by Eric Yarnell, ND, RH(AHG)
Copyright 2022. If you want to share this content, link to this page.
Copyright 2022. If you want to share this content, link to this page.
Last updated 28 May 2022
Summary
The preponderance of evidence from clinical trials confirm that garlic does NOT significantly inhibit platelets or cause bleeding in humans, and does NOT interact with anticoagulant or antiplatelet drugs. Older studies suggesting inhibition of platelet aggregation have mostly demonstrated only mild effects of dubious clinical significance (<20% reductions in all but one study). Case studies suggesting a problem combining garlic with anticoagulants were likely due to other issues, including the fact that these drugs commonly cause bleeding all on their own in people not taking garlic. The same conclusions are likely with other Allium vegetables, but based on far less research in humans.
Introduction
In vitro studies have repeatedly shown that various extracts of and compounds from garlic, onions, and some related plants (see list below) can inhibit platelet aggregation in many different models (Hosono, et al. 2020; Rahman, et al. 2016; Wang and Di 2014; Thompson, et al. 2013; Sabha, et al. 2012; Cavagnaro and Galmarini 2012; Allison, et al. 2012; Hiyasat, et al. 2009; Rahman 2007; Allison, et al. 2006; Teranishi, et al. 2003; Chen, et al. 2000; Ali, et al. 1999; Ali 1995; Apitz-Castro, et al. 1994; Srivastava and Tyagi 1993; Sendl, et al. 1992; Lawson, et al. 1992; Apitz-Castro, et al. 1991; Srivastava and Justesen 1989; Okuyama, et al. 1989; Srivastava 1986a and b; Srivastava 1984; Ariga, et al. 1981; Vanderhoek, et al. 1980; Makheia, et al. 1979). These studies looked at various different parts of these plants including the bulbs and aerial parts, and their preparation by a dizzying array of means. At least one study found various sulfur-containing compounds in garlic more potent than aspirin in vitro (Briggs, et al. 2000).
Animal studies in mice, rats, rabbits, and dogs seem to generally confirm these findings (Irfan, et al. 2019; Morihara and Hino 2017; Chan, et al. 2007; Briggs, et al. 2001; Alnaqeeb, et al. 1992; Ali, et al. 1990; Apitz-Castro, et al. 1988; Ali and Mohammed 1986).
Human trials are quite variable in terms of the products and doses used, the duration of use, and methods of analyzing effects of various Allium vegetables on platelet aggregation and fibrinolysis. The table below reviews clinical trials to show the variability, but generally supports that garlic at least has some mild platelet-inhibiting effects at reasonable doses.
However, no study so far shows any harmful interaction of garlic with anticoagulant or antiplatelet drugs. Those studies that have been published show no interaction, be it pharmacokinetic or pharmacodynamic, in humans. This further supports the effects of garlic on coagulation and platelets are at most mild.
Animal studies in mice, rats, rabbits, and dogs seem to generally confirm these findings (Irfan, et al. 2019; Morihara and Hino 2017; Chan, et al. 2007; Briggs, et al. 2001; Alnaqeeb, et al. 1992; Ali, et al. 1990; Apitz-Castro, et al. 1988; Ali and Mohammed 1986).
Human trials are quite variable in terms of the products and doses used, the duration of use, and methods of analyzing effects of various Allium vegetables on platelet aggregation and fibrinolysis. The table below reviews clinical trials to show the variability, but generally supports that garlic at least has some mild platelet-inhibiting effects at reasonable doses.
However, no study so far shows any harmful interaction of garlic with anticoagulant or antiplatelet drugs. Those studies that have been published show no interaction, be it pharmacokinetic or pharmacodynamic, in humans. This further supports the effects of garlic on coagulation and platelets are at most mild.
Major Members of Genus Allium, Subfamily Allioideae, Family Amaryllidaceae
- Allium cepa* (onion)
- Allium cepa cv Aggregatum Group (shallot)
- Allium cepa var cepa (western scallion)
- Allium chinense* = A. bakeri (Chinese scallion, Japanese scallion, 薤白 xiè bái, củ kiệu, 辣韮 or 薤 rakkyō)
- Allium fistulosum* (Welsh onion [actually native to China], bunching onion, scallion, 蔥白 cōng bái, ソウハク sōhaku, 총뱈 chongbaek)
- Allium sativum* (garlic, ajo, aglio, ail, 大蒜 dà suàn, 大蒜 たいさん taisan, にんにくninniku, 댓안 taesan, Knoblauch)
- Allium ampeloprasum = Allium porrum (leek)
- Allium ampeloprasum var ampeloprasum (elephant garlic)
- Allium schoenoprasum (chives)
- Allium tuberosum (garlic chives, Asian chives, 韭菜 jiǔ cài, hẹ, กุยช่าย kuichai, 부추 buchu, 韮 にら or ニラ nira)
- Allium ursinum* (wild garlic)
* = Preclinical evidence of being platelet inhibiting.
Effects of Allium Vegetables on Platelets in Humans
(in reverse chronological order of publication)
| Reference (trial type) | Patient population | Dose, form, duration | Results |
| Shafiekhani 2016 (OR) | n=62 healthy Iranian adults | One, two or three tablets garlic (equal to 1250 mg fresh garlic each) compared to 80 mg aspirin | No dose of garlic affected any measure of platelet aggregation |
| Sobenin 2012 (DBPCR) | n=29 Russian men with atherosclerosis and elevated platelet aggregation | Time-release garlic extract 300 mg bid vs placebo x 14 days | No sig effect on platelet aggregation or fibrinolysis between groups |
| Fakhar 2012 (OR) | n=36 healthy Iranian adults | One, two or three tablets of garlic (500 mg each, details not provided) compared to 75 mg clopidogrel x 3 wk | The two highest garlic doses inhibited platelet aggregation mildly vs. baseline, no effect on bleeding time, no between-group statistics provided |
| Scharbert 2007 (SBPCR) | n=18 healthy Austrian adults | Raw garlic 4.2 g in tsatsiki or just tsatsiki, single dose | No effect on any measure of platelet aggregation |
| Wojcikowski 2007 (DBPCR) | n=14 healthy Australian adults | Garlic oil (solvent extracted from 9.9 g garlic) vs. placebo, single dose | Epinephrine-induced platelet aggregation inhibited 12% vs. placebo (sig. difference), no other measure of platelet aggregation difference between groups |
| Hubbard 2006 (DBPCR) | n=6 healthy British adults | Onion soup, 500 g, high or low quercetin, 1 dose | Nonsig. difference between soups on platelet aggregation |
| Ziaei 2001 (DBPCR) | n=100 Iranian primagravidas | Garlic powder cap 800 mg qd for 3rd trimester | No effect on platelet aggregation, didn't prevent pre-eclampsia, no adverse effects |
| Steiner 2001 (DBPCR) | n=34 healthy American adults | Aged garlic extract 2.4 or 7.2 g qd or placebo x 6 weeks | Some measures of platelet aggregation decreased with 7.2 g dose vs. placebo, others did not |
| Rahman 2000 (ONR) | n=23 Health British adults | Aged garlic extract 5 ml qd x 13 wk | Mild inhibition of platelet aggregation |
| Steiner 1998 (DBPCR?) | n=15 healthy American men with high LDL cholesterol | Aged garlic extract 7.2 g qd vs placebo x 10 months | Three measures of platelet inhibition reduced sig. vs placebo, one was not |
| Bordia 1998 (DB?PCR) | n=60 Indian adults with CAD | Ethyl acetate garlic extract 2 cap bid (each cap made from 1 g raw garlic) vs placebo | No effect on fibrinolysis; only in vitro results reported for platelet aggregation |
| Bordia 1996 (???) | n=??? Some healthy, some with CAD | Ethyl acetate extract of raw garlic x 3 mon | Fibrinolytic activity increased |
| Morris 1995 (DBPCR) | n=14 healthy Australian men | Steam-distilled garlic oil 85.8 mg daily (extremely low dose, dubious extract) vs placebo | No effects on any measure of platelet aggregation |
| Legnani 1993 (DBPCR) | n=12 healthy Italian adults | Garlic powder 900 mg qd vs placebo, single dose and 14 days | Platelet aggregation sig. lower with garlic vs. placebo after 14 d (but not after single dose), but not fibrinolytic activity or tPA |
| Kiesewetter 1993 (DBPCR) | n=60 German adults with excessive platelet aggregation | Garlic powder 800 mg, coated tablets x 4 wk | Circulating platelet aggregates reduced ~10% (sig. vs. placebo), platelet aggregation reduced ~56% (sig. vs. placebo) |
| Barrie 1987 (DBPCR) | n=20 healthy American adults | Garlic oil, cold-pressed 18 mg (from 9 g garlic) vs placebo x 4 wk | ADP-stimulated platelet aggregation inhibited 16% (apparently sig. vs. placebo) |
| Chutani 1981 (OR?) | n=20 East Indian adults with ischemic heart disease | Raw or fried garlic, dose?, 4 wk | Fibrinolytic activity increased 84.8% (sig vs baseline?) with raw and 72% with fried garlic |
Light green = no effect on platelets or clotting; light red = inhibited platelets (effect may be mild); white = mixed results
Abbreviations: BP = blood pressure; CAD = coronary artery disease; DBPCR = double-blind, placebo-controlled, randomized; nonsig = not statistically significant; sig = statistically significant; ONR = open non-randomized; OR = open randomized
Abbreviations: BP = blood pressure; CAD = coronary artery disease; DBPCR = double-blind, placebo-controlled, randomized; nonsig = not statistically significant; sig = statistically significant; ONR = open non-randomized; OR = open randomized
Problems with comparing human clinical trials of Allium vegetables are manifold (Neil and Silagy 1994). First, different extracts and forms were use in almost every study, and different doses, making comparison technically impossible. Second, most trial were conducted in healthy adults, which while this might be relevant for assessing the preventative effects of these foods, are not relevant for treatment effects. Third, the methods of assessing platelet aggregation used varied significantly between many of the trials. Importantly, no clinical trial report any spontaneous bleeding in any subject. Fourth, the sample sizes were very small in most of these trials. A definitive, large clinical trial on a well-characterized and widely available garlic extract, as well as garlic as food, is awaited to clarify the situation.
Effects of Allium Vegetables on Anticoagulant/Antiplatelet Drugs in Humans
(alphabetical by drug)
| Reference (trial type) | Patient population | Dose, form, duration | Results |
| Mahdavi-Roshan 2016 (DBPCR) | n=56 Iranian adults with coronary artery disease | Garlic powder 400 mg (1.2 mg allicin) bid x 3 mon | No interaction with aspirin + clopidogrel |
| Mateen 2011 (OR) | n=10 East Indian adults with diabetes mellitus type 2 | Aged garlic extract 600 mg or placebo + 100 mg cilostazol | No synergy or problems combined with cilostazol |
| Macan 2006 (DBPCR) | n=52 American adults on warfarin therapy | Aged garlic extract 5 ml bid x 12 weeks | No interaction with warfarin |
| Mohammed Abdul 2004 (OR) | n=7 Healthy Australian men | Garlic extract 2 g qd (3.72 mg allicin qd) x 2 weeks | No interaction with warfarin |
Abbreviations: DBPCR = double-blind, placebo-controlled, randomized; sig = statistically significant; OR = open randomized
References: Preclinical Studies
Ali M (1995) "Mechanism by which garlic (Allium sativum) inhibits cyclooxygenase activity. Effect of raw versus boiled garlic extract on the synthesis of prostanoids" Prostaglandins Leukot Essent Fatty Acids 53(6):397–400.
Ali M, Bordia T, Mustafa T (1999) "Effect of raw versus boiled aqueous extract of garlic and onion on platelet aggregation" Prostaglandins Leukot Essent Fatty Acids 60(1):43–7.
Ali M, Mohammed SY (1986) "Selective suppression of platelet thromboxane formation with sparing of vascular prostacyclin synthesis by aqueous extract of garlic in rabbits" Prostaglandins Leukot Med 25(2–3):139–46.
Ali M, Thomson M, Alnaqeeb MA, et al. (1990) "Antithrombotic activity of garlic: its inhibition of the synthesis of thromboxane-B2 during infusion of arachidonic acid and collagen in rabbits" Prostaglandins Leukot Essent Fatty Acids 41(2):95–9.
Allison GL, Lowe GM, Rahman K (2006) "Aged garlic extract may inhibit aggregation in human platelets by suppressing calcium mobilization" J Nutr 136(3 Suppl):789S–92S.
Allison GL, Lowe GM, Rahman K (2012) "Aged garlic extract inhibits platelet activation by increasing intracellular cAMP and reducing the interaction of GPIIb/IIIa receptor with fibrinogen" Life Sci 91(25–26):1275–80.
Alnaqeeb MA, Ali M, Thomson M, et al. (1992) "Histopathological evidence of protective action of garlic against collagen and arachidonic acid toxicity in rabbits" Prostaglandins Leukot Essent Fatty Acids 46(4):301–6.
Apitz-Castro R, Badimon JJ, Badimon L (1994) "A garlic derivative, ajoene, inhibits platelet deposition on severely damaged vessel wall in an in vivo porcine experimental model" Thromb Res 75(3):243–9.
Apitz-Castro R, Jain MK, Bartoli F, et al. (1991) "Evidence for direct coupling of primary agonist-receptor interaction to the exposure of functional IIb-IIIa complexes in human blood platelets. Results from studies with the antiplatelet compound ajoene" Biochim Biophys Acta 1094(3):269–80.
Apitz-Castro R, Ledezma E, Escalante J, et al. (1988) "Reversible prevention of platelet activation by (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide (ajoene) in dogs under extracorporeal circulation" Arzneimittelforschung 38(7):901–4.
Ariga T, Oshiba S, Tamada T (1981) "Platelet aggregation inhibitor in garlic" Lancet 1(8212):150–1.
Barrie SA, Wright JV, Pizzorno JE (1987) "Effects of garlic oil on platelet aggregation, serum lipids and blood pressure in humans" J Orthomolecular Med 2(1):15–21.
Bordia A (1978) "Effect of garlic on human platelet aggregation in vitro" Atherosclerosis 30(4):355–60.
Briggs WH, Xiao H, Parkin KL, et al. (2000) "Differential inhibition of human platelet aggregation by selected Allium thiosulfinates" J Agric Food Chem 48(11):5731–5.
Briggs WH, Folts JD, Osman HE, Goldman IL (2001) "Administration of raw onion inhibits platelet-mediated thrombosis in dogs" J Nutr 131(10):2619–22.
Cavagnaro PF, Galmarini CR (2012) "Effect of processing and cooking conditions on onion (Allium cepa L) induced antiplatelet activity and thiosulfinate content" J Agric Food Chem 60(35):8731–7.
Chan KC, Yin MC, Chao WJ (2007) "Effect of diallyl trisulfide-rich garlic oil on blood coagulation and plasma activity of anticoagulation factors in rats" Food Chem Toxicol 45(3):502–7.
Chen JH, Chen HI, Wang JS, et al. (2000) "Effects of Welsh onion extracts on human platelet function in vitro" Life Sci 66(17):1571–9.
Hiyasat B, Sabha D, Grotzinger K, et al. (2009) "Antiplatelet activity of Allium ursinum and Allium sativum" Pharmacology 83(4):197–204.
Hosono T, Sato A, Nakaguchi N, et al. (2020) "Diallyl trisulfide inhibits platelet aggregation through the modification of sulfhydryl groups" J Agric Food Chem 68(6):1571–8.
Irfan M, Kim M, Kim KS, et al. (2019) "Fermented garlic ameliorates hypercholesterolemia and inhibits platelet activation" Evid Based Complement Alternat Med 2019:3030967.
Lawson LD, Ransom DK, Hughes BG (1992) "Inhibition of whole blood platelet-aggregation by compounds in garlic clove extracts and commercial garlic products" Thromb Res 65(2):141–56.
Makheia AN, Vanderhoek JY, Bailey JM (1979) "Inhibition of platelet aggregation and thromboxane synthesis by onion and garlic" Lancet 1(8119):781.
Malladi N, Johny E, Uppulapu SK, et al. (2021) "Understanding the activation of platelets in diabetes and its modulation by allyl methyl sulfide, an active metabolite of garlic" J Diabetes Res 2021:6404438.
Morihara N, Hino A (2017) "Aged garlic extract suppresses platelet aggregation by changing the functional property of platelets" J Nat Med 71(1):249–256.
Okuyama T, Fujita K, Shibata S, et al. (1989) "Effects of Chinese drugs 'xiebai' and 'dasuan' on human platelet aggregation (Allium bakeri, A. sativum)" Planta Med 55(3):242–4.
Qi R, Liao F, Inoue K, et al. (2000) "Inhibition by diallyl trisulfide, a garlic component, of intracellular Ca(2+) mobilization without affecting inositol-1,4, 5-trisphosphate (IP(3)) formation in activated platelets" Biochem Pharmacol 60(10):1475–83.
Rahman K (2007) "Effects of garlic on platelet biochemistry and physiology" Mol Nutr Food Res 51(11):1335–44.
Rahman K, Lowe GM, Smith S (2016) "Aged garlic extract inhibits human platelet aggregation by altering intracellular signaling and platelet shape change" J Nutr 146(2):410S–15S.
Sabha D, Hiyasat B, Grötzinger K, et al. (2012) "Allium ursinum L: Bioassay-guided isolation and identification of a galactolipid and a phytosterol exerting antiaggregatory effects" Pharmacology 89(5–6):260–9.
Sendl A, Elbl G, Steinke B, et al. (1992) "Comparative pharmacological investigations of Allium ursinum and Allium sativum" Planta Med 58(1):1–7.
Srivastava KC (1984) "Aqueous extracts of onion, garlic and ginger inhibit platelet aggregation and alter arachidonic acid metabolism" Biomed Biochim Acta 43(8–9):S335–46.
Srivastava KC (1986a) "Evidence for the mechanism by which garlic inhibits platelet aggregation" Prostaglandins Leukot Med 22(3):313–21.
Srivastava KC (1986b) "Onion exerts antiaggregatory effects by altering arachidonic acid metabolism in platelets" Prostaglandins Leukot Med 24(1):43–50.
Srivastava KC, Justesen U (1989) "Isolation and effects of some garlic components on platelet aggregation and metabolism of arachidonic acid in human blood platelets" Wien Klin Wochenschr 101(8):293–9.
Srivastava KC, Tyagi OD (1993) "Effects of a garlic-derived principle (ajoene) on aggregation and arachidonic acid metabolism in human blood platelets" Prostaglandins Leukot Essent Fatty Acids 49(2):587–95.
Teranishi K, Apitz-Castro R, Robson SC, et al. (2003) "Inhibition of baboon platelet aggregation in vitro and in vivo by the garlic derivative, ajoene" Xenotransplantation 10(4):374–9.
Thomson SJ, Rippon P, Butts C, et al. (2013) "Inhibition of platelet activation by lachrymatory factor synthase (LFS)-silenced (tearless) onion juice" J Agric Food Chem 61(44):10574–81.
Vanderhoek JY, Makheja AN, Bailey JM (1980) "Inhibition of fatty acid oxygenases by onion and garlic oils. Evidence for the mechanism by which these oils inhibit platelet aggregation" Biochem Pharmacol 29(23):3169–73.
Wang XH, Di YH (2014) "Mechanism of cooked blanched garlic leaves against platelet aggregation" Zhongguo Shi Yan Xue Ye Xue Za Zhi 22(3):753–7 [in Chinese].
Ali M, Bordia T, Mustafa T (1999) "Effect of raw versus boiled aqueous extract of garlic and onion on platelet aggregation" Prostaglandins Leukot Essent Fatty Acids 60(1):43–7.
Ali M, Mohammed SY (1986) "Selective suppression of platelet thromboxane formation with sparing of vascular prostacyclin synthesis by aqueous extract of garlic in rabbits" Prostaglandins Leukot Med 25(2–3):139–46.
Ali M, Thomson M, Alnaqeeb MA, et al. (1990) "Antithrombotic activity of garlic: its inhibition of the synthesis of thromboxane-B2 during infusion of arachidonic acid and collagen in rabbits" Prostaglandins Leukot Essent Fatty Acids 41(2):95–9.
Allison GL, Lowe GM, Rahman K (2006) "Aged garlic extract may inhibit aggregation in human platelets by suppressing calcium mobilization" J Nutr 136(3 Suppl):789S–92S.
Allison GL, Lowe GM, Rahman K (2012) "Aged garlic extract inhibits platelet activation by increasing intracellular cAMP and reducing the interaction of GPIIb/IIIa receptor with fibrinogen" Life Sci 91(25–26):1275–80.
Alnaqeeb MA, Ali M, Thomson M, et al. (1992) "Histopathological evidence of protective action of garlic against collagen and arachidonic acid toxicity in rabbits" Prostaglandins Leukot Essent Fatty Acids 46(4):301–6.
Apitz-Castro R, Badimon JJ, Badimon L (1994) "A garlic derivative, ajoene, inhibits platelet deposition on severely damaged vessel wall in an in vivo porcine experimental model" Thromb Res 75(3):243–9.
Apitz-Castro R, Jain MK, Bartoli F, et al. (1991) "Evidence for direct coupling of primary agonist-receptor interaction to the exposure of functional IIb-IIIa complexes in human blood platelets. Results from studies with the antiplatelet compound ajoene" Biochim Biophys Acta 1094(3):269–80.
Apitz-Castro R, Ledezma E, Escalante J, et al. (1988) "Reversible prevention of platelet activation by (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide (ajoene) in dogs under extracorporeal circulation" Arzneimittelforschung 38(7):901–4.
Ariga T, Oshiba S, Tamada T (1981) "Platelet aggregation inhibitor in garlic" Lancet 1(8212):150–1.
Barrie SA, Wright JV, Pizzorno JE (1987) "Effects of garlic oil on platelet aggregation, serum lipids and blood pressure in humans" J Orthomolecular Med 2(1):15–21.
Bordia A (1978) "Effect of garlic on human platelet aggregation in vitro" Atherosclerosis 30(4):355–60.
Briggs WH, Xiao H, Parkin KL, et al. (2000) "Differential inhibition of human platelet aggregation by selected Allium thiosulfinates" J Agric Food Chem 48(11):5731–5.
Briggs WH, Folts JD, Osman HE, Goldman IL (2001) "Administration of raw onion inhibits platelet-mediated thrombosis in dogs" J Nutr 131(10):2619–22.
Cavagnaro PF, Galmarini CR (2012) "Effect of processing and cooking conditions on onion (Allium cepa L) induced antiplatelet activity and thiosulfinate content" J Agric Food Chem 60(35):8731–7.
Chan KC, Yin MC, Chao WJ (2007) "Effect of diallyl trisulfide-rich garlic oil on blood coagulation and plasma activity of anticoagulation factors in rats" Food Chem Toxicol 45(3):502–7.
Chen JH, Chen HI, Wang JS, et al. (2000) "Effects of Welsh onion extracts on human platelet function in vitro" Life Sci 66(17):1571–9.
Hiyasat B, Sabha D, Grotzinger K, et al. (2009) "Antiplatelet activity of Allium ursinum and Allium sativum" Pharmacology 83(4):197–204.
Hosono T, Sato A, Nakaguchi N, et al. (2020) "Diallyl trisulfide inhibits platelet aggregation through the modification of sulfhydryl groups" J Agric Food Chem 68(6):1571–8.
Irfan M, Kim M, Kim KS, et al. (2019) "Fermented garlic ameliorates hypercholesterolemia and inhibits platelet activation" Evid Based Complement Alternat Med 2019:3030967.
Lawson LD, Ransom DK, Hughes BG (1992) "Inhibition of whole blood platelet-aggregation by compounds in garlic clove extracts and commercial garlic products" Thromb Res 65(2):141–56.
Makheia AN, Vanderhoek JY, Bailey JM (1979) "Inhibition of platelet aggregation and thromboxane synthesis by onion and garlic" Lancet 1(8119):781.
Malladi N, Johny E, Uppulapu SK, et al. (2021) "Understanding the activation of platelets in diabetes and its modulation by allyl methyl sulfide, an active metabolite of garlic" J Diabetes Res 2021:6404438.
Morihara N, Hino A (2017) "Aged garlic extract suppresses platelet aggregation by changing the functional property of platelets" J Nat Med 71(1):249–256.
Okuyama T, Fujita K, Shibata S, et al. (1989) "Effects of Chinese drugs 'xiebai' and 'dasuan' on human platelet aggregation (Allium bakeri, A. sativum)" Planta Med 55(3):242–4.
Qi R, Liao F, Inoue K, et al. (2000) "Inhibition by diallyl trisulfide, a garlic component, of intracellular Ca(2+) mobilization without affecting inositol-1,4, 5-trisphosphate (IP(3)) formation in activated platelets" Biochem Pharmacol 60(10):1475–83.
Rahman K (2007) "Effects of garlic on platelet biochemistry and physiology" Mol Nutr Food Res 51(11):1335–44.
Rahman K, Lowe GM, Smith S (2016) "Aged garlic extract inhibits human platelet aggregation by altering intracellular signaling and platelet shape change" J Nutr 146(2):410S–15S.
Sabha D, Hiyasat B, Grötzinger K, et al. (2012) "Allium ursinum L: Bioassay-guided isolation and identification of a galactolipid and a phytosterol exerting antiaggregatory effects" Pharmacology 89(5–6):260–9.
Sendl A, Elbl G, Steinke B, et al. (1992) "Comparative pharmacological investigations of Allium ursinum and Allium sativum" Planta Med 58(1):1–7.
Srivastava KC (1984) "Aqueous extracts of onion, garlic and ginger inhibit platelet aggregation and alter arachidonic acid metabolism" Biomed Biochim Acta 43(8–9):S335–46.
Srivastava KC (1986a) "Evidence for the mechanism by which garlic inhibits platelet aggregation" Prostaglandins Leukot Med 22(3):313–21.
Srivastava KC (1986b) "Onion exerts antiaggregatory effects by altering arachidonic acid metabolism in platelets" Prostaglandins Leukot Med 24(1):43–50.
Srivastava KC, Justesen U (1989) "Isolation and effects of some garlic components on platelet aggregation and metabolism of arachidonic acid in human blood platelets" Wien Klin Wochenschr 101(8):293–9.
Srivastava KC, Tyagi OD (1993) "Effects of a garlic-derived principle (ajoene) on aggregation and arachidonic acid metabolism in human blood platelets" Prostaglandins Leukot Essent Fatty Acids 49(2):587–95.
Teranishi K, Apitz-Castro R, Robson SC, et al. (2003) "Inhibition of baboon platelet aggregation in vitro and in vivo by the garlic derivative, ajoene" Xenotransplantation 10(4):374–9.
Thomson SJ, Rippon P, Butts C, et al. (2013) "Inhibition of platelet activation by lachrymatory factor synthase (LFS)-silenced (tearless) onion juice" J Agric Food Chem 61(44):10574–81.
Vanderhoek JY, Makheja AN, Bailey JM (1980) "Inhibition of fatty acid oxygenases by onion and garlic oils. Evidence for the mechanism by which these oils inhibit platelet aggregation" Biochem Pharmacol 29(23):3169–73.
Wang XH, Di YH (2014) "Mechanism of cooked blanched garlic leaves against platelet aggregation" Zhongguo Shi Yan Xue Ye Xue Za Zhi 22(3):753–7 [in Chinese].
References: Clinical Trials
Bordia A, Verma SK, Srivastava KC (1996) "Effect of garlic on platelet aggregation in humans: A study in healthy subjects and patients with coronary artery disease" Prostagl Leukotr Essential Fatty Acids 55:201–5.
Bordia A, Verma SK, Srivastava KC (1998) "Effect of garlic (Allium sativum) on blood lipids, blood sugar, fibrinogen and fibrinolytic activity in patients with coronary artery disease" Prostaglandins Leukot Essent Fatty Acids 58(4):257–63.
Chutani SK, Bordia A (1981) "The effect of fried versus raw garlic on fibrinolytic activity in man" Atherosclerosis 38(3–4):417–21.
Fakhar H, Hashemi Tayer A (2012) "Effect of the garlic pill in comparison with Plavix on platelet aggregation and bleeding time" Iran J Ped Hematol Oncol 2(4):146–52.
Hubbard GP, Wolffram S, de Vos R, et al. (2006) "Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: A pilot study" Br J Nutr 96(3):482–8.
Kiesewetter H, Jung F, Jung EM, et al. (1993) "Effect of garlic on platelet aggregation in patients with increased risk of juvenile ischaemic attack" Eur J Clin Pharmacol 45(4):333–6.
Legnani C, Frascaro M, Guazzaloca G, et al. (1993) "Effects of a dried garlic preparation on fibrinolysis and platelet aggregation in healthy subjects" Arzneimittelforschung 43(2):119–22.
Macan H, Uykimpang R, Alconcel M, et al. (2006) "Aged garlic extract may be safe for patients on warfarin therapy" J Nutr 136(3 Suppl):793S–5S.
Mahdavi-Roshan M, Nasrollahzadeh J, Mohammad Zadeh A, Zahedmehr A (2016) "Does garlic supplementation control blood pressure in patients with severe coronary artery disease? A clinical trial study" Iran Red Crescent Med J 18(11):e23871.
Mateen AA, Rani PU, Naidu MU, Chandrashekar E (2011) "Pharmacodynamic interaction study of Allium sativum (garlic) with cilostazol in patients with type II diabetes mellitus" Indian J Pharmacol 43(3):270–4.
Mohammed Abdul MI, Jiang X, Williams KM, et al. (2008) "Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects" Br J Pharmacol 154(8):1691–700.
Morris J, Burke V, Mori TA, et al. (1995) "Effects of garlic extract on platelet aggregation: A randomized placebo-controlled double-blind study" Clin Exp Pharmacol Physiol 22(6-7):414–7.
Neil A, Silagy C (1994) "Garlic: Its cardio-protective properties" Curr Opin Lipiol 4(1):6–10.
Rahman K, Billington D (2000) "Dietary supplementation with aged garlic extract inhibits ADP-induced platelet aggregation in humans" J Nutr 130(11):2662–5.
Scharbert G, Kalb ML, Duris M, et al. (2007) "Garlic at dietary doses does not impair platelet function" Anesth Analg 105(5):1214–8.
Shafiekhani M, Faridi P, Kojuri J, Namazi S (2016) "Comparison of antiplatelet activity of garlic tablets with cardio-protective dose of aspirin in healthy volunteers: A randomized clinical trial" Avicenna J Phytomed 6(5):550–7.
Sobenin I, Andrianova I, Ionova V, et al. (2012) "Anti-aggregatory and fibrinolytic effects of time-released garlic powder tablets" Appl Technol Innov 7(2):40-45.
Steiner M, Li W (2001) "Aged garlic extract, a modulator of cardiovascular risk factors: A dose-finding study on the effects of AGE on platelet functions" J Nutr 131(3s):980S–4S.
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Sobenin I, Andrianova I, Ionova V, et al. (2012) "Anti-aggregatory and fibrinolytic effects of time-released garlic powder tablets" Appl Technol Innov 7(2):40-45.
Steiner M, Li W (2001) "Aged garlic extract, a modulator of cardiovascular risk factors: A dose-finding study on the effects of AGE on platelet functions" J Nutr 131(3s):980S–4S.
Steiner M, Lin RS (1998) "Changes in platelet function and susceptibility of lipoproteins to oxidation associated with administration of aged garlic extract" J Cardiovasc Pharmacol 31(6):904–8.
Wojcikowski K, Myers S, Brooks L (2007) "Effects of garlic oil on platelet aggregation: A double blind placebo controlled crossover study" Platelets 18(1):29–34.
Ziaei S, Hantoshzadeh S, Rezasoltani P, Lamyian M (2001) "The effect of garlic tablet on plasma lipids and platelet aggregation in nulliparous pregnants at high risk of preeclampsia" Eur J Obstet Gynecol Reprod Biol 99(2):201–6.