the three most commonly encountered forms of mercury are metal vapor ( hg ) , ionic compounds ( hg ) and organic mercury , principally methyl mercury ( hgch3 ) . organic mercury is the most deadly of the mercury compounds , probably due to its ability to penetrate cells . within the cell it can destroy various components selectively or in total by releasing lysosomes , damaging dna and rupturing the cell membrane . the toxicity of high levels of mercury contamination was brought to public attention in the 1950s as a result of mercury dumping in the minamata bay in japan 8 9 ] . the general population is primarily exposed to mercury via food , fish being a major source of methyl mercury exposure . mercury is incorporated into the food chain as methyl mercury , primarily through the action of bacteria and other microbes transforming elemental or inorganic forms . humans are also exposed to mercury via thimerosal ( a preservative added to vaccines and many other pharmaceuticals ) , and  amalgam  or mercury - based dental fillings . mercury vapor released from mercury dental fillings is absorbed very rapidly and thoroughly by the body , mainly through inhalation and swallowing . adverse health effects , particularly of a neurological nature , have resulted from low exposure levels , especially to the fetus in pregnant women . using young rats as a model of mercury toxicity , results from previous studies and from our group have demonstrated that exposure to hgcl2 ( 25 mg / kg ) for only five consecutive days causes cerebral and whole body weight losses , increases in kidney weight , mercury accumulation in tissues , inhibition of porphobilinogen synthase activity[1517 ] , alterations in renal and hepatic functions and glycemia . metal intoxication is usually treated with chelating agents , which are not specific and are often more toxic than the metal itself . because chelation therapy for heavy metals intoxication can also be toxic , researchers are looking for natural preventive and therapeutic agents for heavy metal toxicity . kumis , also known as koumiss , is an alcoholic beverage made from fermented mare 's milk . mare 's milk is usually not consumed raw , because it tends to have a strong laxative effect , although this effect is sometimes used medically . instead , fermentation destroys lactose in milk , converting it into lactic acid , ethanol , and carbon dioxide . fermentation takes place in 3 - 8 hours and is carried out by a mixture of indigenous yeasts and lactic acid bacteria . currently , kumis is manufactured at an industrial level in some countries using pure cultures of yeasts and lactic acid bacteria . kumis is rich in ferments , trace elements , antibiotics , vitamins a , b1 , b2 , b12 , d , e , c , ethyl alcohol , lactic acid and carbonic acid . kumis drinking has a healing influence on the gastrointestinal tract , metabolism , cardiovascular and nervous systems , and kidneys ; it aids the development of immunity ; and has been used to treat weight loss and anemia . adding soluble fiber to the diet has also been shown to have positive effects on health . various studies have shown a reduction in colon cancer risk and enhanced health by consuming inulin and oligo fructose in ratios ranging from 2% to 10% . probiotics include viable lactic acid bacteria and other bacilli that are able to survive in the intestine . prebiotics include carbohydrates that are not digested in the upper part of the gastrointestinal tract , but selectively fermented by bacteria in the colon . this selective fermentation affects the composition of the intestinal microflora by stimulating bifidobacteria and lactobacilli , both in humans and in animals , where these bacteria have health promoting properties . we have combined these three health - promoting materials to produce a functional food composed of fermented mare 's milk plus a high level ( 6% ) of soluble fiber and probiotics . the current study was designed to determine if feeding the high fiber probiotic fermented mare 's milk could alleviate the toxic effects of mercury in rat model . starter cultures of streptococcus thermophilus , lactobacillus acidophilus , and bifidobacterium bifidum were obtained from hansen 's laboratory , copenhagen , denmark . dandelion root ( taraxacum officinale ) was purchased from haraz herbal market , cairo , egypt . fresh mare 's milk was obtained from lactating and healthy arabian mares in the experimental animal unit , college of agriculture and veterinary medicine , qassim university , saudi arabia . briefly , fresh mare 's milk ( 11% total solid ) was heated at 85 c for 15 minutes , cooled to 40 c , then inoculated with the 1.0  10 probiotic bacteria streptococcus thermophilus , lactobacillus acidophilus and bifidobacterium bifidum and was then incubated for 4 - 8 hours at 42 c. after coagulation , the curd was tested for ph and stored refrigerated ( 4 - 6 c ) . a hot water extract of soluble dandelion root fiber was prepared according the methods described by abdel - salam et al .. dandelion roots were cut into small pieces and boiled for 10 minutes in distilled water . the mixture was filtered twice : first through cheesecloth ( 50% cotton/50% polyester ) , and then through filter paper ( whatman no.2 ) . the solutions obtained were preserved in sterile dark bottles in a cool environment ( 4 c ) until use . the high fiber probiotic mare 's milk was prepared by mixing the concentrated hot water extract of dandelion root with the fermented mare 's milk at 6% total solids . a sensory evaluation test of the fermented milk products was adopted from the national aeronautics and space administration ( n.a.s.a . ) . the evaluation was performed by a panel composed of the staff and students in the department of food science and human nutrition . the evaluation rated the appearance , color , odor , flavor , and overall impression of the product , and results were expressed as very good ( + + + ) , good ( + + ) , acceptable ( + ) , or unacceptable ( - ) . antioxidant capacity was measured with a 1,1-diphenyl-2-picrylhydrazyl ( dpph ) assay according to the method of brand - williams et al . with some modifications . a stock solution was prepared by dissolving 24 mg of dpph in 100 ml methanol . the working solution was obtained by mixing 10 ml stock solution with 45 ml methanol to obtain an absorbance of 1.1  0.02 units at 515 nm using a spectrophotometer . milk extracts ( 750 l ) were allowed to react with 1500 l of the dpph solution for 5 minutes in the dark . trolox is a water - soluble derivative of vitamin e it is an antioxidant , like vitamin e , and is used in biological or biochemical applications to reduce oxidative stress or damage . trolox equivalent antioxidant activity ( teac ) is a measurement of antioxidant strength based on trolox , measured in units called trolox equivalents ( te ) , trolox equivalency is used as a benchmark for the antioxidant capacity of such a mixture . thirty male adult swiss albino rats weighing 200 - 250 g  40 g were used . the animals were housed in standard cages and were assigned to a specific treatment diet . the composition of the basal diet was as follows : milk protein ( 12% ) , sucrose ( 5% ) , fat ( 10% ) , vitamin mixtures ( 1% ) , salt mixtures ( 4% ) , fiber ( 4% ) and starch ( 64 % ) . the positive control group was fed the basal diet and received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water . the third group was fed the basal diet , received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water , and was fed the high fiber fermented mare 's milk solution containing probiotics . the weights of the rats were measured at the beginning and end of the experiment . sera were harvested , labeled and stored frozen ( -20 c ) pending analysis . in sera the following parameters were analyzed : urea was determined according to the methods of tietz . glutathione - s - transferase ( gst ) activity was determined according to habig et.al .. lactate dehydrogenase ( ldh ) activity was determined according to bergmeyer . samples of brain , cerebellum , and kidneys were taken , and fixed in 10% neutral buffered formalin for 24 hours . paraffin sections 6 m thick were prepared and stained with hematoxylin and eosin ( h & e ) for the examination of tissue and cellular changes by light microscopy . mean and standard deviation of the data from each experimental group were calculated and briefly , fresh mare 's milk ( 11% total solid ) was heated at 85 c for 15 minutes , cooled to 40 c , then inoculated with the 1.0  10 probiotic bacteria streptococcus thermophilus , lactobacillus acidophilus and bifidobacterium bifidum and was then incubated for 4 - 8 hours at 42 c. after coagulation , the curd was tested for ph and stored refrigerated ( 4 - 6 c ) . a hot water extract of soluble dandelion root fiber was prepared according the methods described by abdel - salam et al .. dandelion roots were cut into small pieces and boiled for 10 minutes in distilled water . the mixture was filtered twice : first through cheesecloth ( 50% cotton/50% polyester ) , and then through filter paper ( whatman no.2 ) . the solutions obtained were preserved in sterile dark bottles in a cool environment ( 4 c ) until use . the high fiber probiotic mare 's milk was prepared by mixing the concentrated hot water extract of dandelion root with the fermented mare 's milk at 6% total solids . a sensory evaluation test of the fermented milk products was adopted from the national aeronautics and space administration ( n.a.s.a . ) . the evaluation was performed by a panel composed of the staff and students in the department of food science and human nutrition . the evaluation rated the appearance , color , odor , flavor , and overall impression of the product , and results were expressed as very good ( + + + ) , good ( + + ) , acceptable ( + ) , or unacceptable ( - ) . antioxidant capacity was measured with a 1,1-diphenyl-2-picrylhydrazyl ( dpph ) assay according to the method of brand - williams et al . with some modifications . a stock solution was prepared by dissolving 24 mg of dpph in 100 ml methanol . the working solution was obtained by mixing 10 ml stock solution with 45 ml methanol to obtain an absorbance of 1.1  0.02 units at 515 nm using a spectrophotometer . milk extracts ( 750 l ) were allowed to react with 1500 l of the dpph solution for 5 minutes in the dark . trolox is a water - soluble derivative of vitamin e it is an antioxidant , like vitamin e , and is used in biological or biochemical applications to reduce oxidative stress or damage . trolox equivalent antioxidant activity ( teac ) is a measurement of antioxidant strength based on trolox , measured in units called trolox equivalents ( te ) , trolox equivalency is used as a benchmark for the antioxidant capacity of such a mixture . thirty male adult swiss albino rats weighing 200 - 250 g  40 g were used . the animals were housed in standard cages and were assigned to a specific treatment diet . the composition of the basal diet was as follows : milk protein ( 12% ) , sucrose ( 5% ) , fat ( 10% ) , vitamin mixtures ( 1% ) , salt mixtures ( 4% ) , fiber ( 4% ) and starch ( 64 % ) . the positive control group was fed the basal diet and received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water . the third group was fed the basal diet , received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water , and was fed the high fiber fermented mare 's milk solution containing probiotics . the weights of the rats were measured at the beginning and end of the experiment . sera were harvested , labeled and stored frozen ( -20 c ) pending analysis . in sera the following parameters were analyzed : urea was determined according to the methods of tietz . glutathione - s - transferase ( gst ) activity was determined according to habig et.al .. lactate dehydrogenase ( ldh ) activity was determined according to bergmeyer . samples of brain , cerebellum , and kidneys were taken , and fixed in 10% neutral buffered formalin for 24 hours . paraffin sections 6 m thick were prepared and stained with hematoxylin and eosin ( h & e ) for the examination of tissue and cellular changes by light microscopy . mean and standard deviation of the data from each experimental group were calculated and according the method described by miller and miller . briefly , fresh mare 's milk ( 11% total solid ) was heated at 85 c for 15 minutes , cooled to 40 c , then inoculated with the 1.0  10 probiotic bacteria streptococcus thermophilus , lactobacillus acidophilus and bifidobacterium bifidum and was then incubated for 4 - 8 hours at 42 c. after coagulation , the curd was tested for ph and stored refrigerated ( 4 - 6 c ) . a hot water extract of soluble dandelion root fiber was prepared according the methods described by abdel - salam et al .. dandelion roots were cut into small pieces and boiled for 10 minutes in distilled water . the mixture was filtered twice : first through cheesecloth ( 50% cotton/50% polyester ) , and then through filter paper ( whatman no.2 ) . the solutions obtained were preserved in sterile dark bottles in a cool environment ( 4 c ) until use . the high fiber probiotic mare 's milk was prepared by mixing the concentrated hot water extract of dandelion root with the fermented mare 's milk at 6% total solids . a sensory evaluation test of the fermented milk products was adopted from the national aeronautics and space administration ( n.a.s.a . ) . the evaluation was performed by a panel composed of the staff and students in the department of food science and human nutrition . the evaluation rated the appearance , color , odor , flavor , and overall impression of the product , and results were expressed as very good ( + + + ) , good ( + + ) , acceptable ( + ) , or unacceptable ( - ) . antioxidant capacity was measured with a 1,1-diphenyl-2-picrylhydrazyl ( dpph ) assay according to the method of brand - williams et al . with some modifications . a stock solution was prepared by dissolving 24 mg of dpph in 100 ml methanol . the working solution was obtained by mixing 10 ml stock solution with 45 ml methanol to obtain an absorbance of 1.1  0.02 units at 515 nm using a spectrophotometer . milk extracts ( 750 l ) were allowed to react with 1500 l of the dpph solution for 5 minutes in the dark . trolox is a water - soluble derivative of vitamin e it is an antioxidant , like vitamin e , and is used in biological or biochemical applications to reduce oxidative stress or damage . trolox equivalent antioxidant activity ( teac ) is a measurement of antioxidant strength based on trolox , measured in units called trolox equivalents ( te ) , trolox equivalency is used as a benchmark for the antioxidant capacity of such a mixture . thirty male adult swiss albino rats weighing 200 - 250 g  40 g were used . the animals were housed in standard cages and were assigned to a specific treatment diet . the composition of the basal diet was as follows : milk protein ( 12% ) , sucrose ( 5% ) , fat ( 10% ) , vitamin mixtures ( 1% ) , salt mixtures ( 4% ) , fiber ( 4% ) and starch ( 64 % ) . the positive control group was fed the basal diet and received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water . the third group was fed the basal diet , received 25 ppm mercury as mercuric chloride ( hgcl2 ) in drinking water , and was fed the high fiber fermented mare 's milk solution containing probiotics . the weights of the rats were measured at the beginning and end of the experiment . in sera the following parameters were analyzed : urea was determined according to the methods of tietz . glutathione - s - transferase ( gst ) activity was determined according to habig et.al .. lactate dehydrogenase ( ldh ) activity was determined according to bergmeyer . samples of brain , cerebellum , and kidneys were taken , and fixed in 10% neutral buffered formalin for 24 hours . paraffin sections 6 m thick were prepared and stained with hematoxylin and eosin ( h & e ) for the examination of tissue and cellular changes by light microscopy . mean and standard deviation of the data from each experimental group were calculated and according the method described by miller and miller . the results of the sensory evaluation of the high fiber fermented mare 's milk containing probiotics showed that it 's appearance and color were rated good  , and it 's odor , flavor , and overall impression were rated table 1 shows a comparison of the composition and antioxidant capacity of fresh , fermented , and high fiber fermented mare 's milk containing probiotics . although the composition of all 3 was similar , the antioxidant capacity was highest in the high fiber probiotic fermented mare 's milk compared to fresh or fermented mare 's milk . chemical compositions and antioxidant capacity of fresh , fermented , and high fiber fermented mare 's milk as shown in table 2 , the untreated ( negative control ) rats gained weight during this experiment , while there was a large decrease in the weight of the rats in the positive control group . the weight of the rats consuming the high fiber probiotic fermented mare 's milk treated group increased rather than decreased during the course of this experiment . body weight changes following different treatments treatment with mercuric chloride ( positive control)resulted in an increase in the rat 's kidney weight compared to the untreated negative control rats ( table 3 ) . less kidney weight increase was observed in rats treated with mercury and high fiber probiotic fermented mare 's milk , compared to the positive control animals . kidney weight following different treatments the values of several biochemical markers measured in serum are shown in table 4 . there was a decrease in the activity of glutathione - s- transferase ( gst ) in the sera of the positive control rats compared to the untreated negative control rats . however , gst activity increased in the rats receiving the high fiber probiotic fermented mare 's milk in addition to mercury . the activity of lactate dehydrogenase ( ldh ) increased in the group treated with mercuric chloride only ; however , ldh activity decreased in the group that received mercuric chloride and high fiber probiotic fermented mare 's milk . serum creatinine levels in the positive control group decreased compared to the negative control . however , treatment with high fiber probiotic fermented mare 's milk resulted in serum creatinine levels returning to normal values . there was a decrease in the concentration of serum triglycerides in the control positive group receiving mercury only , but the concentration of serum triglycerides was almost normal in the group that received mercury together with high fiber probiotic fermented mare 's milk . there was a significant increase in the level of uric acid and urea in serum of the positive control group compared to the negative controls . however , uric acid and urea were lower in the group that ingested high fiber probiotic fermented mare 's milk with mercury than in the negative control group . biochemical markers of kidney function measured in serum histopathological changes in the brain and kidney sections stained with h&e were evaluated by light microscopy . there was generalized and localized edema in the white matter of cerebrum and cerebellum in the positive control rats . the positive controls also showed congested blood vessels in both cerebrum and cerebellum which may occur prior to edema . these sections showed neuronal necrosis in cerebrum , necrosis and chromatolysis of purkinje cells in the cerebellum , and demyelination in the axons of the neuropil . histopathological changes in rat brain and kidney following different treatments the histopathological changes in kidneys of rats were also evaluated . in the positive control group , the renal epithelium suffered vacuolar and hydropic degeneration in most tubules . necrotic debris occasionally formed acidophil casts within the tubuli . in some cases , necrosis of the whole tubules was observed . a few tubules showed hyaline droplet degeneration in their epithelium , together with some hyaline casts within tubular lumen . perivascular and interstitial inflammatory cellular infiltrate with pyknosis of the nucleus was observed , as was severe cloudy swelling of renal tubular epithelium with moderate necrosis and hydropic degeneration but no significant histological alterations were shown in the glomeruli . administration of high fiber probiotic fermented mare 's milk partially protected the kidneys from the histopathological changes produced by mercury . the histopathological changes were severe with mercury alone but they were moderate to mild when mercury was administered together with high fiber probiotic fermented mare 's milk . rats treated with high fiber probiotic fermented mare 's milk showed no histopathological changes in the brain . mild changes were observed in kidneys as manifested by hydrophobic degeneration , necrosis , and hemorrhage , but no inflammatory cells or cloudy swelling were observed . these results indicate that high fiber probiotic fermented mare 's milk protected the rats against the adverse effects produced by mercury in brain and kidney . in recent years the popularity of complementary medicine , such as the use of probiotics and functional foods has increased . knowledge is accumulating that microbiota modulates gut physiology , immunological functions , and may produce other beneficial effects . this has led scientists to investigate the efficacy of probiotics , prebiotics and synbiotics in the treatment of diseases and toxicities . increasing the variety of functional foods is a challenge , and the promotion and formulation of functional foods and may enhance human health . it is well documented that hgcl2 exposure promotes hg accumulation in all tissues , with the highest levels in the liver , followed by the kidney and blood . the increased blood urea and creatinine are in agreement with the results obtained by rana et al . in male rats treated with mercury . elevated blood urea is known to be a function of or related to increased protein catabolism in mammals and/or the conversion of ammonia to urea as a result of increased synthesis of arginase enzyme involved in urea production . in agreement with this , the present results show that body weights decreased in animals treated with mercury indicating body wasting and increased protein catabolism . the increase in plasma urea and creatinine concentrations in the present experiment may be due to kidney dysfunction , as suggested by the increased weight of the kidneys . the decrease in the activity of gst in serum of rats receiving mercury is similar to the findings reported by el - missiry and shalaby , who found that the heavy metal cadmium decreased the activity of gst in brain and testes of male rats . el - demerdash also reported that cadmium caused a decrease in gst activity in fish . gst catalyses the reaction of alkylating agents with the thiol ( -sh ) group of glutathione , thereby neutralizing an electrophilic site and rendering the products more water soluble . the decline in serum gst activity may be due to the effect of mercury on glutathione . mercury has a high affinity to this molecule where a sulfhydryl , an amino and two carboxylic acid groups , as well as two peptide linkages , represents reactive sites for metals . reactions of metals with glutathione may lead to either the formation of complexes or the oxidation of glutathione . high fiber probiotics fermented mare 's milk was found to have a high antioxidant capacity ( table 1 ) . this high antioxidant capacity may contribute in ameliorating the oxidative stress effects and damage produced by mercury . our results were similar to those of hussain et al , who found that the nervous system is affected by mercuric chloride toxicity . in our study , cellular and tissue changes were noticed in the positive control , including generalized and localized edema in the white mater of cerebrum and cerebellum . edema is a clear sign of compromised blood - brain barrier to mercuric chloride intoxication . the positive control also showed congested blood vessels in both cerebrum and cerebellum which could be prior to edema . the neuronal changes could be due to oxidative stress secondary to mercuric chloride toxicity . in the rats fed the high fiber fermented mare 's milk containing probiotic , the histological picture improved ; this could be due to antioxidative stress effect of the high fiber fermented mare 's milk containing probiotic . oxidative stress may induce peroxidation injury in the membrane of lipids and protein as well as dna fragmentation , which can result in disruption of nerve cell function and integrity . it is well known that brain is more sensitive tissue to oxidative damage because of its high concentration of unsaturated lipids and its high rate of oxidative metabolism . we conclude that high fiber fermented mare 's milk containing probiotic had a protective effect against brain and kidney alterations produced by mercury toxicity .
background : since the advent of the industrial revolution in the late 19th century , we have all been unfortunately exposed to an increasingly toxic and polluted world . among the most dangerous of these pollutants is mercury , which is considered to be the most toxic non - radioactive heavy metal . 
 fermented foods may help cleanse the body of heavy metals . 
 fermentation breaks down the nutrients in foods by the action of beneficial microorganisms and creates natural chelators that are available to bind toxins and remove them from the body.aims:the current study was designed to determine the impact of feeding a high fiber probiotic fermented mare 's milk on the biological effects of mercury toxicity in rat model.methods and materials : the high fiber fermented mare 's milk containing probiotics was prepared and its sensory properties , chemical composition , and antioxidant activity were determined . 
 a rat model of mercury toxicity was used . 
 the effect of feeding the high fiber probiotic fermented mare 's milk to rats , along with mercury ingestion , was determined by the analysis of several biochemical markers in serum and histopathological examinations of brain and kidney.results:the high fiber fermented mare 's milk containing probiotics was found to be acceptable by all test panels and volunteers . 
 mercury ingestion was found to cause biochemical and histopathological alterations in rat serum and tissues . 
 the mercury - treated rats showed a decrease in body weight and an increase in kidney weight . 
 sera of the mercury treated rats showed alterations in biochemical parameters , and histopathological changes in brain and kidney . 
 however , the rats fed high fiber fermented mare`s milk along with mercury ingestion showed improved histopathology of kidney and brain , and there was restoration of the biochemical parameters in serum to almost normal values.conclusions:feeding high fiber fermented mare`s milk may reduce the toxic effects of mercury .