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reference
Ried K, Frank OR, Stocks NP. Aged garlic extract reduces blood pressure in patients with treated but uncontrolled hypertension: A randomized controlled trial.Maturitas. 2010;67(2):144-150.
design
This study by Ried et al. investigated the effect, tolerability and acceptability of aged garlic extract (AGE) as adjunctive treatment to existing antihypertensive medications in patients with treated but uncontrolled hypertension. They used a double-blind, randomized, placebo-controlled trial with 50 patients. Patients received AGE 960 mg (containing 2.4 mg S-allylcysteine) or matching placebo daily for 12 weeks.
Key findings
In patients with uncontrolled hypertension (SBP ≥ 140 mm Hg), systolic blood pressure averaged 10.2 ± 4.3 mm Hg (P=0.03) lower with garlic therapy compared to placebo. Blood pressure changes between groups were not significant in patients with SBP <140 mmHg at baseline. AGE was well tolerated by 92% of participants.
Effects on practice
This study, one of several currently using AGE, demonstrates the potential blood pressure-lowering effects of this supplement. Several previous studies have used AGE to assess hypertension. This current study is the best designed and most thorough evaluation of the product.
The authors showed that AGE is similar to current first-line medications for hypertension.
It is interesting to note that AGE reduced blood pressure quite significantly in people with baseline hypertension (>140 mm Hg), but not in people with normal or near-normal blood pressure values. This has major implications for the use of the product in people without hypertension because although it shows that AGE has the potential to lower blood pressure, the supplement did not induce hypotension in people with normal blood pressure. This is similar to drugs such as ramipril, which showed significant reductions in blood pressure in patients with hypertension but had little effect on blood pressure in normotensive individuals. In the Heart Outcomes Prevention Evaluation study, ramipril significantly reduced cardiovascular events despite no significant change in blood pressure in normotensive patients.1
Furthermore, this reinforces the multiple effects of AGE on cardiovascular outcomes. In several double-blind, randomized, controlled trials, AGE has been shown to lower total cholesterol, increase high-density lipoprotein cholesterol, reduce homocysteine, improve endothelial function, and slow the progression of atherosclerosis.2,3,4AGE has even been shown to reduce the accumulation of fatty tissue around the heart.4Thus, the current study by Ried et al. the beneficial effects of this supplement further. Given the popularity of complementary therapies and patients' motivation and compliance with treatment,5Further research on AGE in heart disease and cardiovascular risk factors is needed.
restrictions
The small size of the study population somewhat limits the implications. Obviously, a clinical outcomes study would be more powerful, but prospective studies of antihypertensive drugs consistently show that the magnitude of event reduction is directly related to blood pressure reduction and that greater reductions in blood pressure lead to greater reductions in risk.6Thus, this AGE-induced 10-point drop in blood pressure should be associated with an approximately 22% reduction in overall major cardiovascular events.