GarlicHigh Blood Pressure

Effect of garlic on blood pressure

Garlic preparations are better than placebo in reducing blood pressure in people with high blood pressure, according to this review by researchers from The University of Adelaide in Australia.

First, the details.

  • A literature search found 25 studies.
  • 11 were suitable for a combined reanalysis of the data — meta-analysis.

And, the results.

  • Those taking garlic had a significantly greater average decrease in systolic blood pressure of 5 mmHg compared to placebo.
  • In those with high blood pressure, the average decrease was 8 mmHg for systolic blood pressure and 7 mmHg for diastolic blood pressure — both significant changes.
  • People with higher blood pressure at the start of treatment had the greatest decreased in blood pressure with garlic treatment.

The bottom line?
The authors concluded, “Garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension.”

They also tell us “the effect of garlic preparations on systolic and diastolic blood pressures are comparable to the hypotensive effects of commonly-prescribed blood pressure drugs.” For example, a 5 mmHg decline in systolic blood pressure with beta-blockers, 8 mmHg for angiotensin converting enzyme inhibitors, and 10 mmHg with angiotensin receptor blockers.

Reducing systolic pressure 4 to 5 mmHg and diastolic pressure 2 to 3 mmHg reduces the risk of cardiovascular morbidity and mortality by 8% to 20%.

Most studies included in this review used garlic powder at a dose of 600–900 mg per day, providing potentially 4 to 5 mg of allicin (the active compound in garlic). Fresh garlic cloves weighing about 2 grams each provide 5 to 9 mg allicin.

If you’re inclined to take garlic to treat blood pressure, garlic preparations offer advantages over raw garlic, including less or no garlic breath and body odor. You also avoid the possible destruction of the active compounds from cooking.

Overall, the authors found taking garlic preparations to be well tolerated and “an acceptable alternative or complementary treatment option for hypertension.” More information and cautions on this topic are here.

7/26/08 16:40 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.