FWD 2 Expanded Commission E: Garlic

Herbal Medicine: Expanded Commission E

Garlic

Latin Name: Allium sativum
Pharmacopeial Name: Allii sativi bulbus
Other Names: garlic clove

Overview

In the United States and Western Europe, garlic is one of the most popular substances used to reduce various risks associated with cardiovascular disease. Most of its popularity is based on the herb's strong folkloric familiarity and awareness that scientist research suggests cardiovascular benefits associated with ingestion of the herb as a conventional food and as a dietary supplement.

Uses for garlic and its preparations cover cardiovascular effects (lipid, blood pressure and blood sugar lowering, and fibrinolytic activity); chemoprevention; antimicrobial, antifungal, antiprotozoal, and antioxidant activities; and immunologic activity, among others. By 1996 there were at least 1,808 scientific studies (chemical, pharmacological, clinical, and epidemiological) investigating the activities of garlic. Pharmacological and clinical studies have been published in the following areas: antimicrobial effects (252 pharmacological/35 clinical), anticancer effects (221/2, plus 10 epidemiological studies), effect on blood sugar levels (28/3), immune stimulation (15/3), anti-inflammatory (11/1), and antioxidant (60/4), as well as additional studies researching other areas (Lawson, 1998a). In the areas of cardiovascular effects, the studies break down as follows: blood lipids (179/62, plus 2 epidemiological studies), blood pressure (78/18), blood fibrinolysis, coagulation, and flow (51/18), platelet aggregation (76/6), and atherosclerosis (23/2) (Lawson, 1998a). A comprehensive and detailed review of the therapeutic aspects of garlic and its preparations is provided in a recent book dealing with the history, chemistry, and medical aspects of the herb (Koch and Lawson, 1996). Numerous studies are outlined—all conducted on garlic as a food or in dietary supplement or pharmaceutical preparations. Also cited are 9 epidemiological studies correlating cancer prevention and garlic consumption as food.

Clinical studies conducted on garlic to measure cardiovascular effects have been performed with both healthy persons and patients with hyperlipidemia and hypercholesterolemia. In recognition of the clinical trials suggesting the low-density lipoprotein (LDL) cholesterol-lowering ability of garlic preparations, garlic received a positive evaluation by the Commission E. Garlic is the subject of a monograph by the European Scientific Cooperative on Phytotherapy (ESCOP), a western European group of scientists developing harmonized drug monographs on phytomedicines for the European Union (ESCOP, 1997). Additionally, the World Health Organization (WHO) has prepared a monograph on standards and therapeutic uses of garlic (WHO, 1999). (See Uses section, below.)

Meta-analyses of clinical trials have documented its use for lowering cholesterol in hyperlipidemia (Silagy and Neil, 1994a; Warshafsky et al., 1993) and in treating hypertension (Silagy and Neil, 1994b). Another study has investigated garlic's effectiveness in treating peripheral arterial occlusive disease, as measured by pain-free walking distance (Kiesewetter et al., 1993b). Research on garlic treatment for hyperlipidemic pediatric patients, however, has yielded insignificant results (McCrindle et al., 1998). Garlic has also been shown to be effective in respiratory infections and catarrhal conditions (Bradley, 1992; ESCOP, 1997).

The primary objective of a significant number (104) of clinical trials conducted on garlic has been to evaluate its ability to regulate serum lipid levels, i.e., total cholesterol (TC), and in particular, LDL cholesterol. There is much evidence to support such an application. The influence of garlic on atherogenic LDL has been investigated in at least 9 clinical studies, with 7 reporting a significant decrease (mean decrease of 16%) (Koch and Lawson, 1996).

In 40 studies that investigated the effect of various garlic preparations on the TC levels of 43 groups of patients and volunteers, the mean decrease in serum cholesterol levels was 10.6%, with the treatment lasting from three weeks to several months. The 13 placebo-controlled studies with alliin/allicin-standardized garlic powder tablets on 427 treatment patients showed an average decrease of 10.3%. Serum triglyceride levels were also measured in 32 of the 40 studies, with an average decrease of 13.4%—the 12 placebo-controlled studies with garlic powder tablets resulted in an 8.5% decrease in the 406 treatment patients. Most European clinical trials measuring cardiovascular activity of garlic used garlic powder tablets (the German brand Kwai®, Lichtwer Pharma, Berlin), which has long been standardized on 1.3/0.6% of the alliin/allicin-yield (Brown, 1996; Koch and Lawson, 1996).

Two meta-analyses have analyzed the results of clinical studies on the effect of garlic on serum TC (Warshafsky et al., 1993; Silagy and Neil, 1994a). They indicated that over a one- to three-month period, the administration of garlic powder in a dietary supplement form (tablets: usually 100 mg each; dosage: 600–900 mg daily) resulted in an average reduction in serum TC of 9 to 12% (range, 6 to 21%); triglyceride levels fell from 8 to 27%, mean 13% (Silagy and Neil, 1994a).

The goal of the Warshafsky study was to assess the range and consistency of garlic's effect on serum TC in persons with cholesterol levels greater than 5.17 mmol/l (200 mg/dl). Five of 28 clinical trials were selected for review; all were randomized and placebo-controlled, with at least 75% of the patients having cholesterol levels greater than 200 mg/dl. Patients treated with garlic consistently showed a greater decrease in TC levels than those receiving placebo. Meta-analysis of homogeneous trials estimated a net cholesterol decrease attributable to garlic of 0.59 mmol/l. The study concluded that the best available evidence suggests that garlic, in an amount approximating one-half to one clove per day, decreased serum TC levels by about 9% in the groups of patients studied (Warshafsky et al., 1993).

To determine the effect of garlic on serum lipids and lipoproteins relative to placebo or to other lipid-lowering agents, the Silagy and Neil meta-analysis reviewed randomized, controlled trials of garlic preparations of at least four weeks duration. Sixteen trials with data from 952 subjects were included. The mean difference in reduction of TC between garlic-treated subjects and those receiving placebo (or avoiding garlic in their diet) was –0.77 mmol/l. These changes represent a 12% reduction with garlic therapy beyond the final levels achieved with placebo alone. In the commercial preparations made from dried garlic powders, in which the allicin yield is purportedly standardized, 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 (Silagy and Neil, 1994a).

A 12-week study compared the effect of standardized garlic powder tablets (Kwai®) with that of bezafibrate, the most commonly prescribed blood lipid-lowering drug in Germany (Holzgartner et al., 1992). This multicenter, double-blind study involved 98 patients with primary hyperlipoproteinemia, and cholesterol and/or triglyceride values exceeding 250 mg/dl. The daily doses of the active substances were 900 mg of garlic powder (standardized to 1.3% alliin) and 600 mg of bezafibrate, respectively. In the course of the treatment, decreases in TC, LDL cholesterol, and triglyceride levels were statistically significant, with no differences between the effects of garlic and bezafibrate. High-density lipoprotein (HDL) cholesterol values also increased significantly, with no differences between the two regimens.

However, a dissenting 12-week randomized, double-blind, placebo-controlled, parallel treatment study could not confirm previous reports that standardized garlic powder tablets (Kwai®) were effective in lowering cholesterol levels in patients with hypercholesterolemia. Twenty-eight patients received 300 mg of Kwai® three times daily for 12 weeks. There were no significant lipid or lipoprotein changes in either the placebo- or garlic-treated groups and no significant difference between changes in the placebo-treated group compared with changes in the garlic-treated patients (Isaacsohn et al., 1998).

An eight-week randomized, double-blind, placebo-controlled clinical trial again disputed garlic as therapy for hypercholesterolemia by concluding that Kwai® had no significant effect on cardiovascular risk factors in pediatric patients with familial hyperlipidemia. The 30 hypercholesterolemic children were given 300 mg of Kwai® three times daily for eight weeks and tested for absolute and relative changes in fasting lipid parameters. Researchers found no significant reduction attributable to garlic extract therapy in cardiovascular risk factors, with the exception of a small increase in apolipoprotein A-I levels. Authors note that adult studies have yielded positive results. It is management of hyperlipidemia in children that remains controversial (McCrindle et al., 1998).

A likely reason for the failure of these two trials (Isaacsohn et al., 1998 and McCrindle et al., 1998) to show an effect on serum cholesterol while many prior studies with the same brand (Kwai®) gave positive effects is that the Kwai® tablets used in these negative studies appear to have released only one-third as much allicin as the Kwai® tablets used in older trials under simulated gastrointestinal conditions, as has been shown with Kwai® tablets made at the same time as the trials were conducted (Lawson, 1998c).

In a study that received significant media attention, 25 patients with moderate hypercholesterolemia were studied in a randomized, double-blind, placebo-controlled trial (Berthold et al., 1998). Five mg of steam-distilled garlic oil preparation (Tegra®, Hermes, Munich, Germany) was given to patients twice daily for 12 weeks. The product studied did not influence serum lipoproteins, cholesterol absorption, or cholesterol synthesis and the authors concluded that garlic cannot be recommended for hypercholesterolemia. This study was criticized for using garlic oil bound to b-cyclodextrin to form a solid slow-release tablet, which was found to greatly reduce the total absorption of the garlic oil compared to liquid oil. Thus, the results of this trial are not applicable to other forms of garlic (Lawson, 1998b).

A six-week randomized, placebo-controlled, double-blind study investigated the efficacy of a standardized garlic powder preparation (brands Kwai® and Sapec®, 900 mg daily) on alimentary hypertriglyceridemia after intake of a standardized fatty test meal containing 100 g of butter (Rotzsch et al., 1992). (Sapec® is also made by Lichtwer. It is the same material as Kwai®, but in a larger tablet, 300 mg compared to 100 mg for Kwai®.) The 24 volunteers had low plasma HDL2-cholesterol concentrations of less than 10 mg/dl (men) and 15 mg/dl (women). Control measurements were made on the 1st, 22nd, and 43rd day of treatment, at 0, 3, and 5 hours after the meal. The increase in plasma triglycerides was reduced by up to 35% after garlic consumption in comparison with the placebo group. The regular intake of the garlic preparation over the six weeks also showed a significant lowering of the fasting values of triglycerides in comparison to placebo.

In another study using brands Kwai® and Sapec®, the effect of standardized garlic powder tablets in the treatment of hyperlipidemia was investigated (Mader, 1990). This multicenter, placebo-controlled, randomized study had 261 patients with TC and/or triglyceride values more than 200 mg/dl. Patients were given a daily dose of 800 mg (standardized to 1.3% of alliin content) for 16 weeks. There was a 12% decrease in mean serum cholesterol levels, and a 17% decrease in mean triglyceride values.

In one of only two trials on garlic conducted in the United States, researchers assessed the effects of standardized garlic powder tablets (Kwai®) on serum lipids and lipoproteins, glucose, and blood pressure (Jain et al., 1993). Forty-two healthy adult patients, with a serum TC level of 220 mg/dl or greater, received a daily dose of 900 mg or placebo. After 12 weeks of treatment, the baseline serum TC level of 262 mg/dl was reduced to 247 mg/dl. The placebo group went from 276 to 274 mg/dl. LDL cholesterol was reduced 11% by garlic treatment and 3% by placebo. The study concluded that treatment with standardized garlic (900 mg/day) produced a significantly greater reduction in serum TC and LDL cholesterol than placebo.

In addition to the cholesterol-lowering action documented above, other clinical studies conducted on garlic preparations have examined their effects on plaque-reduction and blood pressure lowering actions (Auer et al., 1990), as well as on garlic's reputed antibiotic, anticancer, antioxidant, and immunomodulatory effects (Brown, 1996; Koch and Lawson, 1996). Other clinical studies have concluded that garlic is helpful in lessening pain in patients with intermittent claudication (Kiesewetter et al., 1993b).

In the longest clinical trial on garlic to date, garlic's ability to prevent and possibly reverse atherosclerosis was tested in a randomized, double-blind, placebo-controlled, four-year study in which 152 men and women were given 900 mg garlic powder as tablets (Kwai®) per day (Koscielny et al., 1999). The subjects were chosen because they possessed significant plaque buildup and at least one additional cardiovascular risk factor (e.g., high LDL cholesterol levels, hypertension, diabetes, and/or history of smoking). Increased plaque volume is correlated with increased risk of heart attack or stroke. The amount of plaque in both carotid and femoral arteries was determined by ultrasound and was shown to be reduced over the four year period, as measured at 16, 36, and 48 months. After the four years, those in the garlic group had an average 2.6% reduction in plaque volume while the plaque in the placebo group increased 15.6%. Researchers concluded: "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."

In a Danish multicenter study on Kwai® garlic tablets the effects of the tablets on blood lipids and blood pressure were measured. A total of 48 patients (with TC levels over 6.5 mmol/l) were treated with a daily dose of 600 mg (standardized on 1.3% alliin, equal to 0.6% allicin) for a period of 18 weeks. Mean serum cholesterol levels dropped 8%. LDL cholesterol dropped 5% while HDL cholesterol rose 5%. These changes improved the HDL-LDL cholesterol ratio 12%, from 6.6 to 5.9. Also, triglyceride levels were reduced by 11%. Of the patients, 23 with mild hypertension (diastolic blood pressure greater than 95 mmHg) showed reductions in both systolic and diastolic blood pressure. Systolic blood pressure dropped 7%, from 158 to 147 mmHg, while diastolic blood pressure dropped 4%, from 96 to 92 mmHg (Gr nwald et al., 1992).

One hypertension study found that when 47 non-hospitalized patients with mild hypertension were administered either 600 mg of a garlic powder preparation or placebo for 12 weeks, after 8 weeks blood pressure was significantly reduced from 171/102 mmHg to 155/91 mmHg (Auer et al., 1990). A double-blind, placebo-controlled study of 60 patients with constantly elevated spontaneous platelet aggregation who were given 800 mg of a standardized garlic powder preparation for four weeks, resulted in the reduction of the spontaneous platelet aggregation by 56.3% with no significant change in the placebo group (Kiesewetter et al., 1992 in Koch and Lawson , 1996).

A double-blind crossover study comparing the effect of an odorless, aged garlic extract (AGE, Wakunaga, Japan) to a placebo on blood lipids was performed on a group of 41 moderately hypercholesteremic men (220–290 mg/dl). After a four-week baseline period in which the subjects were told to maintain a National Cholesterol Education Program Step I diet, the verum group was given 7.2 g of AGE (capsules: 800 mg each; dosage: 9 capsules daily) for six months. The garlic and placebo group then crossed over for four months without a washout period. TC levels were lowered 6.1 or 7.0% compared to placebo period or baseline, respectively. LDL cholesterol was decreased by 4.0% compared to average baseline values and 4.6% compared to placebo period levels. There was also a 5.5% decrease in systolic blood pressure and "modest" reduction of diastolic pressure in the AGE group (Steiner et al., 1996).

Regarding anticancer effects, epidemiological evidence suggests the possibility that garlic and other members of the genus Allium can reduce incidence of risk of certain types of cancer. In their comprehensive book on garlic, Koch and Lawson (1996) cite at least 15 statistical studies and review articles that correlate garlic consumption to low cancer rates in Europe, Egypt, India, China, and other Third World countries "where the favorable effects of garlic for cancer are well known" (Koch and Lawson, 1996). They also include data from 10 epidemiological studies on cancer and consumption of raw or cooked garlic cloves. Two comparison studies in China concluded that dietary garlic inhibited formation of carcinogenic nitroso compounds (Mei et al., 1982). Another study involving 564 patients with stomach cancer and 1,131 controls in an area of China with a high incidence of gastric cancer revealed a significant reduction in stomach cancer risk with increased consumption of Allium vegetables (garlic, onions, leeks, shallots, and chives) (You et al., 1989).

By the end of 1996, of the 221 anticancer studies conducted on garlic, 72 had been conducted on fresh whole garlic (including the 10 epidemiological studies), 82 had been conducted with the allyl sulfides (garlic oil components), and 19 had been conducted on AGE. This garlic preparation is processed in a proprietary manner to produce a chemically distinct product that does not contain these intermediate sulfur-based compounds (e.g., allicin), which tend to further decompose into other sulfur compounds. AGE is the material formerly used for research by the National Cancer Institute for its Designer Foods Program. By 1996 there were at least 90 research papers and meeting abstracts published on various aspects of AGE (Koch and Lawson, 1996).

U.S. pharmacopeial grade garlic consists of the fresh or dried compound bulbs of Allium sativum L. It must contain not less than 0.5% alliin, as determined by liquid chromatography, calculated on a dry weight basis. Botanical identity must be confirmed by a thin-layer chromatography (TLC) test as well as macroscopic and microscopic examinations. USP powdered garlic consists of garlic that has been cut, freeze-dried or dried at a temperature not greater than 65? C, then powdered. It must contain not less than 0.3% alliin, calculated on the dried basis (USP 24–NF 19, 1999). The difference in values reflects a potential loss of 40% of the alliin due to the powdering process. European pharmacopeial grade garlic powder has identity and purity test requirements closely comparable to the USP monograph, though it must yield (does not contain) not less than 0.45% allicin calculated with reference to the dried drug (Ph.Eur., 1999). The ESCOP garlic powder monograph requires that the material comply with the quality requirements of the European Pharmacopoeia (ESCOP, 1997). The British Herbal Pharmacopoeia contains separate quantitative standards for powdered garlic from Egypt and from China. Powdered garlic from Egypt is typically produced from the entire bulbs (cloves, skins, and roots). It may contain not more than 12% total ash and must contain not less than 70% water-soluble extractive, calculated with reference to the oven-dried material. Powdered garlic from China, however, is typically produced from the cloves only (skins peeled). It may contain not more than 5% total ash and must contain not less than 80% water-soluble extractive (BHP, 1996). The Ghana Herbal Pharmacopoeia includes a monograph for the fresh, whole, intact garlic bulb for manufacture of an alcoholic tincture preparation (GHP, 1992).

Description

Garlic, fresh or carefully dried, consists of the main bulb with several secondary bulbs (cloves) of A. sativum L. [Fam. Alliaceae] and its preparations in effective dosage. Garlic contains alliin and its transformation products and sulfur-containing essential oil.

Chemistry and Pharmacology

Garlic contains a large number of compounds, but only the thiosulfinates (allicin) have been found to have significant activity at levels representing normal garlic consumption (3–5 g/day). Allicin has been shown to be essential to most of the antimicrobial and hypocholesterolemic effects of garlic and probably to most of the antithrombotic and antioxidant effects. The anticancer effects appear to be shared about equally between allicin and other unidentified compounds (Lawson, 1998a).

Garlic contains about 1% alliin, which converts to allicin in the presence of the enzyme alliinase (ESCOP, 1997). Pharmacological research on garlic has shown for the thiosulfinates free radical scavenging, inhibition of lipid peroxidation (Harris et al., 1995; Phelps and Harris, 1993), inhibition of platelet aggregation (Barrie et al., 1987; Kiesewetter et al., 1993a), stimulation of fibrinolysis (Kiesewetter et al., 1990), and reduction of serum cholesterol and lipid levels Brosche et al., 1990; Bordia, 1981; Jain et al., Mader, 1990; Rotzsch et al., 1992).

Garlic bulbs contain about 65% water, 28% carbohydrates (mainly fructans), 2.3% organosulfur compounds, 2% protein (mainly alliinase), 1.2% free amino acids (mainly arginine), 1.5% fiber, 0.15% lipids, and small amounts of phytic acid (0.08%), saponins (0.07%), and b-sitosterol (0.0015%). No vitamin or mineral is sufficiently abundant to meet 2% of the U.S. RDA for a 3–5 g clove. The main organosulphur compounds in whole garlic are the S-(+)-alkyl-L-cysteine sulfoxides [alliin (1%), methiin (0.12%), isoalliin (0.06%), and cycloalliin (0.1%)] and the g-L-glutamyl-S-alkyl-L-cysteines [g-glutamyl-S-trans-1-propenylcysteine (0.6%) and g-glutamyl-S-allylcysteine (0.4%)]. Upon disrupting the cells by bruising, crushing, chewing, or mincing the bulb, the enzyme alliinase comes into contact with the amino acid alliin, causing its rapid transformation into allylsulphenic acid, and subsequent conversion to allicin. One mg of alliin produces 0.458 mg of allicin. Allicin potentially becomes the main precursor of various other transformation compounds found in commercially produced garlic oils, such as allyl sulfides, ajoenes, and vinyldithiins, depending on the method of processing (Lawson 1998a, Block, 1985; Bradley, 1992; Budavari, 1996; ESCOP, 1997).

According to some chemical reviews, aging garlic to produce the odorless aged garlic extract (AGE) reduces the content of all sulfur compounds. Thus, AGE contains 3% of the alliin and 6% of the g-glutamylcysteines found in fresh garlic. Its most abundant sulfur compound is S-allylcysteine, representing about 21% of the g-glutamyl-S-allylcysteine from which it is derived (Lawson, 1998a).

The Commission E reported antibacterial, antimycotic, lipid-lowering, inhibiting of platelet aggregation, prolonging of bleeding and clotting time, and enhancing of fibrinolytic activity. In vitro and in vivo animal studies have also demonstrated garlic's ability to inhibit tumor formation (Belman, 1983; Weisberger and Pensky, 1958) and reduce blood pressure (Elbl, 1991; Koch, 1992). Garlic powder, fresh garlic, aged garlic, and garlic oil have been found to exhibit anti-aggregative, antibacterial, antimycotic, antiviral, and antihepatotoxic action in vitro and in vivo. Otherin vitro studies have concluded that garlic possesses direct anti-atherosclerosis effects and inhibition of cholesterol biosynthesis by allicin and ajoene. In vivo studies in animals have concluded that garlic powder, fresh garlic, and garlic oil reduced experimentally induced hyperlipidemia and atherosclerosis (ESCOP, 1997). Gamma-glutamylpeptides, scordinins, steroids, triterpenoids, flavonoids, and fructans also possess pharmacological activity and are believed to contribute to these hypotensive and anticancer effects (Koch and Lawson, 1996). (Despite extensive and persistent popular beliefs in Transylvania and Wallachia (Romania), both the Commission E and the editors of this volume were unable to document scientific data to confirm the anti-vampiral activity of garlic.)

Uses

Commission E approved the use of garlic as a support to dietary measures at elevated levels of lipids in the blood and as a preventive measure for age-dependent vascular changes.

Based on clinical studies, ESCOP recognizes the following indications for garlic: "Prophylaxis of atherosclerosis. Treatment of elevated blood lipid levels insufficiently influenced by diet. Improvement of blood flow in arterial vascular disease" (ESCOP, 1997). ESCOP also noted that garlic has been used traditionally for relief of cough, colds, catarrh, and rhinitis, although clinical trials are not as abundant to support such uses.

WHO notes in the "Uses supported by clinical data" section of its garlic monograph: "As an adjuvant to dietetic management in the treatment of hyperlipidaemia, and in the prevention of atherosclerotic (age-dependent) vascular changes. The drug may be useful in the treatment of mild hypertension" (WHO, 1999).

Contraindications

The Commission E reported that none were known. Some sources suggest that substantial amounts of garlic should not be consumed prior to surgery, since it can prolong bleeding time (Burnham, 1995). WHO notes that garlic is contraindicated in those individuals who have a known allergy to garlic (WHO, 1999).

Side Effects

In rare instances there may be gastrointestinal symptoms, changes to the flora of the intestine, or allergic reactions.

Note: The odor of garlic may pervade the breath and skin.

Use During Pregnancy and Lactation

Not recommended during lactation (Chadha, 1988; McGuffin et al., 1997).

Interactions with Other Drugs

In 1988, Commission E reported that none were known. ESCOP notes that "none [are] reported" (ESCOP, 1997). Garlic consumption substantially increases the anticoagulant effects of warfarin (Sunter, 1991). WHO notes that, "Patients with on warfarin therapy should be warned that garlic supplements may increase bleeding times. Blood clotting times have been reported to double in patients taking warfarin and garlic supplements" (WHO, 1999).

Dosage and Administration

Internal:

Unless otherwise prescribed: 4 g per day of fresh, minced garlic bulb.

Infusion: 4 g in 150 ml of water.

Fluidextract 1:1 (g/ml): 4 ml.

Tincture 1:5 (g/ml): 20 ml.

References

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Barrie, S.A., J.V. Wright, J.E. Pizzorono. 1987. Effects of garlic oil on platelet aggregation, serum lipids and blood pressure in humans. J Orthomolec Med 2:1521.

Belman, S. 1983. Onion and garlic oils inhibit tumor promotion. Carcinogenesis 4(8):10631065.

Berthold, H.K., T. Sudhop, K. von Bergmann. 1998. Effect of a garlic oil preparation on serum lipoproteins and cholesterol metabolism: a randomized controlled trial. JAMA 279(23):19001902.

BHP. See British Herbal Pharmacopoeia.

Block, E. 1985. The chemistry of garlic and onions. Sci Am 252(3):114119.

Bordia, A. 1981. Effect of garlic on blood lipids in patients with coronary heart disease. Am J Clin Nutr 34(10):21002103.

Bradley, P.R. (ed.). 1992. British Herbal Compendium, Vol. 1. Bournemouth: British Herbal Medicine Association. 105108.

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Brown, D.J. 1996. Herbal Prescriptions for Better Health. Rocklin, CA: Prima Publishing. 97109.

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Chadha, Y.R. et al. (eds.). 19521988. The Wealth of India (Raw Materials), Vols. 111. New Delhi: Publications and Information Directorate, CSIR.

Elbl, G. 1991. Chemisch-biologische Untersuchungen pflanzlicher Inhibitoren des Angiotensin I-converting Enzyms (ACE), insbesondere die der Arzneipflanzen Lespedeza capitata (Michx.) und Allium ursinum (L.). Dissertation, University of Munich (Abstract).

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Gr nwald, J. et al. 1992. Effects of garlic powder tablets on blood lipids and blood pressure. The Danish Multicenter Kwai Study. Eur J Clin Res 3:179186.

Harris, W.S., S.L. Windsor, J. Lickteig. 1995. Garlic and lipoprotein resistance to oxidation. Z Phytother Abstr 16:15.

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Isaacsohn, J.L. et al. 1998. Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial. Arch Intern Med 158(11):11891194.

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Kiesewetter, H. et al. 1993b. Effects of garlic coated tablets in peripheral arterial occlusive disease. Clin Investig 71(5):383386.

Kiesewetter, H. et al. 1990. Effects of garlic on blood fluidity and fibrinolytic activity: a randomised, placebo-controlled, double-blind study. Br J Clin Pract Suppl 44(suppl. 69):2429.

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Koch, H.P. and L.D. Lawson (eds.). 1996. Garlic: The Science and Therapeutic Application of Allium sativum L. and Related Species, 2nd ed. Baltimore: Williams & Wilkins Publishing Co.

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Lawson, L.D. 1998a. Garlic: A Review of its Medicinal Effects and Indicated Active Compounds. In: Lawson, L.D. and R. Bauer (eds.). Phytomedicines of Europe: Chemistry and Biological Activity. Washington, DC: American Chemical Society. 176209.

. 1998b. Effect of garlic on serum lipids (letter). JAMA 280(18):1568.

. 1998c. Garlic powder for hyperlipidemiaanalysis of recent negative results. Quart Rev Nat Med 187189.

Mader, F.H. 1990. Treatment of hyperlipidemia with garlic-powder tablets. Evidence from the German Association of General Practitioners' multicentric placebo-controlled double-blind study. Arzneimforsch 40(10):11111116.

McCrindle, B.W., E. Helden, W.T. Conner. 1998. Garlic extract therapy in children with hypercholesterlemia. Arch Pediatr Adolesc Med 152(11):10891094.

McGuffin, M., C. Hobbs, R. Upton, A. Goldberg. 1997. American Herbal Product Association's Botanical Safety Handbook. Boca Raton: CRC Press.

Mei, X. et al. 1982. Garlic and gastric cancer: the influence of garlic on the level of nitrate and nitrite in gastric juice. Acta Nutr Sin 4:5356.

Phelps, S. and W.S. Harris. 1993. Garlic supplementation and lipoprotein oxidation susceptibility. Lipids 28(5):475477.

Ph.Eur. See Europäisches Arzneibuch.

Rotzsch W., V. Richter, F. Rassoul, A. Walper. 1992. [Postprandial lipemia under treatment with Allium sativum. Controlled double-blind study of subjects with reduced HDL2-cholesterol] [In German]. Arzneimforsch 42(10):12231227.

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. 1994b. A meta-analysis of the effect of garlic on blood pressure. J Hypertens 12(4):463468.

Steiner, M., A.H. Khan, D. Holbert, R.I. Lin. 1996. 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 64(6):866870.

Sunter, W.H. 1991. Warfarin and garlic. Pharmaceut J 246:722.

United States Pharmacopeia, 24th rev. and National Formulary, 19th ed. (USP 24NF19). 1999. Rockville, MD: United States Pharmacopeial Convention, Inc. 24552456.

Warshafsky S., R.S. Kamer, S.L. Sivak. 1993. Effect of garlic on total serum cholesterol. Ann Intern Med 119(7 pt. 1):599605.

Weisberger, A.S. and J. Pensky. 1958. Tumor inhibition by a sulfhydryl-blocking agent related to an active principle of garlic. Cancer Res 18:13011308.

World Health Organization (WHO). 1999. 'Allii Sativi Bulbus.' WHO Monographs on Selected Medicinal Plants, Vol. 1. Geneva: World Health Organization. 515.

You, W.C. et al. 1989. Allium vegetables and reduced risk of stomach cancer. J Natl Cancer Inst 81(2):162164.

Additional Resources

Anon. 1997. Aged Garlic Extract. 1997's Research Excerpts from Peer Reviewed Scientific Journals & Scientific Meetings. Mission Viejo, CA: Wakunaga of America Co., Ltd.

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This material was adapted from The Complete German Commission E MonographsTherapeutic Guide to Herbal Medicines. M. Blumenthal, W.R. Busse, A. Goldberg, J. Gruenwald, T. Hall, C.W. Riggins, R.S. Rister (eds.) S. Klein and R.S. Rister (trans.). 1998. Austin: American Botanical Council; Boston: Integrative Medicine Communications.

1) The Overview section is new information.

2) Description, Chemistry and Pharmacology, Uses, Contraindications, Side Effects, Interactions with Other Drugs, and Dosage sections have been drawn from the original work. Additional information has been added in some or all of these sections, as noted with references.

3) The dosage for equivalent preparations (tea infusion, fluidextract, and tincture) have been provided based on the following example:

  • Unless otherwise prescribed: 2 g per day of [powdered, crushed, cut or whole] [plant part]
  • Infusion: 2 g in 150 ml of water
  • Fluidextract 1:1 (g/ml): 2 ml
  • Tincture 1:5 (g/ml): 10 ml

4) The References and Additional Resources sections are new sections. Additional Resources are not cited in the monograph but are included for research purposes.

This monograph, published by the Commission E in 1994, was modified based on new scientific research. It contains more extensive pharmacological and therapeutic information taken directly from the Commission E.

Excerpt from Herbal Medicine: Expanded Commission E Monographs
Copyright 2000 American Botanical Council
Published by Integrative Medicine Communications
Available from the American Botanical Council.