Garlic Benefits

Allium sativum, camphor of the poor, clove garlic, nectar of the gods, poor man’s treacle, rustic treacle, stinking rose

Garlic was valued as an exchange medium in ancient Egypt and its virtues were described in inscriptions on pyramids. The folk uses of garlic have ranged from the treatment of leprosy in humans to managing clotting disorders in horses.

Healers prescribed the herb during the Middle Ages to cure deafness, and the Native Americans used garlic as a remedy for earaches, flatulence, and scurvy.

Medicinal ingredients of garlic are obtained from the bulb of the A. sativum plant. The aroma, flavor, and medicinal properties of garlic are primarily the result of sulfur compounds including alli-in, ajoen, and allicin. Also found in garlic are vitamins, minerals, and the trace elements germanium and selenium.

Garlic may act as an HMG-reductase inhibitor, thus moderately decreasing cholesterol and triglyceride levels. It can increase fibrinolytic activity and inhibit platelet aggregation, which is probably the work of allicin and ajoene. (Garlic oil used alone does not have this effect.) Garlic lowers blood pressure and may lower blood glucose level by increasing the body’s circulating insulin and by increasing glycogen storage in the liver. It works as an antibacterial against both gram-positive and gram-negative organisms, including Helicobacter pylori (the causative organism in many peptic ulcers and in certain gastric cancers). It may also have antifungal, antiviral, and antitumorigenic effects. Garlic prevents endothelial cell depletion of glutathione, which is thought to be responsible for its antioxidant effects.

Garlic is available as aqueous extract (1:1), capsules, fresh cloves, garlic oil, powdered cloves, softgel capsules, solid garlic extract, tablets, cream (ajoene 0.4%), and gel (ajoene 0.6%). Common trade names include Garlicin, Garlic Powermax, Garlinase 4,000, GarliPure, Garlique, Garlitrin 4,000, Kwai, Kyolic Liquid, and Wellness Garlicell.

Reported uses

Garlic is used most commonly to decrease total cholesterol and triglyceride levels, and to increase HDL cholesterol level. It’s also used to help prevent atherosclerosis because of its effect on blood pressure and platelet aggregation. Garlic is used to decrease the risk of cancer, especially cancer of the GI tract. In traditional medicine it’s used to treat cough, colds, fevers, and sore throats. Garlic is also used orally and topically to fight infection through its antibacterial and antifungal effects.


Garlic is taken as 900 mg of dried powder, 2 to 5 mg of allicin, or 2 to 5 g of fresh clove. The average dose is 4 g of fresh garlic or 8 mg of garlic oil every day.


Adverse reactions associated with garlic include headache, insomnia, fatigue, vertigo, tachycardia, orthostasis, halitosis, heartburn, flatulence, GI distress, nausea, vomiting, bloating, diarrhea, asthma, shortness of breath, contact dermatitis, burns, facial flushing, and body odor.

When taken with anticoagulants, NSAIDs, antiplatelet agents, or other herbs that exert anticoagulation effects such as feverfew and ginkgo, garlic may increase bleeding time, PT, and INR. Blood glucose level may be decreased with hypoglycemics and herbs that exert hypoglycemic effects, like glucomannan. Acetaminophen and other drugs metabolized by the cytochrome P450 enzymes 2E1, 2B1, and 2D6 may be altered by garlic. Garlic can lower serum cholesterol concentrations and test results.

Patients allergic to garlic should avoid use. Pregnant and breast-feeding patients should avoid use if consuming it in amounts greater than used in cooking. Should be used with caution in young children and in those with severe hepatic or renal disease.

Safety Risk Garlic has been associated with hypersensitivity reactiOns. Clinical considerations

  • Therapeutic doses of garlic aren’t recommended for patients with diabetes, insomnia, pemphigus, organ transplants, or rheumatoid arthritis, or for post-surgical patients.
  • Monitor patient for signs and symptoms of bleeding.
  • Garlic may lower blood glucose level. If patient is taking an antihyperglycemic, watch for signs and symptoms of hypoglycemia and monitor his serum glucose level.
  • Advise patient not to delay seeking appropriate medical evaluation because doing so may delay diagnosis of a potentially serious medical condition.
  • Advise patient to consume garlic in moderation, to minimize the risk of adverse reactions.
  • Discourage heavy use of garlic before surgery.
  • Advise patient that using garlic with anticoagulants or antiplatelet agents like NSAIDs may increase the risk of bleeding.
  • Caution patient using garlic as a topical antiseptic to avoid prolonged exposure to the skin because burns can occur.
  • Tell patient to remind pharmacist of any herbal or dietary supplement that he’s taking when obtaining a new prescription.
  • Advise patient to consult his health care provider before using an herbal preparation because a treatment with proven efficacy may be available.

Safety Risk Garlic oil shouldn’t be used to treat inner ear infections in children.

Research summary

Garlic and its extracts have a long history of folk use and recent research has indicated that the herb has significant pharmacologic activity when administered even in small doses. These include effects on blood sugar, cholesterol and lipid levels, and a distinct antithrombotic effect.

Research In one study, 432 individuals who had suffered a heart. attack were given either garlic oil extract or no treatment over a period of 3 years. (Bordia, 1989) The results showed a significant reduction of second heart attacks and about a 50% reduction in death rate among those taking garlic.

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