Garlic

Selected Aged Garlic Research

Historical perspective on garlic and cardiovascular disease.

Rahman K.

School of Biomolecular Sciences, Liverpool John Moore University, Liverpool L3 3AF, UK.

Cardiovascular disease is a complex and multifactorial disease characterized by such factors as high cholesterol, hypertension, reduced fibrinolysis, increase in blood-clotting time and increased platelet aggregation. Dietary therapy is the first step in the treatment of hyperlipidemia; garlic has been used medicinally for centuries and is still included in the traditional medicine of many cultures. Historically, there has been great interest in the role of garlic in reducing cardiovascular risk factors.

Evidence from numerous studies points to the fact that garlic can bring about the normalization of plasma lipids, enhancement of fibrinolytic activity, inhibition of platelet aggregation and reduction of blood pressure and glucose. However, some contradictory results have also emerged as a result of methodological shortcomings, the use of different formulations/preparations of garlic and different time scales of the studies. Accordingly, further clinical studies are required in which standardized formulations of garlic with known compositions can be used. Such formulations (e.g., Aged Garlic Extract) are now available and are being investigated.

Evidence obtained from these studies indicates that garlic has potential in the prevention and control of cardiovascular disorders and is beneficial when taken as a dietary supplement.

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Pleiotropic effects of garlic [Original article in German]

Siegel G, Walter A, Engel S, Walper A, Michel F.

Institut fur Physiologie, Universitatsklinikums Benjamin Franklin, Freien Universitat Berlin, Deutschland. siegel@mail.grumed.fu-berlin.de

Garlic as a herbal remedy reduces a multitude of risk factors which play a decisive role in the genesis and progression of arteriosclerosis: decrease in total and LDL-cholesterol, increase in HDL-cholesterol, reduction of serum triglyceride and fibrinogen concentration, lowering of arterial blood pressure and promotion of organ perfusion, and, finally, enhancement in fibrinolysis, inhibition of platelet aggregation, and diminution of plasma viscosity. In a prospective, 4-year clinical trial with primary endpoint ‘arteriosclerotic plaque volume’ it was proven not only a 9 to 18% reduction and 3% regression in plaque volume of the total collective under the influence of standardized garlic powder dragees (900 mg/die LI 111), but also of some facets of the phytopharmacologic pleiotropy of this herb: decrease in LDL level by 4%, increase in HDL concentration by 8%, and lowering in blood pressure by 7%. The reduction of arterial blood pressure is due to an additional opening of K(Ca) ion channels in the membrane of vascular smooth muscle cells that effects its hyperpolarization. This membrane hyperpolarization closes about 20% of the L-type Ca2+ channels, consequence of which is vasodilatation. In human coronary arteries, the increase in vascular diameter by 4% is closely associated with an improvement of coronary perfusion by 18%. These pleiotropic effects of garlic result in a reduction of relative cardiovascular risk for infarction and stroke by more than 50%.

PMID: 10483684 [PubMed - indexed for MEDLINE]

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Cardiovascular effect of garlic (Allium sativum)
[Original article in Spanish]

Garcia Gomez LJ, Sanchez-Muniz FJ.

Departamento de Nutricion y Bromatologia I (Nutricion), Facultad de Farmacia, Universidad Complutense de Madrid, Madrid-Espana.

Garlic has been used for centuries, and even nowadays is part of popular medicine in many cultures. New data have increased the interest in garlic and its role in normalization and treatment of cardiovascular disease risk factors. Recent studies have shown the complex composition of garlic, containing many compounds, that present potential positive effect in the field of health. The aim of the present paper was to review results of some studies that have found a relationship between garlic and cardiovascular diseases . From some of them it can be summarized that garlic can normalize plasma lipid, check lipid peroxidation, stimulate fibrinolytic activity, inhibit platelet aggregation, smooth the thickening and structural changes of artery wall related to aging and atherosclerosis, and decrease blood pressure

PMID: 11347290 [PubMed - indexed for MEDLINE]

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Antioxidant effects of tetrahydro-beta-carboline derivatives identified in aged garlic extract.

Ichikawa M, Ryu K, Yoshida J, Ide N, Yoshida S, Sasaoka T, Sumi S.

Healthcare Research Institute, Wakunaga Pharmaceutical Co., Ltd., 1624, Shimokotachi, Koda-cho, Takata-gun, Hiroshima, 739-1195, Japan .

1,2,3,4-Tetrahydro-beta-carboline derivatives (THbetaCs) are formed through Pictet-Spengler chemical condensation between tryptophan and aldehydes during food production, storage and processing. In the present study, in order to identify the antioxidants in aged garlic extract (AGE), we fractionated it and identified four THbetaCs; 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids (MTCC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-1,3-dicarboxylic acid (MTCdiC) in both diastereoisomers using liquid chromatography mass spectrometry (LC-MS). Interestingly, these compounds were not detected in raw garlic, but the contents increased during the natural aging process of garlic. In in vitro assay systems, all of these compounds have shown strong hydrogen peroxide scavenging activities. (1S, 3S)-MTCdiC was found to be stronger than the common antioxidant, ascorbic acid. MTCC and MTCdiC inhibited AAPH-induced lipid peroxidation. Both MTCdiCs also inhibited LPS-induced nitrite production from murine macrophages at 10-100 microM. Our data suggest that these compounds are potent antioxidants in AGE, and thus may be useful for prevention of disorders associated with oxidative stress.

PMID: 14530594 [PubMed - in process]

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Antioxidant properties of aged garlic extract: an in vitro study incorporating human low density lipoprotein.

Dillon SA, Burmi RS, Lowe GM, Billington D, Rahman K.

School of Biomolecular Sciences, Liverpool John Moores University, Byrom Street, L3 3AF, Liverpool, UK.

Oxidation of low-density lipoprotein (LDL) has been recognized as playing an important role in the development and progression of atherosclerotic heart disease. Human LDL was isolated and challenged with a range of oxidants either in the presence or absence of AGE or its diethyl ether extract. Oxidative modification of the LDL fraction using CuSO(4), 5-lipoxygenase and xanthine/xanthine oxidase was monitored by both the appearance of thiobarbituric-acid substances (TBA-RS) and an increase in electrophoretic mobility.This study indicates that AGE is an effective antioxidant as it scavenged superoxide ions and reduced lipid peroxide formation in cell free assays. Superoxide production was completely inhibited in the presence of a 10% (v/v) aqueous preparation of AGE and reduced by 34% in the presence of a 10% (v/v) diethyl ether extract of AGE. The presence of 10% (v/v) diethyl ether extract of AGE significantly reduced Cu(2+) and 15-lipoxygenase-mediated lipid peroxidation of isolated LDL by 81% and 37%, respectively. In addition, it was found that AGE also had the capacity to chelate copper ions. In contrast, the diethyl ether extract of AGE displayed no copper binding capacity, but demonstrated distinct antioxidant properties. These results support the view that AGE inhibits the in vitro oxidation of isolated LDL by scavenging superoxide and inhibiting the formation of lipid peroxides. AGE was also shown to reduce LDL oxidation by the chelation of Cu(2+). Thus, AGE may have a role to play in preventing the development and progression of atherosclerotic disease.

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Protective action on human LDL against oxidation and glycation by four organosulfur compounds derived from garlic.

Ou CC, Tsao SM, Lin MC, Yin MC.

Department of Nutritional Science, Chungshan Medical University, Taichung City, Taiwan, ROC.

Human LDL were used to study the protective action of four organosulfur compounds (diallyl sulfide, DAS; diallyl disulfide, DADS; S-ethylcysteine, SEC; N-acetylcysteine, NAC) derived from garlic against oxidation and glycation. The four organosulfur compounds significantly inhibited superoxide production by xanthine-xanthine oxidase (P < 0.05) and showed marked copper-chelating capability. DAS and DADS exhibited greater antioxidant activities against copper- and amphotericin B-induced LDL oxidation (P < 0.05) than SEC and NAC. However, SEC and NAC were more effective in sparing LDL alpha-tocopherol (P < 0.05). When oxidation was minimized, SEC was the most powerful agent against LDL glycation (P < 0.05); however, DADS was superior to other agents in suppressing both oxidation and glycation when LDL oxidation occurred simultaneously with glycation. These results suggest that the four organosulfur compounds derived from garlic are potent agents for protecting LDL against oxidation and glycation, and that they may benefit patients with diabetes mellitus or cardiovascular diseases by preventing complications.

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Cardioprotective actions of garlic (Allium sativum) – Arrhythmia

Isensee H, Rietz B, Jacob R.

Institute of Physiology II, University of Tubingen, Fed. Rep. of Germany. Arzneimittelforschung 1993 Feb;43(2):

The influence of an intake of garlic powder (1%–corresponding to Kwai/Sapec–added to a standard chow for a 10-week period) on the susceptibility to ventricular arrhythmias under ischemia and reperfusion was investigated in the isolated rat heart (Langendorff preparation) perfused with a modified Krebs-Henseleit solution.

The incidence of ventricular tachycardia (VT) and fibrillation (VF) after ligation of the descending branch of the left coronary artery (LAD) (20 min) was significantly reduced in the garlic group as compared to untreated controls (VT: 0% vs. 35.5%; VF: 50% vs. 88%). The size of the ischemic zone was significantly smaller (31.7% vs. 40.9% of total heart tissue). The reperfusion experiments (5 min after 10 min ischemia) revealed similar results (VT: 50% vs. 100%; VF: 30% vs. 90 %). The time until occurrence of extrasystoles and VT or VF was prolonged in most cases, and the duration of arrhythmias was abbreviated.

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Effects of garlic on blood fluidity and fibrinolytic activity: a randomised, placebo-controlled, double-blind study.

Kiesewetter H, Jung F, Mrowietz C, Pindur G, Heiden M, Wenzel E, Gu LD.

Department of Clinical Haemostaseology and Transfusion, Saarland University, Homburg/Saar, West Germany.

In summary, it can be said that the improvement of blood fluidity and the simultaneous increase in fibrinolytic activity are an ideal complement. While the increase in fibrinolytic activity supports the physiological reparation process in the microcirculation, the improvement of blood fluidity produces an increase in capillary perfusion that has, in some way, a cleaning effect, with a ‘purification’ of the microcirculation.

Publication Types: Clinical Trial and Randomized Controlled Trial

PMID: 2128029 [PubMed - indexed for MEDLINE]

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The antiatherosclerotic effect of Allium sativum.

Koscielny J, Klussendorf D, Latza R, Schmitt R, Radtke H, Siegel G, Kiesewetter H.

Institute for Transfusion Medicine and Immunohematology, University Clinic Charite of the Humboldt University, Berlin, Germany.

In a randomized, double-blind, placebo-controlled clinical trial, the plaque volumes in both carotid and femoral arteries of 152 probationers were determined by B-mode ultrasound. Continuous intake of high-dose garlic powder dragees reduced significantly the increase in arteriosclerotic plaque volume by 5-18% or even effected a slight regression within the observational period of 48 months.

Also the age-dependent representation of the plaque volume shows an increase between 50 and 80 years that is diminished under garlic treatment by 6-13% related to 4 years. It seems even more important that with garlic application the plaque volume in the whole collective remained practically constant within the age-span of 50-80 years. These results substantiated that not only a preventive but possibly also a curative role in arteriosclerosis therapy (plaque regression) may be ascribed to garlic remedies.

PMID: 10381297 [PubMed - indexed for MEDLINE]

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Effects of garlic coated tablets in peripheral arterial occlusive disease.

Kiesewetter H, Jung F, Jung EM, Blume J, Mrowietz C, Birk A, Koscielny J, Wenzel E.

Abteilung fur Klinische Hamostaseologie und Transfusionsmedizin, Universitat des Saarlandes, Homburg/Saar.

For the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 +/- 65.1 to 207.1 +/- 85.0 m) was significantly higher (P < 0.05) than in the placebo group (by 31 m, from 172.0 +/- 60.9 to 203.1 +/- 72.8). Both groups received physical therapy twice a week . The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication.

Publication Types: Clinical Trial and Randomised Controlled Trial

PMID: 8508009 [PubMed - indexed for MEDLINE]

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Effect of garlic (Allium sativum) on blood lipids, blood sugar, fibrinogen and fibrinolytic activity in patients with coronary artery disease.

Bordia A, Verma SK, Srivastava KC.

Department of Medicine, RNT Medical College, Udaipur, India.

Thirty patients with coronary artery disease (CAD) were administered garlic (study group) while another 30 patients received the placebo (control group). Various risk parameters were determined at 1.5 and 3 months of garlic administration. Garlic, administered in a daily dose of 2 x 2 capsules (each capsule containing ethyl acetate extract from 1 g peeled and crushed raw garlic), reduced significantly total serum cholesterol and triglycerides, and increased significantly HDL-cholesterol and fibrinolytic activity. There was no effect on the fibrinogen and glucose levels. In vitro effects of the garlic oil on platelet aggregation (PAg) and eicosanoid metabolism were examined; it inhibited PAg induced by several platelet agonists, and also platelet thromboxane formation. Two important paraffinic polysulphides – diallyl disulphide (DADS) and diallyl trisulphide (DATS) – derived from garlic and are usual constituents of garlic oil, showed antiplatelet activity, and also inhibited platelet thromboxane formation . In this respect DATS was more potent than DADS. The nature of inhibition of PAg by DATS was found to be reversible.

PMID: 9654398 [PubMed - indexed for MEDLINE]

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Effect of garlic on platelet aggregation in humans: a study in healthy subjects and patients with coronary artery disease.

Bordia A, Verma SK, Srivastava KC.

Department of Medicine, R.N.T. Medical College, Udaipur, India.

Garlic’s value in preventing cardiovascular disease has been reported by several research groups. Garlic and its components are known to possess antiplatelet activity which has been demonstrated mostly in vitro. It was found that garlic oil administration to healthy subjects and patients with coronary artery disease (CAD) inhibited platelet aggregation ex vivo . Though garlic components leave the body quickly, a slow build-up of the active ingredients may take place. This was evident from the observation that though a 2-3 fold higher dose was not effective in inhibiting platelet aggregation when administered once, a lower dose became effective in long-term administration.

PMID: 8931120 [PubMed - indexed for MEDLINE]

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Direct anti-atherosclerosis-related effects of garlic.

Orekhov AN, Tertov VV, Sobenin IA, Pivovarova EM.

Institute of Experimental Cardiology, Russian Academy of Medical Sciences, Moscow.

Direct anti-atherosclerosis-related effects of garlic were studied using cell culture. An aqueous extract from garlic powder (GPE) was added to smooth muscle cells cultured from atherosclerotic plaques of human aorta.

During a 24-hour incubation, GPE significantly reduced the level of cholesteryl esters and free cholesterol in these cultured cells and inhibited their proliferative activity. In addition, GPE significantly reduced cholesterol accumulation and inhibited cell proliferation stimulated by blood serum taken from patients with angiographically assessed coronary atherosclerosis, i.e. GPE reduced atherogenic manifestations of patients’ serum. Garlic effect on blood atherogenicity of patients with coronary atherosclerosis has also been studied ex vivo. Following a 24-hour incubation with cultured cells, patients’ blood serum caused an increase of total cell cholesterol. Blood serum taken 2 hours after an oral administration of 300 mg garlic powder tablet caused substantially less cholesterol accumulation in cultured cells. This suggests that garlic powder manifests direct anti-atherogenic-related action not only in vitro but also in vivo.

PMID: 7742001 [PubMed - indexed for MEDLINE]

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Postprandial lipemia under treatment with Allium sativum. Controlled double-blind study of subjects with reduced HDL2-cholesterol
[Original article in German]

Rotzsch W, Richter V, Rassoul F, Walper A.

Institut fur Klinische Chemie und Laboratoriumsdiagnostik, Universitat Leipzig.

Postprandial Lipaemia under Treatment with Allium sativum/Controlled double-blind study in healthy volunteers with reduced HDL2-cholesterol levels. The effectiveness of a standardized garlic powder preparation (Sapec, Kwai) on alimentary hypertriglyceridaemia after intake of a standardized fatty test meal containing 100 g butter was analyzed in a randomized placebo-controlled double-blind study. 24 volunteers with HDL2-cholesterol concentrations in plasma of less than 10 mg/dl (men) respectively 15 mg/dl (women) participated in the study. The volunteers received 3 times 1 tablet daily over a period of 6 weeks equivalent to a daily dosage of 900 mg garlic powder in the active treated group. Control measurements were made on the 1st, 22nd and 43rd day of treatment and 0, 3 and 5 h after intake of the meal. The postprandial increase of triglycerides was clearly reduced under garlic medication as compared to placebo treatment. The determined AUC-values for the triglycerides were up to 35% lower in the garlic group compared to the placebo group . The regular intake of the garlic preparation over the period of 6 weeks showed a significant lowering of the fasting values of triglycerides in comparison to placebo. Under garlic medication HDL2-cholesterol increased more than under placebo in tendency.

Publication Types: Clinical Trial and Randomised Controlled Trial

PMID: 1472142 [PubMed - indexed for MEDLINE]

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Garlic as a lipid lowering agent – a meta-analysis.

Silagy C, Neil A.

Department of Public Health and Primary Care, University of Oxford.

Garlic supplements may have an important role to play in the treatment of hypercholesterolaemia. To determine the effect of garlic on serum lipids and lipoproteins relative to placebo and other lipid lowering agents, a systematic review, including meta-analysis, was undertaken of published and unpublished tandardiz controlled trials of garlic preparations of at least four weeks’ duration. Studies were identified by a search of MEDLINE and the ALTERNATIVE MEDICINE electronic databases, from references listed in primary and review articles, and through direct contact with garlic manufacturers. Sixteen trials, with data from 952 subjects, were included in the analyses. Many of the trials had methodological shortcomings. The pooled mean difference in the absolute change (from baseline to final measurement in mmol/l) of total serum cholesterol, triglycerides, and high-density lipoprotein (HDL)-cholesterol was compared between subjects treated with garlic therapy against those treated with placebo or other agents. The mean difference in reduction of total cholesterol between garlic-treated subjects and those receiving placebo (or avoiding garlic in their diet) was -0.77 mmol/l (95% CI: -0.65, -0.89 mmol/l ). These changes represent a 12% reduction with garlic therapy beyond the final levels achieved with placebo alone. The reduction was evident after one month of therapy and persisted for at least six months . In the dried garlic powders , in which the allicin content is tandardized, there was no significant difference in the size of the reduction across the dose range of 600-900 mg daily . Dried garlic powder preparations also significantly lowered serum triglyceride by 0.31 mmol/l compared to placebo (95% CI: -0.14, -0.49)

(ABSTRACT TRUNCATED AT 250 WORDS)

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Treatment of hyperlipidaemia with garlic-powder tablets.
Evidence from the German Association of General Practitioners’ multicentric placebo-controlled double-blind study.

Mader FH.

Study Group on Phytotherapy of the German Association of General Practitioners, Nittendorf.

In a multicentric placebo-controlled randomised study the effect of standardized garlic-powder tablets (Kwai, Sapec) in the treatment of hyperlipidaemia was investigated.

A total of 261 patients of 30 general practitioners in West Germany with total cholesterol and/or triglyceride values more than 200 mg/dl (mostly hyperlipoproteinaemia type II a/II b) took part in the study . Patients were randomly allocated to take tablets containing a total of 800 mg garlic powder (standardized to 1.3% of alliin content) daily or the same number of placebo tablets for 16 weeks (monthly controlled). 221 patients were used for statistical analysis of total cholesterol and 219 patients for the analysis of triglyceride values. Mean serum cholesterol levels dropped in the verum group from 266 to 235 mg/dl (i.e. 12%) during the 4 month treatment period, mean triglyceride values fell in the verum group from 226 to 188 mg/dl (i.e. 17%). The best cholesterol lowering effects were seen in the patients with initial total cholesterol values between 250-300 mg/dl. The difference between the verum and placebo group was highly significant (p less than 0.001). A mild garlic smell was observed in up to 21% of the verum group and up to 9% in the placebo group. Only one of the patients left the study for this reason . Standardized garlic tablets have been shown to be effective in the treatment of hyperlipidaemia by lowering total cholesterol values by an average of 12% and triglyceride values by an average of 17%.

Publication Types: Clinical Trial, Multicenter Study and Randomized Controlled Trial

PMID: 2291748 [PubMed - indexed for MEDLINE]

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A meta-analysis of the effect of garlic on blood pressure.

Silagy CA, Neil HA.

Department of General Practice, Flinders University of South Australia, Adelaide.

OBJECTIVE: To undertake a systematic review, including meta-analysis, of published and unpublished randomized controlled trials of garlic preparations to determine the effect of garlic on blood pressure relative to placebo and other antihypertensive agents. DATA IDENTIFICATION: Studies were identified by a search of Medline and the Alternative Medicine electronic databases, from references listed in primary and review articles, and through direct contact with garlic manufacturers. STUDY SELECTION: Only randomized controlled trials of garlic preparations that were at least 4 weeks in duration were deemed eligible for inclusion in the review. DATA EXTRACTION: Data were extracted from the published reports by the two authors independently, with disagreements resolved by discussion. RESULTS: Eight trials were identified (all using the same dried garlic powder preparation (Kwai) with data from 415 subjects included in the analyses. Only three of the trials were specifically conducted in hypertensive subjects, and many had other methodological shortcomings. Of the seven trials that compared the effect of garlic with that of placebo, three showed a significant reduction in systolic blood pressure (SBP) and four in diastolic blood pressure (DBP). The overall pooled mean difference in the absolute change (from baseline to final measurement) of SBP was greater in the subjects who were treated with garlic then in those treated with placebo. For DBP the corresponding reduction in the garlic-treated subjects was slightly smaller.

CONCLUSIONS: The results suggest that this garlic powder preparation may be of some clinical use in subjects with mild hypertension. However, there is still insufficient evidence to recommend it as a routine clinical therapy for the treatment of hypertensive subjects. More-rigorously designed and analysed trials are needed.

PMID: 8064171 [PubMed - indexed for MEDLINE]

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Therapy with garlic: results of a placebo-controlled, double-blind study.

Vorberg G, Schneider B.

University of Hanover, West Germany.

A double-blind study of 40 hypercholesterolaemic out-patients was carried out over a period of four months to examine the effects of a garlic powder preparation*. The drug group received 900 mg garlic powder per day, equivalent to 2,700 mg of fresh garlic. During the therapy, the drug group showed significantly lower total cholesterol, triglycerides and blood pressure than those of the placebo group. In addition, results of a self-evaluation questionnaire indicated that patients in the drug group had a greater feeling of ‘well-being’.

Publication Types: Clinical Trial and Randomized Controlled Trial

PMID: 2083173 [PubMed - indexed for MEDLINE]

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Garlic and aging: new insights into an old remedy.
(Aging Res Rev. 2003 Jan;2(1):39-56).

Rahman K.

School of Biomolecular Sciences, Liverpool John Moores University, Byrom Street, L3 3AF, Liverpool, UK.

There has been an impressive gain in individual life expectancy with parallel increases in age-related chronicdiseases of the cardiovascular, brain and immune systems. These can cause loss of autonomy, dependence and high social costs for individuals and society. It is now accepted that aging and age-related diseases are in part caused by free radical reactions. The arrest of aging and stimulation of rejuvenation of the human body is also being sought. Over the last 20 years the use of herbs and natural products has gained popularity and these are being consumed backed by epidemiological evidence. One such herb is garlic, which has been used throughout the history of civilization for treating a wide variety of ailments associated with aging. The role of garlic in preventing age-related diseases has been investigated extensively over the last 10-15 years. Garlic has strong antioxidant properties and it has been suggested that garlic can prevent cardiovascular disease, inhibit platelet aggregation, thrombus formation, prevent cancer, diseases associated with cerebral aging, arthritis, cataract formation, and rejuvenate skin, improve blood circulation and energy levels . This review provides an insight in to garlic’s antioxidant properties and presents evidence that it may either prevent or delay chronic diseases associated with aging.

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Effect of garlic on platelet aggregation in patients with increased risk of juvenile ischaemic attack.

Kiesewetter H, Jung F, Jung EM, Mroweitz C, Koscielny J, Wenzel E.

Department of Clinical Haemostasiology and Transfusion Medicine, University of the Saarland, Homburg/Saar, Germany.

A platelet-inhibiting effect is described for garlic . In this double-blind, placebo-controlled study on 60 voluntary subjects with cerebrovascular risk factors and constantly increased platelet aggregation it was demonstrated that the daily ingestion of 800 mg of powdered garlic (in the form of coated tablets) over 4 weeks led to a significant inhibition of the pathologically increased ratio of circulating platelet aggregates and of spontaneous platelet aggregation. The ratio of circulating platelet aggregates decreased by 10.3%, from 1.17 +/- 0.08 to 1.05 +/- 0.11 (P < 0.01), and spontaneous platelet aggregation by 56.3%, from 40.7 +/- 23.3 to 17.8 +/- 23.2 degrees (P < 0.01) during the garlic phase. There were no significant changes in the placebo group. The parallel group comparison (garlic versus placebo) revealed a significantly different ratio of circulating platelet aggregates after 4 weeks of treatment (P < 0.05). After the 4-week wash-out phase the values increased again to 1.19 +/- 0.32 and 34.9 +/- 28.7 degrees, reaching the initial values (run-in phase prior to the ingestion of garlic). Since garlic is well tolerated it would be worth testing it in a controlled clinical trial for usefulness in preventing disease manifestations associated with platelet aggregation.

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Comparative effects of garlic and aspirin on diabetic cardiovascular complications.

Patumraj S, Tewit S, Amatyakul S, Jariyapongskul A, Maneesri S, Kasantikul V, Shepro D.

Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

By using streptozotocin-induced diabetic rats as a studied model, our previous experimental results have indicated that daily oral feeding of garlic extract (100 mg/kg BW) could increase the cardiovascular functions in streptozotocin (STZ) rats; the abnormality of lipid profile was prevented; and garlic extract could increase fibrinolitic activities with the decrease of platelet aggregation. Moreover, the plasma insulin level was increased concomitantly with the decrease of plasma glucose level. However, due to the high incidence of atherosclerosis in diabetes, the present study has been continued for further investigation of the effect of garlic extract on the coronary vascular ultrastructural changes. In addition, to identify the possible mechanism(s) of garlic’s therapeutic effects, the cyclooxygenase inhibitor, aspirin, has been included in this present study.

By using transmission electron microscopic studies, 16 weeks of daily oral feeding of garlic extract (100 mg/kg BW) caused as an antiatherosclerotic agent at the coronary arteriolar (15-30 microns) wall in STZ-rats. Interestingly, the thickening of coronary capillary (5-10 microns) basement membrane also was significantly attenuated within the group of STZ-rats treated with garlic extract. However, the possible direct action of garlic through the cyclooxygenase pathway has not been confirmed by the results of aspirin: The daily oral feeding of aspirin (10 mg/kg BW) in 16-week STZ-rats has not showed reduced arteriolar vascular wall abnormalities. The irregular patterns of fiber matrix, arranging the basement membrane at the arteriolar walls, were still recognized in the same manner as in STZ-rats. Interestingly, the thickening of the capillary basement membrane occurred in 16-week STZ-rats seems to be attenuated by the aspirin received. At present, garlic extract may open the new era in the medicinal use of garlic to prevent diabetic cardiovascular complications .

PMID: 10892409 [PubMed - indexed for MEDLINE]

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Antioxidants and radical scavenging properties of vegetable extracts in rats fed aflatoxin-contaminated diet.

Abdel-Wahhab MA, Aly SE.

Department of Food Toxicology and Contaminants, National Research Center, Dokki, Cairo, Egypt. Mosaad_attia@yahoo.com

The present study evaluated the protection role of garlic , cabbage, and onion extracts against the toxic effects of aflatoxin. One hundred and twenty mature male Sprague-Dawley rats were randomly assigned to eight experimental groups and treated for 15 days with extracts with or without aflatoxin. Blood samples were collected from all animals from the retro-orbital venous plexus at the end of the experimentation period for biochemical analysis. Livers and kidneys were removed at the end of the treatment period for determination of glutathione, malondialdehyde, and superoxide dismutase. The results indicated that animals treated with aflatoxin showed significant signs of aflatoxicosis. Extracts alone had insignificant effects on all parameters tested, whereas cotreatment with aflatoxin and extracts resulted in a significant improvement in all parameters; moreover, garlic extract was found to be the most effective in the prevention of aflatoxin-induced toxicity and free radical generation in rats.

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Mechanism of garlic (Allium sativum) induced reduction of hypertension in 2K-1C rats: a possible mediation of Na/H exchanger isoform-1.

Al-Qattan KK, Khan I, Alnaqeeb MA, Ali M.

Department of Biological Sciences, Faculty of Sciences, Kuwait University, Kuwait.

Garlic causes reduction in blood pressure (BP), however the role of Na/H exchanger (NHE) which mediates hypertension and related tissue-damage is poorly understood. In this study the effect of an established dose of raw garlic extract was investigated on the expression of NHE-1 and -3 and sodium pump activity in a 2K-1C model of hypertension in rats. 2K-1C animals showed high BP, increased serum concentration of PGE2 and TxB2, hypertrophy of the unclipped kidneys, but not in the clipped kidneys In addition, NHE-1 and NHE-3 isoforms were increased in both the 2K-1C kidneys, whereas alpha-actin was increased in the clipped but not in unclipped kidneys. Sodium pump activity was decreased in the clipped kidneys, but remained unchanged in the unclipped kidneys. Garlic treatment reduced the induction of NHE-1 only in the unclipped 2K-1C kidneys, whereas garlic treatment increased the sodium pump activity in both the 2K-1C kidneys. These findings demonstrate that the antihypertensive action of garlic is associated with a reversal of NHE-1 induction in the unclipped kidneys. Induction of NHE isoforms together with a reduced sodium pump activity might cause necrosis in the 2K-1C clipped kidneys due to cellular retention of Na+. On the other hand, activation of sodium pump by garlic extract in the kidneys should reduce intracellular Na+ concentration and normalize BP . These findings signify the use of garlic in the treatment of hypertension.