Oral nutritional supplements and heart disease: a review

The use of nutritional supplements in the treatment of cardiovascular disease is rapidly growing in the United States. Many substances are marketed with anecdotal claims of efficacy. Most have not been scientifically studied. Excitement exists in the lay press about the homocysteine hypothesis of coronary artery disease and vitamin cures. A MEDLINE search and review of papers covering the study of popular nutritional supplements were undertaken. The papers were limited to peer-review journals using patient series reports, double-blinded prospective studies, and population studies. A compendium of the available data was obtained and an analysis of each paper's methodology was done. A review of the most popular and most studied oral nutritional supplements for the treatment of heart disease demonstrated relatively few well-founded indications for the widespread application of substances with the exception of the bioflavonoids. Some modest effects for endothelial dysfunction were noted for vitamins C and E. Red wines and beers were also noted to be beneficial. The majority of substances either had no effect or were deleterious.

Efficacy of naturopathic extracts in the management of ear pain associated with acute otitis media

OBJECTIVE

To determine the efficacy and tolerance of Otikon Otic Solution (Healthy-On Ltd, Petach-Tikva, Israel), a naturopathic herbal extract (containing Allium sativum, Verbascum thapsus, Calendula flores, and Hypericum perforatum in olive oil), compared with Anaesthetic (Vitamed Pharmaceutical Ltd, Benyamina, Israel) ear drops (containing ametocaine and phenazone in glycerin) in the management of ear pain associated with acute otitis media (AOM).

DESIGN

Children between the ages of 6 and 18 years who experienced ear pain (otalgia) and who were diagnosed with eardrum problems associated with AOM were randomly assigned to be treated with Otikon or Anaesthetic ear drops, which were instilled into the external canal(s) of the affected ear(s). Ear pain was assessed using 2 visual analog scales: a linear scale and a color scale. Pain assessment took place throughout the course of 3 days. The mean score of pain reduction was used to measure outcome.

SETTING

Primary pediatric community ambulatory centers.

PARTICIPANTS

One hundred three children aged 6 to 18 years who were diagnosed with otalgia associated with AOM.

RESULTS

Each of the 2 treatment groups were comparable on the basis of age, sex, laterality of AOM, and the effectiveness of ameliorating symptoms of otalgia. The 2 groups were also comparable to each other in the initial ear pain score and in the scores at each application of Otikon or Anaesthetic drops. There was a statistically significant improvement in ear pain score throughout the course of the study period (P =.007).

CONCLUSIONS

Otikon, an ear drop formulation of naturopathic origin, is as effective as Anaesthetic ear drops and was proven appropriate for the management of AOM-associated ear pain.

Efficacy of garlic supplementation in lowering serum cholesterol levels

Previous studies using garlic have found alterations on a number of cardiovascular disease (CVD) risk factors including blood pressure, plasma viscosity, platelet activity, and serum lipid levels. The latest clinical research suggests that consumption of garlic powder does not play a significant role in lowering plasma lipid levels when in conjunction with a low-fat, low-cholesterol diet. Additional well-controlled, long-term studies that explore dosage and preparation type are necessary to confirm the efficacy of garlic in lowering cholesterol levels and to fully understand garlic's potential role in CVD.

An intervention trial to inhibit the progression of precancerous gastric lesions: compliance, serum micronutrients and S-allyl cysteine levels, and toxicity

Gastric cancer is the second most frequent cause of death from cancer in the world and the leading cause of death from cancer in China. In September 1995, we launched a randomized multi-intervention trial to inhibit the progression of precancerous gastric lesions in Linqu County, Shandong Province, an area of China with one of the world's highest rates of gastric cancer. Treatment compliance was measured by pill counts and quarterly serum concentrations of vitamin C, vitamin E and S-allyl cysteine. In 1999, toxicity information was collected from each trial participant to evaluate treatment-related side-effects during the trial. Compliance rates were 93% and 92.9% for 39 months of treatment with the vitamins/mineral and garlic preparation, respectively. The means for serum concentrations of vitamins C and E were 7.2 microg/ml and 1695 microg/dl among subjects in the active treatment groups compared with 3.1 microg/ml and 752 microg/dl among subjects in the placebo treatment group, respectively. No significant differences in side-effects were observed between the placebo treatment group and the vitamins/mineral and garlic preparation treatment groups during the 39-month trial period.

Garlic prevents ultrastructural alterations caused by dehydration in mouse cerebral microvessels

Dehydration is known to significantly reduce both the time required for the first platelet aggregate and the time to full occlusion in photochemically-induced thrombosis, in vivo. Ultrastructural changes that contribute to such events remain unknown. Therefore, the effect of water deprivation for 24 hr, (as a model for dehydration) on the ultrastructure of mouse pial microvessels was investigated. The possible beneficial effect of garlic in preventing such ultrastructural changes was also investigated. Four groups of TO strain: control, control-garlic treated, dehydrated, and dehydrated-garlic treated male mice, 10/group, were used. Dehydration was induced by water deprivation for 24 hr. Garlic solution was i.p. injected at 0.1 ml/10g body weight. In urethane-anesthetized (2 mg/g, i.p.) mice, topical and transvessel bimodal fixation of pial microvessels was done with a phosphate buffered mixture of glutaraldehyde and paraformaldehyde, followed by a conventional electron microscopy procedure. Examination of control cerebral pial microvessels showed no evidence of cellular damage. Membranes of endothelial cells were intact. Within pial microvessels there was no evidence of platelet aggregation. Garlic treatments did not cause any ultrastructure abnormalities in control mice. Compared with control, dehydration caused the appearance of thrombi that consisted of platelet aggregates. Discoid platelets containing granules, spheroid degranulated platelets, and those with large pseudopodia were present in 80% of dehydrated mice. The venular endothelial surface of dehydrated mice revealed dilated profiles of endoplasmic reticulum and variously shaped vacuoles. Swelling of nuclear envelopes and mitochondrial distension were also present in dehydrated mice. Concomitant garlic treatment prevented most of these ultrastructural changes. These findings demonstrated the extent of damage to the pial microvessels in response to water deprivation and demonstrated the beneficial effect of garlic as a possible mean of protection against oncoming vascular pathology.

Garlic shows promise for improving some cardiovascular risk factors

OBJECTIVES

To summarize the effects of garlic on several cardiovascular-related factors and to note its adverse effects.

METHODS

English and non-English citations were identified from 11 electronic databases, references, manufacturers, and experts from January 1966 through February 2000 (depending on the database searched). Reports of cardiovascular-related effects were limited to randomized controlled trials lasting at least 4 weeks. Reports of adverse effects were not limited by study design. From 1798 pertinent records, 45 randomized trials and 73 additional studies reporting adverse events were identified. Two physicians abstracted outcomes and assessed adequacy of randomization, blinding, and handling of dropouts. Standardized mean differences of lipid outcomes from placebo-controlled trials were adjusted for baseline differences and pooled using random effects methods.

RESULTS

Compared with placebo, garlic preparations may lead to small reductions in the total cholesterol level at 1 month (range of average pooled reductions, 0.03-0.45 mmol/L [1.2-17.3 mg/dL]) and at 3 months (range of average pooled reductions 0.32-0.66 mmol/L [12.4-25.4 mg/dL]), but not at 6 months. Changes in low-density lipoprotein levels and triglyceride levels paralleled total cholesterol level results; no statistically significant changes in high-density lipoprotein levels were observed. Trials also reported significant reductions in platelet aggregation and mixed effects on blood pressure outcomes. No effects on glycemic-related outcomes were found. Proven adverse effects included malodorous breath and body odor. Other unproven effects included flatulence, esophageal and abdominal pain, allergic reactions, and bleeding.

CONCLUSIONS

Trials suggest possible small short-term benefits of garlic on some lipid and antiplatelet factors, insignificant effects on blood pressure, and no effect on glucose levels. Conclusions regarding clinical significance are limited by the marginal quality and short duration of many trials and by the unpredictable release and inadequate definition of active constituents in study preparations.

[Cancer of the prostate: influence of nutritional factors. A new nutritional approach]

FIBERS: A group of vegetarian subjects have been shown to have a lower risk of cancer of the prostate than a control group. But the exact role of food fiber remains to be determined because plant foods also have an antioxidant effect on their own. PLANT PRODUCTS AND EXTRACTS: A compound called PD SPEC has been showed to have antitumor effects both in vitro and in vivo. Evaluated in patients with a cancer escaping hormone control, the clinical response was a lower level of prostate specific antigen (PSA). SOYBEANS: Several studies have demonstrated the interesting properties of soybeans. No study has however been able to demonstrate the optimal dose per day. A prospective study is currently under way using a 40 g/day dose. OVERALL NUTRITIONAL APPROACH: Several studies are being conducted using a proposed diet where 15% of the total energy intake comes from fat (associated with a low saturated/unsaturated ratio), high fiber content (18 g/100 kcal) and 40 g daily soybean protein. Although large-scale studies with rigorous methodology are lacking, an overall nutritional approach could be an interesting strategy for the management of cancer of the prostate.

A possible emerging role of phytochemicals in improving age-related neurological dysfunctions: a multiplicity of effects

It is rare to see a day pass in which we are not told through some popular medium that the population is becoming older. Along with this information comes the "new" revelation that as we enter the next millennium there will be increases in age-associated diseases (e.g., cancer, cardiovascular disease) including the most devastating of these, which involve the nervous system (e.g., Alzheimer's disease [AD] and Parkinson's disease [PD]). It is estimated that within the next 50 years approximately 30% of the population will be aged 65 years or older. Of those between 75 and 84 years of age, 6 million will exhibit some form of AD symptoms, and of those older than 85 years, over 12 million will have some form of dementia associated with AD. What appears more ominous is that many cognitive changes occur even in the absence of specific age-related neurodegenerative diseases. Common components thought to contribute to the manifestation of these disorders and normal age-related declines in brain performance are increased susceptibility to long-term effects of oxidative stress (OS) and inflammatory insults. Unless some means is found to reduce these age-related decrements in neuronal function, health care costs will continue to rise exponentially. Thus, it is extremely important to explore methods to retard or reverse age-related neuronal deficits as well as their subsequent, behavioral manifestations. Fortunately, the growth of knowledge in the biochemistry of cell viability has opened new avenues of research focused at identifying new therapeutic agents that could potentially disrupt the perpetual cycle of events involved in the decrements associated with these detrimental processes. In this regard, a new role in which certain dietary components may play important roles in alleviating certain disorders are beginning to receive increased attention, in particular those involving phytochemicals found in fruits and vegetables.

Historical perspective on garlic and cardiovascular disease

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.

Aged garlic extract, a modulator of cardiovascular risk factors: a dose-finding study on the effects of AGE on platelet functions

Aged garlic extract (AGE) has been shown previously to have moderate cholesterol-lowering and blood pressure-reducing effects. We have now investigated whether platelet function, a potential risk factor for cardiovascular disease, can be inhibited by AGE administration. In a randomized, double-blind study of normal healthy individuals (n = 34), both men and women, the effect of AGE was evaluated in doses between 2.4 and 7.2 g/d vs. equal amounts of placebo. Platelet aggregation and adhesion were measured at 2-wk intervals throughout the study. Threshold concentrations for epinephrine and collagen increased moderately during AGE administration compared with the placebo and baseline periods. Only at the highest supplementation level did AGE show a slight increase in the threshold level of ADP-induced aggregation. Platelet adhesion to collagen, fibrinogen and von Willebrand factor was investigated by perfusing whole blood through a laminar flow chamber under controlled flow conditions. Adherence of platelets was inhibited by AGE in a dose-dependent manner when collagen was the adhesive surface perfused at low shear rates ( approximately 30 s(-1)). At high shear rates (1200 s(-1)), AGE also inhibited platelet adhesion to collagen but only at higher intake levels. Adhesion to von Willebrand factor was reduced only at 7.2 g/d AGE, but adherence to fibrinogen was potently inhibited at all levels of supplementation. Thus, AGE exerts selective inhibition on platelet aggregation and adhesion, platelet functions that may be important for the development of cardiovascular events such as myocardial infarction and ischemic stroke. We briefly review the effect of garlic preparations in general on cardiovascular risk factors and point out differences between AGE and other garlic preparations that we feel are important to explain the efficacy of AGE.

Intake of garlic and its bioactive components

The health benefits of garlic likely arise from a wide variety of components, possibly working synergistically. The complex chemistry of garlic makes it plausible that variations in processing can yield quite different preparations. Highly unstable thiosulfinates, such as allicin, disappear during processing and are quickly transformed into a variety of organosulfur components. The efficacy and safety of these preparations in preparing dietary supplements based on garlic are also contingent on the processing methods employed. Although there are many garlic supplements commercially available, they fall into one of four categories, i.e., dehydrated garlic powder, garlic oil, garlic oil macerate and aged garlic extract (AGE). Garlic and garlic supplements are consumed in many cultures for their hypolipidemic, antiplatelet and procirculatory effects. In addition to these proclaimed beneficial effects, some garlic preparations also appear to possess hepatoprotective, immune-enhancing, anticancer and chemopreventive activities. Some preparations appear to be antioxidative, whereas others may stimulate oxidation. These additional biological effects attributed to AGE may be due to compounds, such as S-allylcysteine, S-allylmercaptocysteine, N(alpha)-fructosyl arginine and others, formed during the extraction process. Although not all of the active ingredients are known, ample research suggests that several bioavailable components likely contribute to the observed beneficial effects of garlic.

Suppression of LDL oxidation by garlic

It has been known for several decades that hypercholesterolemia is a major risk factor for atherosclerosis and that lowering of cholesterol can significantly reduce risk for cardiovascular diseases. More recently, oxidation of LDL has been recognized as playing an important role in the initiation and progression of atherosclerosis. Oxidized LDL, but not native LDL, promotes vascular dysfunction by exerting direct cytotoxicity toward endothelial cells, by increasing chemotactic properties for monocytes, by transforming macrophages to foam cells via scavenger-receptors and by enhancing the proliferation of various cell types, e.g., endothelial cells, monocytes and smooth muscle cells; all of these events are recognized as contributing to atherogenesis. In this paper, experimental evidence is presented that shows that several garlic compounds can effectively suppress LDL oxidation in vitro. Short-term supplementation of garlic in human subjects has demonstrated an increased resistance of LDL to oxidation. These data suggest that suppressed LDL oxidation may be one of the powerful mechanisms accounting for the antiatherosclerotic properties of garlic.

A historical perspective on garlic and cancer

Epidemiological and laboratory studies provide insight into the anticarcinogenic potential of garlic and its constituent compounds. Both water- and lipid-soluble allyl sulfur compounds are effective in blocking a myriad of chemically induced tumors. Part of the protection from these compounds probably relates to a block in nitrosamine formation and metabolism. However, blockage in the initiation and promotion phases of the carcinogenicity of various compounds, including polycyclic hydrocarbons, provide evidence that garlic and its constituents can alter several phase I and II enzymes. Their ability to block experimentally induced tumors in a variety of sites including skin, mammary and colon, suggests a general mechanism of action. Changes in DNA repair and in immunocompetence may also account for some of this protection. Some, but not all, allyl sulfur compounds can also effectively retard tumor proliferation and induce apoptosis. Changes in cellular thiol and phosphorylation stains may account for some of these antitumorigenic properties. The anticarcinogenic potential of garlic can be influenced by several dietary components including specific fatty acids, selenium, and vitamin A. Since garlic and its constituents can suppress carcinogen formation, carcinogen bioactivation, and tumor proliferation it is imperative that biomarkers be established to identify which individuals might benefit most and what intakes can occur with ill consequences.

Molecular basis by which garlic suppresses atherosclerosis

The aim of this study was to determine the mechanism by which the aged garlic extract "Kyolic" has a protective effect against atherosclerosis. Plasma cholesterol of rabbits fed a 1% cholesterol-enriched diet for 6 wk was not reduced by supplementation with 800 microL Kyolic/(kg body. d). In spite of this, Kyolic reduced by 64% (P < 0.05) the surface area of the thoracic aorta covered by fatty streaks and significantly reduced aortic arch cholesterol. Kyolic also significantly inhibited by approximately 50% the development of thickened, lipid-filled lesions in preformed neointimas produced by Fogarty 2F balloon catheter injury of the right carotid artery in cholesterol-fed rabbits. In vitro studies found that Kyolic completely prevented vascular smooth muscle phenotypic change from the contractile, high volume fraction of filament (V(v)myo) state, and inhibited proliferation of smooth muscle cells in the synthetic state with a 50% effective dose (ED(50)) of 0.2%. Kyolic also slightly inhibited the accumulation of lipid in cultured macrophages but not smooth muscle, and had no effect on the expression of adhesion molecules on the surface of the endothelium or the adherence of leukocytes. It is concluded that Kyolic exerts antiatherogenic effects through inhibition of smooth muscle phenotypic change and proliferation, and by another (unclarified) effect on lipid accumulation in the artery wall.

Cholesterol-lowering effect of garlic extracts and organosulfur compounds: human and animal studies

The medicinal use of garlic dates back thousands of years, but there was little scientific support of its therapeutic and pharmacologic properties until recently. In the past decade, the cancer-protective effects of garlic have been well established by epidemiologic studies and animal experiments. However, the cardiovascular-protective properties of garlic are less well understood. In particular, despite the reported hypocholesterolemic effect of garlic, the mechanism of the effect is unclear. In a recent randomized, double-blind, placebo-controlled intervention study, we showed that aged garlic extract (AGE) supplementation was effective in lowering plasma concentration of total cholesterol by 7% and LDL cholesterol by 10% in hypercholesterolemic men compared with subjects consuming a placebo. Supplementation of AGE in animal diets similarly reduced plasma concentrations of total cholesterol and triacylglycerol by 15 and 30%, respectively. In subsequent experiments using cultured rat hepatocytes, we found 44--87% inhibition of cholesterol synthesis by the water-extractable fraction (WEF), methanol-extractable fraction (MEF) and petroleum ether-extractable fraction (PEF) of fresh garlic, and Kyolic (liquid form of AGE). These observations suggested that hydrophilic and hydrophobic compounds of garlic are inhibitory to cholesterol synthesis. Because S-allylcysteine (SAC) alone was less potent than Kyolic, which contains SAC and other sulfur compounds, a maximal inhibition appears to require a concerted action of multiple compounds of garlic. In a series of experiments, we further characterized the inhibitory potency of individual water-soluble and lipid-soluble compounds of garlic. Among water-soluble compounds, SAC, S-ethylcysteine (SEC), and S-propylcysteine (SPC) inhibited cholesterol synthesis by 40--60% compared with 20--35% by gamma-glutamyl-S-allylcysteine (GSAC), gamma-glutamyl-S-methylcysteine (GSMC) and gamma-glutamyl-S-propylcysteine (GSPC). Lipid-soluble sulfur compounds (i.e., diallyl sulfide, diallyl disulfide, diallyl trisulfide, dipropyl sulfide and dipropyl trisulfide) at low concentrations (0.05--0.5 mol/L) slightly (10--15%) inhibited cholesterol synthesis but became highly cytotoxic at high concentrations (1.0--4.0 mol/L). All water-soluble compounds, except S-allylmercaptocysteine, were not cytotoxic, judging from the release of cellular lactate dehydrogenase into the culture medium. Taken together, the results of our studies indicate that the cholesterol-lowering effects of garlic extract, such as AGE, stem in part from inhibition of hepatic cholesterol synthesis by water-soluble sulfur compounds, especially SAC.

Enhanced immunocompetence by garlic: role in bladder cancer and other malignancies

Of the many beneficial actions of garlic, inhibition of the growth of cancer is perhaps the most remarkable. Our previous animal studies demonstrated that aged garlic extract was highly effective, and unlike the approved immunotherapy for human bladder cancer, bacillus Calmette--Guérin (BCG), garlic was effective when added to the diet. To elucidate the mechanism of this antitumor effect, the literature describing antitumor and immune-enhancing effects of garlic is reviewed. Garlic can detoxify carcinogens by stimulation of cytochrome P(450) enzymes, antioxidant activity or sulfur compound binding. Studies demonstrate a direct toxic effect of garlic to sarcoma and gastric, colon, bladder and prostate cancer cells in tissue culture, but these effects cannot explain the inhibition of growth of transplanted cancer in animal models. The most likely explanation of this effect is immune stimulation. Comparison of the effects of garlic to BCG immunotherapy reveals many similarities. Both stimulate proliferation of lymphocytes and macrophage phagocytosis, induce the infiltration of macrophages and lymphocytes in transplanted tumors, induce splenic hypertrophy, stimulate release of interleukin-2, tumor necrosis factor-alpha and interferon-gamma, enhance natural killer cell, killer cell and lymphokine-activated killer cell activity. These activities represent effective stimulation of the immune response. Studies suggest that garlic may be useful in preventing the suppression of immune response that is associated with increased risk of malignancy. Data suggest that maintenance of immune stimulation can significantly reduce the risk of cancer. Clinical trials should be initiated to test the hypothesis that the immune stimulation and other beneficial effects of garlic are able to reduce the incidence of cancer.

Protection against Helicobacter pylori and other bacterial infections by garlic

Louis Pasteur was the first to describe the antibacterial effect of onion and garlic juices. Historically, garlic has been used worldwide to fight bacterial infections. Allium vegetables, particularly garlic (Allium sativum L.) exhibit a broad antibiotic spectrum against both gram-positive and gram-negative bacteria. Noteworthy results published include the following: 1) raw juice of garlic was found to be effective against many common pathogenic bacteria-intestinal bacteria, which are responsible for diarrhea in humans and animals; 2) garlic is effective even against those strains that have become resistant to antibiotics; 3) the combination of garlic with antibiotics leads to partial or total synergism; 4) complete lack of resistance has been observed repeatedly; 5) even toxin production by microorganisms is prevented by garlic. Helicobacter pylori (H. pylori) is a bacterium implicated in the etiology of stomach cancer and ulcers. The incidence of stomach cancer is lower in populations with a high intake of allium vegetables. We have demonstrated in vitro that H. pylori is susceptible to garlic extract at a fairly moderate concentration. Even some antibiotic-resistant H. pylori strains are susceptible to garlic. Clinical trials are necessary to explore the possibility of using garlic as a low-cost remedy for eradicating H. pylori.

Pharmacologic activities of aged garlic extract in comparison with other garlic preparations

We investigated the pharmacologic activities of four garlic preparations, raw garlic juice (RGJ), heated garlic juice (HGJ), dehydrated garlic powder (DGP) and aged garlic extract (AGE). The study used three animal models, i.e., testicular hypogonadism (hypospermatogensis and impotence) induced by warm water treatment, intoxication of acetaldehyde and growth of inoculated tumor cells. RGJ was found to be effective only in recovery of testicular function. The efficacy of HGJ was observed in three models; however, it did not improve impotence. DGP was effective in recovery of spermatogenesis and stimulated acetaldehyde detoxification. Significant beneficial effects of AGE were found in all three models. Although all four garlic preparations significantly enhanced natural killer (NK) and killer cell activities of the spleen cells of tumor-bearing mice, only AGE and HGJ inhibited the growth of inoculated tumor cells. These results suggest that different types of garlic preparations have different pharmacologic properties, and among the four garlic preparations studied, AGE could be the most useful garlic preparation.

In vitro effects of aged garlic extract and other nutritional supplements on sickle erythrocytes

In the circulation of sickle cell anemia patients, a certain population of erythrocytes has an elevated density. These abnormally dense cells are believed to be at the root of the painful crisis and anemia of the patients. We have developed an in vitro method for the preparation of these heavier erythrocytes by a repeated deoxy-oxy cycling of erythrocytes from sickle cell anemia patients. By using this method, we studied whether certain nutritional supplements would inhibit the formation of dense cells in vitro. It was found that aged garlic extract (AGE) as well as its components with antioxidant activity, i.e., S-allylcysteine and N alpha-(1-deoxy-D-fructos-1-yl)-L-arginine (fructosyl arginine), inhibited the formation of dense cells in vitro. Vitamin C, vitamin E and the spin-trapping agents, 5-diethoxyphophoryl-5-methyl-1-pyrroline-N-oxide and alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone were all found to inhibit the formation of dense cells in vitro. These results suggest that, when extremely stretched sickle-shaped cells are formed by the repeated deoxy-oxy cycling, the erythrocyte membrane becomes susceptible to oxidative injury by reactive oxygen species. The protection of the erythrocyte membrane from such an oxidative injury would prevent the membranes from becoming leaky to the calcium ion, thus inhibiting the activation of the calcium-activated potassium efflux channel and the formation of dense cells. We also developed a new ex vivo method of studying the possible efficacy of antioxidants taken orally on the dense cell formation in sickle cell patients. It involved the use of blood plasma taken from a healthy donor (with normal hemoglobin) of AB blood type who had consumed different types of antioxidants orally. By suspending sickle erythrocytes in such plasma and exposing them to the deoxy-oxy cycling, the degree of dense cell formation was determined. The degree of inhibition in vitro by antioxidants taken orally may be related to their efficacy in inhibiting dense cell formation in the patients. On the basis of these in vivo and ex vivo studies, we propose that a cocktail of antioxidants would have beneficial effects in lessening the incidence and severity of crisis and reducing anemia in sickle cell disease.

Ameliorative effect of S-allylcysteine, a major thioallyl constituent in aged garlic extract, on learning deficits in senescence-accelerated mice

This study examined the effect of S:-allylcysteine (SAC), a major thioallyl compound found in aged garlic extract, on the memory deficit and age-related changes of senescence-accelerated mice. Senescence-accelerated prone P8 mice fed a diet supplemented with 40 mg SAC/kg diet for 8 mo had a significantly attenuated decrease in the conditioned avoidance response compared with those not given SAC. In the elevated plus-maze test using senescence-accelerated prone P10 mice, the percentage of time spent on the open arm was greater compared with the senescence-resistant control mice. Chronic dietary treatment with 40 mg SAC/kg diet decreased the time in the open arm in senescence-accelerated prone P10 mice. These studies suggest that diet supplementation with SAC may reduce age-related learning disabilities and cognitive disorders in senescence-accelerated mice.

Garlic and cancer: a critical review of the epidemiologic literature

Animal and in vitro studies provide evidence of an anticarcinogenic effect of active ingredients in garlic. This review of the epidemiologic literature on garlic consumption addresses cancers of the stomach, colon, head and neck, lung, breast and prostate. Nineteen studies reported relative risk estimates for garlic consumption and cancer incidence. Site-specific case-control studies of stomach and colorectal cancer, in which multiple reports were available, suggest a protective effect of high intake of raw and/or cooked garlic. Cohort studies confirm this inverse association for colorectal cancer. Few cohort and case-control studies for other sites of cancer exist. Garlic supplements, as analyzed in four cohort studies and one case-control report, from two distinct populations, do not appear to be related to risk. Low study power, lack of variability in garlic consumption categorization within studies and poor adjustment for potential cofounders may limit the reliability of any conclusions regarding garlic supplements. However, an indication of publication bias was also found by visual inspection of a funnel plot and in a log-rank test (P = 0.004). Evidence from available studies nevertheless suggests a preventive effect of garlic consumption in stomach and colorectal cancers. The study limitations indicate the need for more definitive research and improved nutritional epidemiologic analyses of dietary data.

Historical perspective on the use of garlic

The objective of this review is to examine briefly the medical uses of garlic throughout the ages and the role that it was considered to play in prevention and treatment of disease. Interest in the potential benefits of garlic has origins in antiquity and is one of the earliest documented examples of plants employed for treatment of disease and maintenance of health. Garlic was in use at the beginning of recorded history and was found in Egyptian pyramids and ancient Greek temples. There are Biblical references to garlic. Ancient medical texts from Egypt, Greece, Rome, China and India each prescribed medical applications for garlic. In many cultures, garlic was administered to provide strength and increase work capacity for laborers. Hippocrates, the revered physician, prescribed garlic for a variety of conditions. Garlic was given to the original Olympic athletes in Greece, as perhaps one of the earliest "performance enhancing" agents. It is of interest that cultures that developed without contact with one another came to similar conclusions about the efficacy of garlic. Modern science is tending to confirm many of the beliefs of ancient cultures regarding garlic, defining mechanisms of action and exploring garlic's potential for disease prevention and treatment.

[Pharmaceutical importance of Allium sativum L. 1. Organic sulfur compounds and their transformation based on present knowledge]

The paper sums up new experimental knowledge concerning the individual groups of organic sulfurous substances of the garlic: sulfoxides, thiosulfinate, ajoens, vinyldithiines, alkyl and alkene sulfides and glutamylpeptides of sulfurous amino acids, their transformation reactions (based on the temperature, pH, extraction medium, and time) and the final products of transformations (Scheme 1, 2). It deals with the activity of the enzyme alliinase necessary for the transformation of sulfoxides present in the whole garlic, its isolation and stability as well as the stability of the dominant thiosulfinate allicin in various media and simulated body fluids. It refers to the studies of the metabolism and transformations of the most important sulfurous components performed in vitro on the hepatocytes and on the isolated rat liver, and those carried out in vivo on the rats and including the examination of the composition of the exhaled air. It follows from published papers that all different degradation products of thiosulfinates, mainly the prevailing allicin, are carriers of various biological activities. The paper also lists the types of commercial preparations prepared from the garlic, their differences, and considerable variability of their contents of active principles.

Thromboxane-B2, prostaglandin-E2 and hypertension in the rat 2-kidney 1-clip model: a possible mechanism of the garlic induced hypotension

Serum collected from unilaterally clipped and unclipped rats before and after treatment with water, garlic or cilazapril and subsequent to measuring blood pressure was assayed for thromboxane-B2 and prostaglandin-E2. The unclipped rats' thromboxane-B2 and prostaglandin-E2 levels were about 23 ng/ml and 2 ng/ml, respectively, and blood pressure was 126+/-3 mmHg. These values were not affected by either water or garlic administration. The clipped rats' thromboxane-B2 and prostaglandin-E2 concentrations were close to 34 ng/ml and 4 ng/ml, respectively, and declined only in response to garlic (by 15 ng/ml and 3 ng/ml) and cilazapril (by 12 ng/ml and 1.5 ng/ml). The blood pressure of these rats was 196+/-7 mmHg and again was reduced only by garlic to 169+/-14 mmHg and cilazapril to 137+/-5 mmHg. The no-treatment and water-treatment readings were significantly higher in the clipped rats. The data suggest that prostanoid system activity in the 2-kidney 1-clip rat is enhanced and mostly toward maintaining the hypertension. Furthermore, the blood pressure lowering effects of garlic and cilazapril might have been induced partially by a greater reduction in the synthesis of vasoconstrictor prostanoids.

Post-transcriptional control of catalase expression in garlic-treated rats

Regulation of catalase (CAT) expression, a major antioxidant enzyme that detoxifies H2O2, is very complex. Garlic is effective to prevent or ameliorate oxidative stress probably through its intrinsic antioxidant properties and/or to its ability to modify antioxidant enzyme expression. In this paper we studied the effect of a 2% garlic diet on the renal and hepatic CAT expression (mRNA levels, and enzyme activity, content, synthesis, and degradation). The study was made 2 weeks after feeding rats with a 2% garlic diet. CAT activity and content were measured by a spectrophotometric method and Western blot, respectively. CAT mRNA levels and CAT synthesis (k(s)) and degradation (kD) in vivo were measured by Northern blot and kinetic of reappearance of CAT activity after aminotriazole injection, respectively. Garlic-treatment decreased CAT activity and content, and CAT mRNA levels were unchanged in both tissues. k(s) decreased and kD remained unchanged in kidney and liver. The decrease in k(s) without changes in kD and CAT mRNA levels could explain the low CAT expression in garlic-fed rats. In vivo H2O2 generation in kidney and liver was markedly decreased in garlic-fed rats which could be due to a direct antioxidant effect of garlic. This may be the initial event in the garlic-fed rats that leads to the decreased CAT expression. Our data strongly suggest that the diminished renal and hepatic CAT expression in garlic-fed rats is mediated by post-transcriptional changes (mainly low translational efficiency) which could be an adaptation to the low H2O2.

Inhibition of chemically induced liver carcinogenesis in Wistar rats by garlic (Allium sativum)

The effects of garlic on diethylnitrosoamine (DEN)-induced hepatocarcinogenesis were examined in male Wistar rats using the medium term bioassay system of Ito based on the two-step model of hepatocarcinogenesis. Carcinogenic potential was scored by comparing the number and area/cm(2) of induced glutathione S-transferase placental form (GST-P) positive foci in the liver with those of the corresponding group (control) of rats given diethylnitrosoamine alone. Treatment with garlic (therapeutic dose 20 mg/kg body wt/day) reduced significantly the number (50% reduction, p < 0.003) and area (48% reduction, p < 0.0007) of GST-P positive foci compared with the control group of animals receiving distilled water. Histopathological examination of rat livers using H & E staining indicated that there was no significant difference between the control group and the garlic treated group in the two pathological parameters namely granularity and vacuolation of the cytoplasm. Our results provide strong supportive evidence for the anticarcinogenic activity of garlic.

Functional foods and cardiovascular disease

Functional foods are foods that, by virtue of physiologically active food components, provide health benefits beyond basic nutrition. Many functional foods have been found to be potentially beneficial in the prevention and treatment of cardiovascular disease, the leading cause of mortality in the United States. These foods include soybeans, oats, psyllium, flaxseed, garlic, tea, fish, grapes, nuts, and stanol- and sterol ester enhanced margarine. When eaten in adequate amounts on a consistent basis, these foods may aid in decreasing the risk of cardiovascular disease by several potential mechanisms: lowering blood lipid levels, improving arterial compliance, reducing low-density lipoprotein oxidation, decreasing plaque formation, scavenging free radicals, and inhibiting platelet aggregation.

Dietary supplementation with aged garlic extract inhibits ADP-induced platelet aggregation in humans

Garlic has been widely reported to protect against cardiovascular disease by reducing serum cholesterol concentrations and blood pressure and by inhibiting platelet aggregation. However, most of these studies have been performed in hypercholesterolemic subjects or in animal models. We performed a 13-wk study in normolipidemic subjects who ingested 5 mL of aged garlic extract (AGE, Kyolic) per day. Blood was drawn from these subjects at the beginning and end of the study. Aggregation of platelet-rich plasma was induced by ADP; full lipid profiles and liver function tests were determined on serum, and plasma concentrations of eicosanoids were also measured. Dietary supplementation with AGE significantly inhibited both the total percentage and initial rate of platelet aggregation at concentrations of ADP up to 10 micromol/L. The K:(M) for ADP-induced aggregation were approximately doubled after supplementation with AGE, whereas the maximum rate of aggregation was unaffected. No significant changes in plasma thromboxane B(2) and 6-ketoprostaglandin F(1alpha) concentrations or serum lipid profiles were observed. We conclude that AGE, when taken as a dietary supplement by normolipidemic subjects, may be beneficial in protecting against cardiovascular disease as a result of inhibiting platelet aggregation.

Garlic induces a shift in cytokine pattern in Leishmania major-infected BALB/c mice

The regulation of T helper (Th)1- and Th2-type cytokine patterns is important in the final outcome of leishmaniasis in human and murine models. We examined the efficacy of garlic therapy or a combination of garlic and an antimonial drug (glucantime) in promoting healing and regulation of Th1/Th2 cytokine patterns in highly susceptible BALB/c mice infected with Leishmania major. Separate groups of infected mice received 20 mg/kg/day garlic, 60 mg/kg/day glucantime or a combination of the two, from day 30 after infection for 2 weeks. An enzyme-linked immunosorbant assay (ELISA) was performed on spleen cell culture supernatants for interferon(IFN)-gamma interleukin(IL)-2, IL-4 and IL-10. The results indicate that garlic therapy is more effective than the usual antileishmanial drug in curing the infection. Garlic-treated mice developed Th1-type cytokine responses. In contrast, glucantime therapy led to a Th2-type response in the control group with a lower level of IL-2. However, a combination of garlic and glucantime treatment was more effective than either treatment alone, and resulted in a Th1-type response similar to that which developed with garlic treatment. These results suggest that garlic extract in combination with an antimonial drug, may provide effective therapy against L. major. The immunomodulatory properties of garlic were elucidated in terms of shifting the cytokine response to a Th1-type pattern and therefore causing the protective response.

Topical application of garlic reduces northern fowl mite infestation in laying hens

Northern fowl mites (NFM) are external parasites that can lower egg production and cause anemia and even death in laying hens. An experiment was conducted with New Hampshire Red and Single Comb White Leghorn laying hens. Hens were individually caged and provided a complete laying diet and water ad libitum. Hens were assigned to groups in a way that assured that treatments, within each breed, would be applied to comparable numbers of birds with light and heavy mite infestations. Each hen was sprayed around the vent with either water or 10% garlic juice in water. Spraying continued each week for 3 wk. During the fourth week, each bird was scored for the presence of NFM on its skin and feathers. A small snippet of feathers was removed from below the vent of each hen and placed in a labeled petri dish with a round, white filter paper insert. The NFM content of each dish was scored by two individuals approximately 1 h after sampling. There was no significant difference in the NFM scores for hens based on breed or future treatment. After the birds were treated for 3 wk, there was no significant difference in external NFM scores based on breed. There were significantly fewer NFM on the birds treated with garlic juice compared with controls, based on external and petri dish scoring (P < 0.002 and P < 0.04, respectively). The reduction in external NFM score was also significant (P < 0.004), with controls declining approximately 0.2 units, whereas garlic-treated hens had a 1.8-unit decrease in external NFM score. Topical application of garlic juice may be an effective way to decrease NFM in laying hens.

Garlic burns

A 3-month-old infant with blistering lesions and a second-degree burn from topical application of garlic is reported. The literature on garlic burns is reviewed.

Garlic elicits a nitric oxide-dependent relaxation and inhibits hypoxic pulmonary vasoconstriction in rats

1. The aims of the present study were to determine the characteristics of garlic extract-induced relaxation in rat isolated pulmonary arteries, its susceptibility to changes in oxygen tension and its protective effect against hypoxic pulmonary vasoconstriction. 2. In normoxia, garlic extract (3-500 microg/mL) produced a dose- and nitric oxide (NO)-dependent relaxation. Following 60 min hypoxia, maximum garlic relaxation was reduced compared with control (mean (-SEM) -86 +/- 3 vs-69 +/- 2% of phenylephrine (PE) precontraction, respectively), but recovered after 60 min reoxygenation (-85 +/- 3% PE precontraction). 3. Acetylcholine (0.1 micromol/L)-induced NO-dependent relaxation was reduced from a control value of -76 +/- 1% to -46 +/- 4% during hypoxia and was further reduced to -35 +/- 2 % after reoxygenation. 4. In endothelium-intact arteries, hypoxic exposure resulted in a triphasic response: early transient contraction (+24 +/- 4%), followed by transient relaxation (-37 +/- 7%) and then sustained contraction (+62 +/- 5%). 5. Pretreatment with NG-nitro-L-arginine methyl ester abolished the early transient contraction, moderately attenuated the sustained contraction and had no effect on the transient relaxation. Mechanical endothelial disruption inhibited all hypoxia-induced vascular changes. 6. Garlic pretreatment had no effect on the early transient contraction (+25 +/- 4%), but inhibited the transient relaxation (-5 +/- 3%; P<0.05) and the sustained contraction (+26 +/- 5%; 7. Garlic also significantly inhibited endothelin-l-induced contractions in a dose-dependent manner. 8. These findings show that garlic extract modulates the production and function of both endothelium-derived relaxing and constricting factors and this may contribute to its protective effect against hypoxic pulmonary vasoconstriction.

Thromboxane-B(2) levels in serum of rabbits receiving a single intravenous dose of aqueous extract of garlic and onion

We have shown previously that fresh garlic extract is effective in reducing thromboxane formation by platelets both in vivo and in vitro animal models of thrombosis. In the present study, the effect of different concentrations of a single dose of aqueous extracts of garlic and onion were evaluated on serum thromboxane-B(2)synthesis in rabbits. Different concentrations of garlic and onion were administered as single doses in the ear vein of rabbits. Rabbits were bled before and at different intervals after the infusion of garlic or onion extracts. Venous blood was collected and allowed to clot at 37 degrees C for 1 h. Thromboxane-B(2)level was measured in the serum by radioimmunoassay. It was observed that garlic inhibits the thrombin-induced platelet synthesis of TXB(2)in a dose-and time-dependent manner. Maximum inhibition of TXB(2)occurred between 0.5 h and 6 h at 25 and 100 mg kg(-1)garlic. At 24 h post-garlic infusion TXB(2)inhibition was reduced to 15% of the control and TXB(2)levels were comparable to that of the control values at 72 h pots-garlic infusion. Infusion of 100 mg kg(-1)onion extract did not elicit any inhibitory effect on TXB(2)synthesis in the serum of rabbit during the treatment period. The rapid recovery of platelet cyclooxygenase activity after infusion of a single dose of garlic suggests that garlic should be taken more frequently in order to achieve beneficial effects in the prevention of thrombosis.

Garlic for treating hypercholesterolemia. A meta-analysis of randomized clinical trials

PURPOSE

To investigate the effect of garlic on total cholesterol level in persons with elevated levels by conducting a meta-analysis of randomized, double-blind, placebo-controlled trials.

DATA SOURCES

Systematic literature searches were conducted on the MEDLINE, EMBASE, BIOSIS, Cochrane Library, AMED, and CISCOM databases. Manufacturers of commercial garlic preparations and experts in the field were asked about published or unpublished trials.

STUDY SELECTION

Selected trials were required to state that they were randomized, double-blind, and placebo-controlled; use garlic monopreparations; include persons with mean total cholesterol levels of at least 5.17 mmol/L (200 mg/dL); and report total cholesterol level as an end point. There were no language restrictions.

DATA EXTRACTION

Two reviewers, blinded to key identifiers of each paper, independently extracted data in a standardized manner and assessed methodologic quality by using the Jadad scale. Discrepancies were settled through discussion.

DATA SYNTHESIS

In the 13 trials included in the meta-analysis, garlic reduced total cholesterol level from baseline significantly more than placebo (P < 0.01); the weighted mean difference was -0.41 mmol/L (95% CI, -0.66 to -0.15 mmol/L) (-15.7 mg/dL [CI, -25.6 to -5. 7 mg/dL]). Six diet-controlled trials with the highest scores for methodologic quality revealed a nonsignificant difference between garlic and placebo groups; the weighted mean difference was -0.11 mmol/L (CI, -0.30 to 0.08 mmol/L) (-4.3 mg/dL [CI, -11.7 to 3.1 mg/dL]).

CONCLUSIONS

The available data suggest that garlic is superior to placebo in reducing total cholesterol levels. However, the size of the effect is modest, and the robustness of the effect is debatable. The use of garlic for hypercholesterolemia is therefore of questionable value.

[Review: cardiovascular effect of garlic (Allium sativum)]

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. However, some other studies do not support these benefits. The positive effects found have promoted many study projects, nevertheless, the extract lability and the lack of result consensus call for a moderate consumption of garlic and garlic extracts. The composition variation due to gathering and aging together with the changes occurring in canning and industrial treatment makes necessary the application of some norms in the production and consumption of this functional food in order to guarantee its use in adequate form and doses.

Garlic ameliorates hyperlipidemia in chronic aminonucleoside nephrosis

Nephrotic syndrome (NS) is characterized by proteinuria, oxidative stress and endogenous hyperlipidemia. Hyperlipidemia and oxidative stress may be involved in coronary heart disease and the progression of renal damage in these patients. Garlic has been suggested to be beneficial in various disease states. Some of the beneficial effects of garlic may be secondary to its hypolipidemic and antioxidant properties. Therefore, the effect of a 2% garlic diet on acute and chronic experimental NS induced by puromycin aminonucleoside (PAN) was studied in this work. Acute NS was induced by a single injection of PAN to rats which were sacrificed 10 days later. Chronic NS was induced by repeated injections of PAN to rats which were sacrificed 84 days after the first injection. Garlic treatment was unable to modify proteinuria in either acute or chronic NS, and hypercholesterolemia and hypertriglyceridemia in acute NS. However, garlic treatment diminished significantly total-cholesterol, LDL-cholesterol and triglycerides, but not HDL-cholesterol in chronic NS. Garlic induced no change in the percentage of sclerotic glomeruli in chronic NS and a significative decrease on the percentage of sclerotic area of these glomeruli (33 +/- 3% in NS+Garlic group vs. 47 +/- 4% in NS group, p = 0.0126). The enhanced in vivo renal H2O2 production and the diminished renal Cu, Zn-SOD and catalase activities in acute NS, and the decreased renal catalase activity in chronic NS were not prevented by garlic treatment. These data indicate that garlic treatment ameliorates hyperlipidemia and renal damage in chronic NS which is unrelated to proteinuria or antioxidant enzymes.

Chemical speciation influences comparative activity of selenium-enriched garlic and yeast in mammary cancer prevention

A recent human intervention trial showed that daily supplementation with selenized yeast (Se-yeast) led to a decrease in the overall cancer morbidity and mortality by nearly 50%; past research has also demonstrated that selenized garlic (Se-garlic) is very effective in mammary cancer chemoprevention in the rat model. The goal of this study was to compare certain biological activities of Se-garlic and Se-yeast and to elucidate the differences based on the chemical forms of selenium found in these two natural products. Characterization of organic selenium compounds in yeast (1922 microg/g Se) and garlic (296 microg/g Se) was carried out by high-performance liquid chromatography with inductively coupled plasma mass spectrometry or with electrospray mass spectrometry. Analytical speciation studies showed that the bulk of the selenium in Se-garlic and Se-yeast is in the form of gamma-glutamyl-Se-methylselenocysteine (73%) and selenomethionine (85%), respectively. The above methodology has the sensitivity and capability to account for >90% of total selenium. In the rat feeding studies, supplementation of Se-garlic in the diet at different levels consistently caused a lower total tissue selenium accumulation when compared to Se-yeast. On the other hand, Se-garlic was significantly more effective in suppressing the development of premalignant lesions and the formation of adenocarcinomas in the mammary gland of carcinogen-treated rats. Given the present finding on the identity of selenomethionine and gamma-glutamyl-Se-methylselenocysteine as the major form of selenium in Se-yeast and Se-garlic, respectively, the metabolism of these two compounds is discussed in an attempt to elucidate how their disposition in tissues might account for the differences in cancer chemopreventive activity.

Protection by garlic against adriamycin induced alterations in the oxido-reductive status of mouse red blood cells

The effects of oral garlic supplementation on the activities of (a) the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) and (b) lipid peroxidation, as assessed by malondialdehyde (MDA) production in red blood cells of normal mice and those subject to oxidative stress by chronic administration of the anti-tumour drug adriamycin has been investigated. As expected, adria-mycin administration resulted in a significant increase in MDA generation (by 105.4%) and a decrease in GPX activity (by 23.8%) in the red blood cells. Although garlic had no significant effects on the basal levels of the antioxidant enzymes or MDA generation in red blood cells of normal mice (untreated with adriamycin), at doses of 20 mg/kg or 100 mg/kg, garlic was able to decrease significantly the adriamycin induced changes in the oxido-reductive status of the red blood cells. Thus, on administration of adriamycin to mice fed diets containing 20 mg/kg or 100 mg/kg garlic, the drug-induced increase in MDA generation was 38.2% and 22.5% respectively, less than that produced by adriamycin in mice fed normal diets, containing no garlic (105.4%). Similarly, in mice fed diets providing 20 mg/kg and 100 mg/kg garlic, adriamycin was able to decrease GPX activity by only 15.1% and 7.6% respectively, less than that produced by adriamycin in rats fed normal diets, containing no garlic (23.9%).

Garlic powder, effect on plasma lipids, postprandial lipemia, low-density lipoprotein particle size, high-density lipoprotein subclass distribution and lipoprotein(a)

OBJECTIVES

To test the hypothesis that a garlic supplement alters plasma lipoproteins, postprandial lipemia, low-density lipoprotein (LDL) size and high-density lipoprotein (HDL) subclass distribution differently in 50 moderately hypercholesterolemic subjects classified as LDL subclass pattern A or B.

BACKGROUND

Garlic has been variably reported to reduce or not affect plasma cholesterol values. Low-density lipoprotein pattern B is a common inherited disorder of lipoprotein metabolism that has been shown to have a significantly greater response to several lipid lowering treatments including low fat diet when compared with LDL pattern A individuals.

METHODS

A double blind, randomized, placebo controlled trial in an outpatient lipid research clinic was performed and included fifty moderately hypercholesterolemic subjects (mean LDL cholesterol = 166 +/- 22 mg/dl) classified as LDL subclass pattern A (predominantly large LDL, n = 22) or B (predominantly small LDL, n = 28). Following a two-month stabilization period, subjects were randomly assigned to a placebo or 300 mg three times a day of a standardized garlic tablet for three months.

RESULTS

For all subjects, LDL pattern A and B subjects combined, garlic treatment for three months resulted in no significant change in total cholesterol, LDL cholesterol, HDL cholesterol, HDL subclass distribution, postprandial triglycerides, apolipoprotein B, lipoprotein (a) (Lp[a]), LDL peak particle diameter or LDL subclass distribution. There was no significant difference in response for the same parameters among subjects classified as LDL pattern A or B with the exception of significantly greater (p = 0.01) reduction in mean peak particle diameter in pattern A subjects treated with either garlic or placebo. There was no significant change in LDL subclass distribution.

CONCLUSIONS

This investigation confirms that garlic therapy has no effect on major plasma lipoproteins and further, that it has no impact on HDL subclasses, Lp(a), apolipoprotein B, postprandial triglycerides or LDL subclass distribution. Garlic may have a greater effect on LDL particle diameter in LDL pattern A compared with pattern B subjects. This difference was not reflected in other plasma lipid measurements.

The potential application of Allium sativum (garlic) for the treatment of bladder cancer

Additional studies are needed to identify the active ingredients in Allium Sativum (garlic) that are responsible for the observed antitumor activity and immune stimulation. Garlic seems to detoxify chemical carcinogens and prevent carcinogenesis and can also directly inhibit the growth of cancer cells. Current data suggest that low molecular weight sulfur compounds and protein F4 have immune-stimulation properties. Garlic is reported to stimulate immunity, including macrophage activity, natural killer and killer cells, and LAK cells, and to increase the production of IL-2, TNF, and interferon-gamma. These cytokines are associated with the beneficial Th1 antitumor response, which is characteristic of effective cancer immunotherapies. As is true of BCG, garlic stimulates the proliferation of macrophages and lymphocytes and protects against the suppression of immunity by chemotherapy and ultraviolet radiation. Garlic is clearly not a panacea for cancer, but its broad range of beneficial effects are worthy of serious consideration in clinical trials for the prevention and treatment of cancer.

Garlic for peripheral arterial occlusive disease

BACKGROUND

Commercially available preparations of garlic have been reported to have beneficial effects on some of the risk factors associated with atherosclerosis.

OBJECTIVES

The objective of this review was to assess the effects of garlic (both dried and non-powdered preparations) for the treatment of peripheral arterial occlusive disease.

SEARCH STRATEGY

The reviewers searched the Cochrane Peripheral Vascular Diseases Group trials register, AMED, EMBASE, BIDS ISI, abstracts of relevant symposia and reference lists of relevant articles up to August 1998. The reviewers also contacted pharmaceutical companies, investigators and experts in garlic therapies.

SELECTION CRITERIA

Randomised trials of garlic therapy in patients with lower limb atherosclerosis. The main outcomes were objective measures of progression of underlying atherosclerosis (e.g. ankle pressure measurements, treadmill testing) and subjective measures (e.g. symptom progression).

DATA COLLECTION AND ANALYSIS

At least two reviewers extracted data and assessed trial quality independently. The reviewers contacted investigators to obtain information needed for the review that could not be found in published reports.

MAIN RESULTS

One eligible trial with 78 participants was found. Both men and women (aged 40-75) were included. The follow-up period was short, 12 weeks only. After twelve weeks of treatment, pain free walking distance increased from 161 to 207 m in the group on garlic and from 172 to 203 m in the placebo group. This was not a statistically significant difference. There was no difference in change of systolic or diastolic blood pressure, heart rate, ankle and brachial pressures. No severe side effects were observed and nine patients taking garlic (28%) and four patients taking placebo (12%) complained of a noticeable garlic smell.

REVIEWER'S CONCLUSIONS

One small trial of short duration found no effect on walking distance.