Written by Edzard Ernst and the CAM-Cancer Consortium.
Updated September 29, 2011

Garlic (Allium sativum)

What is it ?

Scientific / common name

Allium sativum L (Alliaceae/Liliaceae) is commonly referred to as garlic. Ajo is also sometimes used.

Fresh or dried parts of the bulb or the oil from the bulb are commonly used for medicinal purposes.

Ingredients

Alliin, diallyldisulfate, ajoen and others1. Allicin, considered to be one of the main active ingredients, and other sulfur-containing compounds are formed from alliin enzymatically when garlic is crushed or chopped1,2. It is considered that 1 mg alliin is equivalent to 0.45 mg allicin2,3. Commercial garlic preparations are often standardised on the content of sulfur-containing constituents, particularly to alliin, or on the allicin yield2.

Application

It is usually taken orally in the following dosages.
Dried bulb: 2- 4g three times daily for upper respiratory tract infections10,17,18; 0.5-1.0g daily for the prophylaxis of atherosclerosis4,5.
Fresh garlic: 4g daily1,2,6.
Oil: 0.03-0.12 ml three times daily2,7.
Juice of garlic (BPC 1949) 2-4 ml2,8.
Extract: 600-900mg of standardised extract (1.3% alliin content) daily in divided doses1.

History/providers

It has been used medicinally in several ancient cultures. Prescribers today are mainly herbalists, naturopaths and doctors. Many consumers self-prescribe garlic supplements. Garlic is a common food and spice. It is offered as “over the counter “ (OTC) preparations (food supplements) in form of single-ingredient or multi-ingredients preparations by many providers (see list in9).

Claims of efficacy

The Monograph of ESCOP (2003) recommends Allii sativi bulbus for the prophylaxis of atherosclerosis, for the treatment of elevated blood lipid levels insufficiently influenced by diet, for the improvement of the circulation in peripheral arterial vascular disease and for upper respiratory tract infections and catarrhal conditions4,5.

The WHO-Monograph states uses supported by clinical data as adjuvant to the dietetic management in the treatment of hyperlipidaemia, and in the prevention of atherosclerosis, age dependent vascular changes and mild hypertension5,10.

Claims of efficacy in the prevention of cancer are mainly based on in vitro and animal studies2.

Mechanism of action

It has antibacterial, antiviral, antifungal, antihypertensive, blood glucose lowering, antithrombotic, antimutagentic and antiplatelet activities1.

Alleged indications

Some people claim that garlic might reduce the cancer risk.

Prevalence of use

It is widely used as a food and spice. Garlic supplements have become very popular in developed countries. Exact prevalence figures are not available.

Legal issues

Garlic preparations are sold in most countries as food supplements.

Cost and expenditure

A one week supply of garlic supplements would cost between €5 and €10.

Citation

Edzard Ernst, CAM-Cancer Consortium. Garlic (Allium sativum) [online document]. http://www.cam-cancer.org/CAM-Summaries/Herbal-products/Garlic-Allium-sativum. September 29, 2011.

Document history

References

  1. Ernst E, Pittler MH, Wider B, Boddy K. The Desktop Guide to Complementary and Alternative Medicine. 2nd edition. Edinburgh: Elsevier Mosby. 2006.
  2. Barnes J, Anderson LA, Phillipson DJ. Herbal Medicines. London: Pharmaceutical Press. 2007;279-289.
  3. European Scientific Cooperative of Phytotherapy. Monographs on the Medicinal uses of plant drugs: Fascicules 1 and 2 (1996), Fascicules 3, 4 and 5 (1997), Fascicule 6 (1999). Exeter: European Scientific Cooperative of phytotherapy.
  4. Schilcher H, Kammerer S, Wegener T. Leitfaden Phytotherapie. Urban & Fischer Verlag/ Elsevier GmbH, München. 3rd Edition. 2007;151-152.
  5. European Scientific Cooperative of Phytotherapy. Allii sativi bulbus. Monographs on the Medicinal uses of plant drugs. 2nd Edition. Thieme Verlag. 2003.
  6. European Scientific Cooperative of Phytotherapy. Monographs on the Medicinal uses of plant drugs: Fascicules 1 and 2 (1996), Fascicules 3, 4 and 5 (1997), Fascicule 6 (1999). Exeter: European Scientific Cooperative of phytotherapy.
  7. Bradley P. British Herbal Compendium. Vol. 1 Bournemouth: British Herbal Medicine Association. 1992.
  8. British Pharmaceutical Codex 1949: London: Pharmaceutical Press. 1949.
  9. Barnes J, Anderson LA, Phillipson DJ. Herbal Medicines. 2nd ed. London: Pharmaceutical Press. 2002.
  10. WHO. Monograph on selected medicinal plants, Vol 1. Geneva: WHO. 1999.
  11. Fleischauer AT, Poole C, Arab L. Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers. Am J Clin Nutr 2000; 72:1047-1052.
  12. Kim JY, Kwon O. Garlic intake and cancer risk: an analysis using Food and Drug Adminstration's evidence-based review system for the scientific evaluation of health claims. Am J Clin Nutr 2009; 89:257-264.
  13. Satia JA, Littman A, Slatore CG, Galanko JA, White E. Associations of herbal and specialty supplements with lung and colorectal cancer risk in the VITamins and Lifestyle study. Cancer Epidemiol Biomarkers Prev 2009; 18(5):1419-1429.
  14. Bianchini F, Vainio H. Allium vegetables and organosulfur compounds: do they help prevent cancer? Envir Health Persp 2001; 109(9):893-902.
  15. Fulder S. Garlic and the prevention of cardiovascular disease. Cardil Pract 1989; 7:30-35.
  16. Nakagawa S, et al. Acute toxicity test of garlic extract. J Toxicol Sci 1984; 9:57-60.
  17. Papageorgiou C, et al. Allergic contact dermatitis to garlic (Allium sativum L.) Identification of the allergens: The role of mono-, di-, and trisulfides present in garlic. Arch Dermatol Res 1983; 275:229-234.
  18. Symposium on the chemistry, pharmacology and medicinal applications of garlic. Cardiol Pract 7, 1-15. 1989.
  19. Symposium on the chemistry, pharmacology and medicinal applications of garlic. Cardiol Pract 7, 1-15. 1989.
  20. Sunter WH. Warfarin and garlic. Pharm J 1991; 246:722.
  21. Izzo AA, Ernst E. Interactions between herbal medicines and prescribed drugs: a systematic review. Drugs 2009; 69(13):1777-1798.
  22. Berginc K, Trdan T, Trontelj J, Kristl A. HIV protease inhibitors: garlic supplements and first-pass intestinal metabolism impact on the therapeutic efficacy. Biopharm Drug Dispos 2010; 31:495-505.
  23. Tanaka S, Haruma K, Masaki K, Nagata S, Kitadai Y, Manabe N et al. Effects of aged garlic extract (AGE) on colorectal adenomas: a double-blinded study. Hiroshima J Med Sci 2004; 53(3-4):39-45.
  24. Tanaka S, Haruma K, Yoshihara M, Kajiyama G, Amagase H, et al. Aged garlic extract has potential suppressive effect on colorectal adenomas in humans. J Nutr 2006; 136:821S-825S.
  25. Li H, Li H-Q, Wang Y, Xu H-X, Fan W-T, Want M-L et al. An intervention study to prevent gastric cancer by micro-selenium and large dose of allitridum. Chinese Med J 2004; 117(8):1155-1160.
  26. Ishikawa H, Saeki T, Otani T, Suzuki T, Shimozuma K, Nishino H et al. Aged garlic extract prevents a decline of NK cell number and activity in patients with advanced cancer. J Nutr 2006; 136:816S-823S.
  27. You WC, Brown LM, Zhang L, Jin M-L, Chang Y-S, et al. Randomized double-blind factorial trial of three treatments to reduce the prevalence of precancerous gastric lesions. J Natl Cancer Inst 2006; 98:974-983.
  28. Cox MC, Low J, Lee J, Walshe J, Denduluri N, Berman A et al. Influence of garlic (Allium sativum) on the pharmacokinetics of docetaxel. Clin Cancer Res. 2006;12:4636-40.
  29. Markowitz JS, DeVane CL, Chavin KD, Taylor RM, Ruan Y, Donovan JL. Effects of garlic (Allium sativum L.) supplementation on cytochrome P450 2D6 and 3A4 activity in healthy volunteers. Clin Pharmacol Ther. 2003;74:170-177.
  30. Hajda J, Rentsch KM, Gubler C, Steinert H, Stieger B, Fattinger K. Garlic extract induces intestinal P-glycoprotein, but exhibits no effect on intestinal and hepatic CYP3A4 in humans. Eur J Pharm Sci. 2010;41:729-35.
  31. Ho BE, Shen DD, McCune JS, Bui T, Risler L, Yang Z et al. Effects of Garlic on Cytochromes P450 2C9- and 3A4-Mediated Drug Metabolism in Human Hepatocytes. Sci Pharm. 2010;78:473-81.
  32. Greenblatt DJ, Leigh-Pemberton RA, von Moltke LL. In vitro interactions of water-soluble garlic components with human cytochromes p450. J Nutr. 2006;136:806S-9S.
  33. Le Bon AM, Vernevaut MF, Guenot L, Kahane R, Auger J, Arnault I et al. Effects of garlic powders with varying alliin contents on hepatic drug metabolizing enzymes in rats. J Agric Food Chem. 2003;51:7617-23.
  34. Piscitelli SC, Burstein AH, Welden N, Gallicano KD, Falloon J. The effect of garlic supplements on the pharmacokinetics of saquinavir. Clin Infect Dis. 2002;34:234-38.
  35. Berginc K, Milisav I, Kristl A. Garlic flavonoids and organosulfur compounds: impact on the hepatic pharmacokinetics of saquinavir and darunavir. Drug Metab Pharmacokinet. 2010;25:521-30.
Legal notice
The present documentation has been compiled by the CAM-CANCER Project with all due care and expert knowledge. However, the CAM-CANCER Project provides no assurance, guarantee or promise with regard to the correctness, accuracy, up-to-date status or completeness of the information it contains. This information is designed for health professionals. Readers are strongly advised to discuss the information with their physician. Accordingly, the CAM-CANCER Project shall not be liable for damage or loss caused because anyone relies on the information.