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Garlic(Allium sativum) |
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Introduction
Garlic has been advocated as a remedy for the treatment and prevention of a variety of health problems. Oil of Garlic is sometimes used on the skin as an aide for the treatment of skin infections.
Folklore has it that garlic can ward off vampires and werewolves. More recently garlic has been promoted as being capable of lowering bad (LDL), raising good (HDL) cholesterol and lowering blood pressure. Many people, including this author, find garlic to be very tasty when added to certain foods.
How is garlic taken?
Garlic, taken by mouth, is available as powdered extracts, in pill form, garlic oils or garlic cloves.
Does garlic really work?
Its cardioprotective effects seem worthy of study; however, previous studies appear to have been flawed or poorly designed. Review of available well controlled studies- double blind (parallel or cross over ) placebo controlled studies to determine garlic's effect on cholesterol revealed disappointing results. Three of four studies examined showed no benefit of garlic on lowering blood cholesterol levels. 2, 3, 4 The one study that concluded garlic was beneficial in lowering cholesterol and blood pressure showed very modest results that were not likely to be statistically significant. 1
Several studies have suggested that garlic may reversibly inhibit platelet activity. Platelets are a specialized type of blood cell that clump together to prevent bleeding. Aspirin is an irreversible platelet inhibitor. It has been speculated, but not scientifically demonstrated, that this property may help prevent heart attacks and strokes due to the development of blood clots in cholesterol narrowed arteries of the heart and brain.
What other medicines can interact with garlic?
•anti-inflammatory medications, such as ibuprofen or naproxen
•aspirin, ASA
•warfarin
•heparin
•other drugs that affect bleeding or platelets
If you are scheduled to have surgery, remember to tell your surgeon and anesthesia specialist that you are taking garlic. In some cases they may want you to discontinue taking the garlic supplement prior to the surgery.
What should my health professional know before I take garlic?
Even if garlic does not lower cholesterol or blood pressure there is no harm in taking it for a vast majority of people. However, the following persons should notify their physician if taking garlic supplements (or large amounts of natural garlic) on a regular basis:
•abnormal bleeding problems or a history of bleeding
•diabetes or blood glucose problems
•an unusual or allergic reaction to garlic, other prescription or nonprescription medicines, foods, dyes, or preservatives
•pregnant or trying to get pregnant
•breastfeeding
Be aware of any signs of bleeding especially if you have a history of bleeding disorders, are taking "blood thinners" such as warfarin, are taking aspirin or any other anti-inflammatory medicines.
What side effects may I notice from taking garlic?
Rare or uncommon:
•bleeding
•rash
•itching
•swelling of tongue, lips or throat
Side effects that usually do not require medical attention (report to your health care professional if they continue or are bothersome) for oral garlic:
•gas
•nausea
•headache
•upset stomach
Side effects associated with topical garlic applied to the skin should be reported to your physician as soon as possible:
•burning of the skin
•inflammation of the skin (dermatitis)
Bottom Line
Garlic is an ancient herb possessing complex biologic activity that may be beneficial in the prevention of cardiovascular disease. It appears to have inhibitory activity of platelet clotting which might be beneficial in reducing the incidence of heart disease and stroke.
However, further well designed and controlled studies will be needed to prove or disprove this theory. At present evidence does not support garlic significantly lowering blood pressure or cholesterol. The bottom line is to continue using garlic if you enjoy its' taste alone or as a seasoning with food provided you have no contraindications but don't count on it as a miracle pill.
Dietary supplements include vitamins, minerals, amino acids , herbs, botanicals, and other plant-derived substances, and extracts of these substances. These products are easy to identify as they must state "Dietary Supplement" on the label. A "Supplement Facts" panel is provided on the label for most products.
Supplements are not legally considered drugs (although some exhibit "drug" properties) and are not regulated like drugs. Rigid quality control standards are not required for dietary supplements. Big differences in potency and purity of these products can occur. Scientific data to support the use of a dietary supplement for a certain disease or ailment may not be available. This product is not intended to diagnose, treat, cure or prevent any disease.
1. "A double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipids." Steiner M, Khan AH, Holbert D, Lin RI Memorial Hospital of Rhode Island, Pawtucket, USA. Am J Clin Nutr 1996 Dec;64(6):866-70
2. "Effect of a garlic oil preparation on serum lipoproteins and cholesterol metabolism. A randomized controlled trial." Berthold HK, et al. JAMA June 17, 1998;279:1900-2.
3. "Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial." Isaacsohn JL, Moser M, Stein EA, Dudley K, Davey JA, Liskov E, Black HR The Christ Hospital Cardiovascular Research Center, Cincinnati, Ohio, USA Arch Intern Med 1998 Jun 8;158(11):1189-94
4. "Garlic powder in the treatment of moderate hyperlipidaemia: a controlled trial and meta-analysis." Neil HA, Silagy CA, Lancaster T, Hodgeman J, Vos K, Moore JW, Jones L, Cahill J, Fowler GH Department of Public Health and Primary Care, University of Oxford. J R Coll Physicians Lond 1996 Jul-Aug;30(4):329-34
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