Date Last Updated: 27/10/04

Garlic for the treatment of calf pain when walking

Overview

Peripheral arterial disease (PAD) is the narrowing of the large arteries of the lower legs, caused by abnormal thickening and hardening of the arterial walls. People with PAD commonly experience pain in the calf when walking, leg cramps, and numbness or tiredness in the calf or thigh muscles. Garlic is a plant often used in herbal medicine for treating cardiovascular disease and abnormal thickening of the arterial walls (atherosclerosis). This evidence summary identified one health technology assessment, one systematic review and two clinical trials (with a total of 180 patients) on the use of garlic for the treatment of the PAD. The two reviews concluded that there was insufficient information from the identified trials to conclude that garlic has any clear effect on PAD. However, the two trials reported some increase in the distance a person with PAD can walk without pain, in those patients taking garlic. Mild but reversible side effects have been reported with garlic, including bad breath, body odour, flatulence, and inflammation of the skin upon contact (contact dermatitis). More serious side effects have also been reported, including an increase in the risk of bleeding, heart attack, stomach pain, vomiting blood, and lesions on the lining of the stomach.

Background

Peripheral arterial disease
Peripheral arterial disease (PAD) is the narrowing or blockage of the large arteries of the lower leg¹. The commonest cause of this condition is the formation and build-up of calcified fat deposits (atherosclerotic plaques), which lead to the abnormal thickening and hardening of the arterial walls (atherosclerosis)^{2, 3}. This process results in reduced blood flow within the affected arteries. The most common symptom of PAD is pain in the calf area that occurs when walking but stops after rest - usually after one to five minutes⁴ (referred to as intermittent claudication). Along with leg pain, people with intermittent claudication may also experience leg cramps (spasm), and numbness or a sense of tiredness in the calf or thigh muscles¹. When the blood supply to a foot is severely reduced, the foot may become cold, and the skin may become dry, or cracked⁴. Also the person may develop sores on the foot that do not easily heal, especially after injury⁴. In people with severe PAD, wounds in the skin may take weeks or months to heal or may not heal⁴ (referred to as foot or leg ulcers). Cigarette smoking, raised blood cholesterol (hypercholesterolaemia), raised blood pressure (hypertension), and diabetes mellitus increase the risk of developing PAD^{1, 2}.

Prevention⁴ and treatment options⁵ for intermittent claudication include smoking cessation, blood pressure control, treatment of high cholesterol, and managing diabetes. Supervised exercise programs may also improve the functioning of leg muscles, thereby enabling people with intermittent claudication to walk further^{1, 5, 6}. Treatment options for PAD as a whole include foot care and the use of good fitting, protective shoes to protect against injury¹ that could lead to the development of foot ulcers. Surgery on the arteries in the leg and the taking of certain medications that reduce the accumulation of the fatty deposits in the arterial walls are also treatment options¹.

Garlic
Garlic (Allium sativum L.), is a perennial (lasting throughout the year) herb consisting of an underground bulb, with above ground grass-like leaves that grow to about 30-60cm in height. Typically within the bulb there are 6-8 cloves, which can bud further to make 10-20 cloves⁷. Garlic cloves are very strong smelling when crushed^{7, 8}. Garlic has many varieties, including ramson (wild garlic, Allium ursinum), garlic chives, and elephant garlic⁹. Garlic is also called Ail (French), camphor of the poor, Da-Suan, knoblauch (German), La-Juan, poor man’s treacle, rustic treacle, and stinking rose¹⁰. Garlic (specifically the bulb and oil from the bulb) has been used as food and a spice in many countries for centuries^{9, 10}. Garlic also has a long history of medicinal use, dating back to Egyptian times². Orally, garlic has been used to treat raised blood pressure (hypertension), high serum lipids (hypercholesterolaemia), and to prevent coronary heart disease, age-related vascular changes, and abnormal thickening and hardening of the arterial walls (atherosclerosis). Topically, garlic oil has been used to treat fungal skin diseases⁸ and wound infections⁹.

Garlic contains pharmacologically active, organic sulfur compounds, with the main active compound thought to be allicin^{8, 9}. When garlic is taken for medicinal purposes, the clove is mainly used, either whole or chopped, powdered and freeze-dried⁹. Oil extracts from garlic cloves are also used⁹. A common dosage in the majority of clinical trials involving garlic is 600-900 mg per day of concentrated freeze-dried garlic powder (in tablet form) standardised to 1.3% allicin or 0.6% allicin⁹. This dose is equal to about one small clove or about 2-3g of fresh garlic⁹. Other doses of garlic that have been used to treat increased blood cholesterol and to prevent arteriosclerosis include 4g of fresh garlic daily or 8mg of garlic oil daily¹⁰.

Garlic tablets/oil mixes can be obtained as an “over the counter” product from health food shops, supermarkets, pharmacies, etc. A medical herbalist may also prescribe garlic. The practice of herbal medicine is not currently regulated by legislation in New Zealand, however many herbal medicine practitioners are affiliated with a self-regulated professional body (such as the New Zealand Association of Medical Herbalists).

Evidence reviewed in this summary

Efficacy information

Health technology assessments: One health technology assessment on the effect of garlic on multiple conditions¹¹ was identified for this evidence summary. The effect of garlic on intermittent claudication was one of the cardiovascular-related outcomes assessed in this health technology assessment. This review was conducted in 2000 by the Evidence-based Practice Center, University of Texas, USA. This review identified two clinical trials on this topic.
Systematic reviews: One systematic review was identified on the use of garlic for the treatment of PAD². This review was conducted by the Cochrane Peripheral Vascular Diseases Group and was last updated on the 27th August 2003. This review identified one randomised controlled clinical trial on this topic.
Clinical trials: The above health technology assessment and systematic review identified two randomised, double-blind, placebo-controlled clinical trials^{12, 13} on garlic for the treatment of PAD. No trials were identified on the use of garlic for the prevention of PAD. One of the identified trials was included in both reviews¹² and tested standardised dehydrated garlic powder (garlic coated tablets) for 12 weeks at a daily dose of 800mg. The other trial¹³, which was in German, was only included in the health technology assessment¹¹. This trial tested a non-standardised combined garlic preparation of garlic oil macerate/soya lecithin/hawthorn oil/ wheat germ oil taken daily (400 mg) for 26 weeks. The trials involved between 80 and 100 people – a total of 180 participants. No clinical trials of garlic as a treatment for PAD are known to be currently underway see (http://www.controlled-trials.com).
Case-control studies/Cohort studies/Case studies: Although sought for this summary, no case-control, cohort, or case studies were identified on this topic.

Safety information

Health technology assessment: The above health technology assessment¹¹ identified 73 studies, in addition to the efficacy trials identified, that reported information on adverse effects associated with the use of garlic in general.
Systematic reviews: The above systematic review² reported on the side effects associated with the use of garlic for the treatment of PAD.
Clinical trials: The two clinical trials^{12, 13} identified above reported on the side effects associated with the use of garlic for the treatment of PAD.
Other studies: Given the comprehensive information provided by the above studies, no further information on side effects was sought.

Evidence on efficacy

Information on the use of garlic for the treatment of PAD is available from one health technology assessment¹¹, one systematic review², and two clinical trials^{12, 13} involving a total of 180 people. Both reviews concluded that there was insufficient information available to recommend garlic as a treatment option for PAD^{2, 11}. The identified trials were considered by the review authors to be of poor scientific quality. Results from the individual trials are given below:

The largest trial (with 100 participants) reported that people in the garlic group had a significantly greater maximum walking distance at four months than people in the placebo group (114% improvement in the treatment group compared to a 17% improvement in the placebo group)¹³.
The smallest trial (with 80 participants) found no clear difference in the distance walked without pain between the two groups¹². At the end of 12 weeks people in the garlic group had a 28.5% improvement in the distance walked without pain, compared to an 18% improvement in the placebo group¹².

Evidence on safety

Findings from the one health technology assessment¹¹, the one systematic review², and two clinical trials^{12, 13} reviewed for this summary, indicate that side effects associated with the use of garlic for the treatment of PAD tend to be mild and reversible, and include unpleasant breath and body odour¹¹. In one trial, 28% of patients (nine patients) taking garlic complained of a noticeable garlic smell compared to 12% of people (four people) taking the placebo¹².

In terms of side effects associated with the use of garlic in general, the above health technology assessment¹¹ summarised adverse effects according to five groups:

Garlic breath or body odour: Fourteen trials reported that patients taking garlic experienced breath or body odour. Five of these trials (36%) found that people in the garlic group had a significantly higher occurrence of this side effect than people in the placebo group.
Skin reactions: Fourteen reports described people who experienced inflammation of the skin upon contact (contact dermatitis) with garlic. Most of these studies reported that the skin reactions improved once exposure to garlic was stopped. More severe skin reactions (such as blisters and/or a rash) have been documented in 11 case reports, including three reports in children. Most cases of skin reactions were in people using fresh garlic directly on the skin as a remedy for specific health conditions, with exposures varying between five minutes to 24 hours.
Blood clotting problems: Four reports were identified that described people who experienced some internal bleeding after eating garlic. These patients were not taking any medication known to cause bleeding problems. Two of the bleeding incidents occurred after and/or during surgery. All four cases were associated with changes in blood tests that determine a person’s bleeding tendency. Two additional reports were identified that noted an increase in the measure of bleeding tendency in two patients who were on medication that helps prevent blood clots forming (namely warfarin - Coumadin) and were taking garlic pearls or tablets. However, a small, unpublished double-blind trial found no difference in bleeding rates between the garlic group and the placebo group, in patients taking warfarin.
Heart problems: One report was identified that described a 23 year old man with no risk factors for heart (cardiovascular) disease who suffered a heart attack (acute myocardial infarction) after excessive consumption of garlic.
Stomach problems: A number of reports were identified that described a total of 309 patients who had stomach (epigastric) pain, vomited blood (hematemesis), and developed lesions on the lining of the stomach after eating garlic.

Un-refrigerated chopped garlic (mixed with either oil, butter or margarine), left at room temperature has been linked to three cases of botulism (which is a potentially life-threatening condition caused by a bacterial toxin)^{14, 15}.

Cited references

To find out more about any of the references listed below go to the "About page" of this website and read the section titled "How can referenced articles be obtained."

Creager MA, Dzau VJ. Vascular diseases of the extremities. In: Harrison's online. New York: McGraw-Hill Health Professions Division; 2003. p. Part 8, Section 4, Chapter 248.
Jepson RG, Kleijnen J, Leng GC. Garlic for peripheral arterial occlusive disease. Cochrane Database of Systematic Reviews. 2003(3).
US National Library of Medicine. Medline plus medical encyclopedia.
Occlusive peripheral arterial disease. In: The Merck manual of medical information- second home edition. Available from: http://www.merck.com/mrkshared/mmanual_home2/sec03/ch034/ch034b.jsp Accessed on 24.03.04 2004.
Lesho EP, Manngold J, Gey DC. Management of peripheral arterial disease. American Family Physician 2004;69(3):525-533.
Leng GC, Fowler B, Ernst E. Exercise for intermittent claudication. Cochrane Database of Systematic Reviews. 2003(3).
World Health Organisation. Bulbus allii sativi. In: WHO monographs on selected medicinal plants. Volume 1. Geneva: WHO.; 1999. p. 16-32
Natural Medicines Comprehensive Database. Garlic. Available by subscription from: http://www.naturaldatabase.com Accessed on 10.2.04 2003.
Rottblatt M, Ziment I. Evidence-based herbal medicine. Philadelphia, PA.: Hanley & Belfus; 2002.
Ernst E, Pilter MH, Stevinson C, White A. The desktop guide to complementary and alternative medicine: an evidence-based approach. London: Mosby; 2001.
Mulrow C, Lawrence V, Ackermann R, Ramirez G, Morbidoni L, Aguilar C, et al. Garlic: effects on cardiovascular risks and disease, protective effects against cancer, and clinical adverse effects. Rockville, MD: Agency for Healthcare Research and Quality (AHRQ). Available from http://www.ahrq.gov/clinic/garlicsum.htm Accessed on 10.03.04; 2000.
Kiesewetter H, Jung F, Jung EM, Blume J, Mrowietz C, Birk A, et al. Effects of garlic coated tablets in peripheral arterial occlusive disease. Clinical Investigator. 1993;71(5):383-386.
Czerny B, Samochowiec J. Klinische Untersuchung mit einem Knoblauch-Lezithin-Praeparat. Artztezeitschrift fur Naturheilverfahren 1996;37:126-129.
Dasgupta A. Review of abnormal laboratory test results and toxic effects due to use of herbal medicines. American Journal of Clinical Pathology 2003;120(1):127-137.
US Food & Drug Administration Center for Food Safety & Applied Nutrition. Clostridium botulinum. In: "The bad bug book": foodborne pathogenic microorganisms and natural toxins handbook. Available from: http://www.cfsan.fda.gov/~mow/chap2.html Accessed on 23.03.04 1992

Additional references:

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Glossary

Angioedema
Angioedema is an allergic skin disease characterized by patches of circumscribed (bordered/enclosed) swelling involving the skin and its subcutaneous layers, the mucous membranes lining the body passages (eg. the respiratory tract), and sometimes the internal organs of the body (viscera) - called also angioneurotic edema, giant urticaria, Quincke's disease, Quincke's edema

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