The most common symptom of peripheral arterial occlusive disease is intermittent claudication, discomfort in the legs that is triggered by exercise and relieved with rest. The underlying cause is atherosclerosis. Risk factors associated with the development of peripheral arterial disease include cigarette smoking, raised blood cholesterol and other fats (lipids), high blood pressure and diabetes. Garlic has been used as a medicinal therapy since ancient times. The main active ingredient is an unstable odorous sulphurous compound called allicin so that active ingredients may be lost in processing, and with different types of preparation. Commercially available preparations of garlic are reported to have beneficial effects on some of the risk factors for vascular disease. With fresh garlic, at least seven cloves of garlic per day are needed. Apart from the odour, garlic has only minor gastrointestinal side effects.
The review authors made a thorough search of the medical literature and found one controlled trial in which 78 participants with peripheral arterial occlusive disease were randomised to receive garlic or a placebo medication. The dose of garlic was two coated tablets of 200 mg oral standardised garlic powder twice daily. Both men and women, aged 40 to 75 years, were included although sixteen did not keep to their treatment.
After twelve weeks of treatment, pain-free walking distance increased similarly whether receiving garlic or placebo. Similarly there was no difference in the changes in blood pressure, heart rate and pressure differences between the ankle and brachial pressures. No severe side effects were observed although more people taking garlic (28%) than placebo (12%) complained of a noticeable garlic smell. Peripheral arterial occlusive disease is a long-term (chronic) condition and any improvements in symptoms would require longer-term treatment and follow up than in this study.
One small trial of short duration found no statistically significant effect of garlic on walking distance.
Commercially available preparations of garlic have been reported to have beneficial effects on some of the risk factors associated with atherosclerosis.
To assess the effects of garlic (both dried and non-powdered preparations) for the treatment of peripheral arterial occlusive disease.
For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2013) and CENTRAL (2012, Issue 12).
Randomised trials of garlic therapy in patients with lower limb atherosclerosis were included. The main outcomes were objective measures of progression of underlying atherosclerosis (e.g. ankle pressure measurements, treadmill testing) and subjective measures (e.g. symptom progression).
Two review authors (RJ and JK) independently extracted data and assessed trial quality. One author (RJ) contacted investigators to obtain information needed for the review that could not be found in published reports.
One eligible trial with 78 participants was found. Both men and women (aged 40 to 75) were included. The follow-up period was short, 12 weeks only.
After twelve weeks of treatment, pain-free walking distance increased from 161 to 207 metres in the group receiving garlic and from 172 to 203 metres in the placebo group. This was not a statistically significant difference. There was no difference in change of systolic or diastolic blood pressure, heart rate, ankle and brachial pressures. No severe side effects were observed and nine patients taking garlic (28%) and four patients taking placebo (12%) complained of a noticeable garlic smell.
Three trials were excluded from the review because they did not include any clinical measurements.