Garlic

Garlic
Also listed as: Allium sativum

Overview
Plant Description
What's It Made Of?
Available Forms
How to Take It
Precautions
Possible Interactions
Supporting Research


Overview
Garlic has been used as both food and medicine in many cultures for
thousands of years, dating as far back as the time that the Egyptian
pyramids were built. Later, gravediggers in early 18 th -century
France drank a concoction of crushed garlic in wine they believed
would protect them from the plague that killed many people in Europe.
More recently, during both World Wars I and II, soldiers were given
garlic to prevent gangrene. Today garlic is used to help prevent heart
disease, including atherosclerosis (plaque buildup in the arteries
that can block the flow of blood and possibly lead to heart attack or
stroke), high cholesterol, high blood pressure, and to improve the
immune system. Garlic may also protect against cancer.

While the science is not definitive at this point, much of the
research is showing promise, and many clinicians continue to report
improvements in the areas of cancer protection and heart-related risk
factors for patients.

Garlic has antioxidant properties. Antioxidants help destroy free
radicals -- particles that can damage cell membranes, interact with
genetic material, and possibly contribute to the aging process as well
as the development of a number of conditions including heart disease
and cancer. Free radicals occur naturally in the body, but
environmental toxins (including ultraviolet light, radiation,
cigarette smoking, and air pollution) can also increase the number of
these damaging particles. Antioxidants can neutralize free radicals
and may reduce or even help prevent some of the damage they cause over
time.

There are several types of garlic preparations. Most clinical studies
have been performed on aged garlic extract (AGE) or enteric coated,
dried garlic tablets. The conditions for which garlic is showing the
most promise include:

Cardiovascular disease

Studies report that garlic consumption may decrease the progression of
cardiovascular disease. Cardiovascular disease is associated with
several factors, including raised serum total cholesterol, raised low
density lipoprotein (LDL), and an increase in LDL oxidation (free
radical damage), increased platelet aggregation (clumping),
hypertension, and smoking. Garlic may help decrease LDL and total
cholesterol levels while raising good cholesterols (high density
lipoprotein, or HDL), decrease platelet aggregation (helps the blood
flow more easily), and decrease blood pressure. Recently, garlic was
also found to decrease two other markers of cardiovascular disease,
homocysteine and C-reactive protein.

Garlic may also decrease blood pressure. Numerous studies have
reported small reductions in systolic and diastolic blood pressure
associated with the use of oral garlic.

Common cold

A well-designed study of nearly 150 people supports the value of
garlic for preventing and treating the common cold. In this study,
people received either garlic supplements or placebo for 12 weeks
during "cold season" (between the months of November and February).
Those who received the garlic had significantly fewer colds than those
who received placebo. Plus, when faced with a cold, the symptoms
lasted a much shorter time in those receiving garlic compared to those
receiving placebo.

Cancer

Garlic may strengthen the immune system and may help the body fight
diseases such as cancer. Laboratory studies suggest that garlic may
have some anti-cancer activity. Studies which follow groups of people
over time suggest that people who have more raw or cooked garlic in
their diet are less likely to have certain types of cancer,
particularly colon and stomach cancers. Dietary garlic may also offer
some protection against the development of breast, prostate, and
laryngeal (throat) cancers.

A large-scale study, called the Iowa Women's Health Study, looked at
the garlic, fruit, and vegetable consumption in 41,000 middle-aged
women. Results showed that women who regularly consumed garlic,
fruits, and vegetables had 35% lower risk of developing colon cancer.
Garlic may help the immune system function more effectively during
times of need such as in cancer. In a study of 50 patients with
inoperable colorectal, liver, or pancreatic cancer, immune activity
was improved after they were given aged garlic extract for 6 months.
Studies also suggest that aged garlic supplementation may reduce
chemotherapy side effects such as fatigue and anorexia (lack of
appetite). Further results found that the aged garlic decreased heart
and intestinal damage commonly seen with certain chemotherapy agents.
While these results are promising, more research is needed to best
understand whether dietary intake of garlic and other plants in the
same family (such as onions, leeks, scallions, chives, and shallots)
truly help to protect us from cancer.

Other uses

Laboratory studies suggest that large quantities of fresh, raw garlic
may have antiparasitic properties against the roundworm, Ascaris
lumbricoides, which is the most common type of intestinal parasite.
Garlic for this purpose, however, has not yet been tested in people.
Fresh garlic contains allicin, which is reported to be antibacterial,
antiviral, and antifungal. Some studies have reported that garlic
consumption may kill bacteria known to cause ulcers, but there are
also studies that report no effect on this bacteria. Several studies
report that topical application of garlic may help in some fungal skin
conditions, such as Tinea cruris and Tinea corporis.


Plant Description
Garlic originally came from central Asia, and is now cultivated
throughout the world. Garlic is a perennial that can grow 2 feet high
or more. The most important part of this plant for medicinal purposes
is the compound bulb. Each bulb is made up of 4 - 20 cloves, and each
clove weighs about 1 gram. Garlic supplements can either be made from
fresh, dried, aged, or garlic oil, and each may have different effects
on the body.



What's It Made Of?
There are several important components of garlic that have been
identified, and many more that have not. Alliin is an odorless sulfur-
containing chemical derived from the amino acid cysteine. When garlic
bulbs are crushed, alliin is converted into another compound called
allicin. Allicin appears to be at least one of the primary active
compounds that gives garlic its characteristic odor and many of its
healing benefits. However, allicin is not absorbed effectively by the
human body.

To combat this problem, aged garlic is fermented to break allicin down
to usable compounds. These compounds are water-soluble sulfur
compounds (S-allyl cysteine and others) and a small amount of oil-
soluble sulfur compounds. The sulfur containing compounds in aged
garlic give the supplement its reported benefits in cholesterol
levels, heart disease, and cancer.



Available Forms
Garlic supplements are made from whole fresh garlic, dried, or freeze-
dried garlic, garlic oil, and aged garlic extracts.

Not all garlic contains the same amount of active ingredients. There
is a fairly wide variation in the amount of important components in
both fresh garlic and commercial supplements. The amount of healthy
compounds present depends on where the garlic is grown as well as how
the product is prepared. Some experts believe that the wide variation
in the quantity of active ingredients in garlic preparations explains
why there is some variability in how well the substances lower
cholesterol, improve blood pressure, and fight infection in different
people.

Aged garlic products are made by fermenting garlic. Several clinical
studies support the use of aged garlic for cardiovascular disease
prevention. The manufacturers of aged garlic report that allicin, a
compound commonly thought of as having healing effects in the body, is
actually not absorbed efficiently by the body. Aged garlic is high in
sulfur compounds that are absorbed and have beneficial effects on
heart disease and health.

It is important to read the label on all garlic products carefully. It
is best to use standardized garlic products to ensure that you are
getting the most benefit. Also, follow the directions of a qualified
health care provider with knowledge and experience in herbal
medicine.



How to Take It
Pediatric

An appropriate medicinal dose for children has not been established.
For this reason, use of garlic for health-related reasons in children
should be directed by a qualified health care provider who has
experience treating children with herbal remedies.

Adult

Whole garlic clove (as a food supplement): 2 - 4 grams per day of
fresh, minced garlic clove (each clove is approximately 1 gram)

Aged garlic extract: 600 - 1,200 mg, daily in divided doses

Tablets of freeze-dried garlic: 200 mg, 2 tablets 3 times daily,
standardized to 1.3% alliin or 0.6% allicin. Products may also be
found standardized to contain 10 - 12 mg/Gm alliin and 4,000 mcg of
total allicin potential (TAP).

Fluid extract (1:1 w/v): 4 mL, daily

Tincture (1:5 w/v): 20 mL, daily

Oil: 0.03 - 0.12 mL, 3 times daily



Precautions
The use of herbs is a time-honored approach to strengthening the body
and treating disease. Herbs, however, contain components that can
trigger side effects and that can interact with other herbs,
supplements, or medications. For these reasons, herbs should be taken
with care, under the supervision of a health care provider qualified
in the field of botanical medicine.

Garlic is considered to have very low toxicity and is listed as
Generally Recognized as Safe (GRAS) by the U.S. Food and Drug
Administration.

Side effects from garlic include upset stomach, bloating, bad breath,
body odor, and a stinging sensation on the skin from handling too much
fresh or dried garlic. Handling garlic may also cause the appearance
of skin lesions. Other, more rare side effects that have been reported
by those taking garlic supplements include headache, fatigue, loss of
appetite, muscle aches, dizziness described as vertigo (dizziness),
and allergies such as an asthmatic reaction or contact dermatitis
(skin rash).

Garlic has blood-thinning properties. This is also important to know
if you are going to have surgery or deliver a baby. Too much garlic
can increase your risk for bleeding during or after those procedures.



Possible Interactions
Garlic may alter the function of certain prescription medications. If
you are being treated with any of the following medications, you
should not use garlic supplements without first talking to your health
care provider.

Antiplatelet medications -- Garlic may exaggerate the activity of
medications that inhibit the action of platelets in the body. Examples
of such medications include indomethacin, dipyridamole, Plavix, and
aspirin.

Blood-thinning medications -- There have been reports of a possible
interaction between garlic and warfarin that could increase the risk
of bleeding in people taking this blood thinning medication.
Therefore, when taking medications that may thin the blood, such as
aspirin and warfarin, you not use garlic supplements unless you are
under the supervision of a doctor.

Protease inhibitors -- Garlic may reduce blood levels of protease
inhibitors, a medication used to treat people with the human
immunodeficiency virus (HIV). Protease inhibitors inclue indinavir,
ritinavir, and saquinavir.



Supporting Research
Ackermann RT, Mulrow CD, Ramirez G, Gardner CD, Morbidoni L, Lawrence
VA. Garlic shows promise for improving some cardiovascular risk
factors. Arch Intern Med . 2001;161:813-824.

Alder R, Lookinland S, Berry JA, et al. A systematic review of the
effectiveness of garlic as an anti-hyperlipidemic agent. J Am Acad
Nurse Pract . 2003;15(3):120-129.

Ang-Lee MK, Moss J, Yuan C-S. Herbal medicines and perioperative care
[review]. JAMA . 2001;286(2):208-216.

Apitz-Castro R, Escalante J, Vargas R, et al. Ajoene, the antiplatelet
principle of garlic, synergistically potentiates the antiaggregatory
action of prostacyclin, forskolin, indomethacin, and dipyridamole on
human platelets. Thromb Res . 1986;42(3):303-311.

Ashraf R, Aamir K, Shaikh AR, Ahmed T. Effects of garlic on
dyslipidemia in patients with type 2 diabetes mellitus. J Ayub Med
Coll Abbottabad . 2005;17(3):60-4.

Bailey C, Day C. Traditional plants medicine as treatments for
diabetes. Diabetes Care . 1989;12:553-564.

Berthold HK, Sudhop T. Galic preparation for prevention of
atherosclerosis. Curr Opin Lipidol . 1998;9(6):565-569.

Berthold HK, Sudhop T, von Bergmann K. Effect of a garlic oil
preparation on serum lipoproteins and cholesterol metabolism. JAMA .
1998;279.

Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded
Commission E Monographs . Newton, MA: Integrative Medicine
Communications; 2000:139-148.

Caron MF, White CM. Evaluation of the antihyperlipidemic properties of
dietary supplements. Pharmacotherapy . 2001;21(4):481-487.

Delaha EC, Garagusi VF. Inhibition of mycobacteria by garlic extract
( Alliumsativum ). Antimicrob Agents Chemother . 1985;27(4):485-486.

Dillon SA, Burmi RS, Lowe GM, et al. Antioxidant properties of aged
garlic extract: an in vitro study incorporating human low density
lipoprotein. Life Sci . 2003;72(14):1583-1594.

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(3):477-484.

Dorant E, van den Brandt PA, Goldbohm RA. Allium vegetable
consumption, garlic supplement intake, and female breast carcinoma
incidence. Breast Cancer Res Treat . 1995;33(2):163-170.

Dorant E, van den Brandt PA, Goldbohm RA, Hermus RJ, Sturmans F.
Garlic and its significance for the prevention of caner in humans: a
critical view. Br J Cancer . 1993;67(3):424-429.

Fleischauer AT, Arab L. Garlic and cancer: a critical review of the
epidemiologic literature. J Nutr . 2001;131:1032S-1040S.

Fleischauer AT, Poole C, Arab L. Garlic consumption and cancer
prevention: meta-analyses of colorectal and stomach cancers. Am J Clin
Nutr . 2000;72:1047-1052.

Fugh-Berman A. Herb-drug interactions [review]. Lancet .
2000;355:134-138.

Fugh-Berman A. Herbs and dietary supplements in the prevention and
treatment of cardiovascular disease. Prev Cardiol . 2000;3:24-32.

Garlic supplements can impede HIV medication. J Am Coll Surg .
2002;194(2):251.

Gallicano K, Foster B, Choudhri S. Effect of short-term administration
of garlic supplements on single-dose ritonavir pharmacokinetics in
healthy volunteers. Br J Clin Pharmacol . 2003;55(2):199-202.

Hassan ZM, Yaraee R, Zare N, et al. Immunomodulatory affect of R10
fraction of garlic extract on natural killer activity. Int
Immunopharmacol . 2003;3(10-11):1483-1489.

Heck AM, DeWitt BA, Lukes AL. Potential interactions between
alternative therapies and warfarin. Am J Health Syst Pharm .
2000;57(13):1221-1227.

Heron S, Yarnell E. Treating parasitic infections with botanical
medicines. Altern Complement Ther . 1999;8:214-224.

Isaacsohn JL, Moser M, Stein EA, et al. Garlic powder and plasma
lipids and lipoproteins: a multicenter, randomized, placebo-controlled
trial. Arch Intern Med . 1998;158(11):1189-1194.

Izzo AA, Ernst E. Interactions between herbal medicines and prescribed
drugs: a systematic review. Drugs . 2001;61(15):2163-2175.

Jain RC. Anti tubercular activity of garlic oil [letter]. Indian J
Pathol Microbiol . 1998;41(1):131.

James JS. Garlic reduces squinavir blood levels 50%; may affect other
drugs. AIDS Treat News . 2001;375:2-3.

Josling P. Preventing the common cold with a garlic supplement: a
double blind, placebo-controlled survey. Adv Ther . 2001;18(4):
189-193.

Kannar D, Wattanapenpaiboon N, Savige GS, Wahlqvist ML.
Hypocholesterolemic effect of an enteric coated garlic supplement. J
Am Coll Nutr . 2001;20(3):225-231.

Kasuga S, Uda N, Kyo E, et al. Pharmacologic activities of aged garlic
extract in comparison with other garlic preparations. J Nutr .
2001;131(3s):1080S-1084S.

Kendler BS. Recent nutritional approaches to the prevention and
therapy of cardiovascular disease. Prog Cardiovasc Nurs . 1997;12(3):
3-23.

Koscielny J, Klubendorf D, Latza R, Schmitt R, Radtke H, Siegel G,
Kiesewetter H. The antiatherosclerotic effect of Allium sativum.
Atherosclerosis . 1999;144:237-249.

Larkin M. Surgery patients at risk for herb-anaesthesia interactions.
Lancet . 1999;354(9187):1362.

LaValle JB, Krinsky DL, Hawkins EB, et al. Natural Therapeutics Pocket
Guide . Hudson, OH: LexiComp; 2000:438-440.

Levi F, Pasche C, La Vecchia C, Lucchini F, Franceschi S. Food groups
and colorectal cancer risk. Br J Cancer . 1999;79(7-8):1283-1287.

Loy MH, Rivlin RS. Garlic and cardiovascular disease. Nutr Clin Care .
2000;3(3):146-151.

Mantle D, Lennard TW, Pickering AT. Therapeutic applications of
medicinal plants in the treatment of breast cancer: a review of their
pharmacology, efficacy and tolerability. Adverse Drug React Toxicol
Rev . 2000;19(3):223-240.

Markowitz JS, Devane CL, Chavin KD, et al. Effects of garlic (Allium
sativum L.) supplementation on cytochrome P450 2D6 and 3A4 activity in
healthy volunteers. Clin Pharmacol Ther . 2003;74(2):170-177.

Mashour NH, Lin GI, Frishman WH. Herbal medicine for the treatment of
cardiovascular disease. Arch Intern Med . 1998;158:2225–2234.

Miller LG. Herbal medicinals: selected clinical considerations
focusing on known or potential drug-herb interactions [review]. Arch
Intern Med . 1998;158:2200-2211.

Milner JA. A historical perspective on garlic and cancer. J Nutr .
2001;131(3s):1027S-1031S.

Morelli V, Zoorob RJ. Alternative therapies: part I. Depression,
diabetes, obesity. Am Fam Physician . 2000;62(5):1051-1060.

Munday JS, James KA, Fray LM, Kirkwood SW, Thompson KG. Daily
supplementation with aged garlic extract, but not raw garlic, protects
low density lipoprotein against in vitro oxidation. Atherosclerosis .
1999;143(2):399-404.

Nies LK, Cymbala AA, Kasten SL, et al., Complementary and alternative
therapies for the management of dyslipidemia. Ann Pharmacother.
2006;40(11):1984-92.

Peleg A, Hershcovici T, Lipa R, et al. Effect of garlic on lipid
profile and psychopathologic parameters in people with mild to
moderate hypercholesterolemia. Isr Med Assoc . J 2003;5(9):637-640.

Pinto JT, Rivlin RS. Antiproliferative effects of allium derivatives
from garlic. J Nutr . 2001;131(3S):1058S-1060S.

Rahman K. Historical perspective on garlic and cardiovascular disease.
J Nutr . 2001;131(3s):977S-979S.

Rose KD, Croissant PD, Parliament CF, Levin MB. Spontaneous spinal
epidural hematoma with associated platelet dysfunction from excessive
garlic ingestion: a case report. Neurosurgery . 1990;26:880–882.

Sarrell EM, Mandelberg A, Cohen HA. Efficacy of naturopathic extracts
in the management of ear pain associated with acute otitis media. Arch
Pediatr Adolesc Med . 2001;155:796-799.

Salih BA, Abasiyanik FM. Does regular garlic intake affect the
prevalence of Helicobacter pylori in asymptomatic subjects? Saudi Med
J. 2003;24(8):842-845.

Siegers CP, Steffen B, Robke A, Pentz R. The effects of garlic
preparations against human tumor cell proliferation. Phytomedicine .
1999;6(1):7-11.

Silagy CA, Neil AW. A meta-analysis of the effect of garlic on blood
pressure. J Hypertens . 1994;12:463-468.

Spigelski D, Jones PJ. Efficacy of garlic supplementation in lowering
serum cholesterol levels. Nutr Rev . 2001;59(7):236-241.

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;64:866–870.

Steinmetz KA, Kushi LH, Bostick RM, Folsom AR, Potter JD. Vegetables,
fruit, and colon cancer in the Iowa Women's Health Study. Am J
Epidemiol . 1994;139(1):1-15.

Stevinson C, Pittler MH, Ernst E. Garlic for treating
hypercholesterolemia. Ann Intern Med . 2000;133(6):420-429.

Superko HR, Krauss RM. Garlic powder, effect on plasma lipids,
postprandial lipemia, low-density lipoprotein particle size, high-
density lipoprotein subclass distribution and lipoprotein(a). J Am
Coll Cardiol . 2000;35(2):321-326.

Wang HX, NG TB. Natural products with hypoglycemic, hypotensive,
hypocholesterolemic, antiatherosclerotic and antithrombotic
activities. Life Sci . 1999;65(25):2663-2677.

Witte JS, Longnecker MP, Bird CL, Lee ER, Frankl HD, Haile RW.
Relation of vegetable, fruit, and grain consumption to colorectal
adenomatous polyps. Am J Epidemiol . 1996;144(11):1015-1025.

Yeh YY, Liu L. Cholesterol-lowering effect of garlic extracts and
organosulfur compounds: human and animal studies. J Nutr. 2001;131(3s):
989S-993S.



Review Date: 1/30/2007
Reviewed By: Ernest B. Hawkins, MS, BSPharm, RPh, Health Education
Resources; and Steven D. Ehrlich, N.M.D., private practice
specializing in complementary and alternative medicine, Phoenix, AZ.
Review provided by VeriMed Healthcare Network.
A.D.A.M., Inc. is accredited by URAC, also known as the American
Accreditation HealthCare Commission (www.urac.org). URAC's
accreditation program is the first of its kind, requiring compliance
with 53 standards of quality and accountability, verified by
independent audit. A.D.A.M. is among the first to achieve this
important distinction for online health information and services.
Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a
founding member of Hi-Ethics (www.hiethics.com) and subscribes to the
principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical
emergency or for the diagnosis or treatment of any medical condition.
A licensed medical professional should be consulted for diagnosis and
treatment of any and all medical conditions. Call 911 for all medical
emergencies. Links to other sites are provided for information only --
they do not constitute endorsements of those other sites. © 1997-2007
A.D.A.M., Inc. Any duplication or distribution of the information
contained herein is strictly prohibited.


© 2008 University of Maryland Medical Center (UMMC). All rights
reserved. UMMC is a member of the University of Maryland Medical
System, 22 S. Greene Street, Baltimore, MD 21201. TDD: 401.328.9600 or
1.800.492.5538

.