Effects of dietary supplementation with pure natural honey on metabolism in growing Sprague-Dawley rats.
Date
2014-03-28
Authors
Ajibola, Abdulwahid
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Abstract
The excessive consumption of refined sugars mainly fructose is linked to metabolic
dysfunction. The early introduction of refined sugars in the diets of children has resulted
in an increased incidence of childhood metabolic dysfunction. There are conflicting
reports on the gender susceptibility to developing metabolic dysfunction. Natural honey
(NH) has been shown to have health benefits when included in the diet. The neonate is
sensitive to dietary manipulations which can have long lasting effects. The short and
long term effects of inclusion of NH in the diets of neonates were investigated in rat
models. This was with a view to determine whether NH can substitute refined sugars
such as cane syrup (GS), without adverse effects, and whether there were any gender
differences in response to the dietary modification.
In the long term study, 59 suckling Sprague-Dawley (SD) rats were fed with either NHor
GS-supplemented diets from age 7 (neonate) to 91 (adulthood) days. For the short
term study to investigate the effects of NH in neonates, 69 SD pups were gavaged with
NH or GS twice daily at 12-hour intervals and allowed to nurse freely in between from
age 7 to 20 days. The rats in all groups were weighed daily during the period when they
were gavaged and then twice weekly thereafter to assess body weight gain (BWG) over
the study periods. The adult rats were subjected to an oral glucose tolerance test
(OGTT) at 13 weeks of age before termination. The rats’ growth was determined
through their BWG and linear growth was assessed by measurements on the bones
(femur and tibia) weight, length and density. Blood was collected for the assessment of
clinical biochemistry and plasma markers of general health including the circulating
metabolic substrates (glucose, triglycerides (TGs), free fatty acids (FFAs)); hormones
(insulin, leptin); liver and renal functions were also obtained. Morphometric
measurements (weight, lengths and histology) were also done on the abdominal
viscera. Hepatic storage of metabolic substrates (glycogen and lipids) was determined.
The analysis of the proximate composition of the NH and GS as well as the diets was
performed with the Student’s t-test. A repeated measures two-way analysis of variance
(ANOVA) with Bonferonni’s post hoc test was used to analyse the BWG and OGTT,
while the other parameters were analysed by one-way ANOVA with Neuman-Keul’s
post hoc test, and level of significance was set at p < 0.05.
The matched diets were found to be isonitrogenous and isocalorific. Following the long
term study, the NH fed rats showed tolerance to an oral glucose load. GS increased
fasting blood glucose (FBG), TGs (p < 0.05), FFAs (p < 0.0001), visceral fat weight (p <
0.0001), and caused hypercholesterolemia, hyperinsulinemia, hepatomegaly and fatty
liver in the males. NH increased intestinal villi growth and preserved the liver integrity in
both males and females. Although, the GS-fed female rats did not suffer multiple risks of
metabolic syndrome (MetS), there were high FBG concentration and
hypercholesterolemia induced at low dose and metabolic dyslipidemia shown as high
TG levels at high dose. These findings were contrary to the notion about the females
having a lower susceptibility to developing metabolic syndrome than males.
Some traditional rites include the feeding of honey to infants at birth, and there is
evidence of the dietary inclusion of sugars in infant formulations. The need to evaluate
the safety of honey consumption vis-à-vis refined sugars in children becomes
imperative. Thus, after inducing metabolic syndrome in the rats through 12-week GS
feeding, the effects of both diets on neonates were studied. In the neonates, there was
no difference in all the parameters measured except the higher circulating non fasting
FFAs (p < 0.0001) and hepatic storage of lipids (p < 0.001) in GS-fed than the NH-fed
pups. Metabolic syndrome did not develop within the short term.
NH was thus found to be a healthy source of dietary sugars, improved glycaemic control
and metabolic profiles. The study underscored the differential effects of dietary
treatments in male and female rodents. This pointed to the advantages of gender based
comparative studies in biomedical research. The study confirmed the nutraceutical
value of NH, and advocated for its consumption as a healthy substitute to refined
sugars. The consumption of refined sugars by infants should be discouraged, and
females should also be cautious in excessive sugar intake, as they can also be
susceptible to the metabolic adverse health effects of artificial sweeteners.