DEPARTMENT OF ANIMAL SCIENCE
FACULTY OF AGRICULTURE AND NATURAL RESOURCES
MANAGEMENT
CASE STUDY
EFFECTS OF
DIETARY GARLIC (ALLIUM SATIVUM) ON PERFORMANCE OF IMMUNE
RESPONSE OF BROILER CHICKEN
INTRODUCTION
Antibiotic –
based growth promoters have been commonly used as supplements in animal feeds
for many years because they are well known to help growing animals to digest
their food more efficiently and to grow strong and healthy individuals (Sojoudi
et al., 2012). Some of the common
antibiotics used in animal feeds are virginiamycin, salinomycin, neomycin,
doxyclin and avilamycin (kumar et al.,
2010). The use of antibiotic – based growth promoters has faced serious
criticism and global concern due to their purported hazardous effects including
microbial resistance and their potentially harmful effects on human health (Rahmatnejad
et al., 2009). These shortcomings
lead to the search for alternative substances that eliminate these threats
(Manesh, 2012). Nowadays there is increasing interest in the use of natural
growth promoters such as probiotics, prebiotics or their combination and
medicinal plants as feed additives in poultry diets to enhance the performance
of poultry birds (Khan et al., 2012,
2011a).
Garlic (Allium Sativum) has been known in
folk medicine for thousands of years in the history of Greeks and Egyptians
(Horton et al., 1991). Garlic is best
known as a spice and herbal medicine for the treatment and prevention of an
array of diseases (Adibmoradi et al.,
2006).
Garlic contains
at least 33 sulphur containing compounds, several enzymes and 17 amino acids
and minerals including selenium (Newall et
al.,1996). The major active ingredients in garlic active ingredients in
garlic are allicin, ajoene, diakyl polysulphides, s– allylcysteine, diallylsulphide,
s – methyl – cysteine sulphoxide and s– allylcysteine sulphoxide, which may be
responsible for the therapeutic properties of garlic observed (Chi et al., 1982; Canogullari et al., 2010). In the last decade, garlic
has been widely reported to be incorporated into poultry diets to determine any
effects on poultry performance. In this review, the literature regarding the
use of this natural product is discussed.
EFFECTS
OF GARLIC ON BROILER PRODUCTION
Numerous reports
have been published, advocating the beneficial effects of garlic on feed
efficiency and growth of broiler chickens. According to (Mansoub, 2011), feed
conversion ratio (FCR) and body weight (BW) of broilers were improved when they
were fed garlic (Ig/kg) in the basal diet. (Aji et al., 2011) reported that administration of 100mg of garlic resulted
in improved body weight gain at 7, 14 and 21days of treatment in broilers
chicks, although feed intake, FCR and carcass yield did not change. (Kumar et al., 2010) found that a garlic
supplemented diet (250 ppm) significantly increased the body weight grain of
broilers chickens in a 42 days trial. In the same year, (Pourali et al., 2010), reported that garlic
powder improved average daily feed intake, body weight, FCR, performance index
as well as survivability. (Mahmood et al.,
2009), Concluded that a basal feed containing 0.5% garlic improved FCR and body
weight gain in broilers but failed to produce positive effects on carcass yield
in term of dressing percentage, relative weight of heart, gizzard, liver,
spleen and pancrease.(Javed et
al.,2009),found that feed intake and FCR, body weight and carcass quality (dressing
percentage, breast weight and leg weight) were improved in a 35days experimental
trial, when broilers were supplemented (at the rate of 10ml/litre of drinking
water) with an aqueous extract of medicinal plants containing garlic. (Ramakrishna
et al., (2003), suggested that garlic
supplementation enhances the activity of pancreatic enzymes and provides an
environment for better absorption of nutrients. (Javandel et al., 2008), observed that feeding garlic at the level of 0.125
and 0.25% resulted in higher feed intake during the starter phase of broilers
although the same levels were not efficacious during the growing phase.
Additionally, in this experiment, the authors did not find any difference in
body weight and carcass characteristics in term of percentage of carcass, small
intestines, proventriculus, gizzard, liver and abdominal fat. (Ashayerizadeh et al., 2009), Demonstrated that garlic
powder added into broilers feed had a significant effect on carcass yield, but
feed intake and efficiency body weight, thigh and breast weight did not change,
although abdominal fat percentage decreased in garlic supplemented birds. Similarly,
(Mohebbifar and Torki., (2011), reported that feeding garlic at of 0 or 2g/kg
did not affect feed intake, FCR and weight gain in Ross broilers (Rahmatnejad et al., 2009), concluded that garlic
given at the rate of 1000g/ ton of feed did not affect feed intake, FCR and
body weight gain. (Horton et al.,
1991); (Konjufea et al., 1997), could
not trace any effect of garlic supplementation on the performance of broiler
chicks .such a wide range of results may be attributed to the dose, duration
and processing of the medicinal plants as well as the experimental conditions.
(Khan et al., 2008), suggested that
difference in the results determined by different authors may be due to the use
of different commercial garlic products may be divided into raw garlic (Allicin
rich) and processed garlic (non-Allicin rich) which differ in the active
substance they contain.
EFFECT
ON LAYING HEN PERFORMANCE
Egg
production and Quality are heritable traits of major concern for breeders,
industry and consumers. To improve these characteristics, correct nutritional,
management and environmental practices are needed to enhance egg production and
quality. Eggs are a delicate product which can be lose quality rapidly during
the period of collection to consumption. Thus improvement in egg quality is of
paramount importance in the field of production and management (Mahmound et al., 2010). There is a dearth
literature available concerning the beneficial effects of garlic on egg quality.
For example (Yalcin et al., 2006),
found that egg weight increased when laying hen were fed 5 and 10g/kg garlic
powder. (Khan et al., 2007), reported
that egg production increased during the six weeks in which 0, 2, 6, or 8%
garlic powder was fed to laying hens.(lim et
al., (2006) concluded that with increasing dietary garlic powder, the Haugh
unit increased linearly after two weeks. (Chowdhury et al.,2002) also reported that yolk weight responded in a
quadratic manner to increasing level, of sun – dried dietary garlic paste,
(canogullari et al., 2010)
demonstrated that egg production increased significantly by adding 1% garlic
powder in the feed of the laying hens although egg weight yolk index, shell
weight, shell thickness, yolk weight did not change. In the same experiment,
egg shield index and haugh unit decreased significantly in the birds
supplemented with 4% garlic powder. (Yalcin et
al., 2006), reported that supplementation of garlic powder had no
significantly effect on egg albumen index, egg shell index, egg haugh unit
value, when laying hens were fed 5 and 10g/kg garlic powder for 22 weeks.
According to (Mahmond et al., 2010),
egg albumin, yolk and shell weight as well as albumin height and haugh unit were
improved when laying hens were supplemented with 0.25, 0.50 and 1% garlic juice.
(Mottaghitalab and
Taraz. 2002), showed that the inclusion of 0, 5, 10 and 15g/kg garlic powder
significantly decreased yolk weight. (Reddy et
al., 1991); Chowdhury et al.,
2002). Concluded that supple mentation of garlic did not affect egg production.
(Khan et al., 2008) ,concluded that
feeding 8% dried garlic powder may result in better egg production in Densi
laying hens, with no effect in egg mass and egg weight. The difference in the results
of different reports may be due to the different experimental protocols and
garlic preparation in their experiments (Canogullari et al., 2010).
IMMUNO – MODULATING EFFECTS
The immune
system of poultry can be broadly divided into two categories namely, the
lymphoid and non-lymphoid systems, bursa of fabricius and thymus are considered
to be the primary lymphoid Organs, where as spleen is usually termed as
secondary lymphoid organ. The non-lymphoid parts of the immune system include
cells that provide a non – specific immunological defence of the host. Blood
monocytes and tissue macrophages are unique due to their ubiquitous distribution
throughout the body fluids, organs and cavities (Khan et al., 2011b). Recently, (Zialarimi et al., 2011), found that aqueous extract of garlic was more
effective in inhibiting E.coli culture than mint (Menthe spp.) and onion (Allium
Cepa) in broiler Chicks, Suggesting the role of garlic in Suppressing
pathogenic bacteria.
Several reports
are available advocating the strong Immune potentiating effects of garlic. (Szigeti
et al., 1998), reported that supplementing chickens with a modified product
including garlic increased antibody production against Salmonella enteritidis,
Pasteur rella multocida and leptospira Pomona bacteria. (Ahsan-ul-Haq et al.,
1999), reported that feeding broilers at the rate of 20g/kg increased significantly
antibody titre against Newcastle disease virus (NDV) and infectious bursal
disease (IBD) in broiler Chicks. (Szigeti et al., 1998), found that a product
containing garlic, acidifers and bacterial cell extracts enhances antibody
production against NDV, where as, (Jafari et al., 2008), reported that
supplementing boilers with garlic (1 or 3%) does not have any beneficial
effects on antibody production. (Hanieh et al.,2010), found that feeding garlic
at the level of 10g/kg diet enhanced titre against NDV and sheep red blood cell, (RBC,) in white leghorn chickens,
although such effect , were not recorded when the dose was at high as 30g/kg. In the same line ,(Dorhoi et al., 2006)
observed that macro phage engulfing RBCs
percentage was higher when the laying hen were supplemented with 50ug/ml of garlic
and the engulfment was low when the dose was increased to 200ug/ml. Recently,
(Nidaullah et al., 2010) found that a plant mixture containing garlic at the
level of 4g produced better antibody response against NDV and IBD in boilers
chicks.(Rahimi et al.,2011) found that o.1% garlic in the diet of broilers
improved antibody response against sheep RBC, and NDV, increased bursa of
fabricious weight and spleen weight and Augmented hypersensitivity coetaneous
baso philic response. (Dorhoi et al.,2006), reported that garlic supplemented
birds had heavier spleen and thymus weight and white blood cells, (WBC) count .
The increase in the weight of the spleen and thymus are attributed to the
enhanced lymphocyte proliferation and the increase in the WBC productions. (pourali
et al., 2010) showed that different concentration of garlic powder improved
antibody titre against NDV virus at 14th day of age. (Hanieh et al., 2010), suggested that the immuno
– modulating effect of garlic is associated with it ability to enhanced phagocytosis
of peritoneal macrophages, increased production of interleukins, interferon (INF
– Y) and tumour necrosis factors (TNF – a) secretary metabolism of macrophages,
antigen presenting cells and antioxidant function of this plant. (Mohebbifar and
Torki., 2011), demonstrated that adding 0 or 2g/kg garlic in the basal feed of
Ross broilers did not affect the heterophil, lymphocyte, monocytes, eosinophil,
basophil and heterophil to eosinophil ratio nor the serum antibody against NDV
was positively changed. The discrepancies observed in the results are likely
related to the preparation methods of garlic. In addition, the experimental
design and dose of garlic used have a great deal in the differences of the
results of immune functions (Hanieh et al.,
2010).
ANTI
– CHOLESTEREMIC EFFECT
In the
scientific literature, the hypolipidic and hypocholesterolimic effects of
garlic are well documented. (Ahsan – ul – Haq et al.,
1999), reported that feeding garlic at the rate of 20g/kg decreased blood
cholesterol significantly in broiler chicks. Egg yolk cholesterol of laying
hens decreased significantly in birds supplemented with I and 2% garlic powder
(Canogullari et al., 2010).
(Chowdhury et al., 2002), concluded that
cholesterol concentration per gram of yolk decreased linearly with increasing
levels of sun – dried dietary garlic paste. (Khan et al., 2007), showed that feeding dietary garlic at 2, 6 or 8%
reduced egg yolk cholesterol, on average over six weeks, by 5.7, 14.3 and 23.6%
respectively. (Khan et al., 2008),
found that garlic powder given at the level of 8% may result in better serum
and egg yolk cholesterol profile in laying hens. However (Mahmoud et al., 2010), observed that egg
cholesterol did not change when laying
hens were supplemented with garlic extracts in different concentration (0,
0.25, 0.5, and 1%). If egg cholesterol can be reduced to minimum level, it
would assist in the consumer perception regarding the healthiness of table eggs
(Mahmond et al., 2010). Recently, in
the study of (Canogullari et al.,
2010), garlic powder at the rate of 1, 2 and 4% were found to reduced total
lipid concentration and total triglyceride level was reduced by garlic powder
supplementation at the levels of 1 and 2% garlic in laying hens (Azeke and Ekpo.,
2008). Similarly, (Yalcin et al.,
2006), reported a significant decrease in plasma triglycerides with the
supplementation of garlic powder (Youn et
al., 1996) concluded that serum triglyceride was lowered by supplementing
garlic powder to the diet.
(Horton et al., 1991), found that broilers fed
garlic at 10,000 mg/kg reduced plasma cholesterol in 35days treatment.
Publications by (Qureshi et al.,
1983b), documented that the serum cholesterol concentration in white leghorn
pullets was reduced from 20 to 25% using supplements of garlic paste, solvent
extracted from garlic paste and commercial garlic oil (Canogullari et al., 2010), found that 1, 2 and 4%
garlic powder increased high density lipoprotein (HDL) cholesterol in laying
quails. However, (Lim et al., 2006),
did not found any difference in HDL – Cholesterol concentration by feeding garlic
(1, 3 and 5%). (Qureshi et al.,
1983b), reported a 28 – 41% reduction in low density lipoprotein (LDL)
cholesterol in an experimental diet containing 3.8% garlic paste or a solvent extract
of garlic paste, the residue or commercial garlic oil fed for four weeks. Recently,
(Mansoub, 2011) reported reduction in total cholesterol, LDL – cholesterol and
triglycerides when broilers were
supplemented with 1g/kg garlic. (Prasad et al.,2009),observed that total
cholesterol triglycerides, LDL and very low density lipoprotein (VLDL) were
significantly decreases, while HDL was significantly increased by garlic
supplementation in chicken up to eight 8 weeks of age in comparison to control
group. (Rahimi et al., 2011) noted
that supplementation of 0.1% garlic decreased cholesterol, triglyceride and LDL
cholesterol but increased HDL level. Recently, (Rehman et al., 2011), documented that a mixture of plants containing
garlic as an active ingredient improved the cholesterol profile in terms of
cholesterol, triglyceride, LDL cholesterol, VLDL cholesterol, total cholesterol
to HDL ratio, LDL to HDL ratio, VLDL to HDL ratio in broiler chicken serum.
(Konjufea et al., 1997), conducted an
experiment on male Ross 208 which were fed a basal diet supplemented with 1.5,
3.0 or 4.5% commercial garlic powder from hatching to 21 days of age, and found
that garlic powder resulted in reduced level of plasma cholesterol, liver cholesterol,
breast and thigh muscle cholesterol.
The mechanism by
which garlic reduces plasma cholesterol concentration is not fully understood.
Some of the investigators are of the opinion that garlic depresses lipogenic
and cholesterogenic activities of liver enzymes such as malic enzyme, fatly
acid synthase, glucose – 6- phosphate dehydrogenases and 3 – hydroxyl – 3 –
methyl – glutaryl – COA (HMG – COA) reductase (Qureshi et al., 1983a; 1983b; Youn et
al., 1996; Chowdhury et al.,
2002; Canogullari et al., 2010; (Mahmoud
et al., 2010). This hypothesis was
demonstrated when several researchers measured cholesterol – clearing enzymes.
For example. (Qureshi et al., 1983a),
reported a dose dependent inhibition of hepatic HMG – COA reducase and cholesterol
7a – hydroxylase and falty acid synthetase in chicken fed polar fractions of
garlic powder equivalent to 1, 2, 4, 6, and 8% of fresh garlic paste. (Knojufca
et al., 1997), reported that feeding
3% commercial garlic powder reduced the activities of HMG – COA reductase and
cholesterol 7a – hydrotylase by 40%. Allicin has been proposed as the active
compound in garlic responsible for health promotion and hypocholesterolaemic
benefits (Lawson, 1998). In terms of the mechanism of action, it is believed to
reduce cholesterol synthesis, and platelet aggregation and prevent thrombosis (Canogullari
et al., 2010). Allicin is a volatile
organic compound which has been shown to reduce serum lipids, phospholipids and
total cholesterol and suppress cholesterol synthesis in chickens (Horton et al., 1991). According to (Mahmoud et al., 2010), the difference in the
results may be due to allicin degradation as it is an unstable compound and
poorly absorbed from the gut, Additionally, they suggested that the garlic
preparation that involved heating or solvent processes may destroy active
allicin.
ANTI
– MICROBIAL ACTIVITY OF GARLIC
Several studies
have pointed out the possibility to use essential oils and/or their components
for medical purposes as well as in the food industry for controlling micro –
organisms responsible for food spoilage (Cantore et al., 2009). Today we know that the essential oils and plant
extracts have broad activity against the Gram – positive and Gram – negative
Bacteria and also antifungal activity (Kotzekidou et al., 2008). Garlic oil has antimicrobial activity (Feldberg et al., 1988) and a high dose of garlic
could have detrimental effects on ruminal fermentation. For instance, (Busquet et al., 2005b) reported that the molar
proportion of acetate was reduced by 11% and NDF digestibility was decreased by
22% when 312mg of garlic L-1 was added to in vitro batch culture
rumen fermentation at a constant PH (busquet et al., 2005a). several studies have suggested that essential oils
may be conserves of degradation of AMINO acid
(AA) in rumen by inhibiting microbial deamination (Newbold et al., 2004).
Antibacterial
properties of garlic and onion were described by Louis Pasteur. The sulphur –
containing compounds from these plants act against both gram positive and gram
negative bacterial (Carson, 1987). The extracts of garlic and onion are known
to inhibit growth of many pathogenic fungi belonging to Aspergillus, Candida
and other species (Carson, 1987).
HYPOLIPIDEMIC/HYPOCHOLESTEROLEMIC EFFECT
A recent review
(Srinivasan et al., 2004) shows the
following results. The spices Fungreek, red pepper, turmeric, garlic, onion and
ginger were found to be effective as hypocholesterolemic agents under various
conditions of experimentally induced hyper cholesterolemia/hyperlipemia.
Furthermore, fenugreek, onion and garlic are effective in human with
hyperlipemic condition. Curcumin and capsaicin, the active principles of
turmeric and red pepper, respectively, are also efficacious at doses comparable
to calculated human daily intake. Turmeric and curcumin showed excellent hypo cholesteremic
effect in experimental animals. However, endogenous cholesterol synthesis was
not affected. Extracts of garlic and onion inhibit platelet aggregation and
lower cholesterol levels. The raw form is more effective than the cooked form.
About 50g of onion and garlic corresponding to 5 – 6 cloves per day may be
adequate to bring these beneficial effects.
Other work also
documents hypo cholesterolemic effects of spices. Fenugreek seeds were hypo
cholesterolemic in rats with hyperlipidemia induced by either high fat (Singhal
et al., 1982) or a high cholesterol
diet (Sharma, 1984, 1986). Defatted fenugreek seed was effective in diabetic hyper
cholesterolemia in dogs (valette et al.,
1984) and in humans (Sherma, 1986). The hypolipidemic effectiveness of
tumeric/curcumin (Srimal, 1997), red pepper/capsaicin (Suzuki and Iwai, 1984;
Govindarajan and Satyanarayana, 1991; Surh and Lee, 1995; Majid et al., 1997) and of onion and garlic
(Fenwick and Hanley, 1985; Carson, 1987; Jain and Apitz castro, 1994) has been
periodically reviewed in recent years by different authors .
(Kleijnen et al., 1989) reviewed the Clinical research
concerning garlic and its preparations. Their main concern is that large
amounts of garlic (up to 20 cloves) are needed to prove clinical effectiveness.
This is indeed true because large quantities are reguired to provide relatively
very small amounts of active oils or other derivatives. But with the
introduction of dehydrated garlic powder containing a standardized level of the
parent sulphur compound, alliin, effective clinical work could be undertaken with
a relatively low and acceptable daily dosage of 300 – 900mg (= 1 clove of
garlic) this level produces a consistent 10% - 13% reduction in blood
cholesterol and triglycerides.
In a resent study,
dietary supplementation with aged garlic extract showed better beneficial effects,
relative to flesh garlic, on the lipid profile and blood pressure of moderately
hyper cholesterolemic subjects (Steiner et
al., 1996). In another study (Adler and Holub, 1997), garlic
supplementation significantly decreased both total and LDL cholesterol in hyper
cholesterolemic subjects. Co-administration of garlic with fish oil had a
better beneficial effect on serum lipid and lipoprotein concentrations by
providing a combined lowering of total cholesterol, LDL cholesterol, and Triglyceride
concentration as well as the rations of total cholesterol to HDL cholesterol.
According to (Lin, 1994), the antiplatelet aggregation, the antiplatelet adhesion
and the anti proliferation properties of aged garlic extracts appear to
contribute more to cardiovascular protection than do the hypolipodemic
properties. Apart from the hypo cholesterolemic effect on overall lipid
metabolism under different conditions of lipemia has also been reported
(Srinivasan and satyanarayana, 1987, 1988; Sambaiah and Satyanarayara, 1982).
ANTIDIABETIC POTENTIAL OF GARLIC
Garlic and onion
and other spices that have been widely
used for their anti-diabetic potential. both spices were shown to be
hypoglycemic in different Diabetic animal models and in limited human trails.
The hypoglycemic potency of garlic and onion has been attributed to the sulphur
compounds, namely di (2 – propenyl) disulphide and 2 – propenylpropyl disulphide,
respectively (Kumudkumari et al.,
1995; Augusti and Sheela, 1996). Animal studies indicate that the isolated
compounds possess as much as 60% - 90% of the hypoglycemic action probably
involves direct or indirect Stimulation of secretion of insulin by the pancreas.
In addition, it is also suggested that these disulphide compounds have an
insulin – sparing effect by protecting – SH inactivation by reacting with
endogenous thiol – containing molecules such as cysteine, glutathione, and
serum albumins (Srinivasan, K. 2004).
ANTI-HYPERTENSIVE ACTIVITY OF GARLIC
Garlic (Allium Sativum) is reported to
have many biological activities, including protective role in cardiovascular
function (Mukherjee et al., 2009) as
an antihypertensive (Ried et al.,
2008). Allicin, a major constituent of garlic, was evaluated for its
antihypertensive effects. Chronic oral administration of allicin lowered blood
pressure in hypertensive rats (Ali et ai.,
2000). Allicin also caused pulmonary vasodilatation in lung at rat (Kin – park
and KU, 2000).
ANTIOXIDANT
ACTIVITY OF GARLIC
It have been
reported that garlic and garlic extracts, through their antioxidant activities
prevent free radical damage in the body. (Chung, 2006) investigated antioxidant
properties of garlic compounds (Alliin, Allylcysteine, Allyl Disulphide and
Allicin) prepared by chemical synthesis or purification. Alliin Scavenge
superoxide, while Allyl cysteine and Allyl sulphide did not scavenge superoxide,
Allicin suppresses the formation of superoxide by the xanthine / xanthine
oxidase system, likely through thiol exchange mechanism. Garlic compounds such
as Alliin, Allyl cysteine and allyl disulphide scavenge hydroxyl radicals.
Allin, allicin and allyl cysteine did not prevent microsomal lipid peroxidation
but alliin and allyl cysteine were scourer of hydroxyl and allyl disulphide was
a lipid peroxidation terminator. In summary, allyl disulphide, alliin, allicin
and allyl cysteine indicates different patterns of anti-oxidants as protective
compounds against free radicals damage (chung, 2006).
DIGESTIVE
STIMULANT ACTION OF GARLIC.
Spices are well recognized to stimulate
gastric function. They are generally believed to intensify salivary flow and
gastric juice secretion and, hence, aid in digestion (Glatzel, 1968). Spices
like turmeric are know to reduce the pungency of the food and irritation to stomach.
Turmeric has the property of increasing the mucin content of the gastric juice.
Spices such as ginger, mint, Ajowen, Cumin, fennel, coriander, and garlic are
used as ingredients of commercial digestive stimulants as well as of home remedies
for digestive disorders. Earlier reports on the digestive stimulant action of
spices are largely empirical; its only in recent years that this beneficial attribute
of spices has been authenticated in exhaustive animal studies (Platel and Srinivasan,
2004).
Animal studies
have revealed that a good number of spices, when consumed through diet, bring
about an enhanced secretion of bile with a higher bile acid content, which
plays a vital role in fat digestion and absorption (Bhat et al., 1984, 1985; Sambaiah and Srinivasan, 1991:Platel and
Srinivasan, 2000). Spices that stimulate bile acid production by the liver and
its secretion into bile include curcumin (Turmeric), capsaicin (red pepper), ginger,
cumin, coriander, Ajowen, fenugreek, mustard, onion, and tarnarind. Spices such
as curcumin, capsaicin, piperine, ginger, and mint have also been shown to
stimulate pancreatic digestive enzymes like lipase, amylase, trypsin, and
chymotrypsin, which play a crucial role in food digestion (Platel and
Srinivasan, 2000a, 2001). A few spices have been shown to have beneficial effect
on the terminal digestive enzymes of small intestinal mucosa (platel and
sririvasan, 1996, 2000a,). Thus, many of the common spices act as digestive stimulants
by enhancing biliary secretion of bile acids, which are vital for fat digestion
and absorption, and by stimulating the activities of pancreatic and intestinal enzymes
involved in digestion.
ANTI-MUTAGENIC
AND ANTI – CARCINOGENIC PROPERTY
Garlic is yet
another spice widely studied in recent years for its chemo preventive
potential. Epidemiological studies have shown that higher intake of allium
products is associated with reduced risk of several types of cancers,
especially stomach and colorectal (Fleis chauer and Arab, 2001). These
epidemiological findings are well correlated with several laboratory
investigations. Several mechanisms have been proposed to explain the cancer –
preventive effects of garlic and its organosulphur compounds, As recently
reviewed (sengupta et al., 2004).
Suggested mechanisms include inhibition of mutagenesis, modulation of enzyme
activities that suppress bioactivation of carcinogen molecules, inhibition of carcinogen-DNA
adducts formation, free radical scavenging, inhibitory effects on cell
proliferation and tumor growth, and induction of a large apoptosis. Although
there is a large body of evidence supporting these mechanisms, they are still
speculative, and further research is needed to support causality between such
properties and cancer preventive activity in experimental animals. The
important observation on the cancer preventive potential of garlic and its
sulphur compounds are summarized in the table below .
Garlic
and cancer prevention
Model/Cancer
|
Treatment
|
Carcinogen
|
remarks
|
Reference
|
Rat/Liver,
mammary gland
|
Dietary
garlic powder
|
DMBA,
nitrosamine
|
in
vivo inhibition of DNA adduct
|
Liu
et al., 1992, 1992a; Lin et al., 1992.
|
Rat/Colon,
esophagus
|
Diallylsulphide
|
N-nitrosomethyl-benzylamine.
|
prevention
|
Wargovich
et al., 1988.
|
Rat/Mammary
|
Garlic,
S-Allyl cysteine, DADS
|
vinylcarbamate
|
Delayed
onset
|
Schaffer
et al., 1996.
|
Rat/Liver
|
Dietary
garlic powder
|
Diethylnitrosamine
|
inhibiton
|
Park
et al., 2002
|
Mice/Colon
|
Diallylsulphide
|
Dimethylhydrazine
|
prevention
|
Sumiyoshi
and wargovich, 1990
|
Mice/Skin
|
Garlic
oil-topical
|
DMBA
|
inhibition
|
Belman,
1983
|
Mice/Skin
|
Diallylsulphide
|
NDMA
|
Inhibition
|
Surh
et al., 1995
|
Mice/Skin
|
Ajoene
|
DMBA
|
suppression
Inhibition
|
Nishikawa
et al., 2002
|
Mice/Skin
|
Diallylsulphide-topical
|
DMBA
|
inhibiton
|
Arora
et al., 2004
|
Hamster/Buccal
pouch
|
S-Allyl
cysteine
|
DMBA
|
Inhibition
|
Balasenthil
et al., 2001
|
Humans
|
||||
Normal
|
Crushed
fresh garlic: 5g
|
Inhibition
of nitrosation
|
Mei
et al., 1989
|
|
Epidemiological:
|
||||
China
(Cangshan Country)
|
Garlic:
20g/day
|
decreased gastric cancer mortality, decreased NO2 in
gastric juice.
|
Mei
et al., 1985; You et al., 1989
|
|
china
|
Garlic
consumption
|
Decreased
incidence of stomach and colo-rectal cancer
|
Fleischauer
and Arab, 2001
|
|
China
|
Garlic
consumption
|
Lesser
incidence of prostate cancer
|
Hsing
et al., 2002
|
CONCLUSION
From
the overview of Garlic, It has high nutritive value, Anti-microbial activity,
anti-oxidant, hypo cholesterolemic, Anti diabetic, Anti-mutagenic and anti –
Carcinogenic, Anti – hypertensive, immuno – modulating activities. Garlic may be a useful alternative to antibiotic in
poultry production due to it wide range safety margin. Garlic may be a useful
alternative to antibiotic in poultry production due to it wide range safety
margin.
REFERENCE
AibmoradDI, M.,
Navidshad, B., Seifdavati, J. and Royan, M. (2006). Effect of Dietary garlic
meal on histological structure of small intestrine in broiler chicken. Journal
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