Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Aug 15;2012(8):CD007653.
doi: 10.1002/14651858.CD007653.pub2.

Garlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients

Sarah N Stabler  1 , Aaron M Tejani, Fong Huynh, Claire Fowkes
Affiliations

Garlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients

Sarah N Stabler et al. Cochrane Database Syst Rev. .

Abstract

Background: Garlic is widely used by patients for its blood pressure lowering effects. A meta-analysis published in 2008 concluded that garlic consumption lowers blood pressure in hypertensive and normotensive patients. Therefore, it is important to review the currently available evidence to determine whether garlic may also have a beneficial role in the reduction of cardiovascular events and mortality rates in patients with hypertension.

Objectives: To determine whether the use of garlic as monotherapy, in hypertensive patients, lowers the risk of cardiovascular morbidity and mortality compared to placebo.

Search methods: A systematic search for trials was conducted in the Cochrane Hypertension Group Specialised Register, CENTRAL, MEDLINE, EMBASE, AGRICOLA, AMED, and CINAHL up to November 2011. A hand search of reference lists of identified reviews was conducted. Experts in the area were also contacted to identify trials not found in the electronic search. Clinicaltrials.gov was searched for ongoing trials.

Selection criteria: Randomized, placebo-controlled trials of any garlic preparation versus placebo for the treatment of hypertension were included.

Data collection and analysis: Two reviewers independently extracted data and assessed trial quality using the risk of bias tool. Data synthesis and analysis was performed using RevMan 5.

Main results: The search identified two randomized controlled trials for inclusion. One trial included 47 hypertensive patients and showed that garlic significantly reduces mean supine systolic blood pressure by 12 mmHg (95% CI 0.56 to 23.44 mmHg, p=0.04) and mean supine diastolic blood pressure by 9 mmHg (95% CI 2.49 to 15.51 mmHg, p=0.007) versus placebo. The authors state that garlic was "free from side effects" and that no serious side effects were reported. There were 3 cases "where a slight smell of garlic was noted."The second trial could not be meta-analysed as they did not report the number of people randomized to each treatment group. They did report that 200 mg of garlic powder given three times daily, in addition to hydrochlorothiazide-triamterene baseline therapy, produced a mean reduction of systolic blood pressure by 10-11 mmHg and of diastolic blood pressure by 6-8 mmHg versus placebo.Neither trial reported clinical outcomes and insufficient data was provided on adverse events.

Authors' conclusions: There is insufficient evidence to determine if garlic provides a therapeutic advantage versus placebo in terms of reducing the risk of mortality and cardiovascular morbidity in patients diagnosed with hypertension. There is also insufficient evidence to determine the difference in withdrawals due to adverse events between patients treated with garlic or placebo.Based on 2 trials in 87 hypertensive patients, it appears that garlic reduces mean supine systolic and diastolic blood pressure by approximately 10-12 mmHg and 6-9 mmHg, respectively, over and above the effect of placebo but the confidence intervals for these effect estimates are not precise and this difference in blood pressure reduction falls within the known variability in blood pressure measurements. This makes it difficult to determine the true impact of garlic on lowering blood pressure.

PubMed Disclaimer

Conflict of interest statement

None known.

Figures

1
1
Study Flow Diagram
2
2
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
3
3
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
4
4
Forest plot of comparison: 1 Garlic versus Placebo, outcome: 1.1 Mean reduction in supine systolic blood pressure [mmHg].
5
5
Forest plot of comparison: 1 Garlic versus Placebo, outcome: 1.2 Mean reduction in supine diastolic blood pressure [mmHg].
1.1
1.1. Analysis
Comparison 1 Garlic versus Placebo, Outcome 1 Mean reduction in supine systolic blood pressure.
1.2
1.2. Analysis
Comparison 1 Garlic versus Placebo, Outcome 2 Mean reduction in supine diastolic blood pressure.
See this image and copyright information in PMC

Update of

  • doi: 10.1002/14651858.CD007653

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

References to studies included in this review

Auer 1990 {published data only}
    1. Auer W, Eiber A, Hertkorn E, Koehrle U, Lorenz A, Mader F, Merx W, Otto G, Schmidt‐Otto B, Taubenheim H. Hypertension and hyperlipidaemia: garlic helps in mild cases. Br J Clin Pract 1990;Supplement 69:3‐6. - PubMed
Kandziora 1988 {published data only}
    1. Kandaziora J. Blood pressure and lipid lowering effect of garlic preparations in combination with a diuretic [Blutdruk‐ und lipidsenkende Wirkung eines Knoblauch‐Praparates in Kombination mit einem Diuretikum]. Artzliche Forschung 1988;35:1‐8.

References to studies excluded from this review

Barrie 1987 {published data only}
    1. Barrie S, Wright J, Pizzorno JE. Effects of garlic oil on platelet aggregation, serum lipids and blood pressure in humans. Journal of Orthomol Med 1987;2(1):15‐21.
Czerny 1996 {published data only}
    1. Czerny B, Sarnochowiec S. Clinical Investigations with a Garlic‐Lecithin Preparation [Klinishce Untersuchungen mit einem Knoblauch‐Lezithin‐Praparat]. Arztezellschrift for Naturheltvorfahren 1996;37(2):126‐136.
De A Santos 1993 {published data only}
    1. A Santos OS, Grunwald J. Effect of garlic powder tablets on blood lipids and blood pressure‐a six month placebo controlled, double blind trial. Br J Clin Res 1993;4:37‐44.
De A Santos 1995 {published data only}
    1. A Santos OS, Johns RA. Effects of garlic powder and garlic oil preparations on blood lipids, blood pressure and well‐being.. Br J Clin Res 1995;6:91‐100.
Gardner 2001 {published data only}
    1. Gardner CD, Chatterjee LM, Carlson JJ. The effect of a garlic preparation on plasma lipid levels in moderately hypercholesterolemic adults. Atherosclerosis 2001;154:213‐220. - PubMed
Han 2011 {published and unpublished data}
    1. Han CH, Liu JC, Lin YS, et al. Antihypertensive activities of processed garlic on spontaneously hypertensive rats and hypertensive humans. Botanical Studies 2011;52:277‐283.
Holzgartner 1992 {published data only}
    1. Holzgartner H, Schmidt U, Kuhn U. Comparison of the efficacy and tolerance of a garlic preparation vs. bezafibrate. Arzneimittelforschung 1992;42(12):1473–1477. [PUBMED: 1288512] - PubMed
Isaacsohn 1998 {published data only}
    1. Isaacsohn JL, Moser M, Stein EA, Dudley K, Davey J, Liskov E, Black HR. Garlic Powder and Plasma Lipids and Lipoproteins. Arch Intern Med 1998;138:1189‐1194. - PubMed
Jain 1993 {published data only}
    1. Jain AK, Vargas R, Gotzkowsky S, McMahon FG. Can Garlic Reduce Levels of Serum Lipids? A Controlled Clinical Study. Am J Med 1993;94:632‐635. - PubMed
Kandaziora 1988 (2) {published data only}
    1. Kandziora J. Antihypertensive efficacy and tolerability of garlic preparations [Antihypertensive Wirksamkeit und Vertraglichkeit eines Knoblauch‐Praparates (Study 2)]. Artzliche Forschung 1988;35:1‐8.
Kiesewetter 1993 {published data only}
    1. Kiesewetter H, Jung F, Jung EM, Blume J, Mrowietz C, Birk A, Koscienly J, Wenzel E. Effects of garlic coated tablets in peripheral arterial occlusive disease. Clin Invetsig 1993;71(5):383‐386. - PubMed
Kieswetter 1991 {published data only}
    1. Kieswetter H, Jung F, Pindur EM, Mrowietz C, Wenzel E. Effect of garlic on thrombocyte aggregation, microcirculation and other risk factors. Int J Clin Pharmacol Therapy and Tox 1991;29(4):151‐155. - PubMed
Luley 1986 {published data only}
    1. Luley C, Lehmann‐Leo W, Moller B, Martin T, Schwatrzkopf W. Lack of efficacy of dried garlic in patients with hyperlipoproteinemia. Arzneimittelforschung 1986;36(4):766‐8. - PubMed
Lutomski 1984 {published data only}
    1. Lutomski J, Poznan, Polen. Clinical investigations of the therapeutic efficacy of Ilja Rogogg(R) garlic pills with rutin [Klinische Untersuchungen zur therapeutischen Wirksamkeit von Ilja Rogogg(r) Knoblauchpillen mit Rutin]. Zeutschrift fur Phytotherapie 1984;5(15):938‐942.
Mansell 1996 {published data only}
    1. Mansell P, Reckless JPD, Lloyd J, Leatherdale B. The Effect of Dried Garlic Powder Tablets On Serum Lipids in Non‐Insulin Dependent Diabetic Patients. Eur J Clin Res 1996;8:25‐26.
McMahon 1992 {published data only}
    1. McMahon FG, Jain A, Vargas R, Kadowitz P, McNamara D. Clinical Effects of a Garlic Powder Preparation on Various Cardiovascular Risk Factors. Eur J Clin Res 1992;3A:8‐9.
Mousa 2007 {published data only}
    1. Mousa AS, Mousa SA. Cellular effects of garlic supplements and antioxidants on high blood pressure in humans: pilot study. Nutr Res 2007;27(2):119‐123.
Mrozikiewicz 1989 {published data only}
    1. Mrozikiewicz VA, Lutomski J. Efficacy of Some Garlic Preparations. Pharmacological and Clinical Studies in Poland. [Wirkungseffekte einiger Knoblauchpraparate. Pharmakologische und klinische Untersuchungen in Polen]. Deutsche Apotheker‐Zeitung 1989;129:16.
Ried 2010 {published data only}
    1. Ried K, Frank OR, Stocks NP. Aged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: A randomised controlled trial. Maturitas 2010;67:144‐150. - PubMed
Rotzsch 1992 {published data only}
    1. Rotzsch W, Richter V, Rassoul F, Walper A. Postprandial Lipamie with medication of Allium sativum [Postprandiale Lipamie unter Medikation von Allium sativum]. Lipidsenker Lipid Reducers 1992;42 (II)(10):1223‐1226. - PubMed
Saradeth 1994 {published data only}
    1. Saradeth T, Seidl S, Resch KL, Ernst E. Does garlic alter the lipid pattern in normal volunteers?. Phytomedicine 1994;1:183‐185. - PubMed
Satitvipawee 2003 {published data only}
    1. Satitvipawee P, Indrabhakti S, Getn‐Gern P, Rawdaree P, Ratanasuwan, T, Viwatwongkasem C. No effect of garlic extract supplement on serum lipid levels in hypercholesterolemic subjects. J Med Assoc Thai 2003;86:750‐757. - PubMed
Schiewe 1995 {published data only}
    1. Schiewe FP, Hein T, Koln. Garlic in hyperlipidemia [Knoblauch bei Hyperlipidamie]. Zeitschrift fur Phytotherapie 1995;16:343‐348.
Simons 1995 {published data only}
    1. Simons L, Balasubramaniam S, Konigsmark M, Parfitt A, Simons J, Peters W. On the effect of garlic on plasma lipids and lipoproteins in mild hypercholesterolaemia. Atherosclerosis 1995;113(2):219‐225. - PubMed
Sobenin 2007 {published data only}
    1. Sobenin IA, Prianishnikov VV, Kunnova LM, Rabinovich EA, Orekhov AN. Use of allicor to lower the risk of myocardial infarction (Article in Russian). Ter Arkh 2007;85(3):25‐28. - PubMed
Steiner 1996 {published data only}
    1. Steiner A, Khan A, Holbert D, Lin R. A double‐blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipids. Am J Clin Nutr 1996;64(6):866‐870. - PubMed
Superko 2000 {published data only}
    1. Superko HR, Krauss RM. Garlic Powder, Effect on Plasma Lipids, Postprandial Lipemia, Low‐Density Lipoprotein Particle Size, High‐Density Lipoprotein Subclass Distribution and Lipoprotein(a). J Am Coll Cardiol 2000;35(2):321‐326. - PubMed
Turner 2004 {published data only}
    1. Turner B, Molgaard C, Marckmann P. Effect of garlic (Allium sativum) powder tablets on serum lipids, blood pressure and arterial stiffness in normo‐lipidaemic volunteers: a randomised, double‐blind, placebo‐controlled trial. Br J of Nutr 2004;92:701‐706. - PubMed
Vorberg 1990 {published data only}
    1. Vorberg G, Schneider B. Therapey with Garlic: Results of a Placebo‐Controlled, Double‐Blind Study. Br J Clin Pract 1009;68:7‐11. - PubMed
Williams 2005 {published data only}
    1. Williams MJA, Sutherland WJF, McCormick MP, Yeoman DJ, Jong SA. Aged garlic extract improves endothelial function in men with coronary artery disease. Phytother Res 2005;19:314‐319. - PubMed
Zhang 2000 {published data only}
    1. Zhang XH, Lowe D, Giles P, Fell S, Board AR, Baughan JA, Connock MJ, Maslin DJ. A randomized trial of the effects of garlic oil upon coronary heart disease risk factors in trained male runners. Blood Caogul Fibrin 2000;11:67‐74. - PubMed

Additional references

Banerjee 2002
    1. Banerjee Sk, Maulik SK. Effect of garlic on cardiovascular disorders: a review. Nutr J 2002;1:4. - PMC - PubMed
Bongiorno 2008
    1. Bongiorno PB, Fratellone PM, LoGiudice P. Potential health benefits of garlic (allium staivum): a narrative review. Journal of Complement and Int Med 2008;5:1‐15.
CHEP 2008
    1. Canadian Hypertension Education Program (CHEP) Guidelines 2008. Available from: URL: http://hypertension.ca/chep/wp‐content/uploads/2008/03/2008‐chepspiral‐b....
Chobanian 2003
    1. Chobanian AV, Bakris GL, Black HR, et al. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report.. JAMA 2003;289(19):2560‐2572. - PubMed
Harunobu 2001
    1. Harunobu A, Petesch B, Matsuura H, et al. Intake of garlic and its bioactive components. J Nutr 2001;131(3):955S‐962S. - PubMed
Jellin 2006
    1. Jellin Jm, Gregory PJ, Batz F, Hitchens K, et al. Garlic [Garlic]. Pharmacists Letter / Prescribers Letter Natural Medicine Comprehensive Database. 8th Edition. Stockton CA: Therapeutic Research Faculty, 2006:556‐61.
Lanzotti 2006
    1. Lanzotti V. The analysis of onion and garlic. J CHROMATOGR A 2006;1112(1‐2,21):3‐22. - PubMed
Matsuura 2001
    1. Matsuura H. Saponins in Garlic as Modifiers of the Risk of Cardiovascular Disease. J Nutr 2001;31(3):1000S‐1005. - PubMed
Musini 2009
    1. Musini V, Wright J. Factors Affecting Blood Pressure Variability: Lessons Learned from Two Systematic Reviews of Randomized Controlled Trials.. PLoS One 2009;4(5):e5673. [DOI: 10.1371/journal.pone.0005673] - DOI - PMC - PubMed
Rahman 2006
    1. Rahman K, Lowe G. Garlic and Cardiovasular Disease: A Critical Review. J Nutr. 2006;136:736S‐740S. - PubMed
Ried 2008
    1. Ried K, Frank OR, Stocks NP, et al. Effect of garlic on blood pressure: a systematic review and meta‐analysis. BMC Cardiovascular Disorders 2008;8(13):1‐12. [DOI: 10.1186/1471-2261-8-13] - DOI - PMC - PubMed
Rivlin 2001
    1. Rivlin R. Historical perspective on the use of garlic. J Nutr 2001;31(3):951S‐954S. - PubMed
Silagy 1994
    1. Silagy CA, Neil HA. A meta‐analysis of the effect of garlic on blood pressure. J Hypertens 1994;12:463‐468. - PubMed
Timbo 2006
    1. Timbo BB, Ross MP, McCarthy PV, et al. Dietary supplements in a national survey: prevalence of use and reports of adverse events. Am Diet Assoc 2006;106:1966‐1974.. - PubMed
WHO 2003
    1. World Health Organization, International Society of Hypertension Writing Group. 2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension. J Hypertens 2003;21:1983‐1992. - PubMed
Wright 2009
    1. Wright JM, Musini VM. First‐line drugs for hypertension. Cochrane Database of Systematic Reviews 2009, Issue 3. [DOI: 10.1002/14651858.CD001841.pub2] - DOI - PubMed

Publication types

MeSH terms