Garlic
Keywords: cholesterol, atherosclerosis, heart disease
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| © Steven Foster |
Introduction
This fact sheet provides basic information about garlic--uses, potential side effects, and resources for more information. Garlic is the edible bulb from a plant in the lily family. It has been used as both a medicine and a spice for thousands of years.
Common Names--garlic
Latin Names--Allium sativum
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What It Is Used For
- Garlic's most common uses as a dietary supplement are for high cholesterol, heart disease, and high blood pressure.
- Garlic is also used to prevent certain types of cancer, including stomach and colon cancers.
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How It Is Used
Garlic cloves can be eaten raw or cooked. They may also be dried or powdered and used in tablets and capsules. Raw garlic cloves can be used to make oils and liquid extracts.
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What the Science Says
- Some evidence indicates that taking garlic can slightly lower blood cholesterol levels; studies have shown positive effects for short-term (1 to 3 months) use.
- Preliminary research suggests that taking garlic may slow the development of atherosclerosis (hardening of the arteries), a condition that can lead to heart disease or stroke.
- Evidence is mixed on whether taking garlic can slightly lower blood pressure.
- Some studies suggest consuming garlic as a regular part of the diet may lower the risk of certain cancers. However, no clinical trials have examined this.
- NCCAM is supporting a study on the safety and effectiveness of three garlic preparations (fresh garlic, dried powdered garlic tablets, and aged garlic extract tablets) for lowering blood cholesterol levels. NCCAM studies are also looking at how garlic interacts with certain drugs and how it can thin blood.
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Side Effects and Cautions
- Garlic appears to be safe for most adults.
- Side effects include breath and body odor, heartburn, upset stomach, and allergic reactions. These side effects are more common with raw garlic.
- Garlic can thin the blood (reduce the ability of blood to clot) in a manner similar to aspirin. This effect may be a problem during or after surgery. Use garlic with caution if you are planning to have surgery or dental work, or if you have a bleeding disorder. A cautious approach is to avoid garlic in your diet or as a supplement for at least 1 week before surgery.
- Garlic has been found to interfere with the effectiveness of saquinavir, a drug used to treat HIV infection. Its effect on other drugs has not been well studied.
- Tell your health care providers about any herb or dietary supplement you are using, including garlic. This helps to ensure safe and coordinated care.
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Sources
National Cancer Institute. Garlic and Cancer Prevention: Questions and Answers. National Cancer Institute Web site. Accessed at cancer.gov/newscenter/pressreleases/garlic on April 28, 2006.
Agency for Healthcare Research and Quality. Garlic: Effects on Cardiovascular Risks and Disease, Protective Effects Against Cancer, and Clinical Adverse Effects. Accessed at ahrq.gov/clinic/epcsums/garlicsum.htm on April 28, 2006.
Garlic. Natural Medicines Comprehensive Database Web site. Accessed April 28, 2006.
Garlic (Allium sativum L.). Natural Standard Database Web site. Accessed April 28, 2006.
Garlic. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Lippincott Williams & Wilkins; 2000:139-148.
Milner JA. Garlic (Allium sativum). In: Coates P, Blackman M, Cragg G, et al., eds. Encyclopedia of Dietary Supplements. New York: NY: Marcel Dekker; 2005:229-240.
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For More Information
Visit the NCCAM Web site and view:
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NCCAM Clearinghouse
Toll-free in the U.S.: 1-888-644-6226
TTY (for deaf and hard-of-hearing callers): 1-866-464-3615
E-mail: info@nccam.nih.gov
CAM on PubMed
Web site: nccam.nih.gov
NIH Office of Dietary Supplements
Web site: ods.od.nih.gov
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information courtesy of NCCAM, National Institutes of Health |
