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Hypoglycemic and antilipidemic properties of kombucha tea in alloxan-induced
BMC Complementary and Alternative Medicine 2012, 12:63doi:10.1186/1472-6882-12-63
Ahmed Aloulou (email@example.com)
Khaled Hamden (firstname.lastname@example.org)
Dhouha Elloumi (email@example.com)
Madiha Bou Ali (firstname.lastname@example.org)
Khaoula Hargafi (email@example.com)
Bassem Jaouadi (firstname.lastname@example.org)
Fatma Ayadi (email@example.com)
Abdelfettah El Feki (firstname.lastname@example.org)
Emna Ammar (email@example.com)
10 October 2011
16 May 2012
16 May 2012
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Hypoglycemic and antilipidemic properties of
kombucha tea in alloxan-induced diabetic rats
* Corresponding author
Madiha Bou Ali1
1 Laboratory of Biochemistry and Enzymatic Engineering of Lipases, National
School of Engineers of Sfax, University of Sfax, Sfax 3038, Tunisia
2 Biotechnology High School of Sfax, University of Sfax, Sfax 3052, Tunisia
3 Research Unit Management of Coastal and Urban environments, National
School of Engineers of Sfax, University of Sfax, Sfax 3038, Tunisia
4 Research Unit Molecular Bases of Human Diseases, Sfax College of Medicine,
University of Sfax, Sfax 3000, Tunisia
5 Laboratory of Microorganisms and Biomolecules, Centre of Biotechnology of
Sfax, University of Sfax, Sfax 3018, Tunisia
Diabetes has become a serious health problem and a major risk factor associated with
troublesome health complications, such as metabolism disorders and liver-kidney
dysfunctions. The inadequacies associated with conventional medicines have led to a
determined search for alternative natural therapeutic agents. The present study aimed to
investigate and compare the hypoglycemic and antilipidemic effects of kombucha and black
tea, two natural drinks commonly consumed around the world, in surviving diabetic rats.
Alloxan diabetic rats were orally supplied with kombucha and black tea at a dose of 5 mL/kg
body weight per day for 30 days, fasted overnight, and sacrificed on the 31st day of the
experiment. Their bloods were collected and submitted to various biochemical measurements,
including blood glucose, cholesterol, triglcerides, urea, creatinine, transaminases,
transpeptidase, lipase, and amylase activities. Their pancreases were isolated and processed to
measure lipase and α-amylase activities and to perform histological analysis.
The findings revealed that, compared to black tea, kombucha tea was a better inhibitor of α-
amylase and lipase activities in the plasma and pancreas and a better suppressor of increased
blood glucose levels. Interestingly, kombucha was noted to induce a marked delay in the
absorption of LDL-cholesterol and triglycerides and a significant increase in HDL-
cholesterol. Histological analyses also showed that it exerted an ameliorative action on the
pancreases and efficiently protected the liver-kidney functions of diabetic rats, evidenced by
significant decreases in aspartate transaminase, alanine transaminase, and gamma-glytamyl
transpeptidase activities in the plasma, as well as in the creatinine and urea contents.
The findings revealed that kombucha tea administration induced attractive curative effects on
diabetic rats, particularly in terms of liver-kidney functions. Kombucha tea can, therefore, be
considered as a potential strong candidate for future application as a functional supplement
for the treatment and prevention of diabetes.
Diabetes mellitus (DM) is a chronic metabolic disorder that constitutes a major public health
problem throughout the world. Current estimates indicate that approximately 4% of the
global population suffer from DM, a percentage which is expected to reach 5.4% in 2025 .
This disease is a multifactor disorder associated with chronic hyperglycemia and troublesome
disruptions in carbohydrate, fat, and protein metabolisms emanating from deficiencies or
disruptions in insulin secretion , defects in reactive oxygen species scavenging enzymes
, and high oxidative stress impairing pancreatic beta cells [4,5]. Hyperglycemia leads to
long-term tissue damages and complications, such as liver-kidney dysfunctions, often
associated with serious diseases [6,7].
The prevalence of type 2 diabetes mellitus is increasing worldwide at alarming rates. Several
therapeutic strategies are currently available for the treatment of this chronic metabolic
disorder, including the stimulation of endogenous insulin secretion, enhancement of insulin
action at the target tissues, inhibition of dietary starch and lipid degradation, and treatment
with oral hypoglycemic agents . The limitations associated with those therapeutic
strategies have led to a determined search for more efficient and cost-effective alternatives.
This trend has been further intensified by increasing doubts surrounding current dietary and
other lifestyle behaviors together with growing interests in functional foods and
nutraceuticals . Complementary and alternative medicine applications have attracted
special attention in recent research for they offer new promising opportunities for the
development of efficient, side effect-free, and lower cost alternatives to existing synthetic
hypoglycemic agents [10-12].
Of particular relevance to this argument, kombucha tea (KT), a traditional drink made from a
particular fermentation of sugared black tea (BT) and a symbiosis of yeast species, fungi, and
acetic acid bacteria, is commonly consumed throughout the world as a medicinal health-
promoting beverage . Although the beneficial and/or adverse effects of kombucha tea on
human health have not been scientifically determined yet, there are several reasons to believe
that kombucha may have desirable positive effects on human health. In fact, the metabolic
and health effects of several probiotic products are gathering increasing momentum in recent
years. A number of currently commercialized food products (e.g. yogurt, cheese, fermented
vegetables and kefir) are known to contain live bacteria, or metabolites of bacteria, produced
during similar fermentation processes, and are considered as health promoting probiotic
foodstuffs [14,15]. Moreover, several studies have recently demonstrated that kombucha can
reduce cell damage induced by oxidative stress [16-20]. Kombucha has also been reported to
constitute a potent therapeutic supplement that improved resistance against cancer, prevented
cardiovascular diseases, promoted digestive functions, stimulated the immune system, and
reduced inflammatory problems [17,21-23].
Tea and kombucha are presented in the literature as two very distinct beverages and no
correlation has so far been reported between them . Some of the effects reported for
kombucha intakes are, however, very similar to those described for tea . Nevertheless,
while the composition, properties, and effects of tea on chronic and progressive illnesses,
such as diabetes, are well documented in the literature , little data are currently available
on these issues with regards to kombucha. In fact, most of the data on kombucha tea is
anecdotal and further studies are needed to elucidate its putative therapeutic potential,
particularly against DM.
In this context, pancreatic lipase, a complex enzyme that plays a key role in lipid metabolism,
has often been employed in human and animal model studies involving the evaluation of
natural products for potential application as antiobesity and antidiabetic agents . The
inhibition of this enzyme significantly decreases the digestion and uptake of lipids, thereby
decreasing the level of postprandial blood glucose in non-insulin-dependent diabetic patients.
Pancreatic α-amylase is a key enzyme in the digestive system that catalyses the initial step in
the hydrolysis of starch to a mixture of smaller oligosaccharides consisting of maltose,
maltotriose, and a number of oligoglucans. These are then acted on by α-glucosidases and
further degraded to glucose that enters the blood-stream. The degradation of this dietary
starch proceeds rapidly and leads to elevated postprandial hyperglycemia. Inhibitors of
pancreatic α-amylase delay carbohydrate digestion, thus reducing glucose absorption rates
and lowering postprandial serum glucose levels .
Considering the increasing concerns over the alarming rates recorded for DM and in light of
the promising opportunities that kombucha might open with regards to the alleviation and/or
prevention of this troublesome disease, the present study was undertaken to investigate and
assess the hypoglycemic and antilipidemic effects of kombucha using a diabetic rat model. It
aims to gain principled insights with regards to the biological activities of kombucha towards
pancreatic lipase and α-amylase as well as its effects on liver-kidney function, which may
provide a starting point for the understanding of the antidiabetic potential of kombucha. For
the sake of pertinence, the biological activities of kombucha were compared to those reported
for black tea .
Black tea preparation
One hundred grams of sugar were added to 1 L of distilled water, and the solution was boiled
for 15 min in a sterile conical flask. Black tea powder (Lipton) was added to the flask (12
g/L), which was then left to cool down at room temperature for one hour. The mixture was
filtered using a sterile nylon mesh, and the filtrate was used as black tea .
The kombucha cultures employed in the present work were purchased from a French
commercial online outlet (Kombucha-Shop). They are known as symbionts of yeasts (e.g.
Zygosaccharomyces, Schizosaccharomyces, Torulospora, Rhodotorula, Brettanomyces,
Candida, Pichia, and Zygosaccharomyces) and bacteria (e.g. Acetobacter) [17,28]. The
cultures were stored at 4°C prior to fermentation. Black tea was poured into 1-L glass jars,
which were sterilized beforehand, and inoculated with 2.5% (w/v) of freshly grown
kombucha mat that had been grown and maintained in the same medium . The
fermentation, kept under aseptic conditions, was carried out by incubating the kombucha
culture at 28 ± 1°C for 12 days. The flask was covered with clean cheese cloth and fixed with
rubber bands. The medium (brew) was then centrifuged aseptically at 1500 × g for 30 min
and stored in polypropylene vials at −20°C for further use . New kombucha mat
developed over the mother culture.
Animals and treatments
The experimental protocols and procedures used in the present work were approved by the
Ethics Committee of the University of Sfax (Sfax, Tunisia) for the care and use of laboratory
animals. Adult male Wistar rats, weighing 179 ± 10 g, were obtained from the Central
Pharmacy (Tunisia). The animals were kept in an environmentally controlled breeding room
where they had free access to tap water and pellet diet (Sico, Tunisia) .
Induction of diabetes
Diabetes was induced through a single intraperitoneal injection of a freshly prepared alloxan
(Sigma-Aldrich, USA) solution in normal saline at a dose of 150 mg/kg body weight. Since
the injection of alloxan can provoke fatal hypoglycemia due to a reactive massive release of
pancreatic insulin, the rats were also orally given 5–10 ml of a 20% glucose solution after 6
h. The animals were then kept with free access to 5% glucose solution for the next 24 h to
prevent severe hypoglycemia . Two weeks later, the rats with moderate diabetes having
glycosuria and hyperglycemia (i.e. with blood glucose levels of ≥2 g/l) were chosen for the
experiments. They were fasted overnight before being sacrificed by decapitation for blood
and tissue analyses.
The rats were subdivided into six experimental groups of eight animals each. Each group was
submitted to a specific treatment as follows. Normal control and diabetic rats, referred to as
[Con] and [Diab] groups, respectively, were fed with normal diet and drinking water ad
libitum. Diabetic rats that received KT and BT by gastric gavage (5 ml per kg of body
weight) every day  were designated as [Diab + KT] and [Diab + BT] groups, respectively.
Normal rats that were given KT and BT by gastric gavage (5 ml per kg of body weight) every
day were termed as [Con + KT] and [Con + BT] groups, respectively.
One month later, the rats were weighed and sacrificed by decapitation, and their trunk bloods
were collected. Plasma was immediately separated by centrifugation at 4°C and 1500 × g for
15 min. The pancreases were removed and trimmed free of fat. The samples were stored at
−80°C until further use.
The pancreas of each rat was excised and then homogenized and centrifuged (5000 × g, 20
min, 4°C). The supernatant was frozen and stored till further use in subsequent enzymatic
assays. Protein content was estimated by the method described by Lowry et al. . The
activities of aspartate transaminase , alanine transaminase (ALT), gamma-glutamyl
transpeptidase (GGT), and α-amylase as well as the levels of glucose, urea, creatinine, total
cholesterol, triglycerides (TG), and high-density lipoprotein-cholesterol (HDL-Ch) in the
serum were measured using commercial kits from Biomaghreb Analyticals (Tunisia). All
assessment assays and kits were performed in accordance with the manufacturers’
instructions and protocols. Lipase activity was measured on tributyrin using a pH-stat titrator
at pH 8 and 37°C as previously described elsewhere .
For histological analyses, pieces of pancreas were fixed in a Bouin solution for 24 h and then
embedded in paraffin. Sections of 5 µm thickness were stained with hematoxylin-eosin and
examined under an Olympus CX41 light microscope [34,35].
Statistical analysis was performed using the Statistical Package for the Social Sciences
(SPSS, Version 10.0). Data are presented as means ± SD. Determinations were obtained from
eight animals per group, and the differences were examined using one-way analysis of
variance (ANOVA) followed by the Fisher test (Stat View). Statistical significance was
accepted at p < 0.05.
Effect of kombucha on the pancreatic tissue architecture of diabetic rats
The findings from the histopathological analyses revealed that while the pancreatic tissues of
the control rats (Figure 1A) exhibited normal islets, those of the alloxan-induced diabetic rats
showed clear atrophy of β-Cells (Figure 1B). The pancreas of the diabetic rats that were
treated either with kombucha or black teas were, on the other hand, noted to undergo a
marked amelioration (Figure 1C and 1D). Furthermore, the architectures of the pancreas of
the normal rats treated with the kombucha and black teas were noted to be similar to that of
the normal control rats (data not shown).
Figure 1 Effect of KT and BT on the histological changes of the pancreas of the rats
evaluated by haematoxylin and eosin (H&E) staining (100×). (A) Normal control rats
(Con) showed normal β cells. (B) Severe injury in the β-Cells of the pancreas of diabetic
control rats (Diab). (C) and (D) ameliorative action of KT and BT on the architecture of the
pancreas of diabetic rats treated with BT and KT, respectively
Plasma and pancreas α-amylase activity and plasma glucose level
Figure 2 shows that, compared to the their counterparts from the normal control group, the
rats from the control diabetic rats underwent significant increases in terms of plasma and
pancreas α-amylase activities, which reached up to 405 ± 53% (p < 0.05) and 225 ± 52% (p <
0.05), respectively. The black tea supplement administered to diabetic rats was, however,
noted to bring about a significant decrease in the plasma and pancreas α-amylase activities,
reaching to 52 ± 11% (p < 0.05) and 70 ± 17% (p < 0.05), when compared to untreated
diabetic rats. This inhibitory effect of black tea on α-amylase activity was followed by a
decrease in the rate of blood glucose that reached up to 65 ± 14% (p < 0.05) (Figure 2C).
Considerable α-amylase activity reductions of up to 37 ± 8% (p < 0.05) and 52 ± 7% (p <
0.05) were also observed in the plasma and pancreas of the diabetic rats treated with
kombucha, respectively, as compared to those of the untreated diabetic rats. The kombucha
supplement was also observed to bring about a significant decrease of 50 ± 11% in terms of
blood glucose concentration (p < 0.05) (Figure 2C).
Figure 2 Effect of KT and BT on α-amylase activity in plasma (A), pancreas (B), and
blood glucose levels (C) of surviving diabetic rats. Data represent mean ± S.D (n = 8 for
each group). The values are statistically significant and presented as follows: single asterisk
(*), p < 0.05 vs. control diabetic rats (Diab); commercial at (@), p < 0.05 vs. respective
control rats (Con) [i.e. on the same corresponding tea treatment]; number sign (#), p < 0.05
vs. diabetic rats treated with BT (Diab + BT)
Plasma and pancreas lipase activity and plasma lipids concentration
Figure 3 indicates that, when compared to that of non-diabetic rats, the lipase activity in both
the plasma and pancreas of diabetic rats underwent significant (p < 0.05) increases of up to
194 ± 35% and 220 ± 41% respectively. This increase in lipase activity stimulated lipid
absorption and, consequently, led to significant (p < 0.05) increases of 194 ± 50% and 404 ±
107% (p < 0.05) in the TG and low-density lipoprotein-cholesterol (LDL-Ch) concentrations
in the plasma, respectively, as compared to non-diabetic rats (Figure 4). The administration of
black tea to diabetic rats was, on the other hand, noted to induce significant (p < 0.05)
reductions of 80 ± 15% and 68 ± 17% (p < 0.05) in terms of lipase activity in the plasma and
pancreas and of 59 ± 21% and 65 ± 14% in terms of blood TG and LDL-Ch levels,
respectively, again as compared to those of the untreated diabetic rats. The administration of
kombucha to surviving diabetic rats was also observed to have reverted the activity of lipase
in plasma and pancreas back to 68 ± 10% and 62 ± 10% (p < 0.05), respectively. This
supplement was, also, observed to bring about a considerable decrease in LDL-Ch and TG
concentrations in the plasma. Moreover, while diabetes was noted to induce a significant (p <
0.05) decrease of 58 ± 12% in the plasma HDL-Ch concentration, black tea and kombucha
supplements were observed to revert this decrease back to 137 ± 18% and 157 ± 30% (p <
Figure 3 Effect of KT and BT on lipase activity in plasma (A) and pancreas (B) of
surviving diabetic rats. Data represent mean ± S.D (n = 8 for each group). The values are
statistically significant and presented as follows: single asterisk (*), p < 0.05 vs. control
diabetic rats (Diab); commercial at (@), p < 0.05 vs. respective control rats (Con) [i.e. on the
same corresponding tea treatment]; number sign (#), p < 0.05 vs. diabetic rats treated with BT
(Diab + BT)
Figure 4 Effect of KT and BT on TG (A), LDL-Ch (B), and HDL-Ch (C) levels in
plasma of surviving diabetic rats. Data represent mean ± S.D (n = 8 for each group). The
values are statistically significant and presented as follows: single asterisk (*), p < 0.05 vs.
control diabetic rats (Diab); commercial at (@), p < 0.05 vs. respective control rats (Con) [i.e.
on the same corresponding tea treatment]; number sign (#), p < 0.05 vs. diabetic rats treated
with BT (Diab + BT)
Liver-kidney dysfunction indices
Table 1 illustrates that the activities of AST, ALT and GGT in the plasma of the diabetic rats
underwent significant (p < 0.05) increases of up to 242 ± 35%, 301 ± 35%, and 296 ± 29%
respectively, when compared to non-diabetic rats. The administration of kombucha or black
tea was found to bring about marked decreases in terms of the three indices of liver toxicity.
Moreover, and when compared to non-diabetic rats, the diabetic rats were noted to undergo
significant (p < 0.05) increases of 203 ± 17% and 196 ± 15% in terms of the urea and
creatinine rates in the plasma, respectively. Interestingly, the administration of kombucha and
black tea to diabetic rats was observed to have reverted this increase back to normal. The
findings from histological analyses further confirmed the positive effect of those two
supplements on the liver and kidney (data not shown).
Table 1 Effect of KT and BT on liver-kidney dysfunction indices in plasma of surviving
Con + BT
Con + KT
Liver dysfunction indices
AST (U/L) 32 ± 2.37* 31.67 ± 3.56* 29.5 ± 3.02*
ALT (U/L) 24.25 ± 2.79* 23.33 ± 4.13* 21.33 ± 4.13* 72.33 ± 5.47 41.67 ± 5.16*@
GGT (U/L) 15.67 ± 2.73* 16.50 ± 4.76* 13.67 ± 1.63* 45.83 ± 6.15 26.83 ± 6.40*@
Kidney toxicity indices
Creatinine (mg/L) 13.02 ± 1.42* 12 ± 2.19*
Urea (g/L) 0.52 ± 0.07* 0.5 ± 0.09*
Data represent mean ± S.D (n = 8 for each group). The values are statistically presented as
follows: single asterisk (*), p < 0.05 vs. control diabetic rats (Diab); commercial at (@), p <
0.05 vs. respective control rats (Con) [i.e. on the same corresponding tea treatment].
77.17 ± 9.35 52.58 ± 23.75
Diab + BT
Diab + KT
47.75 ± 36.14
36.9 ± 10.68*@
23.67 ± 5.88*
15.4 ± 2.59*
0.63 ± 0.25*
9.83 ± 1.47*
0.47 ± 0.06*
25.5 ± 2.59
1.05 ± 0.11
18.83 ± 2.86*@
0.77 ± 0.36*
Although kombucha tea is popular around the world as a beneficial medicinal health-
promoting drink, its beneficial and/or adverse effects on human health have not been
scientifically determined yet. No previous study has, for instance, so far reported on the
systematic investigation and evaluation of the antidiabetic activity of kombucha. To the
authors’ knowledge, the present work is the first attempt to investigate the protective effects
of kombucha on diabetes and its complications on the functions of the liver, kidney, and
Several of the enzymes secreted by the pancreas, namely α-amylase and lipase, are known to
break down dietary polysaccharides and lipids into monosaccharides and free fatty acids,
which represent some of the major nutrients needed to maintain human health [36,37].
Although most of the research so far conducted on diabetes has focused on dyslipidemia as a
major risk factor for cardiac, cerebral, and renal complications, several studies have recently
showed an impairment of pancreatic exocrine function in type 1 and type 2 diabetes. The
analysis of serum/plasma pancreatic enzymes was suggested to provide additional
informative parameters for the assessment of the chronicity and progress of the illness as well
as of the response to therapy [38-41].
The findings of the present study showed that the administration of kombucha to surviving
diabetic rats significantly reduced pancreatic α-amylase activity, which plays a key role in the
digestion of carbohydrates. This was indicative of lowered levels of absorbable glucose being
formed from the digestion of carbohydrate and leading to reduced levels of blood glucose.
The inhibition of pancreatic α-amylase activity in the human digestive tract represents one of
the therapeutic approaches commonly used for the control and prevention of postprandial
hyperglycemia in non-insulin-dependent diabetic patients through reducing the uptake of
glucose released by those enzymes from starch [42,43].
To produce kombucha, black tea ingredients and sucrose undergo progressive modifications
due to the action of the tea fungus. Several metabolites can be identified in the fermented
beverage, including acetic, lactic, gluconic and glucuronic acids, ethanol, glycerol and
polyphenols [20,44-46]. Most of the properties of kombucha are attributed to the
polyphenolic composition of the beverage. Tea polyphenolics were previously reported to
inhibit and reduce α-amylase activity in the in the saliva and intestines of rats, respectively,
which, in turn, were described to lower the hydrolysis of starch to glucose and to reduce the
assimilation of glucose .
The present study also showed that the administration of kumbucha to surviving diabetic rats
reduced pancreatic lipase activity, a decrease that is responsible for the hydrolysis of non-
absorbable dietary triglycerides into absorbable monoglycerides and free fatty acids, which,
in turn, leads to the decrease of plasma cholesterol and TG level [48-50]. This represents one
of the therapeutic approaches commonly used for the control and prevention of dyslipidemia.
Polyphenols were reported to inhibit pancreatic lipase in vitro. Previous data suggested that
the presence of galloyl moieties within polyphenol chemical structures was required for the
enhancement of pancreatic lipase inhibition .
Alloxan is a specific toxin that destroys the pancreatic β-cells, provoking a state of primary
deficiency in insulin without affecting other types of islets. The diabetic effect of alloxan is
due to an excess in the production of reactive oxygen species (ROS). This excess leads to
toxicity in pancreatic cells, which, in turn, reduces the synthesis and release of insulin while
concurrently affecting other organs, such as liver . Increased lipid peroxidation products
and decreased plasma or tissue concentrations of superoxide dismutase, catalase, and
glutathione have been well documented in the literature on alloxan-induced diabetes [30,53].
Chronic hyperglycemia and dyslipidemia are associated with a variety of metabolic disorders
in human and animal diabetic patients [54,55], causing oxidative stress, depleting the activity
of the antioxidative defense system, and resulting in elevated levels of ROS [30,43].
Oxidative environments might cause the damage of cells and tissues in the liver and kidney
, which is observed in the increased levels of AST, ALT, and GGT activities (indices of
liver dysfunction) and of urea and creatinine (indices of kidney dysfunction). As far as the
present study is concerned, the findings showed that kombucha proved remarkably efficient
in the decrease of the liver and kidney dysfunction indices in surviving diabetic rats, namely
the AST, ALT, and GGT activities and the urea and creatinine levels. This supplement could,
therefore, be considered as a potential strong candidate for future industrial application as a
therapeutic agent against liver and kidney toxicity.
Several recent studies have provided ample support for the strong candidacy of kombucha for
application as an antioxidant agent for the alleviation of oxidative stress and free radicals as
well as the enhancement of enzymatic defenses. Bhattacharya et al. have, for instance,
showed that murine hepatocytes treated with KT prevented the disruption of mitochondrial
membrane potential and blocked the activation of mitochondria-dependent apoptotic
signaling pathways, thus displaying a significant reduction of tertiary butyl hydroperoxide-
induced ROS generation and a considerable attenuation of malonaldehyde levels . The
inhibition of radical species could, therefore, be one of the mechanisms involved in the
efficient hepatoprotective and curative properties of KT. These findings are, in fact, in good
agreement with the results previously reported by Murugesan et al. showing that KT has the
potential to revert the CCl4-induced hepatotoxicity back through the production of
antioxidant molecules during fermentation . The presence of glucaric acid and its
derivatives, as potent detoxifying agents, could also be considered as another reason for the
hepatoprotective effects of KT .
Furthermore, Gharib et al. showed that, owing to its antioxidant potential, KT can ameliorate
trichloroethylene-induced kidney damage by preventing lipid peroxidation and ROS species
formation . The nephroprotective effects kombucha were also attributed to organic acids
(e.g. acetic and glucuronic acids) which are known to facilitate the detoxification process
through conjugation with toxins, which they then solubilise and eliminate from the body .
Kombucha polyphenols may, therefore, prevent the damage and death of pancreatic β-cells,
and/or stimulate the regeneration of this type of cells in diabetic rats. Coskun et al. have
reported that the administration of polyphenols, such as quercetin and epicatechin, to
surviving diabetic rats protects the architecture of pancreatic β-cells, preserves the secretion
of insulin, and stimulates the regeneration of this type of cells . The administration of an
antioxidant-rich beverage, such as kombucha, to diabetic rats would, therefore, presumably
decrease the ROS-mediated toxicity in pancreatic β-cells . The ability of kombucha to
reduce the blood glucose level could also be attributed to its ability to modulate the immune
system , leading to the decrease of β-cell damages. It is worth noting that the findings
indicated that the curative effects achieved with the administration of KT were more
pronounced than those reported for BT, which could presumably be attributed to the large
amounts of polyphenols and flavonoids present in KT as compared to black tea . In fact,
further studies on the mechanisms and modes of action of kombucha are needed to fully
appreciate its values and limitations.
Overall, the present study demonstrated that the hypoglycemic and antilipidemic activities
exhibited by kombucha tea were effective enough to alleviate alloxan-induced diabetes in
experimental rats. The beneficial effect of dietary kombucha is presumably attributed to its
potent hypoglycemic and antilipidemic properties, as well as antioxidant potential. Further
studies are obviously needed to capitalize on the protective effects of kombucha tea in
humans and to make its use suitable as an effective functional food with therapeutic potential.
The findings presented in this work are encouraging and substantiate the search for newer
pharmacophores in kombucha behind the hypoglycemic and antilipidemic effects. The
possible mechanisms underlying the inhibition of pancreatic α-amylase and lipase are also yet
to be studied.
KT, Kombucha tea; BT, Black tea; AST, Aspartate transaminase; ALT, Alanine
transaminase; GGT, Gamma-glytamyl transpeptidase; HDL-Ch, High-density lipoprotein-
cholesterol; LDL-Ch, Low-density lipoprotein-cholesterol; TG, Triglycerides; ROS, Reactive
oxygen species; DM, Diabetes mellitus.
The authors declare that they have no competing interests.
All authors participated in the conception, set up, and carrying out of the study, as well as in
the handling and interpretation of its findings, and the writing and reviewing of its text. AA
and KH have equally contributed to this work and undertook data analysis. DE, MB and KH
contributed to the interpretation of the data. BJ helped in the writing and reviewing process.
FA contributed in the design of the study and the discussion of the data. EA and AE
supervised the work. All authors have read and approved of the final manuscript.
This research was supported by the Tunisian Ministry of Higher Education and Scientific
Research and Technology and the Tunisian Ministry of Public Health. The authors would like
to thank Mr Anouar Smaoui from the English Language Section at the Faculty of Science of
Sfax, Tunisia, for his valuable help with regards to the proofreading and language polishing
of the present paper.
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