PDR for Herbal Medicines

328 /GARLIC PDR FOR HERBAL MEDICINES

key enzymes in cholesterol biosynthesis, including HMG

CoA reductase (Gebhardt, 1993; Gebhardt, 1996).

Garlic tablets studied in vitro were found to enhance natural

killer (NK) cells, which are an important part of the immune

system in fighting cancers, viruses and certain bacteria.

Antioxidative effects of garlic, determined by an increase in

intracellular glutathione (GSH) levels, are responsible for

decreasing poor cellular function and premature aging.

Antiviral activity was also noted in vitro with garlic tablets

(See, 1999).

Ajoen is the antithrombotic compound that inhibits fibrino-

gen receptors on platelets (Robbers, 1996). The allicin and

oligosulfides in garlic oil have antiplatelet activity through

inhibition of adenosine diphosphate, collagen and beta-

thromboglobulin release after collagen stimulation. The

compounds also exert antithrombotic effects through inhibi-

tion of platelet thromboxane formation (Bordia, 1998;

Legnani 1993).

CLINICAL TRIALS

A randomized, placebo-controlled, double-blind study in-

volving 42 outpatients was conducted over a 12-week period

to assess the effects of standardized garlic powder tablets on

serum lipids and lipoproteins, glucose and blood pressure.

Standardized garlic powder administered 900 mg daily

produced a significantly greater reduction in serum total

cholesterol (262+/- 34mg/dL to 247 +/-40mg/dL with garlic

compared to 276+/-34mg/dL to 274+/- 29mg/dL with

placebo). Low-density lipoprotein cholesterol (LDL-C) was

significantly reduced with garlic treatment by 11% compared

to 3% with placebo treatment. No significant change was

demonstrated in high-density lipoprotein cholesterol, triglyc-

erides, serum glucose, blood pressure and other monitored

parameters (Jain, 1993).

The lipid-lowering effect of garlic powder tablets was tested

by administering a dose of 900 mg daily (equivalent to

approximately 2.7 grams or 1 clove of fresh garlic daily) to

28 outpatients with hypercholesterolemia. After 12 weeks of

treatment, there were no significant lipid or lipoprotein

changes in either the placebo- or garlic-treated groups

(Isaacsohn, 1998).

A 5 mg dose of steam distilled garlic oil was administered
twice daily to 25 outpatients with moderate hypercholesterol-
emia in a randomized, double-blind, placebo-controlled trial.
The hypocholesterolemic effect of garlic oil was determined
after a 12-week period. The commercial garlic oil prepara-
tion did not have a significant effect on serum lipoproteins,
cholesterol absorption or cholesterol synthesis (Berthold,
1998).

Note: There are contradicting results regarding the lipid-

lowering effect of garlic, which may be attributed to lack of

manufacturing standardization of the products used in the

studies. The fresh garlic may contain higher amounts of the

active ingredient, allicin, which is inactivated upon cooking.

INDICATIONS AND USAGE

Approved by Commission E:

• Arteriosclerosis


• Hypertension


• Raised levels of cholesterol

Garlic is used internally as an adjuvant to dietetic measures

for elevated lipid levels. The herb is also used for prevention

of age-related vascular changes and arteriosclerosis.

Unproven Uses: In folk medicine, garlic is utilized internally

for inflammatory respiratory conditions, whooping cough

and bronchitis. Garlic is also used for gastrointestinal

ailments, particularly digestive disorders with flatulence and

gastrointestinal spasms. Other uses consist of menstrual

pains, treatment of diabetes, and as a tonic for diverse

illnesses and debilities. Externally, garlic is used for corns,

warts, calluses, otitis, muscle pain, neuralgia, arthritis and

sciatica.

Indian Medicine: Garlic is used in bronchitis, constipation,

joint pain and fever.

Homeopathic Uses: Garlic is used in conditions such as

inflammation of the upper respiratory tract, digestive com-

plaints and muscle rheumatism in the lumbar region.

PRECAUTIONS AND ADVERSE REACTIONS

General: Adverse effects such as headache, myalgia, fatigue

and vertigo have been seen with therapeutic doses of garlic

(Holzgartner, 1992).

Allergic Reactions: Frequent contact with the drug may

result in allergic reactions such as contact dermatitis and

asthma (Asero, 1998; Lee, 1991).

Burns: Garlic associated partial thickness burns and necrosis

have been reported in several case studies in which the herb

remained in contact with the skin for a minimum of 6 to 18

hours (Roberge, 1997; Garty, 1993; Parish, 1987).

Gastrointestinal: Abdominal discomfort, nausea, vomiting,

diarrhea and a feeling of fullness have occurred with garlic

therapy (Holzgartner, 1992; Berthold, 1998)

Hematologic: A significant decrease in hematocrit values

and plasma viscosity have been associated with the adminis-

tration of garlic powder (Jung, 1991). There has been risk of

postoperative bleeding with TURP (trans-urethral resection

of prostate) or mammaplasty surgery (Burnham, 1995;