Discussion
In present exploration, less feed consumption due to
functional drinks is supported by the work of Babu et al[11]. Results for drink consumption are similar to work
of Yang et al. [12]. However, Lee et al. [13] elucidated
suppressed fluid intake in a group provided EGCG solution.
The differences may be due to the fact that they
used EGCG solution without toting up any additive.
However, in the present case drinks were prepared by
adding flavor and artificial sweetener that may be a reason
for improved consumption.
The current results showing reduced body weight gain
in groups consuming drinks containing catechins or
EGCG are in consistent with the study of Basu et al. [14]
and Byun et al. [15] Weight reduction by green tea might
be due to reduced digestibility and an increase in energy
expenditure and fat oxidation through β-adrenoceptor activated
thermogenesis of brown adipose tissue [16,17].
Inhibited lipid absorption from meals might be other reason
for reduced weight gain [18].
Results for decreased cholesterol and LDL levels are
in consistent with the work of Kim et al. [19].
Hypocholesterolemic potential of catechins can be accredited
to increased fecal excretion of cholesterol and bile
acid [20]. Tea catechins increase the bile acid excretion by
preventing reabsorption from small intestine through disruption
of micelle formation of bile acid. This increased
excretion of bile acid and cholesterol activates cholesterol
7α-hydroxylase that enhances the conversion of liver cholesterol
to bile acid to restock this loss thus resulting in
cholesterol reduction. This decrease in hepatic cholesterol
content in turn stimulates LDL receptor expression and
lowers blood cholesterol level [21].
Results for non-significant effect of drinks on HDL are
in agreement with previous work of Gomikawa et al.
[22]. The effects could be due to presence of various
bioactive components present in green tea [4]. Roghani
and Baluchnejadmojarad [23] noted LDL reduction in
diabetic rat modeling with EGCG. The proposed mechanism
of LDL reduction by green tea catechins is through inhibition
of cholesterol synthesis and dietary cholesterolabsorption [24]. Crude catechins decrease plasma cholesterol
concentrations by upregulating LDL receptor. The
increase in the LDL receptor improves the uptake of low
density lipoprotein cholesterol from the blood circulation
[25]. Moreover, reduced expression of 3-hydroxy-3-methylglutaryl
coenzyme A reductase (HMGR) might be another
reason for hypocholesterolemic activity of green tea
as green tea EGCG also inhibits HMGR activity [26,27].
Low concentration of triglycerides by green tea might
result from suppressed expression of stearoyl-CoA desaturase
(SCD 1) gene. Because in liver triglyceride synthesis
depends on the expression of the SCD 1 gene, that is
involved in biosynthesis of oleate and palmitoleate, the
major monounsaturated fatty acids of triglycerides. However,
Watanabe et al. [28] is of the view that reduced activity
of acetyl-Co A by green tea catechins is a reason for
low triglycerides synthesis.
Reduced glucose level by green tea is supported by the
work of Polychronopoulos et al. [29] that stated that there
occurs inverse relation between green tea and blood
glucose. The antihyperglycemic effect of green tea may
be due to activated uptake of glucose, inhibited intestinal
glucose transporter and decreased expression of
gluconeogenesis controlling genes [30]. EGCG exhibits
hypoglycemic potential by preventing the intestinal glucose
absorption via sodium-dependent glucose transporter
(SGLT1), lowering the expression of mRNA for
gluconeogenesis controlling enzymes [31] and causing
repression of glucose production, phosphoenolpyruvate
carboxykinase (PEPCK) and glucose-6-phosphatase gene
expression, hepatocyte nuclear factor 1α (HNF1α), and
HNF4α in cells [32]. Additionally, EGCG has direct effect
on hepatic glucose metabolism thus improving glucose
stimulated insulin secretion [32]. Attenuation of insulin
level with functional drinks in current exploration
is supported by the work of Hsu et al. [33]. It is
proposed that amelioration of insulin resistance by
green tea is associated with increased expression of
glucose transporter (GLUT) IV [34]. It can be concluded
that green tea mitigates hypercholesterolemia
and hyperglycemia effectually. It has cholesterol lowering
properties along with hypoinsulinemic capability
that could be associated with improved insulin
sensitivity.
DiscussionIn present exploration, less feed consumption due tofunctional drinks is supported by the work of Babu et al[11]. Results for drink consumption are similar to workof Yang et al. [12]. However, Lee et al. [13] elucidatedsuppressed fluid intake in a group provided EGCG solution.The differences may be due to the fact that theyused EGCG solution without toting up any additive.However, in the present case drinks were prepared byadding flavor and artificial sweetener that may be a reasonfor improved consumption.The current results showing reduced body weight gainin groups consuming drinks containing catechins orEGCG are in consistent with the study of Basu et al. [14]and Byun et al. [15] Weight reduction by green tea mightbe due to reduced digestibility and an increase in energyexpenditure and fat oxidation through β-adrenoceptor activatedthermogenesis of brown adipose tissue [16,17].Inhibited lipid absorption from meals might be other reasonfor reduced weight gain [18].Results for decreased cholesterol and LDL levels arein consistent with the work of Kim et al. [19].Hypocholesterolemic potential of catechins can be accreditedto increased fecal excretion of cholesterol and bileacid [20]. Tea catechins increase the bile acid excretion bypreventing reabsorption from small intestine through disruptionof micelle formation of bile acid. This increasedexcretion of bile acid and cholesterol activates cholesterol7α-hydroxylase that enhances the conversion of liver cholesterolto bile acid to restock this loss thus resulting incholesterol reduction. This decrease in hepatic cholesterolcontent in turn stimulates LDL receptor expression andlowers blood cholesterol level [21].Results for non-significant effect of drinks on HDL arein agreement with previous work of Gomikawa et al.[22]. The effects could be due to presence of variousbioactive components present in green tea [4]. Roghaniand Baluchnejadmojarad [23] noted LDL reduction indiabetic rat modeling with EGCG. The proposed mechanismof LDL reduction by green tea catechins is through inhibitionof cholesterol synthesis and dietary cholesterolabsorption [24]. Crude catechins decrease plasma cholesterolconcentrations by upregulating LDL receptor. Theincrease in the LDL receptor improves the uptake of lowdensity lipoprotein cholesterol from the blood circulation[25]. Moreover, reduced expression of 3-hydroxy-3-methylglutarylcoenzyme A reductase (HMGR) might be anotherreason for hypocholesterolemic activity of green teaas green tea EGCG also inhibits HMGR activity [26,27].Low concentration of triglycerides by green tea mightresult from suppressed expression of stearoyl-CoA desaturase(SCD 1) gene. Because in liver triglyceride synthesisdepends on the expression of the SCD 1 gene, that isinvolved in biosynthesis of oleate and palmitoleate, themajor monounsaturated fatty acids of triglycerides. However,Watanabe et al. [28] is of the view that reduced activityof acetyl-Co A by green tea catechins is a reason forlow triglycerides synthesis.Reduced glucose level by green tea is supported by thework of Polychronopoulos et al. [29] that stated that thereoccurs inverse relation between green tea and bloodglucose. The antihyperglycemic effect of green tea maybe due to activated uptake of glucose, inhibited intestinalglucose transporter and decreased expression ofgluconeogenesis controlling genes [30]. EGCG exhibitshypoglycemic potential by preventing the intestinal glucoseabsorption via sodium-dependent glucose transporter(SGLT1), lowering the expression of mRNA forgluconeogenesis controlling enzymes [31] and causingrepression of glucose production, phosphoenolpyruvatecarboxykinase (PEPCK) and glucose-6-phosphatase geneexpression, hepatocyte nuclear factor 1α (HNF1α), andHNF4α in cells [32]. Additionally, EGCG has direct effecton hepatic glucose metabolism thus improving glucosestimulated insulin secretion [32]. Attenuation of insulinlevel with functional drinks in current explorationis supported by the work of Hsu et al. [33]. It isproposed that amelioration of insulin resistance bygreen tea is associated with increased expression ofglucose transporter (GLUT) IV [34]. It can be concludedthat green tea mitigates hypercholesterolemiaand hyperglycemia effectually. It has cholesterol lowering
properties along with hypoinsulinemic capability
that could be associated with improved insulin
sensitivity.
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