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 Table of Contents  
ORIGINAL ARTICLE
Year : 2013  |  Volume : 2  |  Issue : 2  |  Page : 91-98

Garlic supplement, probiotics enriched fermented milk, and their combination: Effect on glycemia, dyslipidemia and oxidative status in STZ-diabetic rats


Department of Food and Nutrition, King Abdul Aziz University, Jeddah, Saudi Arabia

Date of Web Publication6-Jul-2013

Correspondence Address:
Maha Mohammed Badkook
P. O. Box: 42807, King AbdulAziz University, Jeddah, 21551
Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2278-019X.114720

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  Abstract 

Background: Oxidative stress associated with hyperglycemia is a key factor in the development of diabetic complications. The organosulfur compounds in garlic have been shown to possess antioxidative, antidiabetic and immunological potency. Probiotics in fermented milk (FM) also enhance antioxidant and hypoglycemic therapy through the modulation of gut microbes in type 2 diabetes.
Aim : To examine the effects of administration of garlic supplement, probiotics, and their combination on glycemic, lipid, and antioxidant status in type 2 diabetes.
Materials and Methods : Diabetes was induced by STZ-injection in thirty male albino rats. Animals were equally divided to 5 groups: garlic (G) (20 mg/kgBW/Allicin), probiotics (Prob) (0.5 ml/kg/BW), garlic with probiotics (G + Prob), oral hypoglycemic drug (OGD), diabetic control (DM). After 45 days of treatment, tests were conducted for fasting glucose, glycated hemoglobin (GHbA1c), insulin, malondialdehyde (MDA), total antioxidant capacity (TOAC), total cholesterol (TC), LDL-C, HDL-C, and TG.
Results: Glucose and GHbA1c were significantly reduced with all treatments. GHbA1c was significantly lower in the G and G + P groups compared to DM and OGD. No significant difference was observed for insulin. Garlic reduced TC and TG compared to DM, and reduced LDL-C compared to OGD. G + Prob treatment raised LDL-C compared to G, Prob, and OGD groups. HDL-C significantly increased in the P and G + Prob groups compared to DM, OGD, and G groups. MDA decreased with all treatments, while TOAC increased with G and G + P groups compared to DM and OGD.
Conclusion: G arlic, or its combination with probiotics might promote beneficial effects in controlling glycemia, dyslipidemia, and oxidative stress. Probiotics was not as efficient as G and G + Prob treatments.

Keywords: Diabetes, garlic, oxidative stress, probiotics


How to cite this article:
Badkook MM. Garlic supplement, probiotics enriched fermented milk, and their combination: Effect on glycemia, dyslipidemia and oxidative status in STZ-diabetic rats. J Med Nutr Nutraceut 2013;2:91-8

How to cite this URL:
Badkook MM. Garlic supplement, probiotics enriched fermented milk, and their combination: Effect on glycemia, dyslipidemia and oxidative status in STZ-diabetic rats. J Med Nutr Nutraceut [serial online] 2013 [cited 2020 Dec 2];2:91-8. Available from: https://www.jmnn.org/text.asp?2013/2/2/91/114720


  Introduction Top


Diabetes mellitus (DM) is defined as elevated fasting or postprandial glucose, or glycayted hemoglobin (GHbA1c) levels, resulting from the inability of the pancreas to produce enough insulin, or the ineffective use of insulin by the body. According to the recent World Health Organization report, DM is increasing world-wide with a high prevalence in the middle-eastern region. [1] The International Diabetes Federation (IDF) diabetes  Atlas More Details (5 th ed., 2012 update) ranks Saudi Arabia as one of the top ten countries world-wide in DM prevalence accounting for 23.4%. [2] Type 2 diabetes is associated with an increased rate of oxidative stress and dyslipidemia. The increased oxidative stress in subjects with type 2 diabetes is a consequence of several abnormalities, including hyperglycemia, insulin resistance, hyperinsulinemia, and dyslipidemia, each of which contributes to mitochondrial superoxide overproduction in endothelial cells of large and small vessels, as well as the myocardium. [3] Consequently, preventive strategies, most likely based on a change in dietary habits or the use of food complements, are advocated for diabetic people. Garlic has been considered by some to be a component of alternative medicine as a result of its ancient origins and wide-spread use in folk medicine. [4] A number of studies have demonstrated the chemopreventive activity of garlic by using different garlic preparations including fresh garlic extract, aged garlic, garlic oil, and a number of organosulfur compounds derived from garlic. [5] Garlic's antioxidative, anti-inflammatory, and antiglycative properties are responsible for its role in preventing diabetes-related complications. [6] One study suggested recommending garlic powder tablets, allicor for the treatment of type 2 DM along with dietary treatment and/or sulfonylurea derivatives to achieve better metabolic control. [7] Controversy, however, still exists as to the role of garlic on lipid profile. While one meta-analysis in both healthy and hypercholesterolemic subjects reported no beneficial effects of garlic on serum cholesterol. [8] Another recent meta-analysis indicated the association of garlic with a 5.4% reduction in cholesterol levels and a 6.5% reduction in triglyceride levels. [9]

Fermented milk products rich in probiotics are widely used in combination with garlic as beverages, or in mixed dishes. Probiotics are "live microorganisms that are administered orally and allow colonic colonization and confer a host health benefit. [10] Numerous probiotic microorganisms (e.g. Lactobacillus rhamnosus GG, Lactobacillus reuteri, bifidobacteria and certain strains of Lactobacillus casei or the Lactobacillus acidophilus-group) are used in probiotic food, particularly fermented milk products with regard to their medicinal use. [11] Type 2 diabetes in humans is associated with compositional changes in intestinal microbiota. Modulation of gut microbes with the use of probiotics as a means of protection against obesity and type 2 diabetes has been a subject of growing interest recently. [12] In humans type 2 diabetes has been associated with compositional changes in intestinal microbiota. [13] The use of probiotics for diabetes was found to be beneficial in improving glycemic control through the modulation of gut microbes. [14]

Garlic supplement in combination with probiotics has not been investigated in type 2 diabetes. It is hypothesized that the administration of garlic in combination with fermented milk enriched with the probiotic strain Bifidobacterium lactis DN-173 010 might confer positive health effects with respect to lipid profile and antioxidant status in diabetes. This study examined the effects of administrating garlic supplement, a probiotic-rich yogurt, and their combination on glycemia, lipidemia, and oxidative status in streptozotocin - diabetic rats.


  Materials and Methods Top


Materials

Streptozotocin was purchased from Sigma CO. (Missouri, USA). Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and glycated hemoglobin (GGHbA1c) kits were purchased from Human CO. (Wiesbaden, Germany). Triglycerides (TG), Total antioxidant capacity (TOAC), and lipid peroxide kits were purchased from Biodiagnostic Co (Giza, Egypt), Insulin kit was purchased from Monobind Inc (CA, USA). A glucometer for blood glucose testing (Bayer Contour TM , USA) was purchased from a local medical instruments company. The garlic supplement containing 500 mg/tablet of the bioactive compound Allicin (Nutra-Ingredients-USA, com) was purchased locally from a nutraceutical distributor (General Nutrition Corporation, PA, USA). Fermented milk (Activia) containing the specific probiotic strain B. lactis DN-173 010 was purchased from a local store.

Animals

The experiment was conducted as approved by the Ethical Committee at King Fahad Medical Research Center (KFMRC) King Abdul-Aziz University, Jeddah, Kingdom of Saudi Arabia. Adult male Wistar rats weighing 200-250 g were purchased from KFMRC and kept in the animal house at the center in polypropylene cages (six rats/cage) in a temperature-controlled room at 22°C ± 1°C and relative air humidity 50-60% with 12\12 hr. light-dark cycle. Food and tap water were provided ad-libitum. Rats' body weight was measured weekly throughout the experiment.

Methods

The rats (n = 30) were injected intraperitoneally (i.p) with a single dose of streptozotocin (45 mg/kg) dissolved in 0.01 M citrate buffer, pH 4.5, immediately before use. [15] Blood glucose of this group was determined in whole blood samples collected from the tip of the tail after 3 days of STZ injection. The rats were considered diabetic if fasting blood glucose (FBG) level was 9.0 mmol/L. [16] After confirmation of diabetes, animals were randomly divided into five groups (n = 6): group 1 (G) received through a gavage tube a daily dose of garlic supplement (20 mg/kg BW/day Allicin) dissolved in 5 ml water. Group 2 (Prob) received an oral daily dose (0.5 ml/kg) of fermented milk containing B. lactis DN-173 010 (Activia, Danone Co.), group 3 (G + Prob) received daily a combination of garlic supplement and Activia fermented milk (20 mg/kg BW/day Allicin + 0.5 ml/kg Activia), group 4 (Oral Glycemic Drug (OGD) receiving an oral dose of anti-diabetic drug (glibenclamide, 450 μg/kg), [15] and group 5 diabetic control (DM).

All groups were maintained on a standard diet supplied by Grain Silos and Flour Mills Organization (www.gsfmo.gov.sa). [17] The diets comprised of wheat starch, casein, soybean oil, Cellulose, mineral and vitamin combinations. These diets contained as percentages of energy: 66% carbohydrates, 25% protein, and 9% fat. Treatments were administered to animals via gavage tube for 45 days.

Biochemical analysis

At the end of the experiment, animals were deprived of food overnight before excision. They were anesthetized using diethyl ether. Blood samples (5 ml) were collected from each rat from the retro orbital plexus with capillary tubes. Serum was separated by centrifuge at 3000 r.p.m for 15 min. and aliquots were stored at –80°C until biochemical analysis.

Fasting blood glucose was determined from the tail vein using a glucometer (Bayer Contour TM , USA). Glycated hemoglobin (GHbA1c) was determined in whole blood by fast ion-exchange resin method as described by Nuttall. [18] Serum TC, HDL-C, and TG were assessed using the enzymatic colorimetric method as described [19],[20],[21] respectively. Malondialdehyde (MDA) and TOAC were determined colorimetrically according to the method of [22],[23] respectively. Insulin was determined using enzyme-linked Immunosorbent assay according to the method of. [24] Low-density lipoprotein cholesterol (LDL-C) was calculated using the Friedewald formula. [25]

Statistical methods

Statistical analysis was performed using the statistical package SPSS version 16 (SPSS, Chicago, IL, USA). The mean and SEM were determined for each biomarker. To verify the statistical significance of the studied parameters, one-way ANOVA with subsequent post-hoc multiple comparisons tests were performed. Probability values lower than 0.05 (P < 0.05) were accepted for statistical significance.


  Results Top


Change in body weight

The mean ± SEM was similar for all groups and was in the range (200 ± 12.37-250 ± 29.11 gm) (results are not shown). No significant difference in body weight was observed between groups at the end of the experiment, and the mean ± SEM weight was in the range (287.67 ± 14.72-338.83 ± 36.37 gm), which indicates that all rats gained weight at a similar rate.

Effects of garlic, probiotic, and their combination on glycemic control

As indicated in [Table 1] the Mean ± SEM of FBG was similar at baseline for all diabetic groups. The ANOVA test showed that garlic (G), and (G + Prob) treatments resulted in a significantly lower GHbA1c level (P = 0.002, P = 0.001) respectively compared to the (DM) control group. Furthermore, (G) and (G + Prob) groups showed a significantly lower GHbA1c concentration (P = 0.008, P = 0.000) respectively than that of the (OGD) group. Moreover, both (G) and (G + Prob) groups showed a significantly lower GHbA1c levels (P = 0.007, P = 0.001) respectively compared to treatment with probiotics (Prob). ANOVA test showed no significant difference in insulin concentration between treatment groups, or between treatment groups and the control group.
Table 1: Effect of garlic, probiotic, and their combination on serum concentrations of fasting glucose, glycated hemoglobin and insulin compared to diabetic control, and oral hypoglycemic drug groups at the end of the experiment

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Effects of garlic, probiotic, and their combination on lipidemia

[Table 2] shows that treatment with garlic supplement decreased TC concentration compared to the (DM) control group (P = 0.02), and to the (G + Prob) (P = 0.01) group. Cholesterol concentration was also elevated in the (G + Prob) group (P = 0.04) compared to the drug treated diabetic (OGD) group. [Figure 1] shows that HDL-C concentrations were elevated in both the probiotic (Prob) and the garlic-probiotics (G + Prob) groups (P = 0.012, P = 0.013) respectively, compared to both the DM, as well as to the diabetic drug-treated (OGD) group (P = 0.01) as indicated in [Table 2]. Treatment with probiotics (Prob), or combination of garlic-probiotics (G + Prob) resulted in higher HDL-C level (P = 0.002) compared to treatment with garlic alone.
Figure 1: Effect of treatments with garlic, probiotics, and garlic with probiotics on lipid peroxidation determined by mean serum concentrations of malondialdehyde compared to oral glycemic drug (OGD) treatment and diabetes mellitus (DM) control. Data represent Mean ± SEM *the mean difference is significant at the 0.05 level compared to OGD, **The mean difference is significant at the 0.05 level compared to DM

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Table 2: Effect of garlic, probiotic, and their combination on serum concentrations of lipids profile compared to diabetic control, and oral hypoglycemic drug groups at the end of the experiment

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Treatment with (G + Prob) unexpectedly resulted in a significantly higher LDL-C concentration (P < 0.000) compared to the drug-treated diabetic (OGD) group. Moreover, treatment with (G + Prob) resulted in higher LDL-C level compared to treatment with the garlic or probiotics groups (P = 0.03, P = 0.02) respectively. Furthermore, TG concentration significantly decreased with the garlic treatment compared to the diabetic control group (DM).

Effects of garlic, probiotic, and their combination on oxidative stress biomarkers

[Table 2] indicates that MDA concentration was lower in the garlic group compared to the (OGD) group (P = 0.01), while the probiotics (Prob) and the (G + Prob) groups showed significantly lower levels compared to the (DM) control group (P = 0.001), and also compared to the diabetic drug-treated (OGD) group (P = 0.013, P = 0.02) (P = 0.003) compared [Figure 2].
Figure 2: Effect of treatments with garlic, probiotics, and garlic with probiotics on oxidative stress determined by mean serum concentrations of total antioxidant capacity compared to oral glycemic drug (OGD) treatment and diabetes mellitus (DM) control. Data represent Mean ± SEM *the mean difference is significant at the 0.05 level compared to OGD, **The mean difference is significant at the 0.05 level compared to DM

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TOAC concentrations were elevated with garlic treatment compared to both the diabetic drug-treated group (OGD) and to the (DM) control group (P = 0.000). Furthermore, treatment with a garlic-probiotic combination (G + Prob) caused an elevation in TOAC (P = 0.003) respectively compared to both the diabetic drug-treated (OGD), and the control (DM) groups.


  Discussion Top


Garlic has been experimentally shown to exert antilipidemic, antihypertensive, antibacterial, antineoplastic, immunostimulant, and hypoglycemic actions. [26] The current study examined the use of garlic with and without a probiotic as to their effects on glycemia, lipidemia, and oxidative stress. The decrease in blood glucose and GHbA1c after treatment with garlic, probiotic, and the garlic-probiotic combination compared to the non-significant change in the DM group indicate the potential glycemic control of these treatments. This is consistent with earlier studies indicating the antiglycative properties of diverse forms of garlic administered to animals such as methanolic garlic extract, [27] garlic oil [6] aged and black garlic, [28] and raw garlic in fructose fed rats. [29],[30] Administration of S-allylcysteine (SAC) derived from garlic to diabetic rats showed a decrease in plasma glucose and GHbA1c. [31] Aqueous extracts of garlic used at a high concentration (500 mg/kg) decreased serum-glucose concentration compared to a lower dose (50 mg/kg). [32] The antiglycatic property of garlic has been attributed to the organosulfur compounds mainly allicin. [33],[34] Similar to this study, the early study of Mathew and Augusti [35] reported that serum from allicin-treated alloxan-DM rabbits showed insulin-like activity via glucose uptake in rat diaphragm in vitro. These researchers suggested that the most probable mechanism of action for allicin's effects is its action against insulin-inactivating-sulfhydryl group compounds (e.g., cysteine), which spares insulin from inactivation. Thomson et al., [36] reported a 57% reduction in serum glucose of garlic-treated rats compared to control diabetic rats. Both studies [27],[36] have suggested that the hypoglycemic effect of garlic extracts may be due to restoration of delayed insulin response or due to inhibition of intestinal absorption of glucose. This could be due to the potentiating of insulin by release from bound insulin.

In the current study, the decrease in FBG and GHbA1c ensuing treatment with garlic, probiotics, and their combination supports their role in glycemic control. Moreover, the significant lowering of GHbA1c resulting from G and G + Prob treatments compared to DM control and OGD groups, indicates a potential antiglycative role for this combination. However, the lower GHbA1c level observed with G treatment compared to G + Prob indicates that garlic has a higher glycemic potential than that of the G + Prob combination.

The association of gut microbes to obesity and type 2 diabetes has been recently undergoing considerable investigation. In humans, type 2 diabetes has been associated with compositional changes in intestinal microbiota. [13] The use of probiotics for diabetes was found to be beneficial in improving glycemic control through the modulation of gut microbes. [14] The anti-diabetic properties of probiotics have been mostly limited to animal studies. Harisa et al., [37] showed that treatment with L. acidophilus alone or in combination with an acarbose significantly decreased fasting blood sugar GHbA1c concentrations in diabetic rats. Andersson et al., [38] indicated that in rats fed L. plantarum DSM 15313 together with a high-fat diet (HFD), fasting plasma glucose levels were lower in the group fed the probiotic supplement. An oral glucose tolerance test showed that the group fed probiotics had a significantly lower insulin release compared to the control group suggesting that this probiotic fed with a HFD has anti-diabetic properties. In humans, Ejtahed et al.,[39] reported a decrease in blood glucose and GHbA1c in type 2 diabetic subjects compared to a control group after consumption of 300 g/d of probiotic yogurt.

Although, the induction of diabetes with STZ would result in considerable reduction in pancreatic insulin secretion, the concentration of insulin was not different among the groups at the end of the experiment which might suggest that either the different treatments have maintained the potential of the pancreas to secrete insulin, or that STZ injection caused only a partial destruction of the pancreatic cells which, after 6 weeks, were capable of regaining their function. However, this finding is not in congruence with results of previous studies. Saravanan and Pomurugan [31] showed that the administration of SAC derived from garlic increased plasma insulin levels in SAC treated diabetic rats. Another study showed that the administration of raw garlic to fructose-fed rats significantly reduced serum insulin. [29] In the study of Liu et al., [6] garlic compounds: garlic oil and diallyl trisulfide was accompanied by a significant increased rate of insulin secretion by both garlic compounds. The controversy in the findings of the present study and previous studies might be related to the variation in the form and dose of garlic supplementation used in those studies.

Dyslipidemia is a common characteristic of type 2 diabetes, which constitutes a significant etiopathological factor for atherosclerosis. Allicin has been proposed as the active compound produced by garlic responsible for health promotion and hypocholesterolemic and antiatherosclerotic effect. In this study, treatment with garlic supplement exerted a decrease in total cholesterol and triglyceride concentrations compared to the DM group (P < 0.05). Consistent with this finding, Eidi et al.,[27] showed that oral administration of ethanolic garlic extract significantly decreased total cholesterol and TG in diabetic rats. Also, Thomson et al., [36] indicated a 40% and 35% reduction in serum cholesterol and triglyceride levels respectively in STZ-induced diabetic rats compared to control diabetic rats. Moreover, the study of Gorinstein et al.[40] showed that rats fed a high-cholesterol diet supplemented with 25 mg of lyophilized garlic/kg body weight obtained from raw, boiled and their aqueous extracts over a period of 30 days significantly hindered the rise of TC and LDL-C. In their review, Banerjee and Maulik [41] reported possible mechanisms for the hypolipidemic effect of garlic. (1) The depression of the hepatic activities of lipogenic and cholesterogenic enzymes such as malic enzyme, fatty acid synthase, glucose-6 phosphate dehydrogenase, and 3-hydroxy-3-methyl-glutaryl-CoA reductase. (2) The increased excretion of cholesterol, as manifested by enhanced excretion of acidic and neutral steroids after garlic feeding.

On the other hand, in human studies, the effect of garlic on dyslipidemia has been controversial. The administration of garlic for 12 weeks to type 2 diabetic patients and hypercholesterolemic patients caused a significant reduction in serum TC and LDL-C in comparison to placebo intake. [42],[43] Researchers suggested possible small short term benefits of garlic on dyslipidemia in type 2 diabetic patients. However, other studies reported non-significant changes in lipid profile after treatment with enteric garlic-coated garlic extract in subjects with hypercholesterolemia, [44] or in adults fed raw garlic, powdered supplement, aged garlic extract supplement. [45] Furthermore, long-term garlic supplementation to subjects with moderate cholesterol concentrations did not find a significant effect on serum concentrations of total, HDL, or LDL cholesterol after 3.3 year and 7.3 year of intervention. [46] This inconsistency with the findings of this study could be accounted in part to the composition and amount of sulfur components of different protocol designs of garlic preparations used in various studies.

Probiotics role on dyslipidemia associated with type 2 diabetes has been scarcely examined in previous studies. In this study, treatment with the probiotics-garlic combination G + Prob caused an elevation in TC and LDL-C concentrations compared to both the garlic treated group and the OGD group (P < 0.05). Moreover, LDL-C was significantly higher in the G + Prob group compared to the probiotics treated group (Prob). This finding might indicate that this type of probiotics with garlic combination might deter the hypolipidemic effect of garlic or probiotics if each is ingested by itself. On the other hand, treatment with Prob and G + Prob resulted in a significantly higher HDL-C level compared to that of DM, OGD, and G groups. This might indicate that the elevation in TC and LDL-C encountered with G + Prob administration must have been counterbalanced by the high HDL-C observed with such treatment and promote a beneficial effect on type 2 dyslipidemia. The hypocholesterolemic effects of probiotics are subject of controversy. Studies published in the 1970's and 1980's consistently reported 5-17% reductions in serum cholesterol concentrations after 2-4 week of daily consumption of fermented milk products, but these data have been challenged by the results of more recent studies, almost all of which did not report any significant effect. [47] However, more studies are required to elucidate this effect. In humans, a recent study of participants consuming a daily dose of 300 g of probiotic yogurt containing L. acidophilus La5 and B. lactis Bb12 or 300 g for 6 weeks revealed a decrease in TC and LDL-C. [39] In hypercholesterolemic subjects, yogurt containing 2 types of probiotic bacteria strains, L. acidophilus and B. lactis, resulted in a cholesterol-lowering effect. [48] Thus, it is apparent that in this study, each type of treatment was effective in regulating the dyslipidemia encountered in diabetes. Furthermore, probiotics might enhance the effect of garlic on dyslipidemia when both are administered together.

Lipid peroxidation is increased in diabetes due to increased peroxidation of membrane lipids and accumulation of MDA in erythrocytes of diabetic patients. [49] In this study, administration of garlic supplement resulted in a significantly lower MDA concentration compared to the OGD group. This finding is consistent with previous studies, which indicated a decrease in lipid peroxidation products despite the difference in the forms of garlic treatments used. Plants belonging to the Allium family have been found to have antioxidant properties in several earlier studies, and their antioxidant activity is attributed to their ability to scavenge free radicals or to inhibit lipid peroxidation. [50] In the study of Saravanan and Ponmurugan [31] the administration of SAC derived from garlic given to diabetic rats caused a decrease in thiobarbituric acid reactive substances (TBARS). Another study showed that garlic administration in the form of methanolic garlic extract in a dose-dependent manner restored and significantly normalized the pre-elevated MDA level due to the hyperglycemia caused by STZ-induction. [51] Lee et al.,[52] also showed that the consumption of both aged black garlic and raw garlic in db/db mice significantly decreased hepatic (TBARS) level compared with the control group. Besides the reduction in MDA concentration, garlic supplementation resulted in a significantly elevated level in the TOAC concentration (P < 0.001) compared to the DM, and the diabetic oral-drug treated (OGD) groups. This is in accordance with the results from the study of Gorinstein et al.,[40] in which a significant increase in the plasma antioxidant activity was registered in rats fed cholesterol-free diets supplemented with garlic.

Moreover, the administration of (Prob) and (G + Prob) caused a significant decrease in MDA concentration compared to both the DM control and to the diabetic (OGD) groups. This indicates the possibility that the 2 types of treatments have the potential to reduce lipid peroxidation and boost the antioxidant status in diabetes. This is especially, apparent with the (G + Prob) treatment that has also resulted in an elevation in the TOAC concentration compared to the diabetic (DM), and the oral-drug treated (OGD) groups in addition to its role in reducing lipid peroxidation. Besides their content of nutrients considered beneficial to the body, fermented milks have been considered as dietary sources of natural antioxidants because of the presence of antioxidant peptides. Most identified bioactive peptides were derived from casein and have been shown to exhibit free radical scavenging and inhibit enzymatic and non-enzymatic lipid peroxidation. [53] In congruence with the results of this study, Harisa et al.[37] showed that treatment with L. acidophilus alone or in combination with acarbose significantly decreased MDA concentration in diabetic rats. In humans, Ejtahed et al.,[39] reported increased total antioxidant status in type 2 diabetic subjects compared with a control group after consumption of 300 g/day of probiotic yogurt. However, another study in humans where the intake of probiotic (Lactobacillus casei) was compared to conventional yoghurt, a significant decrease of the average TOAC and increased MDA values were observed in both tested groups. [54] It is thus apparent that the combination of garlic with probiotics could be recommended to diabetic patients due to their beneficial role in promoting antioxidative status.


  Conclusion Top


This study examined three different types of natural treatments as well as an oral anti-diabetic drug-treatment on biomarkers of glycemia, lipidemia, and oxidative stress. All treatments resulted in an antiglycemic effect with the reduction observed in blood glucose and GHbA1c levels compared to baseline level. Both the garlic G, and the combination G + Prob treatments resulted in a glycemic benefit indicated by the significant decrease in and GHbA1c level compared to the diabetic DM control with garlic having a higher antiglycemic potency over the garlic-probiotics combination. The non-significant difference in serum insulin concentration between groups might suggest that the different treatments used were capable of retaining insulin secretion at a level similar to that of the control groups. Garlic supplement reduced TC, LDL-C and TG, while G+Prob raised LDL-C. HDL-C significantly elevated in the probiotics and the garlic-probiotics combination groups. All treatments resulted in a decrease in MDA levels compared to control groups indicating a potential role in decreasing lipid peroxidation. Furthermore, the TOAC significant increase in the garlic G and garlic-probiotics combination G + P groups compared to control and oral drug groups provides an additional benefit of such treatments in type 2 diabetes.

Some limitations should be noted in this study was the need for the inclusion of a group of rats treated with conventional yoghurt for a better comparison with the probiotics group. Furthermore, weekly measures of the amount of feed intake to determine the food efficiency ratio for each group of rats should have provided a better understanding whether any of the treatments might have had affected the health state of rats.

The positive hypolipidemic and antioxidative effects observed with the administration of the garlic supplement and probiotics provide diverse implications for nutraceutical industries in manufacturing supplements of garlic extracts with probiotic strains, or for the food industry in manufacturing forms of fermented milk or conventional yogurt products supplemented with garlic or Allicin, the potential organosulfur compound of garlic. Further clinical trials concerning the use of garlic and probiotics combination in humans still need to be conducted in the future. The diabetic people are encouraged to incorporate both garlic and probiotics in their diets.

 
  References Top

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