Introduction
Garlic is an herb that is used in cooking and baking. It has also been used to lower blood pressure and help the body fight illness. Garlic can be eaten as a paste, powder, pill, or extract. It can also be made into a tea, eaten plain, or applied to the skin.
Dosages
300 milligrams 2 to 3 times daily
What Research Shows
Likely Effective
- High blood pressure —likely to lower blood pressure D1-D5
May Be Effective
- Diabetes —may help control blood glucose when used with standard treatment C1, C2
- Gingivitis —may ease swelling and control bleeding F1
- High cholesterol —unlikely to lower cholesterol E1-E4
May Not Be Effective
- Peripheral arterial occlusive disease—may not improve walking distance H1
- Preeclampsia —may not prevent I1, I2
Not Enough Data to Assess
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Safety Notes
It is likely safe to take garlic in small doses for a short time, but allergic reactions are possible. Raw garlic and large doses of garlic may not be safe. Not enough studies have been done to say whether it is safe to use for a long period or used on the skin by women who are pregnant or breastfeeding.
Interactions
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.
References
REFA Cardiovascular Disease
REFA1 . Stabler SN, Tejani AM, et al. Garlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients. Cochrane Database Syst Rev. 2012;(8):CD007653.
REFA2 Schwingshackl L, Missbach B, et al. An umbrella review of garlic intake and risk of cardiovascular disease. Phytomedicine. 2016;23(11):1127-1133.
REFB Common Cold
REFB1 Lissiman E, Bhasale AL, et al. Garlic for the common cold. Cochrane Database Syst Rev. 2014;(11):CD006206.
REFC Diabetes
REFC1 Ashraf R, Khan RA, et al. Garlic (Allium sativum) supplementation with standard antidiabetic agent provides better diabetic control in type 2 diabetes patients. Pak J Pharm Sci. 2011;24(4):565-570.
RERFC2 Hou LQ, Liu YH, et al. Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials. Asia Pac J Clin Nutr. 2015;24(4):575-582.
REFD High Blood Pressure
REFD1 Wang HP, Yang J, et al. Effect of garlic on blood pressure: a meta-analysis. J Clin Hypertens (Greenwich). 2015;17(3):223-231.
REFD2 Xiong XJ, Wang PQ, et al. Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials. Phytomedicine. 2015;22(3):352-361.
REFD3 Ried K. Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review. J Nutr. 2016 Feb;146(2):389S-396S.
REFD4 Reinhart KM, Coleman CI, et al. Effects of garlic on blood pressure in patients with and without systolic hypertension: a meta-analysis. Ann Pharmacother. 2008 Dec;42(12):1766-1771.
REFD5 Ried K, Frank OR, et al. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008 Jun 16;8:13.
REFE High Cholesterol
REFE1 Khoo YS, Aziz Z. Garlic supplementation and serum cholesterol: a meta-analysis. J Clin Pharm Ther. 2009;34(2):133-145.
REFE2 Shabani E, Sayemiri K, et al. The effect of garlic on lipid profile and glucose parameters in diabetic patients: A systematic review and meta-analysis. Prim Care Diabetes. 2019 Feb;13(1):28-42.
REFE3 Sun YE, Wang W, et al. Anti-hyperlipidemia of garlic by reducing the level of total cholesterol and low-density lipoprotein: A meta-analysis. Medicine (Baltimore). 2018 May;97(18):e0255.
REFE4 Posadzki P, AlBedah AM, et al. Complementary and alternative medicine for lowering blood lipid levels: A systematic review of systematic reviews. Complement Ther Med. 2016 Dec;29:141-151.
REFF Gingivitis
REFF1 Zini A, Mann J, et al. The Efficacy of Aged Garlic Extract on Gingivitis-A Randomized Clinical Trial. J Clin Dent. 2018;29(2):52-56.
REFG Metabolic Syndrome
REFG1 van den Driessche JJ, Plat J, et al. Effects of superfoods on risk factors of metabolic syndrome: a systematic review of human intervention trials. Food Funct. 2018 Apr 25;9(4):1944-1966.
REFH Peripheral Arterial Occlusive Disease
REFH1 Jepson RG, Kleijnen J, et al. Garlic for peripheral arterial occlusive disease. Cochrane Database Syst Rev. 2013 Apr 30;(4):CD000095.
REFI Preeclampsia
REFI1 Dante G, Pedrielli G, et al. Herb remedies during pregnancy: a systematic review of controlled clinical trials. J Matern Fetal Neonatal Med. 2013 Feb;26(3):306-312.
REFI2 Meher S, Duley L. Garlic for preventing pre-eclampsia and its complications. Cochrane Database Syst Rev. 2006 Jul 19;(3):CD006065.