Writing in Maturitas, scientists from the University of Adelaide report that the benefits were only observed in people with initial systolic pressure (SBP) of 140 mmHg or over, and that no effects were observed in people with lower SBP.
The study is reported to be the first to examine the effects of aged garlic extracts for reducing hypertension, and adds to the body of science supporting the potential cardiovascular benefits of garlic. Consumer awareness of the health benefits of garlic, mostly in terms of cardiovascular and immune system health, has benefited the supplements industry, particularly since consumers seek the benefits of garlic without the odours that accompany the fresh bulb.
The new study used supplementation with four capsules of aged garlic extract providing 960 mg containing 2.4 mg S-allylcysteine) daily for 12 weeks.
“Aged garlic extract is regarded as safe and more tolerable than garlic powder, and superior to raw or cooked garlic in relation to its antihypertensive properties,” explained the researchers. “In addition, the active component S-allylcysteine (SAC) in AGE is less volatile than allicin in garlic powder, and therefore more easily standardised.”
High blood pressure (hypertension),defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg, is a major risk factor for cardiovascular disease (CVD) - a disease that causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.
The Adelaide-based scientists, led by Karin Ried from the School of Population Health and Clinical Practice, recruited 50 people with treated but uncontrolled hypertension to participate in their double-blind parallel randomised placebo-controlled trial.
The participants were randomly assigned to receive either a daily dose of aged garlic extract of 3.84 grams (Kyolic, Garlic High Potency Everyday Formula 112, Wakunga/Wagner) or placebo for 12 weeks. The garlic dose was said to be “equivalent to about 2.5 g of fresh garlic and comparable to the dosage used in the majority of previous trials on garlic supplements and blood pressure”.
Results showed a “marked difference” between the garlic and control groups in subjects with ‘uncontrolled hypertension’. On the other hand, no effects on diastolic blood pressure were observed between the groups, said the researchers.
“Future larger trials are needed to confirm our findings of effectiveness on systolic hypertension, ascertain the effect on diastolic hypertension, investigate dose–response relationships, examine effect in association to conventional blood pressure medication classes, and explore whether supplementation with molybdenum and vitamin B12 improves some patients’ tolerance of garlic,” they concluded.
Volume 67, Issue 2, Pages 144-150
“Aged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: A randomised controlled trial”
Authors: K. Ried, O.R. Frank, N.P. Stocks