Garlic: Overview

If garlic had been created in the laboratory instead of by nature, it would probably be a high-priced prescription drug.  Garlic has been used medicinally for at least 3,000 years, but until recently its benefits were considered little more than folklore.  Medical studies have shown that garlic can lower cholesterol, prevent dangerous blood clots, protect LDL cholesterol and the endothelial lining of the arterial system against oxidation, reduce blood pressure, prevent cancer, and protect against bacterial and fungal infections.

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In what seems to be one of nature's contradictions, raw garlic has less biological activity than when processed in some way.  When it is "damaged", by slicing, cooking or chewing, the enzyme alliinase immediately converts alliin into allicin, which gives garlic its characteristic odor.  Research is continuing to help define which forms of garlic are best for which purposes.

Function; Why it is Recommended

Just what makes garlic so good?  Known scientifically as Allium sativum, garlic contains more than 100 biologically useful chemicals, including substances with names such as alliin, alliinase, allicin, S-allylcysteine, diallyl sulfide and allyl methyl trisulfide.

Scientific research has confirmed garlic's role as a natural antibiotic.  Garlic extract has broad-spectrum antimicrobial activity against many types of bacteria and fungi.  Garlic holds a promising position as a broad-spectrum therapeutic agent because many of the microorganisms susceptible to garlic extract are medically significant. [Medical Hypotheses 1983;12 pp.227-37]

One way garlic enhances the immune system is by promoting phagocytosis, the ability of white blood cells to fight infections.  Another is by stimulating other immune cells, such as macrophages and T-cells to fight bacterial and viral infections and to scavenge for cancer cells.  One report described how garlic enhanced the body's natural killer cell activity against the AIDS virus. [Deutsche Zeitschrift fuer Onkologie, April 1989;21 pp.52-3]

Allicin was once thought to be garlic's principal active ingredient but researchers now know that allicin is rapidly oxidized into more than 100 biologically active compounds.  While allicin may still serve as a general marker of garlic's potency, research increasingly points to S-allylcysteine and other compounds as the most therapeutically active ingredients in garlic.

Garlic is so effective in preventing abnormal arterial blood clotting (thrombosis) that some surgeons advise their patients to avoid garlic one week prior to surgery because garlic can cause excessive bleeding during surgery.

One study found that aged garlic extract at 7.2gm per day reduced total and LDL cholesterol, as well as systolic and diastolic blood pressure. [Cpol 1/99]


So how should you take garlic?  Most scientific studies have, for consistency, used a standardized garlic extract in capsule or liquid form.  However, just about any form offers some benefits.  If you enjoy the taste of garlic, and others are not offended by the odor on your breath, use it liberally in your food.  Otherwise, deodorized garlic provides the desired benefits without the odor.  Either way, garlic is good for your health.

For anti-bacterial or anti-viral effect, raw garlic is better than cooked.  Both raw and cooked garlic seem to have cardiovascular, decongestive and anti-cancer benefits.  Eating more than three raw cloves a day can cause gas, bloating, diarrhea and fever in some people.  Cooked garlic is gentler on the stomach.

Garlic can help with the following:



When taken in high doses, garlic increases fibrinolytic activity.  This increased fibrinolytic activity inhibits platelet aggregation which contributes to the formation of blood clots.


A mechanism by which atherosclerotic plaque accumulates on the walls of arteries is the oxidation of LDL cholesterol.  Garlic has been shown in repeated studies to protect against LDL cholesterol oxidation and oxidation in the linings of the arteries themselves.  Garlic, ginger and onions all have a beneficial effect on platelet aggregation which reduces the tendency to form clots too easily, thus preventing the blockage of narrowed arteries.

Intermittent Claudication

A standardized extract of garlic has been tested as a treatment for intermittent claudication.  In a double-blind trial, the increase in walking distance was significantly greater in people receiving garlic powder extract (400mg twice per day for 12 weeks) than in those given a placebo. [Kiesewetter H, Jung F, Jung EM, et al. Effects of garlic-coated tablets in peripheral arterial occlusive disease. Clin Investig 1993;71: pp.383-6]

Hypertension (High Blood Pressure)

One study found that aged garlic extract at 7.2gm per day reduced total and LDL cholesterol, as well as systolic and diastolic blood pressure.

Varicose Veins

To disperse the build-up of a protein called fibrin that makes skin near varicose veins hard and lumpy, try eating more cayenne pepper, garlic, onion, ginger (zingiber officinale), and pineapple, which contains bromelain, an enzyme that promotes the breakup of fibrin.

Not recommended for


Poor Small Intestine Health

Garlic will kill harmful intestinal bacteria and promote the growth of beneficial acid-producing bacteria.

Environment / Toxicity

Mercury Toxicity (Amalgam Illness)

Garlic chelates heavy metals such as cadmium, gold, lead and mercury, and acts as a detoxifier.

Heavy Metal Toxicity

Garlic chelates heavy metals such as cadmium, gold, lead and mercury, and acts as a detoxifier.



In one study, 10 patients with AIDS who were given 5 to 10gm per day of an aged garlic extract later had increased levels of natural killer cells, a higher helper:suppressor ratio, and reduced infection rates.

Immune System Imbalance (TH2 Dominance)

Garlic, raw or aged extract, promotes TH1 cytokines to help balance the immune system.  Raw garlic can kill many kinds of fungus and bacteria.


Yeast / Candida Infection

Liberal consumption of garlic, ginger, cinnamon and other aromatic herbs can have significant antifungal activity.

Lyme Disease

Include garlic in your diet.  It is a natural antibiotic and immune-booster.

Athletes Foot

Garlic is an excellent antibiotic and studies have shown that its compounds can very effectively kill the fungus that causes athlete's foot.  There are several possible methods of application:

  • Place some freshly crushed garlic on the affected area once per day and leave it there for half an hour; wash with water
  • Rub a broken clove of raw garlic on the fungus, leaving only the juice behind
  • Dust your feet twice daily with garlic powder.

Caution is advised if the skin is badly broken as garlic may produce a significant burning sensation; even if the skin is not broken, blistering may occur.  Aside from the pain, this is not a problem – it shows that the garlic is going its work!  Should the pain prove unbearable, remove any pieces and wash with water.  You may try again later with diluted garlic juice.  If this does not work for you, consider using a different approach.



Garlic is antibacterial and supports the immune system.

Lab Values

High Total Cholesterol

Several studies have shown a mild lowering effect on total cholesterol and LDL cholesterol.  Garlic oil does not produce this cholesterol-lowering benefit like raw, cooked or powdered garlic does.  Large doses are required (6,000 to 8,000mg per day) to produce this effect, which causes gastrointestinal discomfort for some people.  Furthermore, this benefit does not become evident until after 3 months of continuous use.


Sulfur Requirement

Sulfur occurs naturally in garlic and onions and may be partially responsible for the health benefits associated with these foods. [Augusti KT. Therapeutic values of onion (Allium cepa L.) and garlic (Allium sativum L.). Indian J Exp Biol 1996;34: pp.634-40]

Organ Health


Giardiasis Infection

Garlic has traditionally been used as an antiparasitic and antimicrobial agent.  Recent research has substantiated its traditional uses and discovered probable active constituents and possible mechanisms of action.  Harris et al demonstrated the antigiardial activity of both whole raw garlic and some of its constituents.

Whole garlic extract demonstrated an I[C.sub.50] (the concentration that inhibits growth of parasites by 50%) of 0.3mg/ml, while the allicin breakdown products diallyl disulfide, diallyl sulfide, and allyl mercaptan demonstrated I[C.sub.50] values of 0.1mg/ml, 1.3mg/ml, and 0.037mg/ml, respectively.  Other garlic constituents, such as allyl alcohol and dimethyl disulfide were also strongly inhibitory (with I[C.sub.50] values of 0.007mg/ml and 0.2mg/ml, respectively).

Researchers Soffar and Mokhtar performed an open trial investigating the use of garlic in giardiasis.  Twenty-six children infected with G. lamblia took 5ml crude extract (fresh garlic blended with distilled water and then centrifuged and filtered to remove the solids) in 100ml water twice daily or a commercial garlic preparation two capsules (0.6mg capsules) twice daily for three days.  Both preparations were given on an empty stomach two hours before meals.  Clinical symptoms subsided in all cases within 36 hours.  Parasitic cure (according to stool examinations) occurred within three days of beginning treatment.

Pinworm Infection

Studies in humans support the use of garlic to treat various worms, including pinworm. [Garlic: The Science and Therapeutic Application of Allium sativum L. and Related Species. Williams & Wilkins, 1996, pp.173-4]  In addition to consuming garlic, consider carefully peeling a raw garlic clove (don't scratch or nick it), then insert into rectum before bed.



Crush a clove of garlic, apply to wart, tape in place for 24 hours.  The wart may blister and fall off in a week.

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Garlic can help prevent the following:


Tumors, Malignant

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may help with; may help prevent
Moderately useful: often helps with
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often helps with
Very useful: is highly recommended for
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is highly recommended for
Often counterindicated: is often not recommended for
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is often not recommended for
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