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26-08-2012 | Cardiology | Article

Garlic creates a stink for blood pressure study

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medwireNews: Garlic is widely used by patients for its blood pressure (BP)-lowering effects, but it is unclear whether or not it is beneficial in terms of cardiovascular (CV) outcomes, researchers say.

A meta-analysis in the Cochrane Database of Systematic Reviews, conducted by Aaron Tejani (University of British Columbia, Vancouver, Canada) and team, found insufficient evidence to determine whether garlic provides a therapeutic advantage over placebo in reducing the risk for mortality and CV morbidity in hypertensive patients.

"Garlic is considered one of the most popular complementary therapies for BP control and is thought to be used by up to 50% of patients with hypertension," commented Tejani in a podcast accompanying the research.

He says that previous studies have shown garlic-associated BP-lowering effects in studies including both normotensive and hypertensive patients. "But we wanted to know about the effects of garlic just in people who have hypertension… and to see what garlic does to morbidity and mortality for these patients."

In the first of the two randomized controlled trials included in the meta-analysis, 200 mg of garlic administered to 47 hypertensive patients three times a day significantly reduced mean supine systolic BP by 12 mmHg and mean supine diastolic BP by 9 mmHg in comparison with placebo. The authors of this study state that no serious side effects of garlic were reported. However, there were three cases "where a slight smell of garlic was noted."

The second study revealed that 200 mg of garlic powder administered to patients three times a day, in addition to hydrochlorothiazide-triamterene baseline therapy, produced a mean reduction of 10-11 mmHg in systolic BP and a 6-8 mmHg reduction in diastolic BP versus placebo. However, this trial could not be analyzed as the authors did not report the number of individuals randomly assigned to each treatment group, report Tejani et al.

Neither trial reported clinical outcomes and insufficient data were provided on adverse events.

The authors state that although both studies showed a reduction in BP with garlic treatment, there is insufficient evidence to determine whether garlic provides a therapeutic advantage over placebo in reducing the risk for adverse cardiovascular outcomes in patients with hypertension.

"Unfortunately we weren't able to go as far as we liked, because of the small amount of research available," remarked Tejani.

The authors conclude: "This makes it difficult to determine the true impact of garlic on lowering BP."

By Piriya Mahendra, medwireNews Reporter

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