Garlic

Last Updated: July 22, 2023

Garlic (Allium sativum) is a food and is commonly taken as a supplement. It has anti-inflammatory effects and can improve cardiovascular health.

Garlic is most often used for

What is garlic?

Garlic (Allium sativum) is a vegetable that can be eaten raw or cooked. It is also sold as a dietary supplement. Garlic contains several sulfur-containing phytochemicals that are metabolized when eaten and can affect cardiovascular health and inflammation.[1] These chemicals include allicin, diallyl disulfide (DADS), diallyl trisulfide (DATS), and S-allylmercaptocysteine (SAMC).

What are garlic’s main benefits?

Supplementation with garlic lowers circulating markers of oxidative stress[2][3] (e.g., malondialdehyde) and inflammation (e.g., C-reactive protein and TNF-α).[4][5][6] Supplementation with garlic can also reduce total cholesterol levels,[7][8] particularly in people with cardiovascular disease, and improve other measures of cardiovascular health (coronary artery calcium, carotid intima-media thickness, etc.).[9] However, its direct effects on cardiovascular morbidity and mortality are currently unclear.[9][10]

Observational studies also show that garlic consumption, through food or as a supplement, is associated with a lower risk of gastric and colorectal cancers.[11]

What are garlic’s main drawbacks?

Garlic consumption can cause “garlic breath” and body odor, which are typically most pronounced after eating raw garlic.[12] These side effects are also frequent-reported “adverse events” in clinical trials.[12][13][14] Some supplement formulations (e.g., aged garlic extract) are designed to minimize such odors.[15][16]

In rare cases, garlic may cause an allergic reaction.[12]

How does garlic work?

Metabolizing garlic’s sulfur-containing chemicals (i.e., allicin, diallyl disulfide, diallyl trisulfide, and S-allylmercaptocysteine) eventually produces hydrogen sulfide (H2S). H2S is not only responsible for the characteristic garlic odor, but is also a signaling molecule with direct effects on vascular tissue, nerve synapses, inflammatory processes, and more.[17] However, the sulfur-containing chemicals in garlic also have their own direct effects, activating several signaling pathways involved in anti-oxidant, anti-thrombotic, and anti-inflammatory mechanisms,[18][19] which explains garlic's role in cardiovascular health.[9] These chemicals also likely regulate the cell cycle in cancer cells, causing apoptosis (cell death),[11][20] which explains the potential role of garlic in lowering gastric and colorectal cancer risk.[11]

What else is Garlic known as?
Note that Garlic is also known as:
  • Allium sativum
  • Vegetable Viagra
  • Da suan
  • Camphor of the poor
  • Lasun
  • Stinking Rose
  • Ail
  • Ajo
Garlic should not be confused with:
Dosage information

Most studies on garlic use a dosage range of 600-1,200mg a day, usually divided into multiple doses. The minimum effective dose for raw garlic is a single segment of a garlic bulb (called a clove), eaten with meals two or three times a day.

Aged garlic is a popular form of garlic to use for supplementation, since it does not have a fresh garlic scent. Garlic supplementation can also be done through food alone, though side-effects will include strong garlic-scented breath.

Microwaving garlic will partially destroy the beneficial components of the vegetable, but grilling and roasting will not damage the bioactives, provided the garlic is sliced or crushed beforehand. Garlic can be toxic if consumed in very high doses, so supplementation should never go beyond the following maximum dosages:

  • 17.0 grams for a 150lb person
  • 22.7 grams for a 200lb person
  • 28.4 grams for a 250lb person
Examine Database: Garlic
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References
  1. ^Tudu CK, Dutta T, Ghorai M, Biswas P, Samanta D, Oleksak P, Jha NK, Kumar M, Radha , Proćków J, Pérez de la Lastra JM, Dey ATraditional uses, phytochemistry, pharmacology and toxicology of garlic (), a storehouse of diverse phytochemicals: A review of research from the last decade focusing on health and nutritional implications.Front Nutr.(2022)
  2. ^Askari M, Mozaffari H, Darooghegi Mofrad M, Jafari A, Surkan PJ, Amini MR, Azadbakht LEffects of garlic supplementation on oxidative stress and antioxidative capacity biomarkers: A systematic review and meta-analysis of randomized controlled trials.Phytother Res.(2021-Jun)
  3. ^Moosavian SP, Arab A, Paknahad Z, Moradi SThe effects of garlic supplementation on oxidative stress markers: A systematic review and meta-analysis of randomized controlled trials.Complement Ther Med.(2020-May)
  4. ^Taghizadeh M, Hamedifard Z, Jafarnejad SEffect of garlic supplementation on serum C-reactive protein level: A systematic review and meta-analysis of randomized controlled trials.Phytother Res.(2019-Feb)
  5. ^Darooghegi Mofrad M, Milajerdi A, Koohdani F, Surkan PJ, Azadbakht LGarlic Supplementation Reduces Circulating C-reactive Protein, Tumor Necrosis Factor, and Interleukin-6 in Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials.J Nutr.(2019-Apr-01)
  6. ^Mehdi Koushki, Nasrin Amiri-Dashatan, Yasin Pourfarjam, Amir Hossein DoustimotlaghEffect of Garlic Intake on Inflammatory Mediators: A Systematic Review and Meta-Analysis of Randomised Controlled TrialsPostgrad Med J.(2020 Feb 12)
  7. ^Maryam Kheirmandparizi, Pedram Keshavarz, Peyman Nowrouzi-Sohrabi, Mahnaz Hosseini-Bensenjan, Shahla Rezaei, Seyyed Mohammad Amin Kashani, Nazanin Zeidi, Reza Tabrizi, Abdolhamid AlkamelEffects of garlic extract on lipid profile in patients with coronary artery disease: A systematic review and meta-analysis of randomised clinical trialsInt J Clin Pract.(2021 Oct 9)
  8. ^Li S, Guo W, Lau W, Zhang H, Zhan Z, Wang X, Wang HThe association of garlic intake and cardiovascular risk factors: A systematic review and meta-analysis.Crit Rev Food Sci Nutr.(2022-Mar-29)
  9. ^Imaizumi VM, Laurindo LF, Manzan B, Guiguer EL, Oshiiwa M, Otoboni AMMB, Araujo AC, Tofano RJ, Barbalho SMGarlic: A systematic review of the effects on cardiovascular diseases.Crit Rev Food Sci Nutr.(2022-Feb-23)
  10. ^Stabler SN, Tejani AM, Huynh F, Fowkes CGarlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients.Cochrane Database Syst Rev.(2012-Aug-15)
  11. ^Yangyang Wang, Ping Huang, Yufei Wu, Duanrui Liu, Mingyu Ji, Huanjie Li, Yunshan WangAssociation and mechanism of garlic consumption with gastrointestinal cancer risk: A systematic review and meta-analysisOncol Lett.(2022 Apr)
  12. ^Borrelli F, Capasso R, Izzo AAGarlic (Allium sativum L.): adverse effects and drug interactions in humans.Mol Nutr Food Res.(2007-Nov)
  13. ^Stevinson C, Pittler MH, Ernst EGarlic for treating hypercholesterolemia. A meta-analysis of randomized clinical trialsAnn Intern Med.(2000 Sep 19)
  14. ^Josling PPreventing the common cold with a garlic supplement: a double-blind, placebo-controlled surveyAdv Ther.(2001 Jul-Aug)
  15. ^Ana L Colín-González, Ricardo A Santana, Carlos A Silva-Islas, Maria E Chánez-Cárdenas, Abel Santamaría, Perla D MaldonadoThe antioxidant mechanisms underlying the aged garlic extract- and S-allylcysteine-induced protectionOxid Med Cell Longev.(2012)
  16. ^Amagase H, Petesch BL, Matsuura H, Kasuga S, Itakura YIntake of garlic and its bioactive components.J Nutr.(2001-Mar)
  17. ^Mancardi D, Penna C, Merlino A, Del Soldato P, Wink DA, Pagliaro PPhysiological and pharmacological features of the novel gasotransmitter: hydrogen sulfide.Biochim Biophys Acta.(2009-Jul)
  18. ^Li M, Yun W, Wang G, Li A, Gao J, He QRoles and mechanisms of garlic and its extracts on atherosclerosis: A review.Front Pharmacol.(2022)
  19. ^Sánchez-Gloria JL, Arellano-Buendía AS, Juárez-Rojas JG, García-Arroyo FE, Argüello-García R, Sánchez-Muñoz F, Sánchez-Lozada LG, Osorio-Alonso HCellular Mechanisms Underlying the Cardioprotective Role of Allicin on Cardiovascular Diseases.Int J Mol Sci.(2022-Aug-13)
  20. ^Mitra S, Das R, Emran TB, Labib RK, Noor-E-Tabassum , Islam F, Sharma R, Ahmad I, Nainu F, Chidambaram K, Alhumaydhi FA, Chandran D, Capasso R, Wilairatana PDiallyl Disulfide: A Bioactive Garlic Compound with Anticancer Potential.Front Pharmacol.(2022)
Examine Database References
  1. Blood Pressure - Ried K, Frank OR, Stocks NPAged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: a randomised controlled trialMaturitas.(2010 Oct)
  2. Blood Pressure - Steiner M, Khan AH, Holbert D, Lin RIA double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipidsAm J Clin Nutr.(1996 Dec)
  3. Blood Pressure - Veena Dhawan, Sanjay JainGarlic supplementation prevents oxidative DNA damage in essential hypertensionMol Cell Biochem.(2005 Jul)
  4. Blood Pressure - Ried K, Frank OR, Stocks NPAged garlic extract reduces blood pressure in hypertensives: a dose-response trialEur J Clin Nutr.(2013 Jan)
  5. Blood Pressure - Ashraf R, Khan RA, Ashraf I, Qureshi AAEffects of Allium sativum (Garlic) on systolic and diastolic blood pressure in patients with essential hypertensionPak J Pharm Sci.(2013 Sep)
  6. Platelet Aggregation - Steiner M, Lin RSChanges in platelet function and susceptibility of lipoproteins to oxidation associated with administration of aged garlic extractJ Cardiovasc Pharmacol.(1998 Jun)
  7. Hepatopulmonary Syndrome Treatment - De BK, Dutta D, Pal SK, Gangopadhyay S, Das Baksi S, Pani AThe role of garlic in hepatopulmonary syndrome: a randomized controlled trialCan J Gastroenterol.(2010 Mar)
  8. Blood Viscosity - Galduróz JC, Antunes HK, Santos RFGender- and age-related variations in blood viscosity in normal volunteers: a study of the effects of extract of Allium sativum and Ginkgo bilobaPhytomedicine.(2007 Aug)
  9. Arterial Stiffness - Budoff MJ, Takasu J, Flores FR, Niihara Y, Lu B, Lau BH, Rosen RT, Amagase HInhibiting progression of coronary calcification using Aged Garlic Extract in patients receiving statin therapy: a preliminary studyPrev Med.(2004 Nov)
  10. Arterial Stiffness - Breithaupt-Grögler K, Ling M, Boudoulas H, Belz GGProtective effect of chronic garlic intake on elastic properties of aorta in the elderlyCirculation.(1997 Oct 21)
  11. Thromboxane B2 - K Rahman, D BillingtonDietary supplementation with aged garlic extract inhibits ADP-induced platelet aggregation in humansJ Nutr.(2000 Nov)
  12. Total cholesterol - Silagy C, Neil AGarlic as a lipid lowering agent--a meta-analysisJ R Coll Physicians Lond.(1994 Jan-Feb)
  13. Platelet Aggregation - Scharbert G, Kalb ML, Duris M, Marschalek C, Kozek-Langenecker SAGarlic at dietary doses does not impair platelet functionAnesth Analg.(2007 Nov)
  14. Platelet Aggregation - Steiner M, Li WAged garlic extract, a modulator of cardiovascular risk factors: a dose-finding study on the effects of AGE on platelet functionsJ Nutr.(2001 Mar)
  15. Heart Rate - Morris DM, Beloni RK, Wheeler HEEffects of garlic consumption on physiological variables and performance during exercise in hypoxiaAppl Physiol Nutr Metab.(2013 Apr)
  16. Blood Pressure - Sobenin IA, Andrianova IV, Demidova ON, Gorchakova T, Orekhov ANLipid-lowering effects of time-released garlic powder tablets in double-blinded placebo-controlled randomized studyJ Atheroscler Thromb.(2008 Dec)
  17. Blood Pressure - Adler AJ, Holub BJEffect of garlic and fish-oil supplementation on serum lipid and lipoprotein concentrations in hypercholesterolemic menAm J Clin Nutr.(1997 Feb)
  18. Blood Pressure - Simons LA, Balasubramaniam S, von Konigsmark M, Parfitt A, Simons J, Peters WOn the effect of garlic on plasma lipids and lipoproteins in mild hypercholesterolaemiaAtherosclerosis.(1995 Mar)
  19. Triglycerides - Kojuri J, Vosoughi AR, Akrami MEffects of anethum graveolens and garlic on lipid profile in hyperlipidemic patientsLipids Health Dis.(2007 Mar 1)
  20. Triglycerides - Ried K, Toben C, Fakler PEffect of garlic on serum lipids: an updated meta-analysisNutr Rev.(2013 May)
  21. Triglycerides - Mader FHTreatment of hyperlipidaemia with garlic-powder tablets. Evidence from the German Association of General Practitioners' multicentric placebo-controlled double-blind studyArzneimittelforschung.(1990 Oct)
  22. Triglycerides - Sobenin IA, Pryanishnikov VV, Kunnova LM, Rabinovich YA, Martirosyan DM, Orekhov ANThe effects of time-released garlic powder tablets on multifunctional cardiovascular risk in patients with coronary artery diseaseLipids Health Dis.(2010 Oct 19)
  23. Triglycerides - Phelps S, Harris WSGarlic supplementation and lipoprotein oxidation susceptibilityLipids.(1993 May)
  24. Total cholesterol - Stevinson C, Pittler MH, Ernst EGarlic for treating hypercholesterolemia. A meta-analysis of randomized clinical trialsAnn Intern Med.(2000 Sep 19)
  25. Total cholesterol - Warshafsky S, Kamer RS, Sivak SLEffect of garlic on total serum cholesterol. A meta-analysisAnn Intern Med.(1993 Oct 1)
  26. Glycemic Control - Gómez-Arbeláez D, Lahera V, Oubiña P, Valero-Muñoz M, de Las Heras N, Rodríguez Y, García RG, Camacho PA, López-Jaramillo PAged garlic extract improves adiponectin levels in subjects with metabolic syndrome: a double-blind, placebo-controlled, randomized, crossover studyMediators Inflamm.(2013)
  27. Peripheral Vascular Disease Symptoms - Kiesewetter H, Jung F, Jung EM, Blume J, Mrowietz C, Birk A, Koscielny J, Wenzel EEffects of garlic coated tablets in peripheral arterial occlusive diseaseClin Investig.(1993 May)
  28. Heart Rate - Verma SK, Rajeevan V, Jain P, Bordia AEffect of garlic (Allium sativum) oil on exercise tolerance in patients with coronary artery diseaseIndian J Physiol Pharmacol.(2005 Jan)
  29. Peripheral Vascular Disease Symptoms - Jepson RG, Kleijnen J, Leng GCGarlic for peripheral arterial occlusive diseaseCochrane Database Syst Rev.(2013 Apr 30)
  30. Homocysteine - Avci A, Atli T, Ergüder IB, Varli M, Devrim E, Aras S, Durak IEffects of garlic consumption on plasma and erythrocyte antioxidant parameters in elderly subjectsGerontology.(2008)
  31. Nitric Oxide - Mau Bhattacharyya, G V Girish, Soumendra K Karmohapatra, S A Samad, Asru K SinhaSystemic production of IFN-alpha by garlic (Allium sativum) in humansJ Interferon Cytokine Res.(2007 May)
  32. Mineral Bioaccumulation - Kianoush S, Balali-Mood M, Mousavi SR, Moradi V, Sadeghi M, Dadpour B, Rajabi O, Shakeri MTComparison of therapeutic effects of garlic and d-Penicillamine in patients with chronic occupational lead poisoningBasic Clin Pharmacol Toxicol.(2012 May)
  33. Helicobacter Pylori Infection Signs - Graham DY, Anderson SY, Lang TGarlic or jalapeño peppers for treatment of Helicobacter pylori infectionAm J Gastroenterol.(1999 May)
  34. Helicobacter Pylori Infection Signs - McNulty CA, Wilson MP, Havinga W, Johnston B, O'Gara EA, Maslin DJA pilot study to determine the effectiveness of garlic oil capsules in the treatment of dyspeptic patients with Helicobacter pyloriHelicobacter.(2001 Sep)
  35. Benign Prostatic Hyperplasia Symptoms - lker Durak, PhD, Erdal Yılmaz, MD, Erdinç Devrim, MD, Hakkı Perk, MD, Murat Kaçmaz, MDConsumption of aqueous garlic extract leads to significant improvement in patients with benign prostate hyperplasia and prostate cancerNutrition Research.()
  36. Common Cold Symptoms - Nantz MP, Rowe CA, Muller CE, Creasy RA, Stanilka JM, Percival SSSupplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition interventionClin Nutr.(2012 Jun)
  37. Common Cold Symptoms - Josling PPreventing the common cold with a garlic supplement: a double-blind, placebo-controlled surveyAdv Ther.(2001 Jul-Aug)
  38. Cortisol - Ishikawa H, Saeki T, Otani T, Suzuki T, Shimozuma K, Nishino H, Fukuda S, Morimoto KAged garlic extract prevents a decline of NK cell number and activity in patients with advanced cancerJ Nutr.(2006 Mar)
  39. Interleukin 6 - Mozaffari-Khosravi H, Hesabgar HA, Owlia MB, Hadinedoushan H, Barzegar K, Fllahzadeh MHThe effect of garlic tablet on pro-inflammatory cytokines in postmenopausal osteoporotic women: a randomized controlled clinical trialJ Diet Suppl.(2012 Dec)
  40. Esophageal Cancer Risk - Ma JL, Zhang L, Brown LM, Li JY, Shen L, Pan KF, Liu WD, Hu Y, Han ZX, Crystal-Mansour S, Pee D, Blot WJ, Fraumeni JF Jr, You WC, Gail MHFifteen-year effects of Helicobacter pylori, garlic, and vitamin treatments on gastric cancer incidence and mortalityJ Natl Cancer Inst.(2012 Mar 21)
  41. Gastric Cancer Risk - You WC, Brown LM, Zhang L, Li JY, Jin ML, Chang YS, Ma JL, Pan KF, Liu WD, Hu Y, Crystal-Mansour S, Pee D, Blot WJ, Fraumeni JF Jr, Xu GW, Gail MHRandomized double-blind factorial trial of three treatments to reduce the prevalence of precancerous gastric lesionsJ Natl Cancer Inst.(2006 Jul 19)
  42. Upper Respiratory Tract Infection Risk - Andrianova IV, Sobenin IA, Sereda EV, Borodina LI, Studenikin MIEffect of long-acting garlic tablets "allicor" on the incidence of acute respiratory viral infections in childrenTer Arkh.(2003)
  43. Atherosclerotic Signs - Koscielny J, Klüssendorf D, Latza R, Schmitt R, Radtke H, Siegel G, Kiesewetter HThe antiatherosclerotic effect of Allium sativumAtherosclerosis.(1999 May)
  44. Basal Cell Carcinoma Tumor Size - C M L J Tilli, A J W Stavast-Kooy, J D D Vuerstaek, M R T M Thissen, G A M Krekels, F C S Ramaekers, H A M NeumannThe garlic-derived organosulfur component ajoene decreases basal cell carcinoma tumor size by inducing apoptosisArch Dermatol Res.(2003 Jul)