According to a new review of relevant research, garlic supplements may be as effective at lowering blood pressure as some hypertension drugs.
Australian researchers say garlic supplements may provide an acceptable alternative or complementary treatment option for hypertension.
Dr. Karin Ried and colleagues from the University of Adelaide in South Australia say research to date on garlic and blood pressure has had 'inconclusive' results, but only included studies done up until 1994.
They say their meta-analysis, in which the results of several studies are analyzed collectively, provides an updated perspective as it includes more recent studies.
Their analysis identified 11 studies in which the patients were randomly assigned to garlic or a placebo, in doses ranging from 600 mg to 900 mg daily, which study participants took for 12 to 23 weeks.
When the researchers examined the pooled the data from the trials, they found that garlic reduced systolic blood pressure (the top number in a blood pressure reading) by 4.6 mm Hg, on average.
An analysis limited to people with high blood pressure showed garlic reduced systolic blood pressure by 8.4 mm Hg, on average, and diastolic blood pressure (the bottom number) by 7.3 mm Hg and it was found that the higher a person's blood pressure was at the beginning of the study, the more it was reduced by taking garlic.
The researchers suggest the effects were similar to those of drugs widely used to treat hypertension, such as beta blockers, which reduce systolic blood pressure by 5 mm Hg, and ACE inhibitors, which produce an 8 mm Hg average drop in systolic blood pressure.
The researchers say the 600 mg to 900 mg dosage used in the studies (in powder form) is equivalent to 3.6 mg to 5.4 mg of garlic's active ingredient, allicin - a fresh clove of garlic contains 5 mg to 9 mg of allicin.
They say taken on a wider population basis, reducing systolic blood pressure by an average of 4 to 5 points and diastolic blood pressure by 2 to 3 points, could cut the risk of heart disease and heart disease-related death by up to 20 percent.