Garlic lowers blood pressure - study

ADELAIDE - The humble garlic bulb has a big reputation in herbal lore for curing almost everything from the common cold to the plague.

Now it is lowering blood pressure.

A new study shows aged extract of garlic might be able to help lower blood pressure in the 3.7 million Australians who suffer from hypertension.

Karin Ried (Ried) from University of Adelaide's Discipline of General Practice has conducted a 12-week trial with 50 people that shows garlic could be used as an adjunct to conventional drugs for hypertension.

"There is a large proportion of people out there who are on medication and some people are on four different types but they still have high blood pressure, it is uncontrolled," Dr Ried said.

"When we gave them this garlic supplement we were able on average to reduce their blood pressure under the hypertension threshold - so garlic might be a good complementary treatment option to control hypertension."

Raw, cooked and garlic powder aren't as effective as carefully aged garlic extract.

"You know what is in there and it is stable for a long period of time.

"Garlic powder is not as stable and you don't know the dose you are taking, and garlic oil doesn't contain the active substance. Aged garlic is prepared in a special process but you can buy it in the shops here."

Her team found that those with systolic blood pressure above 140 who took the four aged garlic extract capsules each day experienced an average systolic blood pressure 10.2mmHg lower than the control group, who took a placebo.

Garlic is thought to have an antihypertensive effect because it stimulates production of certain chemical substances called nitric oxide and hydrogen sulphide, which helps relax blood vessels.

The team also recently found that dark chocolate was also effective in reducing high blood pressure.

"It doesn't work as well as garlic but it is more loved, and the drawback is it is not really practical for long term use."

About 30 per cent of Australian adults are hypertensive, yet only half are on blood pressure medication and 60 per cent of those are inadequately controlled.

"If garlic gave an answer that would help quite a lot of people," she said.

Garlic has a history of being used as a cure-all and a protection herb. It gained fame during the years of the Black Death after four thieves apparently fended off the plague by using antiseptic garlic vinegar.

- AAP