Elevation of plasma
insulin levels and lowering of blood glucose levels
have been observed in patients with diabetes after
administration of honey (Al-Waili N, 2003; Al-
Waili NS, 2004). Other studies have also
demonstrated that honey may be important in
reduction of some biochemical markers that are
linked to an increased risk of heart disease
(Shambaugh et al 1990). Hyperlipidaemia and
insulin resistance have also been shown to be
better after consumption of honey (Katsilambros et
al 1988).
Ingestion of high doses of fructose over a
prolonged period has been used to induce
persistent hyperglycaemia rats with features
similar to those seen in patients with type 2
diabetes mellitus (DM), hence its use in type 2-
like DM induction in animals (Ostos et al 2002).
Natural honey contains a high concentration of
fructose and so it is puzzling that honey would
lower blood glucose levels in humans with DM.
This study was thus designed to study the
glycaemic effects of honey on alloxan-induced
DM (akin to type 1 DM), and fructose-induced
DM (akin to type 2 DM) in male Wistar rats. It is
assumed that honey would not reduce the level of
hyperglycaemia induced by fructose, even if it
does in the rats with alloxan-induced DM.
Attempts will be made to explain the differential
effects thus elucidated.
MATERIALS AND METHODS
48 matured male Wistar rats, each weighing about
200g, were used for the study. They were allowed
2-week acclimatization to laboratory environment
and were divided randomly into six groups of
eight rats as follows:
• Group 1a served as control rats. They were
given standard rat chow for three weeks.
• Group 1b rats were given honey along with
standard rat chow for three weeks.
• Group 2a rats were administered alloxan
according to standard procedure (Szkudelski et
al, 1998) on day 1 of the study and those that
developed diabetes after three days were
thereafter given standard rat chow for three
weeks.
• Group 2b rats were treated as those of group 2a
but were given honey along with standard rat
chow after diabetes induction with alloxan.
• Group 3a rats were given standard rat chow and
fructose for three weeks.
• Group 3b rats were given standard rat chow
fructose for three weeks. Thereafter honey was
given along with standard rat chow and
fructose for a further period of three weeks.
In effect, corresponding subgroup a served as
control for subgroup b and group 1a also served as
overall control for all the groups.
D-Fructose (BDH, Poole, England) with a
molecular weight of 180.16 was used for the
study. Each rat, regardless of weight, consumed a
solution containing 6.6g of fructose/5ml of
distilled water (through an oral cannula) daily.
The standard rat chow given was obtained from
a commercial outlet in Ibadan, Nigeria as pellets,
which contain 67.9% of starch, 21.0% of protein,
3.5% of fat, 6.0% of fiber, 0.8% of minerals and
0.8% of vitamins. Each rat consumed 3.4g of the
pellets per day.
Fructose (67.9%) was substituted for starch in
the rats that were given fructose (Comte etal,
2004; Grover etal, 2005).
Honey was obtained from, and certified pure by
the Wildlife Unit of the Department of Forestry,
University of Ibadan. Each rat on honey received a
daily dose of 10ml honey/kg/5ml of distilled water
(Busserolles etal, 2002) through an oral cannula.
Alloxan (Sigma Aldrich, St Quentin-Fallavier,
France) with a pH of 7.0 was kept at 370C before
injection through a vein of the penis at a dose of
65mg alloxan/kg (Gruppuso etal 1990; Boylan et

African Journal of Biomedical Research 2008 (Vol. 11) / Fasanmade and Alabi
Glycemic effect of honey on alloxan-induced diabetes 193
al 1992) after a 24-hr fast. Prior, light anaesthesia
was induced in the rats (with 0.6ml of
25%w/v/100g of rat) before intravenous
administration of alloxan. Blood sugar was
evaluated 72hr later to confirm effective induction
of DM (as hperglycaemia).
The rats were weighed weekly from the start of
the study (i.e. at the end of the two weeks of
acclimatization to the laboratory environment),
with a laboratory scale (Harvard Trip Balance,
Florham Park, NJ, USA) to the nearest gram.
Blood was collected from the tail of the rats by
nipping with a pair of fine scissors. Blood sugar
was estimated from a drop of blood so collected
with a glucometer (PRESTIGE SMART
SYSTEMTM, Home Diagnostics, Inc, Ft
Lauderdale, USA). Glucose estimation was made
weekly throughout the period of the study.
The measured glucose values and the weights
of the rats were subjected to statistical analysis,
using the SPSS v 11 statistical package and
Microsoft Excel 2007. Data were expressed as
mean ± SEM. Values were compared using
student – t test and differences in the values were
considered statistically significant when P<0.05.
RESULTS
Six of the rats in group 3a died before the end of
the experiment and supplemental rats were
provided and similarly treated until there were
eight that stayed alive until the end of the study.
Two rats died in group 2a but the rats in the other
groups survived the period of the study.
Rats in groups 1a, 1b, 3a and 3b progressively
gained weight, whereas those of groups 2a and 2b,
i. e. the ones that had alloxan-induced diabetes had
progressive weight loss after an initial slight
weight increase. However, the alloxan-induced
diabetic rats that were given honey had less weight
loss. The weight changes of the rats are shown in
Table 1.
Changes in the blood glucose levels in the rats are
shown in Figure 1. There was a steady rise in the
blood glucose level in all animal groups during the
course of the study. In group 1a, the blood glucose
rise was not significant. Addition of honey as
supplement to the diet (group 1b) led to a steady
significant rise in blood glucose. At the end of the
third week, blood glucose had risen to double the
value at the start of the study.
Table 1:
Changes in body weight (in grams) of the rats
Treatment Group Body weight at
basal level Body weight at end
of wk 1 Body weight at end
of wk 2 Body weight at end
of wk 3
1a – Control: on rat chow 197.04 ± 10.17 196.75 ± 22.91 220.87 ± 28.68 251.25 ± 36.02*
1b – Rat chow + honey 204.63 ± 12.94 243.87 ± 33.59# 285.37 ± 38.94*# 307.50 ± 40.69*#
2a – Alloxan treated + rat
chow 219.72 ± 7.30 220.12 ± 9.04 215.62 ± 12.08 185.00 ± 14.51*
2b – Alloxan + rat chow +
honey 211.62 ± 14.08 229.75 ± 20.78 220.12 ± 17.59 198.75 ± 15.97*
3a – Fructose + rat chow 207.11 ± 8.71 181.25 ± 8.75 198.37 ± 11.76 200.00 ± 13.49*
3b – Fructose + rat chow +
honey 201.14 ± 9.32 213.75 ± 5.64# 237.37 ± 4.64*# 240.00 ± 11.95*#
All values are mean ± S.E.M, n (no of rats per group) = 8
* = statistically different from basal level (p<0.05)
# = statistically different from corresponding values in subgroup a (p<0.05)

African Journal of Biomedical Research 2008 (Vol. 11) / Fasanmade and Alabi
Glycemic effect of honey on alloxan-induced diabetes
194
Figure 1.
Changes in blood glucose levels in the rats (1a – Control: on rat chow; 1b – Rat chow + honey; 2a – Alloxan treated
+ rat chow; 2b – Alloxan + rat chow + honey; 3a – Fructose + rat chow; 3b – Fructose + rat chow + honey
The rise in blood glucose in group 2a rats was
about 10 times the basal value. There was a slight
drop at the end of week 2 and a further drop at the
end of week 3, but the difference in values of the
blood glucose at the end of each week was highly
significant (p < 0.01). Addition of honey as a
supplement to the diet of rats treated with alloxan
(group 2b) caused a significant drop in blood
glucose level. This fall was also steady from the
start to the end of the study. The difference in
corresponding blood glucose levels between
groups 2a and 2b was significant (p<0.05).
The rats that received fructose as part of their diet
(group 3a) had a slight but steady rise in blood
glucose levels, such that at the end of the third
week, the blood glucose level had risen to double
the basal value. Honey supplementation in the rats
receiving fructose (group 3b) resulted in slight
reduction in blood glucose levels. The reduction
was, however, not statistically significant
(p>0.05).
DISCUSSION
Pancreatic β cell destruction with alloxan has been
successfully used in the induction of type 1-like
diabetes mellitus in laboratory animals
(Szkudelski et al 1998). Induction of type 2-like
diabetes has been more difficult. Most of type 2
diabetes models [e.g. Kyoto (York 2004);
Koletsky (Takaya et al 1996); Ob/ob (York and
Hansen 1997) Tubby Mouse (Coleman and Eicher
1990; Zucker (Harris et al 1987)] have been
genetically derived. The method of (Comte et al
2004) used in this study is acceptable in that there
was a significant hyperglycemia following chronic
ingestion of fructose. It is not known, however, if
the hyperglycemia so induced is a reflection of
type 2-like diabetes.
Keeping the rats in the laboratory for a period
of three weeks resulted in progressive increase in
weight and blood glucose level, irrespective of
treatment given to them. It could be that the
regular consumption of the rat chow and aging
0
50
100
150
200
250
300
Basal wk1wk2wk3
Bloodglucoselevel(mg/dL)
Periodofstudy
1a
1b
2a
2b
3a
3b

African Journal of Biomedical Research 2008 (Vol. 11) / Fasanmade and Alabi
Glycemic effect of honey on alloxan-induced diabetes 195
process are important factors to consider in this
study.
It is apparent, however, that addition of honey,
as a supplement to the diet results in further
increase in weight in all the rats, irrespective of
treatment, and a reduction in blood glucose level
in the rats subjected to hyperglycemic maneuvers.
Honey is widely used in medical practice,
principally as a topical antibacterial agent and for
effective healing of ulcers, irrespective of the
cause of the ulcer (Dumronglert 1983). In treating
diarrhea, honey promotes the rehydration of the
body and more quickly clears up the diarrhea and
any vomiting and stomach upsets. The anti-
bacterial properties of honey, both the peroxide
and non-peroxide, are effective against several
strains of bacteria which are notoriously resistant
to antibiotics (Heggers 1987). Other topical uses
of honey include treatment and healing of eczema
and masking of acne (Green 1988). Health benefits
of honey use include anti-allergic properties.
Honey is also a sweetener, and in certain situations
it has replaced sugar. This is especially so in
patients with diabetes mellitus.
The distinct qualities of honey as a useful
agent in medical practice may be due to its unique
components. Honey is composed of minerals like
magnesium, potassium, calcium, sodium chlorine,
sulphur, copper, iodine, zinc, iron and phosphate.
It also contains vitamins B1, B2, C, B6, B5 and
B3, all of which change according to the qualities
of the nectar and pollen. The anti-oxidant effects
of honey (Gheldof et al 2002) would thus make it
a useful adjunct in the management of diabetes
mellitus.
The mechanism for the hypoglycemic effect of
honey is, however, not well understood. Honey is
a mixture of sugars – fructose (about 38.5%) and
glucose (about 31.0%), maltose, sucrose and other
complex carbohydrates. One would thus expect
that consumption of honey would raise the blood
sugar and that in fact the glycemic index of honey
should approach that of glucose. The finding in
several studies that honey causes a reduction in
blood glucose levels in both normal and diabetic
patients is an indication that honey has a
mechanism, probably insulin sensitization effect.
This has been suggested by Al – Waili (2004).
These studies were carried out over a period of
few hours in contrast to the present study which
spanned a period of three weeks. The failure of
honey to reduce blood glucose to appreciable
levels in the control rats (group 1a) despite a great
reduction in rats made hyperglycemic in this study
further buttresses the fact that the hypoglycemic
effect of honey may be as a result of multi-
factorial mechanisms, including insulin
sensitization and anti-oxidant activity. Otherwise
similar effect should have been observed in the
rats that were given fructose, a major constituent
of honey, along with the standard rat chow,
especially as fructose administration caused a
significant weight gain in the rats, similar to the
effect of honey on weight of the rats.
The results of animal experimentation may not
be truly extrapolated to human situation, but the
result of this study provides further evidence that
honey consumption, at least in moderate
quantities, may be a useful adjunct in the
management of diabetes mellitus.
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