Garlic

Botanical Name(s):

Allium sativum. Family: Liliaceae

General Description:

Garlic consists of fresh or dried bulbs of the botanical plant Allium sativum, which is cultivated worldwide. The bulb or clove is the part of the plant most commonly used, but sometimes garlic oil is used. Garlic is best stored hung in plaits in a dry place.

Garlic contains alliin, which, when ground, produces the strong-smelling, potent antibacterial agent allicin. In addition to its supposed antibacterial properties, garlic is claimed to provide protection against atherosclerosis and stroke because of its ability to inhibit platelet aggregation and decrease high blood pressure and high cholesterol.

Medically Valid Uses:

Currently, there is no documented valid medical use for garlic.

Unsubstantiated Claims:

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Garlic contains allicin, a potent antibiotic that is released when cloves are crushed or chewed. Garlic has been used as an antiseptice, antibacterial, and antifungal agent. It is claimed to help the body resist or destroy viruses and other microorganisms by enhancing the body's immune system. It may inhibit platelet aggregation; prolong bleeding time, enhancing fibrinolytic activity.; and reduce blood pressure (antihypertensive).

Garlic is also claimed to fight infection, as well as build up strength. It has been used to reduce cholesterol and lower blood pressure.

Garlic may help treat chronic bronchitis, respiratory catarrh, recurrent colds and respiratory infections, chronic episodes of earache, sore throat, sinus problems and influenza. Garlic is thought to be useful in treating yeast infections and intestinal worms, and to have laxative properties.

Dosing Format:

Garlic is available fresh, dried in capsule form (enteric-coated capsules are easiest for the body to absorb), as an extract and as odorless supplements. The quality of commercial preparations varies greatly.

Normal dosage is 4 g of fresh garlic or 8 mg of essential oil per day (equivalent to 1 fresh clove daily), or as directed on the label.

Side Effects, Toxicity and Interactions:

Garlic has a strong taste and odor, and raw garlic can cause stomach or intestinal upset in some people. Odorless garlic supplements eliminate offending taste and odor and may reduce or eliminate gastrointestinal upset. Some people are allergic to garlic. When taken in large amounts, garlic may have toxic effects, causing stomach ulcers and anemia.

There are no known significant food or drug interactions associated with garlic.

Additional Information:

Click here for a list of reputable Web sites with general information on nutrition.

References:

1. Cilagy C, Neil A. A meta-analysis of the effect of garlic on blood pressure. J Hypertension. 1994;12:463-468.

2. Jain AK. Can garlic reduce levels of serum lipids. JAMA. 1993;94:632-635.

3. Gruenwald J, Brendler T, Jaenicke C, eds. PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company; 1998.

4. Blumenthal M, Gruenwald J, Hall T, Rister RS, eds. German Commission E Monographs. Austin, TX: American Botanical Council; 1997.

5. The US Department of Agriculture publications.

6. Robbers JE, Tyler VE. Tyler's Herbs of Choice: The therapeutic use of phytomedicinals. Binghamton, NY: Haworth Press; 1999.

7. Dr. Duke's phytochemical and ethnobotanical databases. Agricultural research service, Duke University.

8. O'Hara M, Kiefer D, Farrell K, Kemper K. A review of 12 commonly used medicinal herbs. Arch Fam Med. 1998;7:523-536.

9. Gao CM, Takezaki T, Ding JH, Li MS, Tajima K, Protective effect of allium vegetables against both esophageal and stomach cancer: a simultaneous case-referent study of a high-epidemic area in Jiangsu Province, China. Jpn J Cancer Res 1999. 1999;90(6):614-21.

10. Ledezma E, Lopez JC, Marin P, et al. Ajoene in the topical short-term treatment of tinea cruris and tinea corporis in humans. Randomized comparative study with terbinafine. Arzneimittelforschung. 1999;49(6):544-7.

11. Berthold HK, Sudhop T, Garlic preparations for prevention of atherosclerosis. Curr Opin Lipidol. 1998;9(6):565-9.

12. McCrindle BW, Helden E, Conner WT, Garlic extract therapy in children with hypercholesterolemia. Arch Pediatr Adolesc Med. 1998;152(11):1089-94.

13. Isaacsohn JL, Moser M, Stein EA, et al. Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial. Arch Intern Med. 1998;158(11):1189-94.

14. El-Sabban F, Radwan GM. Influence of garlic compared to aspirin on induced photothrombosis in mouse pial microvessels, in vivo. Thromb Res. 1997;88(2):193-203.