Aged Garlic Extract Lowers Blood Pressure

Study finds patients with uncontrolled hypertension have lower systolic blood pressure with garlic therapy.

By Matthew J. Budoff, MD, FACC, FAHA

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Reference

Ried K, Frank OR, Stocks NP. Aged garlic extract lowers 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 evaluated the effect, tolerability, and acceptability of aged garlic extract (AGE) as an adjunct treatment to existing antihypertensive medication in patients with treated, but uncontrolled, hypertension. They used a double-blind, randomized, placebo-controlled trial involving 50 patients. Patients received 960 mg (containing 2.4 mg S-allylcysteine) of AGE daily or matching placebo for 12 weeks.

Key Findings

In patients with uncontrolled hypertension (SBP≥140mm Hg), systolic blood pressure was on average 10.2±4.3 mm Hg (P=0.03) lower with garlic therapy as compared to placebo. Changes in blood pressure between the groups were not significant in patients with SBP<140 mmHg at baseline. AGE was well tolerated by 92% of participants.

Practice Implications

This study, one of several now using AGE, demonstrates the potential antihypertensive activity of this supplement. Several prior studies have used AGE to evaluate for hypertension. This current study is the best-designed and most careful evaluation of the product.

The authors demonstrated that AGE was similar to current first-line therapy medications for hypertension.

It is interesting to note that AGE lowered blood pressure quite significantly in people with baseline hypertension (>140 mm Hg), but did not lower blood pressure in those with normal or near-normal blood pressure levels. This has great implications for use of the product in people without hypertension, because although it demonstrates 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 medications such as ramipril, which demonstrated significant blood pressure–lowering in patients with hypertension, but little effect on blood pressure in normotensive individuals. In the Heart Outcomes Prevention Evaluation trial, despite no significant change in blood pressure in normotensive patients, ramipril lowered cardiovascular events significantly.1

Further, this reinforces the multiple effects of AGE on cardiovascular outcomes. In multiple double-blinded, randomized, controlled trials, AGE has been demonstrated to lower total cholesterol, raise high-density lipoprotein cholesterol, reduce homocysteine, improve endothelial function, and slow the progression of atherosclerosis.2,3,4 AGE was even shown to decrease adipose tissue accumulation around the heart.4 Thus, the recent study by Ried et al further validates the beneficial effects of this supplement. Given the popularity of complementary therapies and patients’ motivation and compliance with treatment,5 further research on AGE for heart disease and cardiovascular risk factors is warranted.

Limitations

The small size of the study population limits the implications somewhat. Obviously, a clinical outcome study would be more definitive, but prospective studies of antihypertensives consistently demonstrate that the magnitude of event reduction is directly related to blood pressure reduction, and larger reductions in blood pressure produce larger reductions in risk.6 Thus, this 10-point drop in blood pressure induced by AGE should be associated with an approximate 22% reduction of total major cardiovascular events.

About the Author

Matthew J. Budoff, MD, FACC, FAHA, is a professor of medicine at the David Geffen School of Medicine and is the director of cardiac CT at Harbor-UCLA Medical Center in Torrance, Calif. Budoff is chief investigator in several active medical research trials and is a frequent lecturer on topics of cardiology at symposia, congresses, and annual conferences on nearly every continent. He has authored or coauthored more than 500 research papers, 6 books, and 36 book chapters. Budoff received the Einstein Award for Scientific Achievement from the International Biographical Centre, Cambridge, UK, and was awarded the Top Oral Abstract at the American Heart Association’s 2009 meeting. Most recently, he was named to the U.S. News & World Report list of Top Doctors for 2011.

References

1. Yusuf S, Sleight P, Pogue J, et al. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high risk patients. The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med. 2000;342:145-153.

2. Budoff MJ, Takasu J, Flores FR, et al. Inhibiting progression of coronary calcification using aged garlic extract in patients receiving statin therapy: a preliminary study. Prev Med. 2004;39:985-991.

3. Budoff MJ, Ahmadi N, Gul KM, et al. Aged garlic extract supplemented with B vitamins, folic acid and l-arginine retards the progression of subclinical atherosclerosis: A randomized clinical trial. Prev Med. 2009 49(2-3):101-107.

4. Naser A, Rezaeian P, Razipour A, et al. Aged garlic extract supplemented with B vitamins, folic acid and L-arginine reduce the progression of adipose tissue and coronary artery calcium. Circulation. 2010:122;A20824.

5. Gohar F, Greenfield SM, Beevers DG, Lip GY, Jolly K. Self-care and adherence to medication: a survey in the hypertension outpatient clinic. BMC Complement Altern Med. 2008;8:4.

6. Turnbull F. Blood Pressure Lowering Treatment Trialists’ Collaboration. Effects of different blood pressure lowering regimens on major cardiovascular events: results of prospectively designed overviews of randomized trials. Lancet. 2003;362:1527-1535.