Garlic is used
for hypertension, hyperlipidemia, coronary heart disease,
age-related vascular changes and atherosclerosis, myocardial
infarction, earaches, chronic fatigue syndrome, and menstrual
disorders. Garlic is also used to treat Helicobacter pylori
infection. Other uses include treatment of allergic rhinitis,
traveller's diarrhoea, colds, and flu. It is also used for immune
system stimulation, and prevention and treatment of bacterial and
fungal infections. Other uses include treatment of fever, coughs,
headache, stomachache,sinus congestion, athlete's foot, gout,
rheumatism, bronchitis, low blood pressure. It is also used as an
aphrodisiac, for enhancing circulation, fighting stress and
garlic oil is used for fungal infections.
garlic is used alone or in combination with yogurt for
foods and beverages, fresh garlic, garlic powder, and garlic oil
are used as flavour components.
concerns regarding safety when used orally and appropriately.
Garlic has been used safely in clinical studies lasting up to 7
years without reports of significant toxicity.63,64,65,66,67,68,69,70,71,72,73,74,75,76
Likely to be safe when used orally and appropriately, short-term.
In one study, garlic extract 300 mg three times daily had side
effects comparable to placebo when used in children ages 8-18
years for eight weeks.77There are no
case reports available of significant adverse events or mortality
in children associated with ingestion of garlic.
Lactation: No concerns regarding safety when used orally in
amounts commonly found in foods.78
Taking low doses of garlic powder orally, 300 mg per day, seems
to lessen age-related decreases in aortic elasticity.
Higher doses of
900 mg per day seem to slow development of atherosclerosis in
both aortic and
arteries when used over a four-year period.79,72,73
cancer. Several population studies suggest that increased dietary
garlic consumption can decrease risk of developing colorectal
supplements do not seem to offer this benefit.83
Some evidence from population studies suggests that increasing
dietary garlic consumption is associated with a decreased risk of
developing stomach cancer.84,85,86
Pressure. Some clinical research shows that taking garlic orally
can modestly reduce blood pressure in patients with hypertension
and in people with normal blood pressure.87,88,89,63,75,90
one analysis, garlic reduced systolic blood pressure by about 8%
and diastolic blood pressure by about 7%, compared to placebo in
patients with hypertension.90
Applying a garlic gel containing 0.6% ajoene seems to be as
effective as terbinafine 1% cream.91
(athlete's foot). Applying a garlic gel containing 1% ajoene
seems to be more effective than 0.6% ajoene gel, and seems to
beas effective as 1% terbinafine (Lamisil) for tinea pedis
infections. Sixty days after completing one week of treatment 1%
ajoene produces 100% mycologic cure, 0.6 % produces 72% mycologic
cure, and 1% terbinafine produces 94% mycologic
SCIENTIFIC EVIDENCE to RATE
Preliminary clinical research suggests garlic might reduce the
frequency and number of colds when taken
applicable part of garlic is the bulb. Garlic is mostly used for
its antihyperlipidemic, antihypertensive, and antifungal effects.
However, it is also reported to have antibacterial, antiparasite
(worms), antiviral, antispasmodic, promotes sweating,
expectorant, immunostimulant, and antithrombotic
effects.95,96,97,98,99Many of the
pharmacological effects of garlic are attributed to the allicin,
ajoene, and other organosulfur constituents such as
that the effectiveness of garlic products might to be determined
by their ability to yield allicin, which in turn triggers
production of other active constituents.100
cells in fresh garlic contain the odorless amino acid, alliin.
When intact cells are broken, alliin comes intocontact with the
enzyme alliinase in garlic, producing allicin, an unstable,
odiferous compound.100,97Fresh garlic
contains approximately 1% alliin. One milligram of alliin is
converted to 0.458mg allicin.101Further
conversion yields ajoene. The amount of allicin in garlic
preparations is dependent upon the method of preparation.
Processes that involve maceration of the garlic clove increase
the activity of allicinase. Freeze-dried garlic may contain
little or no allicin. To improve effectiveness, garlic
preparations may be coated to protect the active constituents
stomach acid.102Heat and steam
distillation used to produce garlic oil from crushed garlic
converts allicin to allyl sulfides which are also thought to have
Garlic is aged
to reduce the content of other sulfur compounds and the odor
commonly associated with garlic. The process to produce odorless
aged garlic extract reduces the alliin content to only 3% of what
is typically contained in fresh garlic.101
extract is usually standardized to S-allyl-L-cysteine, another
major organosulfur constituent in garlic.95
patients with hyperlipidemia, garlic might lower cholesterol
levels by acting as a HMG-CoA reductase inhibitor
(statin).103,104There is some
evidence the constituent S-allyl-L-cysteine may be a potent
inhibitor of hepatic cholesterol synthesis.105
For age-related vascular changes and atherosclerosis, garlic is
thought to be beneficial and protect vascular endothelial cells
from injury by reducing oxidative stress, inhibiting low-density
lipoprotein (LDL) oxidation, and through antithrombotic
There is evidence that LDL oxidation may be inhibited by the
constituents S-allyl cysteine, S-allyl mercaptocysteine, alliin,
allixin, and by N-acetyl-S-allyl cysteine, a metabolite of
Garlic appears to prevent endothelial cell depletion of
glutathione, which may be responsible for its antioxidant
and aged garlic preparations have been shown to have antiplatelet
properties in both patients with cardiovascular disease and in
Garlic has been
found to have antithrombotic properties and can increase
fibrinolytic activity,decrease platelet aggregation and adhesion,
increase the prothrombin time (PT), and inhibit metabolic enzymes
in platelets responsible for the conversion of arachidonic acid
into prostaglandins and other products.95,96,98,112Raw
garlic seems to have more potent antiplatelet properties
before cooking might prevent some of the loss of antiplatelet
activity.115Garlic oil does
not appear to affect platelet aggregation.116
thought to reduce blood pressure by causing smooth muscle
relaxation and vasodilation by activating production of
endothelium-derived relaxation factor (EDRF, nitric
seems to have humoral and cellular immunostimulant
constituents allicin and ajoene are thought to beresponsible for
garlic's antifungal activity against ringworm
but not aged garlic, has shown activity against Escherichia coli,
methicillin-resistant Staph aureus, salmonella enteritidis, and
Candida albicans in the laboratory; it has been suggested as a
food additive to prevent food poisoning.
evidence suggests that garlic compounds might have activity
has dose-relatedadverse effects, which most commonly include
breath and body odour, mouth and gastrointestinal burning or
irritation, heartburn, flatulence, nausea, vomiting, and
diarrhoea. These effects can be more pronounced with consumption
of raw garlic or in patients unaccustomed to eating
garlic.78,65,101Oral use of
garlic can also cause changes to the
intestinalflora,78 ,101which might
result in gastrointestinal upset. Garlic's effect on platelet
function is well known, and can possibly increase the risk of
with Herbs & Supplements:
Herbs and Supplements: Concomitant use of herbs that have
constituents that might affect platelet aggregation could
theoretically increase the risk of bleeding in some people. These
herbs include angelica, clove, danshen, ginger, ginkgo, red
clover, turmeric, vitamin E, willow, and
Drugs including Warfarin.
with Lab Tests:
Garlic can lower blood pressure and blood pressure
Garlic can lower serum cholesterol concentrations and test
with Diseases or Conditions:
(GI) Irritation: Garlic can irritate the GI tract; dose related,
resolves on stopping garlic.
discontinue one to two weeks prior to scheduled
Clare’s Blends: 1gm/day
63. Steiner M,
Khan AH, Holbert D, Lin RI. A double-blind crossover study in
moderately hypercholesterolemic men that compared the effect of
aged garlic extract and placebo administration on blood lipids.
Am J Clin Nutr 1996;58:866-70.
Holzgartner H, Schmidt U, Kuhn U. Comparison of the efficacy and
tolerance of a garlic preparation vs. bezafibrate.
65. Jain AK,
Vargas R, Gotzkowsky S, McMahon FG. Can garlic reduce levels of
serum lipids? A controlled clinical study. Am J Med
1993;94:632-5. 66. Mader FH. Treatment of hyperlipidaemia with
garlic-powder tablets. Evidence from the German Association of
General Practitioners' multicentric placebo-controlled
double-blind study. Arzneimittelforschung 1990;34:1111-6.
67. Rotzsch W,
Richter V, Rassoul F, Walper A. [Postprandial lipemia under
treatment with Allium sativum. Controlled double-blind study of
subjects with reduced HDL2-cholesterol]. [Article in German].
68. Silagy C,
Neil A. Garlic as a lipid lowering agent--a meta-analysis. J R
Coll Physicians Lond 1994;28:33-39.
69. Vorberg G,
Schneider B. Therapy with garlic: results of a
placebo-controlled, double-blind study. Br J Clin Pract Symp
70. Adler AJ,
Holub BJ. Effect of garlic and fish-oilsupplementation on serum
lipid and lipoprotein concentrations in hypercholesterolemic men.
Am J Clin Nutr 1997;59:445-44.
71. Morcos NC.
Modulation of lipid profile by fish oil and garlic combination. J
Natl Med Assoc 1997;89:673-8.
Breithaupt-Grogler K, Ling M, Boudoulas H, Belz GG. Protective
effect of chronic garlic intake on elastic properties of aorta in
the elderly.Circulation 1997;96:2649-49.
J, Klussendorf D, Latza R, et al. The antiatherosclerotic effect
of Allium sativum. Atherosclerosis 1999;144:237-43.
C, Pittler MH, Ernst E. Garlic for treating hypercholesterolemia:
a meta-analysis of randomized clinical trials. Ann Intern Med
RT, Mulrow CD, Ramirez G, et al. Garlic shows promise for
improving some cardiovascular risk factors.
76. You WC,
Brown LM, Zhang L, et al. Randomized double-blind factorial trial
of three treatments to reduce the prevalence of precancerous
gastric lesions. J Natl Cancer Inst 2006;98:974-83.
BW, Helden E, Conner WT. Garlic extract therapy in children with
hypercholesterolemia. Arch Pediatr Adolesc Med 1998;152:108
78. Bloch AS.
Pushing the Envelope of Nutrition Support: Complementary
Therapies. Nutrition 2000;16:236-9.
79. Siegel G,
Klubendorf D. The anti-atherosclerotic effect of Allium sativum:
Statistics re-evaluated. Atherosclerosis 2000;150:437-8.
KA, Kushi LH, Bostick RM, et al. Vegetables, fruit, and colon
cancer in the Iowa Women's Health Study. Am J Epidemiol
81. Witte JS,
Longnecker MP, Bird CL, et al. Relation of vegetable, fruit, and
grain consumption to colorectal adenomatous polyps. Am J
Marchand L, Hankin JH, Wilkens LR, et al. Dietary fiber and
colorectal cancer risk. Epidemiology 1997;8:658-59.
83. Dorant E,
van den Brandt PA, Goldbohm RA. A prospective cohort study on the
relationship between onion and leek consumption, garlic
supplement use and the risk of colorectal carcinoma in The
Netherlands. Carcinogenesis 1996;17:477-84.
Fleischauer AT, Poole C, Arab L. Garlic consumption and cancer
prevention: meta-analyses of colorectal and stomach cancers. Am J
Clin Nutr 2000;72:1047-46.
85. You WC,
Blot WJ, Chang YS, et al. Allium vegetables and reduced risk of
stomach cancer. J Natl Cancer Inst 1989; 81:162-4.
T, Gao CM, Ding JH, et al. Comparative study of lifestyles of
residents in high and low risk areas for gastric cancer in
Jiangsu Province, China; with special reference to allium
vegetables. J Epidemiol 1999;9:297-305.
87. Silagy CA,
Neil HA. A meta-analysis of the effect of garlic on blood
pressure. J Hypertension 1994;12:463-8.
FG, Vargas R. Can garlic lower blood pressure? A pilot study.
89. Auer W,
Eiber A, Hertkorn E, et al. Hypertension and hyperlipidaemia:
garlic helps in mild cases. Br J Clin Pract
90. Ried K,
Frank OR, Stocks NP, et al. Effect of garlic on blood pressure: A
systematic review and meta-analysis. BMC Cardiovasc Disord
91. Ledezma E,
Lopez JC, Marin P, et al. Ajoene in the topical short-term
treatment of tinea cruris and tinea corporis in humans.
Randomized comparative study with terbinafine.
92. Ledezma E,
DeSousa L, Jorquera A, et al. Efficacyof ajoene, an organosulphur
derived from garlic, in the short-term therapy of tinea pedis.
93. Ledezma E,
Marcano K, Jorquera A. Efficacy of ajoene in the treatment of
tinea pedis: A double-blind and comparative study with
terbinafine. J Am Acad Dermatol 2000;37:829-32.
94. Josling P.
Preventing the common cold with a garlic supplement: a
double-blind, placebo-controlled survey. Adv Ther
95. Rahman K,
Billington D. Dietary supplementation with aged garlic extract
inhibits ADP-induced platelet aggregation in humans. J Nutr
96. Steiner M,
Li W. Aged garlic extract, a modulator of cardiovascular risk
factors: a dose-finding study on the effects of AGE on platelet
functions. J Nutr 2001;131:980S-4S.
97. Ankri S,
Mirelman D. Antimicrobial properties ofallicin from garlic.
Microbes Infect 1999;1:125-9.
98. M, Thomson
M, Afzal M. Garlic and onions: their effect on eicosanoid
metabolism and its