The Benefits of Lactic Acid Bacteria in Yogurt on the Gastrointestinal Function and Health

Abstract

The nutritional value of yogurt and Lactic Acid-producing Bacteria (LAB) on the gastrointestinal health and function, have been investigated in this study. Both Lactobacillus bulgaricus and Streptococcus thermophilus (LAB) species, contribute to the formation of yogurt as a result of anaerobic fermentation of lactic acid in the milk. The present study focuses on the effect of yogurt consumption as a basic Mediterranean dietary tradition, improving the health and longevity. Among adults, life expectancy was the highest in the world and the rate of coronary heart disease, cancer and other diet related chronic disease, were among the lowest, in which yogurt is considered the main source of diary products in the Mediterranean diet, incorporated with other healthy foods (fruit, vegetable, brown bread, cereals and olive oil). Numerous studies suggested beneficial therapeutic effect of (LAB) bacteria in the yogurt on the gut health. (LAB) bacteria can protect against enteric infection and inhibit chemically Carcinogens induce tumorization in the gastrointestinal tract. Combination of Probiotics active culture and prebiotics non digestible food ingredient, beneficially affect the host by improving the survival of live microbial dietary supplement through its transit in the gut and by stimulating the activity of colon bacteria, specially Bifidobacteria and Lactobacilli genera. The benefits of yogurt consumption on the gastrointestinal function mediated through the gut micro flora, bowel transit and the enhancement of gastrointestinal immune responses. Certain disease with gastrointestinal tract such as, lactose intolerance, diarrhea, colon Cancer, inflammatory bowel disease and other bacterial infection were inhibited through high consumption of yogurt as based diary food product.

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Pakistan Journal of Nutrition 8 (9): 1404-1410, 2009
ISSN 1680-5194
© Asian Network for Scientific Information, 2009
1404
The Benefits of Lactic Acid Bacteria in Yogurt on the
Gastrointestinal Function and Health
Ayman Suliman Mazahreh and Omer Turki Mamdoh Ershidat
1 2
Department of Applied Sciences, Al-Balqa Applied University,
1
Princes Alia University College, P.O. Box: 941941, Amman 11194, Jordan
AL-Balqa Applied University, Irbid University College, Jordan
2
Abstract: The nutritional value of yogurt and Lactic Acid-producing Bacteria (LAB) on the gastrointestinal
health and function, have been investigated in this study. Both Lactobacillus bulgaricus and Streptococcus
thermophilus (LAB) species, contribute to the formation of yogurt as a result of anaerobic fermentation of
lactic acid in the milk. The present study focuses on the effect of yogurt consumption as a basic
Mediterranean dietary tradition, improving the health and longevity. Among adults, life expectancy was the
highest in the world and the rate of coronary heart disease, cancer and other diet related chronic disease,
were among the lowest, in which yogurt is considered the main source of diary products in the Mediterranean
diet, incorporated with other healthy foods (fruit, vegetable, brown bread, cereals and olive oil). Numerous
studies suggested beneficial therapeutic effect of (LAB) bacteria in the yogurt on the gut health. (LAB) bacteria
can protect against enteric infection and inhibit chemically Carcinogens induce tumorization in the
gastrointestinal tract. Combination of Probiotics active culture and prebiotics non digestible food ingredient,
beneficially affect the host by improving the survival of live microbial dietary supplement through its transit
in the gut and by stimulating the activity of colon bacteria, specially Bifidobacteria and Lactobacilli genera.
The benefits of yogurt consumption on the gastrointestinal function mediated through the gut micro flora,
bowel transit and the enhancement of gastrointestinal immune responses. Certain disease with
gastrointestinal tract such as, lactose intolerance, diarrhea, colon Cancer, inflammatory bowel disease and
other bacterial infection were inhibited through high consumption of yogurt as based diary food product.
Key words: Yogurt, lactic acid-producing bacteria, diary food product
INTRODUCTION
The growing popularity of yogurt over the years, has
largely been increased due to its perceived health
benefits. Yogurt is one of the best-known foods that
contain "probiotics" which is a living microorganism,
upon ingestion in sufficient amount, exerts beneficial
effects on the normal microbial population of the
gastrointestinal tract (Bourlioux et al., 2003). Different
microbial species are considered as probiotics. The
major strains Lactobacillus acidophilus, L. casei. and
various Bifidobacterium species , B. longum, B. bifidum
are the most dominant species in human small and
large intestine, that can inhibit the growth of pathogenic
organisms, through production of organic acids and
bacteriocins (Mazza, 1998).
Among the most important food products, supplemented
with variable probiotic strains, like Lactobacilli and
Bifidobacterium strains is yogurt.
Yogurt is a coagulated milk product, that results from the
fermentation of lactic acid in milk, by (LAB) bacteria
Lactobacillus bulgaricus and Strepetococcus
thermophilus (Pelczar et al., 1986). Its traditionally
manufactured by fortifying whole or skimmed milk by
evaporation, or addition of skim milk powder, heating to
85-95 C for 10-30 min and inoculating with (LAB)
o
Bacteria and then incubating at 42-45 C. Bifidus yogurt
o
prepared, by the addition of B.bifidum and B.longum, to
the yogurt culture and incubating at 42 C for 3-4 h.
o
L.acidophilus can also incorporate with yogurt Culture to
create acidophilus yogurt (Mazza, 1998).
The biological activity of (LAB) bacteria used in the
production of cultured diary product and their
metabolites, the processing steps such as
pasteurization, microfiltration and product formulation,
modify the physiological activity of the final product
(Mazza, 1998). National Yogurt Association rules, define
the active culture yogurt as a final product that contains
live (LAB) bacteria in amount > 10 cells/g at the end
8
time of the manufacture. Diary products such as milk,
cheese and yogurt have been recognized as excellent
sources of vitamins and minerals including riboflavin,
phosophorus and calcium (Table 1) (Mazza, 1998).
Up to date, many research studies focused on the role
of probiotic Including (LAB) bacteria in the yogurt for the
enhancement of the gastrointestinal function through
increasing minerals absorption, reduction in lactose
intolerance (lactase deficiency) and through
consumption of L. acidophilus culture yogurt (Vesa et al.,
2000, Martini et al., 1991). LAB bacteria enables the
inhibition of the Pathogen infection through production of

Pak. J. Nutr., 8 (9): 1404-1410, 2009
1405
Table 1: Milk and diary products as sources of important nutrient
Component Protein Calcium Phosphorus Riboflavin
Unit % % % mg%
Whole milk 3.30 0.12 0.10 0.17
Cheddar cheese 25.4 0.72 0.50 0.45
Cottage cheese 12.6 0.08 0.14 0.24
yogurt 4.30 0.16 0.13 0.21
Ice cream 4.40 0.15 0.11 0.25
acetic acid, lactic acid and bacteriocins (Bianchi-acidophilus, L.jonsonii and L.casei groups are the most
Salvadori, 1986) as well as stabilizing the intestinalassociated to the intestinal tract (Holzapfel et al., 2001)
microflora after long term antibiotics uses (Brown et al., The functional properties and safety of (LAB) strains are
2005). mentioned in (Table 2).
Suppression of the harmful carcinogens associated
with colon cancer (Tavan et al., 2002; Wollowski et al., Nutritional value of yogurt: Nutritional value of the final
1999) and increasing the immune response bydeducts depend on the milk-based Sources
Production of secretory immunoglobulin were achieved(mammalian type, feed, age and lactation stage) and
(Perdigon, 1995, 2003). Relief of Constipation, reduction processing Factors (temperature, heat duration and
of serum cholesterol (Jones, 2002), allergy in youngstorage condition). Also the type Of probiotic strains
adults (Piaia et al., 2003) and control of diarrhea wereused in the fermentation, directly influences the
established through the consumption of yogurtnutritional and physiological value of the final yogurt
(Heyman, 2000). Among adults, life expectancy was theproduct (Mazza, 1998).
highest in the world and the rate of coronary heart
disease, cancer, and other diet related chronic disease,Vitamins: Dairy products are considered a major source
were among the lowest, in which yogurt is considered
the main source of diary products in the Mediterranean
diet, incorporated with other healthy foods (fruit,
vegetable, brown bread, cereals and olive oil) (Willett et
al., 1995).
MATERIALS AND METHODS
This study aimed at reviewing most of the information
related to the Probiotic as basic cultures incorporated in
yogurt production. Significant Information will be
mentioned about (LAB) identity, their habitats, the
mechanisms of their action in improving the immunity of
the host and enhancing the function of theLactose: Dairy products are one of the sources of
gastrointestinal tract, through the following:
CReview the information represented in the studies,
which focused on the role of yogurt on the health
and function of the gut.
CEpidemiological studies, testing the effects of
different probiotics culture including (LAB) bacteria
in preventing certain gastrointestinal disease, will
be discussed. -Data collected from recent scientific
journals will be viewed.
RESULTS AND DISCUSSION
Physiological properties of LAB bacteria: LAB bacteria in the diet. Yogurt is considered as the most
are gram positive, non-spore, catalase-negative bacteria
characterized as fastidious, acid-tolerant and
fermentative microorganisms. (LAB) bacteria are
associated with habitats rich in nutrients, such as food
products and plant materials. Particular (LAB) are
inhabitant, human oral cavity, Vagina and
gastrointestinal tract, through which Lactobacillus,
of vitamins, including vitamin B-6, Vitamin B-12,
riboflavin, niacin and folic acid. Folate is one of the B
vitamins that some (LAB) species can synthesize
(Kneifel et al., 1992). Various bacterial species were
also used for milk fermentation and yogurt production
was examined for its ability to synthesize or utilize folate.
S. thermophilus and Bifidobacteria were folate producer,
while Lactobacilli depleted folate from the milk media.
Fermentation using combination of Bifidobacterium
animals and S. thermophilus result in six-fold increase
in folate concentration (Crittenden et al., 2003).
disaccharide lactose in human diets. Before absorption,
lactose is hydrolyzed by the intestinal brush border B-
galactosidase (lactase) into glucose and galactose.
(LAB)bacteria present in yogurt, Such as L. bulgaricus
and S. thermophilus, expressed functional lactase that
can hydrolyses 20-30% of the lactose, which contribute
to better tolerance of lactose in yogurt than that of milk,
by person with lactose maldigestion (Vesa et al., 2000
and Martini et al., 1991).
Minerals: Dairy products like milk, cheese and
especially yogurt provide 3-4 fold of calcium consumed
concentrated source of this essential mineral and others
like potassium, magnesium, phosphorus and zinc
(Kerry et al., 2001). Calcium plays a role in bone
formation and mineralization, as its needed during
growth, pregnancy and lactation, Average
Recommendation Dietary Allowance (RDA), for calcium
intake is about 900 mg/day for adult, rising to 1200

Pak. J. Nutr., 8 (9): 1404-1410, 2009
1406
Table 2: Successful LAB strains and their functional properties
Lactobacillus rhamnosus Lactobacillus johnsonii Lactobacillus acidophilus
Property Lactobacillus casei Shirota GG (ATCC 53103) LA1 NFCB 1748
Origin Human Human Human -
Safety Verified Verified Verified Verified
Acid stability Good Good Good Good
Bile stability Resistant Resistant Resistant Resistant
Colonization -+ + -
Bacteriocin production No -Yes No
A dherence (Caco-2) No Yes Yes No
Adherenc (mucosa) -Yes Yes Yes
mg/day for adolescent and elderly people (Gueguen and Ershidat and Ayman Suliman Mazahreh, 2009). The
Pointillart, 2000). Calcium in yogurt is better absorbed additional health benefits of yogurt releases of bioactive
than in milk, because this fermented product is wellpeptides such as casein, lactoferrin, serum albumin, -
tolerated by Lactase-deficient people (Smith et al., actoglobulin, enhance the growth of gut microflora (Piaia
1985). Low calcium intake is responsible for low boneet al., 2003). Micelles of casein fraction and whey protein
density and extensive lactose maldigestion that canfraction, are of great source of all essential amino acid
elevate the risk of osteoporosis. A dietary managementthat are needed for tissue growth and maintenance (Bos
strategy for lactose maldigesters is to increase theet al., 2000). Proteolysis occurring during fermentation
calcium consumption from dairy foods, including yogurtmay lead to formation of novel peptides during
(Kerry et al., 2001). Lactose enhances the absorption ofgastrointestinal digestion. Milk fermentation by
calcium, magnesium and zinc (Gueguen and Pointillart,lactobacillus helveticus, releases some amino acid in
2000). the gastrointestinal tract and modifies the protein elution
PH: The acidic PH of yogurt ionizes calcium and thus1997).
facilitates the absorption of calcium in the intestine
(Bronner and Pansu, 1999). Low PH of yogurt reducesLipids: The consumption of dairy fat leads to the
the inhibitory effect of phytic acid on calciumincrease of the concentration of Conjugated Linoleic
bioavailability, Vitamin-D plays a major regulatory role in Acid (CLA), a long-chain bio-hydrogenated derivative of
intestinal and proximal jejunum requires calbindin-D,linoleic acid, in both human milk and adipose tissue
vitamin D-dependent calcium-binding Protein (Norman,(Jiany et al., 1999). Yogurt contains higher concentration
1990). Diary products such as milk and infant formulaof (CLA), than does the milk from which the yogurt was
are fortified with vitamin D, with 2.5 mg (100 IU) Vitaminprocessed. CLA was reported to have anticarcinogenic
D/237-ml, unlike yogurt that is not fortified with vitamin D. properties against breast and colon cancer cells, by
Many studies focused on the effect of yogurt-derivedinhibiting the expression of cyclins and halting the
calcium on bone mineralization. The bioavailability ofprogression of the cell cycle from G1 to S phase. In
calcium in yogurt is greater than other diary products,addition (CLA) induced the expression of the tumor
and yogurt may increase bone mineralization more thansuppressor p 53 (Kemp et al., 2003). Production of
nonfermented milk products do (Gueguen andshort-chain fatty acids (acetate. Butyrate and propionate,
Pointillart, 2000). as a result of indigestible carbohydrates by colonic
Protein: Dietary protein quality is influenced by severalreduce the circulatory serum cholesterol Concentration,
factors, like amino acid composition, nutritional value,by inhibiting hepatic cholesterol synthesis, or by
and physiological properties. Protein content in yogurt is redistributing cholesterol in plasma to liver (Jones,
higher than that of milk, due to the addition of nonfat dry 2002). Consuming of yogurt active (LAB) bacteria,
milk during processing. Even this protein is easilystabilizes the level of total (LDL) Cholesterol in the blood
digested in the yogurt than that from the milk, due to the (Water et al., 1999).
activity of (LAB) bacteria proteolysis enzymes such as
peptidases which increase the final concentration of free Benefits of (LAB) bacteria in yogurt on the
amino acid proline and glycine in the final product (Bosgastrointestinal function and health: Yogurt and (LAB)
et al., 2000). Some bacterial cultures have been shownbacteria contribute to several factors that enhance the
to have more proteolytic activity than other. L. bulgaricus gut function and health: the make of gastrointestinal
has a much higher proteolytic activity during milkflora, the immune response against pathogens. Gut
fermentation than S. thermophilus, as indicated bymicroflora plays a major role against exogenous
increasing the concentration of peptides and free aminoinfectious bacteria through colonization resistance. Most
acid in the fermented yogurt (Omer Turki Mamdohof the bacteria that cross the barriers of stomach and
profiles obtained after digestion with trypsin (Matar et al.,
bacteria, in presence of fermented dairy milk, may

Pak. J. Nutr., 8 (9): 1404-1410, 2009
1407
small intestine will be live, metabolically active andsmall intestine. Specialized transport cells (M cells) and
colonized with in the gut ecosystem (Bourlioux et al., dendrite cells (macrophages) which were found in the
2003) Some of these bacteria are useful to the hostepithelial layer of the patches, can phogocytose soluble
health, such as Bifidobacterium and Lactobacillus,antigens and pathogens bind to such layer (Bourlioux et
which are the most dominant genera in the intestinalal., 2003). The gut microflora (Bifidobacteria and
tract, others are harmful and cause disease to the host.Lactobacilli) plays an important role into protecting the
Selection of strain of Bifidobacteria (B. infantis,mucosal surface from pathogens, avoiding their
B.bifidum, B. adolescentis, and B.longum) as a probiotic, attachment and entry into the intestinal mucosa
to be included in fermented milks, has been based on(Perdigon et al., 2003). Also the interaction of (LAB) with
the survival in the final product and through the intestinal the mucosal epithelial lining of the gastrointestinal tract,
tract (Holzapfel et al., 2001). B. animalis B. adolescentis as well as with the lymphoid cells residing in the gut,
were reported to have a high survival rate duringhave been suggested as the most important
intestinal transit, able to contact the epithelial cells ofmechanism by which (LAB) enhance the gut immune
small and large intestine and induce lisosomalresponse against ingested pathogens (Bourlioux et al.,
activation of the epithelial enterocytes (Perdigon et al., 2003). Sixteen strains of Lactobacillus isolated from
2003). The ability of (LAB) bacteria to bin to the intestinal humans, mice and food product were screened for their
brush border tissue, leads to preventing pathogen fromcapacity to associate with Peyers patches in mice.
accessing the gastrointestinal mucosa, (Bernet et al., Lactobacillus fermentum exhibits a perferntial binding to
1994). Such binding, is influenced by certain adhesionthe follicle-associated epithelium of the Peyers patches
sites with in the intestinal lumen for the bacteria to be(Plant and Conway, 2001). As well for Bifidobacterium
contact. These sites are genetically controlled by theanimalis which demonstrated by fluorescent labeling
host (Bourlioux et al., 2003) LAB bacteria can adapt thetechniques, able to interact with the immune cells of
host intestine and survive against gastric PH, digestivePeyers patches of small intestine and with the large
enzyme and bile Salt (Alm and Pettersson, 1980). LABintestine (Perdigon et al., 2003) The affecter component
species differ in their ability to survive in theof the mucosal immune system is the secretory
gastrointestinal tract. In the group of elderly patients with immunoglobulin A (slgA). It inhibits the colonization of
atrophic-gastritis and hypochlorhydria, Lactobacilluspathogenic bacteria in the gut, as well as the mucosal
gasseri survived passage through the gastrointestinalpenetration of pathogenic antigen. Many studies focused
tract, but S. thermophilus and L. bulgaricus were noton the role of (LAB) bacteria for modulating IgA
recovered (Pedrosa et al., 1995). L.casei present in theconcentration in the gut. Orally administered
fermented diary product, able to survive in the intestineL.acidophilus and L.casei and the feeding of yogurt
of human flora-associated mouse model and initiateincreased both (IgA) production and the number of
new protein synthesis during its transit with the diet, that lamina propria B cells that secrete (IgA) in the small
influence human health related to that protein (Oozier et intestine of mice. Yogurt is able to inhibit the growth of
al., 2002). Association of L.casei with yogurt startersthe intestinal carcinoma by increasing the activity of (IgA,
(LAB) bacteria in the fermented milk, increase the activity T cells and macrophages) (Perdigon et al., 1995).
of glycolytic enzyme, B-galactosidase, improved forModulation of cytokine production by yogurt and (LAB)
lactose digestion and a B-glucosidase, needed for thehas been investigated. In addition to interleukin (IL)-1B
fermentation of resistant starch, which lead to butyrateand Tumor Necrosis Factor (TNF) a, which are produced
production, that improved bowel habits and increaseby macrophages. T lymphocytes (Th1) and (Th2) helper
stool output (Djouzi et al., 1997) The ability of (LAB)cells, upon activation were able to produce 2 patterns of
bacteria to avoid the gastrointestinal invasion ofcytokines (Mossmann et al., 1986) .Th1 cells produce
pathogenic microorganisms has been reported.interferon- (IFN-) and IL-2. IFN-y improves induction of
L.acidophilus-mediated inhibition of the adherence andother cytokines and in mediation of macrophage and
the entry of enteropathogenic Escherichia coli andnatural killer cell activation. TH2 cells augment humoral
Salmonella typhimurium to the enterocyte cell-line Caco- immunity through production of IL-4, IL-5,IL-6 and IL-10
2 cells (Bernet et al., 1994). Also the similar inhibitorycytokines. The production of IFN- y in vitro culture using
effects for tow strain of Bifidobacteria (B. breve and B.human lymphocytes was reported to be greater in the
infantis), were observed (Bernet et al., 1993) Thepresence of LAB (L. bulgaricus and L. thermophilus),
important defensive line of the instestine is based onthan in culture with out LAB.
three essential constituent; gut microflora, mucosalThe most important targets for the functional food are the
lymphoid barrier and the innate immune system gut-gastrointestinal function, including those that control
associated mucosal lymphoid tissue (GALT). GALT istransit time, bowel transit and mucosal motility, as well
divided into inductive and effector sites. The inductiveas those that modulate epithelial cell proliferation,
sites are in the Peyers patches (aggregate glands),balancing colonic microflora and influencing
which consist of large lymphoid follicles in the terminalgastrointestinal immune system. Combination of

Pak. J. Nutr., 8 (9): 1404-1410, 2009
1408
probiotics and prebiotics within diary products, improves carcinogenesis. Different dairy sources that are able to
growth and the survival of gut microflora, Bifidobacteria,
and Lactobacilli, is considered a therapy that enhances
their effect in the large bowel (Roberfroid, 2000).
Combination of two probiotic strains L. gasseri and L.
coryniformis in the diary fermented product, instead of L.
bulgaricus yogurt strain, were able to survive in the
intestine and recorded in high level in the feces of
volunteers. Orally intake of probiotic strains, increases
the concentration of fecal lactic acid bacteria, thus
improving the fecal moisture, frequency and the volume
of the stool (Olivares et al., 2006).
Yogurt and disease of the gastrointestinal tract
Lactose malabsorption: Lactose malabsorption
involves a reduction of lactose activity in the intestinal
brush border of mammals as they age after weaning.
The ingestion of dairy Products containing lactose leads
to symptoms of lactose intolerance, such as bloating
flatus, abdominal pain, abnormal gas and diarrhea
(Shermak et al., 1995). Lactose in yogurt is better
digested than lactose in other dairy food by lactose
intolerance individuals, due to the intra-intestinal activity
of the yogurt (LAB) -galactosidase (Martini et al., 1991).
Most of (LAB) bacteria which are used in milk
fermentation, including L. bulgaricus and S.
thermophilus, can exert their lactase activity in vivo in the
gut lumen of both adults and children, thus facilitating
digestion and alleviating intolerance (Shermak et al.,
1995). L. acidophilus able to modify the lactose
fermentation, by human colonic microflora in vitro in
lactose maldigesters. Furthermore (LAB) can resume
the activity of colonic microflora that has been disrupted
after diarrhea, or antibiotic administration (Jiang and
Savaiano, 1997).
Diarrhea disease: Microbial balance is an important
factor in the maintenance of intestinal homeostasis, live
microbial supplementation (yogurt or fermented milk).
Have been proposed as healthy foods to control
diarrhea as a result of lactose malabsorption, acute viral
and bacterial diarrhea, as well as for antibiotic-
associated diarrhea (Heyman, 2000).
Colon cancer: According to the National Cancer Institute
(2002), cancer of the colon or rectum (colorectal) cancer,
is the fourth most common cancer in men and women
in United States (NCI, 2002). Fermented dairy products,
that contain probiotics and include (LAB) in yogurt, have
shown an inhibitory effect on colon cancer. Heterocyclic
Aromatic Amines (HAA) that are produced during the
cooking of food with high creatine, free amino acid and
sugar content, are known as an initiating agent of colon
cancer in animals and human (Tavan et al., 2002).
Tavan et al. (2002) studied the protective effect of
probiotics in the fermented milk, on male F344 rats,
which were used as a model of HAA-induced colon
decrease the incidence of colonic crypts in rats are as
follows: 66% inhibition with milk-Supplement diet, 96%
inhibition with Bifidobacterium animalis. Fermented
milk-supplement diet and 93% inhibition with
Streptococcus thermophilus fermented milk-
supplement diet. Decrease in HAA metabolism, fecal
mutagenicity and colon DNA lesions were observed.
This effect being pronounced in case of milk-fermented
by (LAB), against 1,2-dimethylhydrazine (DMH)-induced
colon carcinogenesis. Oral treatment with Lactobacillus
bulgaricus against DMH-induced DNA damage in the
colon in vivo, whereas S. thermophilus were not
effective. However, in viirto, both strains prevented DNA
damage of N-methyl-N-nitro-N-nitro-soguanidine
(MNNG) carcinogen, in isolated primary rat colon cells
(Wollowski et al., 1999).
Inflammatory bowel disease: Inflammatory Bowel
Diseases (IBD) refers to a certain chronic immune-
mediated condition that is characterized by acute
intestinal inflammation. These chronic diseases include
(ulcerative colitis, Crohn disease and pouchitis), which
result from abnormal host response to some member
of the intestinal flora, or from a detective mucosal barrier
(Podolsky, 2002). Normally, a healthy mucosal barrier
provides a first defense line against pathogens.
Proportions of different intestinal microflora are altered
in patients with (IBD). Colonic biopsy specimens have
shown lower concentration of Lactobacillus and lower
fecal concentration of both Lactobacillus and
Bifidobacterium species in patient samples. Such
reduction in the intestinal microflora, as well as for TNF-
a pro-inflammatory cytokine, will increase the opportunity
for colonization of pathogens (Borruel et al., 2002).
Abnormal activation of mucosal T-lymphocytes against
enteric bacteria is the key event triggering intestinal
inflammation. Lactobacillus casei is able to reduce the
number of activated T-lymphocytes in the lamina propria
of Crohn disease, which may restore the immune
homeostasis (Carol et al., 2006).
Conclusion and recommendations: Its believed that
consumption of yogurt including active (LAB) and other
fermented dairy products provided with probiotics,
enhance the function of the gastrointestinal tract. Many
studies of the possible health benefits of yogurt in
protecting against gut-associated disease substantiate
some of these beliefs. One of the most interesting
preventive effects is the protection against IBD and colon
cancer as suggested by epidemiologic evidence and
animal studies and the therapeutic action of diarrhea
caused by infectious pathogens, in addition to the
beneficial effect of yogurt containing live and active
culture on the digestion of lactose in patients who suffer
from lactose intolerance. These findings are interesting
and should encourage future studies to investigate the

Pak. J. Nutr., 8 (9): 1404-1410, 2009
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mechanisms of action through which yogurt exerts itsHolzapfel, W., P. Haberer, R. Geisen, J. Bjorkroth and V.
effects and the critical components in yogurt that control
such action.
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