Tell me about...
Garlic
What is garlic?
One of the most popular herbs in existence, garlic is held
in high regard in many parts of the world for its pungent
aroma and flavor. It is often used as a flavoring or complement
for a variety of foods, particularly Mediterranean cuisine.
Sulfur compounds give garlic its distinctive aroma and help
account for some of its flavor. They also appear to be responsible
for most of its medicinal properties, although a pair of trace
minerals (germanium and selenium) may also play a role.
An inert compound in garlic, alliin, is converted to another
compound named allicin once a clove is cut or crushed. In
Europe, standardized garlic extracts are supposed to contain
at least 0.45 percent allicin.
Why do we need garlic? What is it
used for?
The use of garlic as a medicinal is traced back to ancient
Greece and Egypt. For instance, the Ebers Papyrus -- an ancient
medicinal scroll fating to 1550 BC -- mentions 22 herbal remedies
containing garlic. Hippocrates, the "father of medicine,"
prescribed garlic for conditions ranging from leprosy and
toothaches to chest pain.
Modern research has shown garlic to contain a number of antibacterial,
antifungal and other healing properties. For instance, garlic
has been shown to lower levels of low density lipoprotein
(LDL) cholesterol in some individuals, while other research
has shown increases in beneficial HDL (high density lipoprotein)
with long-term use.
Several garlic-derived chemicals can help slow blood clotting
by keeping blood platelets from clumping together. In addition,
garlic helps break up or prevent blood clots. Since many heart
attacks and strokes are believed to be caused by spontaneous
clots in blood vessels, these anticoagulant actions may be
very helpful in stroke and heart attack prevention.
Test tube research has established that garlic extracts are
active against a range of disease-causing bacteria, including
staphylococcus aureus and streptococcus pneumoniae. It is
only about one percent as active as penicillin, however. Garlic
extract can also fight helicobacter pylori, a bacterium that
causes stomach ulcers.
Animal research has demonstrated that garlic has the potential
to improve resistance to tumors. Other tests conducted on
rats and dogs have also shown that garlic can return irregular
heart rhythms back to normal.
One of the most intriguing possibilities for garlic is that
regular consumption may help prevent cancer. Studies in China
comparing people in one region where garlic is commonly eaten
(20 grams a day, on average) with those in another region
where daily consumption is less than half a clove found that
the people who ate more garlic were much less likely to suffer
stomach cancer. Other studies have indicated that people who
eat garlic more often seem less susceptible to colon cancer.
How much garlic should I take?
The National Academy of Sciences has yet to specify a recommended
daily allowance for garlic. As a result, recommended doses
vary depending on type of condition a patient may have and
the type of health practitioner providing information.
The Complete German Commission E Monographs Therapeutic Guide
to Herbal Medicines recommends consumption of four grams of
fresh garlic daily. Other publications and studies have recommended
much lower doses (5-10 milligrams/day).
What forms of garlic are available?
Garlic is available in many forms, including fresh bulbs,
oil-based extracts, steam-distilled extracts and dried powder.
Minced and chopped varieties are also available at most supermarkets.
To maximize the anti-cancer activity of fresh garlic in cooking,
health professionals recommend that it be crushed or minced
at least ten minutes before heating.
What can happen if I take too much
garlic? Are there any interactions I should be aware of? What
precautions should I take?
Most people appear to tolerate garlic well, but some individuals
may experience gastrointestinal irritation. People who handle
garlic products occasionally develop a skin reaction on exposure.
Ingestion of fresh garlic and most extracts may also result
in a characteristic breath odor.
Although there are no studies of drug interactions, in theory
garlic may increase the risk of bleeding in people taking
aspirin or blood-thinning medications such as coumadin. There
is also a possibility that garlic could interact with drugs
such as DiaBeta or Glucotrol that lower blood sugar. Careful
monitoring is recommended for anyone combining garlic products
with prescription drugs.
Garlic appears to inhibit an enzyme called CYP 2E1. In most
cases, this interference is viewed positively, because CYP
2E1 can make carcinogens more dangerous. However, CYP 2E1
is also involved in the metabolism of acetaminophen and a
muscle relaxant called chlorzoxazone. These drugs could possibly
remain in the body longer in people who are taking or eating
garlic.
People with low thyroid function should also be aware that
concentrated garlic products may keep the thyroid gland from
utilizing iodine properly. This could aggravate an underactive
thyroid condition.
Other Resources :
The
More You Know About Garlic
The
More You Know About Nutrition
References
• Graedon J, Graedon T. The People's
Pharmacy Guide To Home And Herbal Remedies. New York: St.
Martins, LLC, 1999.
• Ahsan M, Islam SN. Garlic: a broad spectrum antibacterial
agent effective against common pathogenic bacteria. Fitoterapia
1996;67(4):374-376.
• Blumenthal M, et al. The Complete German Commission
E Monographs Therapeutic Guide to Herbal Medicines. Boston:
Integrative Medicine Communications, 1998, p. 134.
• Aqel MB, Gharaibah MN, Salhab AS. Direct relaxant effects
of garlic juice on smooth and cardiac muscles. Journal of
Ethnopharmacology 1991;33:13-19.
• Barrie SA, Wright JV, Pizzorno JE. Effects of garlic
oil on platelet aggregation, serum lipids and blood pressure
in humans. Journal of Orthomolecular Medicine 1987;2(1):15-21.
• Cellini L, Di Campli E, Masulli M, et al. Inhibition
of helicobacter pylori by garlic extract (allium sativum).
FEMS Immunology and Medical Microbiology 1996;13:273-277.
• De A Santos OS, Johns RA. Effects of garlic powder
and garlic oil preparations on blood lipids, blood pressure
and well-being. British Journal of Clinical Research 1995;6:91-100.
• Kiesewetter H, Jung F, Pindur G, et al. Effect of garlic
on thrombocyte aggregation, microcirculation, and other risk
factors. International Journal of Clinical Pharmacology, Therapy,
and Toxicology 1991;29(4):151-155.
• Moriguchi T, Saito H, Nishiyama N. Anti-ageing effect
of aged garlic extract in the inbred brain atrophy mouse model.
Clinical and Experimental Pharmacology and Physiology 1997;24:235-242.
• Nagourney RA. Garlic: medicinal food or nutritious
medicine? Journal of Medicinal Food 1998;1(1):13-28.
• Singh KV, Shukla NP. Activity on multiple resistant
bacteria of garlic (allium sativum) extract. Fitoterapia 1984;55(5):313-315.
• You W-C, Blot WJ, Chang Y-S, et al. Allium vegetables
and reduced risk of stomach cancer. Journal of the National
Cancer Institute 1989; 81(2): 162-164.
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