Parts used
and where grown
Garlic has
been used since time immemorial as a culinary spice and
medicinal herb. Garlic has been cultivated in the Middle
East for more than 5,000 years and has been an important
part of Traditional Chinese Medicine. The region with
the largest commercial garlic production is central
California. China is also a supplier of commercial
garlic. The bulb is used medicinally.
Historical
or traditional use (may or may not be supported by
scientific studies)
Garlic is
mentioned in the Bible and the Talmud. Hippocrates,
Galen, Pliny the Elder, and Dioscorides all mention the
use of garlic for many conditions, including parasites,
respiratory problems, poor digestion, and low energy.
Its use in China was first mentioned in A.D. 510. Louis
Pasteur studied the antibacterial action of garlic in
1858.
Active
constituents
The sulfur
compound allicin, produced by crushing or chewing fresh
garlic or by taking powdered garlic products with
allicin potential, in turn produces other sulfur
compounds: ajoene, allyl sulfides, and vinyldithiins.
Aged garlic products lack allicin, but may have activity
due to the presence of S-allylcysteine.
Many
publications have shown that garlic supports the
cardiovascular system. While earlier trials suggest it
may mildly lower cholesterol and triglyceride levels in
the blood, more recent trials found garlic to have
minimal success in lowering cholesterol and
triglycerides. Garlic also inhibits platelet stickiness
(aggregation) and increases fibrinolysis, which results
in a slowing of blood coagulation. It is mildly
antihypertensive and has antioxidant
activity.
Garlic’s
cardiovascular protective effects were illustrated in a
four-year clinical trial on people 50–80 years old with
atherosclerosis. It was found that consumption of 900 mg
of a standardized garlic supplement reduced arterial
plaque formation by 5–18%. The benefits were most
notable in women.
In test tube
studies garlic has been found to have antibacterial,
antiviral, and antifungal activity. However, these
actions are less clear in humans and do not suggest that
garlic is a substitute for antibiotics or antifungal
medications.
Human
population studies suggest that eating garlic regularly
reduces the risk of esophageal, stomach, and colon
cancerThis may be partly due to garlic’s ability to
reduce the formation of carcinogenic
compounds.
How much is
usually taken?
People who
wish to consume garlic and have no aversion to its odor
can chew from one to two whole cloves of raw garlic
daily. For those who prefer it with less odor,
enteric-coated tablets or capsules with approximately
1.3% allin are available. Clinical trials have used
600–900 mg (delivering approximately 5,000–6,000 mcg of
allicin potential) per day in two or three divided
amounts. Aged-garlic extracts have been studied in
amounts ranging from 2.4–7.2 grams per day.
Are there
any side effects or interactions?
Many people
enjoy eating garlic. However, some people who are
sensitive to it may experience heartburn and flatulence.
Because of garlic’s anti-clotting properties, people
taking anticoagulant drugs should check with their
doctor before taking garlic. Those scheduled for surgery
should inform their surgeon if they are taking garlic
supplements. Garlic appears to be safe during pregnancy
and breast-feeding. In fact, two studies have shown that
babies like breast milk better from mothers who eat
garlic.
Are there any
drug interactions?
Certain medicines may
interact with garlic.
