What is Garlic?

What is Garlic?

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:

Thanks to the University of North Carolina School of Pharmacy for the use of this article!

Amy Bigus, Deanna Massengill, and Christy Walker

Common Names

  • Garlic – Anglo Saxon origin
  • (gar – a spear, lac – a plant, referring to shape of leaves)
  • "Poor Man's Treacle" – meaning Theriac or "heal all"
  • Allium sativum – Celtic origin (all – meaning pungent)

General description

  • Member of lily family
  • Same group of plants as the onion
  • Long narrow leaves that are flat like grass
  • Bulb is used as medicinal spice or herb – consists of numerous "bulblets" or individual cloves grouped together and enclosed in a thin white skin
  • Whitish flowers are found in groups at the end of the stalk that rises directly from the bulb
  • Cultivated throughout the world – planted in Feb/March, harvested in Aug/Sept
  • Native to Mediterranean regions of Europe & Africa, Origin in central Asia (?), Used extensively in Italian & Greek dishes

Chemical Composition

  • Steamed distillation of crushed fresh bulbs yields 0.1-3.6% of a volatile oil
  • Some sulfur-containing compounds that make up this oil are thought to be responsible for most of garlic's pharmacological properties:
  • Allicin
  • Diallyl disulfide
  • Diallyl trisulfide
  • Others


  • Natural antibiotic - fights bacteria
  • Mainly responsible for pungent odor
  • When garlic cells are "injured," (i.e.cut, crushed, etc.) the enzyme alliinase converts alliin contained in raw garlic to allicin – the garlic produces allicin to protect itself from bacteria & other disease-causing organisms.
  • Extremely unstable & decomposes rapidly at room temperature (half-life only slightly more than a few hours)


  • Inactivated by heat – cooked garlic does not have as strong an odor as raw garlic (nor nearly as powerful physiological effects)


  • Decreases blood cell clumping – (s chances of stroke
  • Released when garlic is ground, chewed or cooked


  • Antioxidant contained in high quantities in garlic
  • Antioxidants fight oxidation & free radicals inside the body that wear out the body & may lead to cancer


  • Lowers blood pressure, decreasing chance of stroke


  • May stimulate the immune system


  • Use predates written history
  • Sanskrit documents its use ~5000 years ago
  • Chinese using it for more than 3000 years
  • Egyptian Medical Papyrus: The "Codex Ebers" ~1550 BC
  • Ward off evil spirits/Vampires (?!)
  • History (cont'd)
  • Great (Bubonic) Plague of 1665 in England
  • Plague of 1721 – Marseilles, France "Four Thieves Vinegar"
  • 1800s – treat influenza in Russia
  • Louis Pasteur – 1858 – noted garlic's antibiotic properties

Folk Use

  • Hypertension
  • Diarrhea
  • Headache
  • Dysentery
  • Snake bites
  • Diphtheria
  • Worms (parasites)
  • Vaginitis
  • Tumors
  • Asthma/Difficulty Breathing
  • Nasal congestion
  • Antiseptic
  • Coughs
  • Typhus
  • Toothache
  • Cholera
  • Earache
  • Whooping cough
  • Dandruff
  • Rheumatism
  • Atherosclerosis
  • Tubercular consumption
  • Epilepsy
  • Hysteria


Antimicrobial Activity ( broad spectrum activity against many bacteria, viruses, worms & fungi)

  • Antibacterial Activity
  • Inhibits growth of Staphylococcus, Streptococcus, Bacillus, Brucella & Vibro species, as well as E. coli, Proteus vulgaris, Salmonella enteritidis, Klebsiella pneumonia and Mycobacteria
  • Antifungal Activity
  • Inhibition of Candida albicans and cryptococcus neoformans;  Garlic has been shown to be more potent than nystatin, gentian, violet & 6 other reputable anti-fungals.

Anthelminitic Effects

  • Activity against common intestinal worms including Ascaris lumbricoides (roundworm) and hookworm

Anti-viral effects

  • Herpes simplex type 1 and 2
  • Parainfluenza virus type 3
  • Human rhinovirus type 2

Immune enhancing effects

  • Mobilizes body's own immune system
  • Stimulates the ability of natural killer cells to destroy tumor cells, virus-infected cells & foreign invaders
  • Increases macrophage activity
  • Increasing importance in AIDS research

Anti-cancer effects

  • Inhibiting tumor growth
  • Blocking carcinogens (reduce potential damage from oxidation, free radicals & nuclear radiation)
  • Enhancing immunity

Cardiovascular effects

  • Protection from heart disease & strokes via effects of atherosclerosis (lower cholesterol & blood pressure)


  • Anti-inflammatory effects – inhibition of formation of inflammatory compounds
  • Hypoglycemic action – due to increased hepatic metabolism, a raise in release of insulin and/or insulin-sparing effect

Miscellaneous Effects:

  • Diuretic
  • Diaphoretic
  • Emmenagogue
  • Expectorant
  • Carminative
  • Anti-spasmodic
  • Digestant

Clinical Applications


A number of double-blind placebo controlled studies in pts with initial cholesterol >200 – supplemented with commercial preparations of at least 10 mg alliin/day or total allicin potential of 4000 mcg/day:

  • decreased total serum cholesterol ~10-12%
  • decreased LDL ~15%
  • increased HDL ~15%
  • decreased triglyceride ~15%

Prevention of heart disease & stroke


  • decreased systolic (~11 mmHg) & diastolic (~5 mmHg) BPs
  • decreased risk stroke ~30-40%
  • decreased risk heart attack ~20-25%

Inhibit Platelet Aggregation

  • Decreased atherosclerosis, heart disease & stroke by decreasing plasma viscosity, decreasing DBP, and decreasing fasting blood glucose


  • increases serum fibrinolytic activity – promote fibrinolysis & therefor offer benefit in prevention of heart attacks, strokes & various thromboembolic events

Prevent LDL-Oxidation

  • New evidence that LDL ox has a role in atherosclerosis development – no studies yet on this

Available Products/Forms:

  • raw or cooked cloves
  • dehydrated powder
  • (powder, capsules, tablets)
  • oil
  • (Kyolic) Aged Garlic Extract
  • syrup
  • juice or milk
  • tincture


  • Standardization for alliin content
  • "Allicin Potential"
  • At least ( 4000 mg fresh garlic equivalent to 1-to-2 cloves, at least 10 mg alliin or a total allicin potential of 4000 (g


  • Generally regarded as safe.
  • Minor Side Effects:
  • GI burning/irritation, bleeding
  • indigestion
  • loss of appetite
  • diarrhea
  • Rare Side Effects:
  • anemia
  • oxidation of essential body components


"Garlic then have power to save from death

Bear with it though it maketh unsavory breath,

And scorn not garlic like some that think

It only maketh men wink and drink and stink."

     Sir John Harrington (1609)


Jain AK, Vargas R, Gotzkowsky S and FG McMahon.  "Can garlic reduce levels of serum lipids?  A controlled clinical study."  American Journal of Medicine.  94(6):  632-5, June 1993.

Murray MT.  The Healing Power of Herbs.  Rocklin, CA:  Prima Publishing, 1996, pp. 121-131.

Orekhov AN, Tertov VV, Sobenin IA and EM Pivovarova.  "Direct anti-atherosclerosis-related effects of garlic.'  Annals of Medicine.  27(1):63-5, Feb. 1995.

Pizzorno JE and MT Murray.  "Allium Sativum," A Textbook of Natural Medicine.  Bothell, WA:  Bastyr University Publications, Vol. 1, 1996.

Silagy CA and HA Neil.  "A meta-analysis of the effect of garlic on blood pressure."  Journal of Hypertension.  12(4):463-8, April 1994.

Steiner M, Khan AH, Holbert D and RI Lin.  "A double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo adminstration on blood lipids."  American Journal of Clinical Nutrition.  64(6):  866-70, 1996.

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