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

Platelet Aggregation Inhibition: An Evidence-Based Systematic Review on the Role of Herbs for Primary Prevention Based on Randomized Controlled Trials

BACKGROUND

Platelet aggregation is a crucial mechanism in the progression of atherothrombotic events. This systematic review aims to introduce the plants studied in healthy people as the primary prevention to inhibit platelet aggregation. We also discuss possible mechanisms that are involved in the inhibition of platelet aggregation.

METHODS

A systematic search on the electronic medical databases from 1970 to February 2020 was performed. The selected keywords were: "herb", "plant", "platelet aggregation", "platelet activation", "clinical trial", "randomized" and "controlled".

RESULTS

The result of the initial search was a pool of 136 articles. After initial abstract reviewing, there were 55 relevant articles. Finally, 28 eligible records fulfilled our inclusion criteria to enter the qualitative synthesis process.

CONCLUSION

Out of the 10 plants evaluated in the clinical trials, nine had inhibitory effects on platelet aggregation. Most of the reviewed plants, including tomato (Solanum lycopersicum L), garlic (Allium sativum), kiwifruit (Actinidia deliciosa), cacao (Theobroma cacao), grape (Vitis vinifera), ginkgo (Ginkgo biloba), flaxseed (Linum usitatissimum), sea buckthorn berry (Hippophae), and argan (Argania spinose) could be potential sources for the primary prevention of atherothrombotic events at an appropriate dosage. Finally, we do not consider phytoceuticals as a replacement for the guideline-directed medical treatment. Large randomized double-blind clinical trials are required to evaluate the anti-platelet characteristics of these plants for the adjuvant primary prevention of cardiovascular disease.

A systematic review of randomized controlled trials related to the effects of garlic supplementation on platelet aggregation

The increment of platelet aggregation factors has been considered a key phenomenon in atherosclerosis. Studies have shown that garlic (Allium sativum) is associated with a reduction in platelet aggregation and thrombosis. Hence, the present systematic review was conducted to evaluate the effect of garlic on platelet aggregation. All randomized controlled trials (RCTs) with keywords related to garlic and platelet aggregation were thoroughly searched in electronic databases including PubMed, Scopus, ISI Web of Science, and Google Scholar up to January 2021. Moreover, the references of all related articles were screened to discover more relevant studies. The quality of each study was reported based on Cochrane Collaboration's tool. In total, 12 studies met the inclusion criteria from 18,235 identified articles (including 595 participants). Most of the studies assessed platelet aggregation in response to different inducers. Of the 12 clinical trials, six studies depicted the beneficial effect of garlic on reducing platelet aggregation. The summary of the quality assessment indicated that most of the studies had high-quality scores. Regarding the small number of RCTs and heterogeneity between studies, it is impossible to make a proper conclusion about the impacts of garlic on platelet aggregation. Therefore, further precise trials with a standard design are necessary to validate the anti-thrombotic effect of garlic.

Short report: Aqueous extract of chives (Allium schoenoprasum L.) plant impairs erythrocyte deformability in sickle cell patients

Sickle cell anemia (SCA) is a genetic disorder characterized by chronic hemolysis and the presence of erythrocytes with low deformability, which may trigger vaso-occlusive crises. We tested the in-vitro effects of aqueous extract of vhives (Allium schoenoprasum L.) on erythrocyte deformability of SCA patients. Blood samples from 6 apparently healthy volunteers and 5 SCA patients were collected into heparin coated tubes. Both apparently healthy and SCA patient blood samples were incubated with 80μg/mL chives plant aqueous extract at 37°C for 60 min and erythrocyte deformability was measured by ektacytometry (3 Pa and 30 Pa; 37°C). Results of incubation of apparently healthy blood samples with plant extract showed that incubation did not alter erythrocyte deformability significantly. However, for SCA blood samples, erythrocyte deformability decreased significantly with plant extract exposure at 3 Pa (p <  0.043) and 30 Pa (p <  0.043). In conclusion, although ex-vivo incubation with plant extract does not fully model gastrointestinal processing of onions, the decrease in SCA erythrocyte deformability following incubation with aqueous chives should stimulate further studies to test the in-vivo effects of this diet in sickle cell mice.

Therapeutic effects of medicinal plants on isoproterenol-induced heart failure in rats

AIMS

Natural products still serves as a hope for some illnesses which modern medicine fails to cure. Many people, either knowing their effects or not, are using these herbal products. Treatment of chronic heart failure (CHF) is yet a complicated clinical challenge and there is need to improve or make new therapeutic targets. Finding new agents for CHF is an important subject in cardiovascular drug research. In this study, we evaluated the effects of ten herbals on treatment of CHF on isoproterenol-induced model.

METHODS AND RESULTS

Ninety-six male Wistar rats (16 weeks old) were used in 12 groups. Transthoracic echocardiography was performed on the rats for confirmation of CHF model by decreasing ejection fraction. After 4 weeks' treatment, hearts were removed and blood samples were collected in tubes to measure plasma levels of laboratory findings. Our results showed that the mean of ejection fraction in model rats was 51.82 ± 3.49 percent and all of our used natural products could significantly increase the ejection fraction (P < 0.01). The most effective herbals in improving the ejection fraction were Allium sativum (30.69 %), Peganum harmala (26.08 %) and Apium graveolens (24.09 %). The best results in decreasing NT-ProBNP, was obtained from Allium sativum, Peganum harmala and Berberis vulgaris respectively. Our results showed that none of natural products had toxic effect on renal and liver tissues.

CONCLUSION

Our results showed that Allium sativum, Peganum harmala and Berberis vulgaris could significantly improve cardiac function by improvement of left ventricular remodeling, lowering hs-CRP and NT-ProBNP and echocardiographic indexes without liver or renal side effects.

Effects of superfoods on risk factors of metabolic syndrome: a systematic review of human intervention trials

Functional foods can be effective in the prevention of metabolic syndrome and subsequently the onset of cardiovascular diseases and type II diabetes mellitus. More recently, however, another term was introduced to describe foods with additional health benefits: "superfoods", for which, to date, no generally accepted definition exists. Nonetheless, their consumption might contribute to the prevention of metabolic syndrome, for example due to the presence of potentially bioactive compounds. This review provides an overview of controlled human intervention studies with foods described as "superfoods" and their effects on metabolic syndrome parameters. First, an Internet search was performed to identify foods described as superfoods. For these superfoods, controlled human intervention trials were identified until April 2017 investigating the effects of superfood consumption on metabolic syndrome parameters: waist circumference or BMI, blood pressure, or concentrations of HDL cholesterol, triacylglycerol or glucose. Seventeen superfoods were identified, including a total of 113 intervention trials: blueberries (8 studies), cranberries (8), goji berries (3), strawberries (7), chili peppers (3), garlic (21), ginger (10), chia seed (5), flaxseed (22), quinoa (1), cocoa (16), maca (1), spirulina (7), wheatgrass (1), acai berries (0), hemp seed (0) and bee pollen (0). Overall, only limited evidence was found for the effects of the foods described as superfoods on metabolic syndrome parameters, since results were not consistent or the number of controlled intervention trials was limited. The inconsistencies might have been related to intervention-related factors, such as duration or dose. Furthermore, conclusions may be different if other health benefits are considered.

Medicinal plants with antithrombotic property in Persian medicine: a mechanistic review

Thrombosis is one of the major causes of morbidity and mortality in a wide range of vessels diseases. Due to the high prevalence of thromboembolic disorders investigations are being carried out on new antithrombotic agents with limited adverse side effects in which herbal medicines are considered as alternative remedies. Persian medicine (PM) as a traditional medicine has a good potential for pharmacotherapy based on its own principles and development of drugs via investigating PM literature. In PM manuscripts there are some concepts that express the management of blood clots and antithrombotic properties. This study reviewed the pharmacological effects of medicinal plants mentioned in PM literature for blood clot management in light of current knowledge. Plants mentioned in PM for management of blood clot belong to 12 families in which Apiaceae, Lamiaceae and Compositae were the most repeated ones. Among the proposed plants Allium sativum, Rosmarinus officinalis, Boswellia serrata, Sesamum indicum, Matricaria chamomilla and Carthamus tinctorius have been the most researched plants in modern antithrombotic studies while for some plants such as Helichrysum stoechas, Dracocephalum kotschi, Carum carvi, Bunium persicum and Lagoecia cuminoides no evidence could be found. One of the interesting notes in clot management in PM texts was introducing the target organ for some of the recommended herbs like Carum carvi and Bunium persicum for dissolving blood clot in stomach and Commiphora mukul for thrombosed hemorrhoid. It seems review of PM recommendations can help to design future researches for antithrombotic drugs discovering with more effectiveness and safety.

S-allylcysteine Improves Blood Flow Recovery and Prevents Ischemic Injury by Augmenting Neovasculogenesis

Studies suggest that a low level of circulating human endothelial progenitor cells (EPCs) is a risk factor for ischemic injury and coronary artery disease (CAD). Consumption of S-allylcysteine (SAC) is known to prevent CAD. However, the protective effects of SAC on the ischemic injury are not yet clear. In this study, we examined whether SAC could improve blood flow recovery in ischemic tissues through EPC-mediated neovasculogenesis. The results demonstrate that SAC significantly enhances the neovasculogenesis of EPCs in vitro. The molecular mechanisms for SAC enhancement of neovasculogenesis include the activation of Akt/endothelial nitric oxide synthase signaling cascades. SAC increased the expression of c-kit, β-catenin, cyclin D1, and Cyclin-dependent kinase 4 (CDK4) proteins in EPCs. Daily intake of SAC at dosages of 0.2 and 2 mg/kg body weight significantly enhanced c-kit protein levels in vivo. We conclude that dietary consumption of SAC improves blood flow recovery and prevents ischemic injury by inducing neovasculogenesis in experimental models.

Perioperative Herbal Supplement Use in Cancer Patients: Potential Implications and Recommendations for Presurgical Screening

BACKGROUND

Products made from botanicals that are used to maintain or improve health are known as herbal supplements, botanicals, or phytomedicines. Many herbs have a long history of use and claimed health benefits. However, many herbal supplements and botanicals have potent pharmacologic activity that can contribute to adverse effects and drug interactions. The use of herbal supplements by cancer patients in the perioperative period is common and consistent with the substantial increase in the use of alternative medical therapies.

METHODS

We reviewed the literature to examine the constituents, safety, pharmacokinetics, and pharmacodynamics of those herbal supplements that are predominantly used by cancer patients.

RESULTS

Different supplements possess antiplatelet activity, adversely interact with corticosteroids and central nervous system depressant drugs, have gastrointestinal manifestations, produce hepatotoxicity and nephrotoxicity, and produce additive effects when used with opioid analgesics.

CONCLUSIONS

With the increasing use of herbal supplements by cancer patients, surgical staff need to screen patients pre-surgically for use of these supplements. Clinical practice guidelines are needed for screening and prevention of herbal supplement usage to prevent potential adverse events that may arise from herbal medications taken alone or combined with conventional therapies during the perioperative period.

Effects of naturopathic medicines on Multiplate and ROTEM: a prospective experimental pilot study in healthy volunteers

BACKGROUND

Of patients undergoing surgery, 22 to 57% have been reported to be using naturopathic medicines. Several of these medicines have been reported to increase bleeding or enhance the effect of other drugs that increase bleeding. The Swedish Medical Products Agency recommends cessation of the use of the naturopathic medicines echinacea, fish oil, ginkgo biloba, ginseng, St. John's wort, valeriana and garlic 2 weeks before surgery. The aim of this pilot study was to examine the effects of these 7 naturopathic medicines in healthy humans by utilising multiple electrode aggregometer (Multiplate) and viscoelastic rotational thromboelastometer (ROTEM) to obtain data for sample size calculation before a larger trial.

METHODS

Thirty-five healthy volunteers ingested one of the listed naturopathic medicines for 7 days. Each naturopathic medicine was taken in a recommended standard dose by 5 volunteers. ROTEM clot initiation (CT), clot formation (CFT), α-angle (AA) and clot structure (MCF) were analysed with tissue factor activated (EXTEM) and native (NATEM) assays. The Multiplate platelet aggregation area under curve (AUC) was measured with adenosine diphosphate (ADP), collagen (COL) and arachidonic acid (ASPI) assays.

RESULTS

Multiplate with ADP agonist decreased from 73 ± 8.7 AUC to 60 ± 5.9 AUC (P = 0.003, 95% confidence interval (CI) -19.2 to -7.6) after medication with fish oil, but fish oil had no effect on COL or ASPI reagents. None of the other naturopathic medicines had any effect on Multiplate aggregometry. ROTEM NATEM-CFT increased from 217 ± 32 s to 283 ± 20 (P = 0.009, 95% CI 26.8 to 107), and NATEM-AA decreased from 52 ± 3.9° to 44 ± 2.3° (P = 0.009, 95 % CI -12.0 to -3.2) after medication with fish oil. There were no significant changes in the other NATEM or EXTEM parameters. The other naturopathic medicines had no significant effects on ROTEM or Multiplate aggregometry.

CONCLUSIONS

We have demonstrated that a recommended standard intake of 1260 mg Ω-3 polyunsaturated fatty acids (fish oil) daily - but not echinacea, ginkgo biloba, ginseng, St. John's wort, valeriana or garlic - may decrease platelet aggregation and clot formation. A larger trial in this setting would be meaningful to perform.

TRIAL REGISTRATION

Trial registration ISRCTN78027929. Registered 19 May 2015.

Warfarin Interactions with Medicinal Herbs

Recognition of the adverse effects of medicinal herbs is not routine and the reports on such effects are even less frequent in clinical practice. Potential herb-drug interactions are of a major safety concern, especially for drugs with narrow therapeutic indices like warfarin, which can lead to severe adverse reactions that are sometimes life-threatening. The interactions between warfarin and medicinal herbs described in the literature have been summarized in this paper relying on Medline database (via PubMed) using the key words: warfarin, herbal supplements and interactions. The references on the analyzed literature have been investigated in order to collect the existing data. The case reports with severe adverse effects such as spontaneous postoperative bleeding, formation of hematomas, hematemesis, melena, thrombosis, subarachnoid hemorrhage and/or subdural hematomas after concomitant use of warfarin and the medicinal herbs: Panax ginseng, Hypericum perforatum, Salvia milthiorizza, Gingko biloba, Serenoa repens, Angelica sinensis, Vaccinium species, Allium sativum, Zingiber officinale, Tanacetum parthenium, Lucium barbarum, Matricaria chamomilla, Boswellia serrata and Camellia sinensis have been estimated. Some of the interactions between warfarin and medicinal herbs have been well assessed proving that they are closely-dependent.

The interactions between warfarin and medicinal herbs, not generally reported in previous reviews, are presented in our review. The health professionals who are involved in treating the patients are expected to be fully informed about the interactions between warfarin and medicinal herbs in order to minimize the health risks of the patients.

Allicin induces anti-human liver cancer cells through the p53 gene modulating apoptosis and autophagy

Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer globally and ranks first among the cancer-related mortalities in Taiwan. This study aims to understand the modes of cell death mechanism induced by allicin, a major phytochemical of crushed garlic, in human hepatoma cells. Our earlier study indicated that allicin induced autophagic cell death in human HCC Hep G2 (p53(wild type)) cells, whereas in the present study, allicin induced apoptotic cell death through caspase-dependent and caspase-independent pathways by reactive oxygen species (ROS) overproduction in human HCC Hep 3B (p53(mutation)) cells. To gain insight into the cell death mechanism in p53 knocked down Hep G2, we silenced the p53 gene using siRNA-mediated silencing. Allicin treatment induced apoptotic cell death in p53 knocked down Hep G2 cells similar to that of Hep 3B cells. These results suggest that allicin induced cell death in human hepatoma cells through either autophagy or apoptosis and might be a potential novel complementary gene therapeutic agent for the treatment of apoptosis-resistant cancer cells.

Organosulfur garlic compounds induce neovasculogenesis in human endothelial progenitor cells through a modulation of MicroRNA 221 and the PI3-K/Akt signaling pathways

Human endothelial progenitor cells (EPCs) play crucial roles in the prevention of ischemic injury via neovasculogenesis. Frequent garlic consumption is reportedly associated with a low incidence of cardiovascular diseases (CVD). However, the molecular mechanisms by which garlic extracts, including diallyl disulfide (DADS) and diallyl trisulfide (DATS), exert an effect on neovasculogenesis have not been elucidated yet. The current study investigated the effects of these organosulfur compounds on neovasculogenesis by using vascular tube formation assay, Western blotting assay, real-time polymerase chain reaction (RT-PCR), and immunohistochemical (IHC) staining assays in both in vitro and in vivo models. The current study demonstrates that DADS and DATS dose-dependently enhance the neovasculogenesis of human EPCs in vitro. The mechanism of actions included the up-regulation of the c-kit protein, as well as the phosphorylation (i.e., activation) of the Akt and ERK 1/2 signaling molecules in human EPCs. Furthermore, DATS suppressed the expression of microRNA (miR) 221 in vitro. In a mouse xenograft model of neovasculogenesis, DATS consumption induced the formation of new blood vessels at a dosage of 10 mg/kg of body weight/day. It is suggested that garlic consumption enhances neovasculogenesis in human EPCs and thereby probably exerts a preventive effect against ischemic injuries.

Garlic and cardioprotection: insights into the molecular mechanisms

Garlic is widely recognized for its immense therapeutic potential. Garlic has been shown to exert its beneficial effects against a wide spectrum of diseases, including cancer, diabetes, and microbial infections, as well as immunological and cardiovascular disorders. Most of the research on garlic has indicated that garlic and its active compounds are effective in reducing cardiovascular and metabolic risk by normalizing abnormal plasma lipids, oxidized low density lipoproteins, abnormal platelet aggregation, high blood pressure, and cardiac injury. Some of the beneficial effects of dietary garlic against cardiovascular disorders are mediated via the generation of hydrogen sulfide and nitric oxide in cardiomyocytes and endothelial cells. Garlic has the potential to protect the heart against myocardial infarction, doxorubicin-induced cardiotoxicity, arrhythmia, hypertrophy, and ischemia-reperfusion injury. The induction of cardiac endogenous antioxidants and the reduction of lipid peroxidation by garlic has been reported by several different groups. Other mechanisms, such as regulating ion channels, modulating Akt signaling pathways, histone deacetylase inhibition, and cytochrome P450 inhibition, could be responsible for the cardioprotective effect of garlic. Although several mechanisms have been identified for the cardioprotective effect of garlic, there is a need for further research to identify the specific molecular mechanism of cardioprotection in different cardiac diseases.

Pharmacodynamic interaction study of Allium sativum (garlic) with cilostazol in patients with type II diabetes mellitus

Aim:

Garlic is available as an over-the-counter herbal supplement and is known to have antiplatelet properties. Because of scarcity of clinical data regarding the safety of concomitant use of garlic supplements and anticoagulants, we tried to evaluate the effects of coadministration of single and multiple doses of garlic and cilostazol on platelet aggregation.

Materials and Methods:

The study was a randomized, open label, placebo-controlled, crossover study of type II diabetic patients, where 14 patients were enrolled and 10 completed the study. The patients were administered 600 mg aged garlic extract, 100 mg cilostazol, 600 mg aged garlic extract, and cilostazol or placebo for seven days as per prior randomization schedule. Blood samples for platelet aggregation and bleeding time and clotting time were collected before and 2, 4, and 6 hours after single-dose drug administration and after seven days of treatment.

Results:

After single- and multiple-dose administration of garlic, there was a significant inhibition of platelet aggregation at 2 hours, whereas with cilostazol, the inhibition was significant at all the three time points tested, with 4 hours showing maximum inhibition. Coadministration of garlic and cilostazol in single and multiple doses for seven days did not produce any significant change in the antiplatelet activity of the individual drugs.

Conclusions:

Coadministration of aged garlic extract and cilostazol did not enhance the antiplatelet activity compared with individual drugs. Large randomized trials are needed to further evaluate the possible interaction of garlic in higher doses and in combination with other antiplatelet activity drugs.

Garlic and cardiovascular disease: a critical review

Epidemiologic studies show an inverse correlation between garlic consumption and progression of cardiovascular disease. Cardiovascular disease is associated with multiple factors such as raised serum total cholesterol, raised LDL and an increase in LDL oxidation, increased platelet aggregation, hypertension, and smoking. Numerous in vitro studies have confirmed the ability of garlic to reduce these parameters. Thus, garlic has been shown to inhibit enzymes involved in lipid synthesis, decrease platelet aggregation, prevent lipid peroxidation of oxidized erythrocytes and LDL, increase antioxidant status, and inhibit angiotension-converting enzyme. These findings have also been addressed in clinical trials. The studies point to the fact that garlic reduces cholesterol, inhibits platelet aggregation, reduces blood pressure, and increases antioxidant status. Since 1993, 44% of clinical trials have indicated a reduction in total cholesterol, and the most profound effect has been observed in garlic's ability to reduce the ability of platelets to aggregate. Mixed results have been obtained in the area of blood pressure and oxidative-stress reduction. The findings are limited because very few trials have addressed these issues. The negative results obtained in some clinical trials may also have resulted from usage of different garlic preparations, unknown active constituents and their bioavalability, inadequate randomization, selection of inappropriate subjects, and short duration of trials. This review analyzes in vitro and in vivo studies published since 1993 and concludes that although garlic appears to hold promise in reducing parameters associated with cardiovascular disease, more in-depth and appropriate studies are required.

The influence of garlic (Allium sativum) extract on interleukin 1alpha-induced expression of endothelial intercellular adhesion molecule-1 and vascular cell adhesion molecule-1

Inflammation plays an important role in both the initiation of atherosclerosis and development of atherothrombotic events. The adherence of leukocytes/monocytes to the endothelium is an early event in atherogenesis. Phytotherapeutica as garlic and garlic extracts were shown to have beneficial modulating effects in patients with atherosclerotic disease. The aim of this study was to evaluate in vitro the influence of water-soluble garlic (Allium sativum) extract on the cytokine-induced expression of endothelial leukocyte adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106). Cytokine-induced expression of cellular adhesion molecules was measured on primary human coronary artery endothelial cell (HCAEC) cultures. HCAEC were cultured in microvascular endothelial cell growth medium and preincubated with garlic extract at various concentrations (0.25-4.0 mg/ml), after which human interleukin-1alpha (IL-1alpha, 10 ng/ml) was added for 1 day. Fluorescein isothiocyanate (FITC)-labeled anti-ICAM-1 and FITC-labeled anti-VCAM-1 were used to analyze the IL-1alpha-induced expression of ICAM-1 and VCAM-1 by flow cytometry. Incubation of HCAEC with garlic extract significantly decreased ICAM-1 and VCAM-1 expression induced by IL-1alpha. In addition, we examined the effects of garlic extract on the adhesion of monocytes to endothelial cells, using the monocytic U937 cell line. The presence of garlic extract significantly inhibited the adhesion of monocytes to IL-1alpha-stimulated endothelial cells. These results indicate that garlic extract modulates the expression of ICAM-1 and VCAM-1, thus potentially contributing to the beneficial effects traditionally attributed to garlic.

Nutraceutical Applications of Garlic and the Intervention of Biotechnology

Garlic (Allium sativum L.) is an important and widely cultivated plant with both culinary and medicinal uses stemming from its biological activities, which include antibiotic, anticancer, anti-thrombotic, and lipid-lowering cardiovascular effects. Though such medicinal use of garlic existed for centuries, there was little scientific support for its therapeutic and pharmacological properties. However, there has been a recent upsurge of research on garlic aiming to understand its exact mechanism of action in each case so that garlic and its products may have more judicious future applications. Since garlic is vegetatively propagated, its improvement for desired traits through conventional means is difficult. The intervention of biotechnological methods such as tissue culture and gene transfer protocols developed recently hold great promise for improving this crop. Due to new innovations in instrumentation and processing technologies coupled with more judicious experimental models, better products are foreseen in the market. The objective of this article was to review the recent developments made towards understanding the mechanism by which garlic imparts different therapeutic effects as well as to review what biotechnology can offer to improve this crop and its products.

Effect of garlic on cardiovascular disorders: a review

Garlic and its preparations have been widely recognized as agents for prevention and treatment of cardiovascular and other metabolic diseases, atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes. Effectiveness of garlic in cardiovascular diseases was more encouraging in experimental studies, which prompted several clinical trials. Though many clinical trials showed a positive effect of garlic on almost all cardiovascular conditions mentioned above, however a number of negative studies have recently cast doubt on the efficacy of garlic specially its cholesterol lowering effect of garlic. It is a great challenge for scientists all over the world to make a proper use of garlic and enjoy its maximum beneficial effect as it is the cheapest way to prevent cardiovascular disease. This review has attempted to make a bridge the gap between experimental and clinical study and to discuss the possible mechanisms of such therapeutic actions of garlic.

The peri-operative implications of herbal medicines

An increasing number of patients are taking herbal medicines such as echinacea, garlic, ginkgo biloba, ginseng, St John's Wort, valerian, ephedra, kava, grapefruit juice and ginger. Although these herbal medications are considered 'natural' products that may have some benefits, adverse effects such as increased bleeding tendencies and drug interactions are associated with their use. Surgeons and anaesthetists may be unaware of their patients' use of these medications because it is common for patients not to disclose their use of this form of medication, and both surgeons and anaesthetists often fail to enquire about their use. Anaesthetists and surgeons must be familiar with the effects of herbal medicines and should specifically enquire about the use of herbal medicines during pre-operative assessment. Currently available data suggest that all herbal medicines should be ceased 2 weeks before surgery.

Wild garlic has a greater effect than regular garlic on blood pressure and blood chemistries of rats

When groups of 10 Spontaneously Hypertensive Rats (SHR) were fed diets containing either 1% w/w regular garlic (Allium sativum) (AS) or 1% w/w wild garlic (Allium ursinum) (AU) for 45 days, the final mean systolic blood pressure (SBP) was reduced significantly compared to control (C) (C 189; AS 175; Au 173 mm Hg). Compared to C, body weight and circulating glucose and triglyceride levels were not significantly different; but circulating insulin was significantly higher (C 23.6; AS 33.9; AU 29.5 uIU/dl), and total cholesterol was significantly lower (C 133; AS 115; AU 117 mg/dl) in the two groups consuming AS or AU. HDL rose in the two garlic groups, but the differences from C were statistically significant only for the AU group. In a second study, the effects of a lower dose of dietary AS and AU (0.1% w/w) on SBP and various blood chemistries were compared head-to-head in 80 SHR-40 control and 40 test rats. Both AS and AU decreased SBP significantly compared to a control group of 10 SHR followed simultaneously. However, AU at this lower concentration produced a significantly greater SBP-lowering effect compared to the AS group. In addition, AU decreased total cholesterol significantly and tended to increase HDL compared to AS. Accordingly, the results suggest that AU has a greater therapeutic benefit compared to AS at a given concentration.

Herbs and dietary supplements in the prevention and treatment of cardiovascular disease

Herbs and dietary supplements can have significant physiological effects. Garlic (Allium sativum) has shown beneficial lipid effects in a majority of trials; dried garlic preparations are superior to oil preparations. There is preliminary evidence that indicates that hawthorn (Crataegus species) may provide benefits in congestive heart failure. Coenzyme Q also may be of benefit in congestive heart failure. Although observational studies indicate a protective effect of dietary or supplemental vitamin E, controlled trails have not shown a beneficial effect on angina and have been mixed on whether supplementation decreases major cardiac events. Although several observational studies have noted that fish intake protects against cardiovascular disease, prospective studies are less impressive. Fish oil supplementation may have a mild beneficial effect on hypertension, but there is no effect on total cholesterol levels. Trials are inconsistent on whether fish oil reduces restenosis rates following coronary angioplasty. Carnitine appears to have beneficial effects on congestive heart failure and angina; there is also preliminary evidence that arginine may benefit patients with congestive heart failure or angina. Herbs and supplements have been associated with adverse effects and interactions; for example, garlic inhibits platelet aggregation and can cause significant anticoagulation, and the Chinese herb danshen (Salvia miltiorrhiza) appears to potentiate warfarin. Several herbs and supplements hold promise as adjuncts in the prevention and treatment of cardiovascular disease. There is a need for definitive research on the potential risks and benefits of these compounds, including appropriate dosages and formulations, and delineation of adverse events and interactions. (c)2000 by CHF, Inc.

Self-care: An Australian case study of chiropractic patients

OBJECTIVE

Self-care is becoming an important objective for achieving a sustainable health care system. This study examines the health care initiatives of chiropractic patients ascertaining their self-care behaviors, knowledge and information sources.

SAMPLE

Convenience sampling of chiropractic patients attending 10 chiropractors in 3 states. Of 155 patients invited to participate, 147 agreed.

METHOD

Patients were interviewed to determine their smoking, alcohol, maintenance chiropractic care, exercise and nutritional supplementation practices. Data collection included dose/frequency of the activity, expected benefits, concerns about side-effects and sources of information. Data was collated and trends identified.

RESULTS

Overall, the chiropractic patient sample reported a healthy lifestyle. Seventy-four percent (74%) had maintenance chiropractic; 69%, regular exercise; 40%, nutritional supplements; 84%, were non-smokers; and 86% were teetotallers or drank alcohol within safe limits. Few displayed appreciation of possible side-effects or 'dose-response' relationships. Lay persons were important information sources.

CONCLUSION

Chiropractic patients' self-care behaviors could be refined by making them more aware of the protean effects of self-care initiatives.

The effect of garlic tablet on plasma lipids and platelet aggregation in nulliparous pregnants at high risk of preeclampsia

OBJECTIVE

This study was designed to determine the effect of garlic tablet (Garlet) on plasma lipids, and platelet aggregation and the efficacy of this treatment in the prevention of preeclampsia.

STUDY DESIGN

In a randomized, single-blind, placebo-controlled study, 100 primigravidas with positive roll-over test were treated with daily doses of 800mg Garlet/day (n=50) or 800mg/day placebo (n=50) during the third trimester of pregnancy. Serum total cholesterol, LDL-and HDL-cholesterol, triglyceride, and platelet aggregation were measured before and after the treatment. Blood pressure, weight, and edema were also examined during the entire study period.

RESULTS

In the case group, there was no significant difference in the means of total cholesterol, HDL, LDL, and triglyceride before and after the experiment. Furthermore, the inhibition of platelet aggregation did not show any significant difference before and after the treatment. There were not any significant difference in the means of HDL, LDL, triglyceride, inhibition of platelet aggregation, the means of systolic and diastolic blood pressure and the mean arterial blood pressure (MAP), between the two groups, but there was a significant difference in the means of total cholesterol (P=0.038) and hypertension alone (P=0.043).

CONCLUSION

The administration of 800mg/day of Garlet during the third trimester of pregnancy was effective in reducing the occurrence of hypertension alone, but it was no effective in preventing of preeclampsia.

The impact of herbal medicines on dermatologic surgery

BACKGROUND

In recent years herbal medicines and supplements have become increasingly popular. With their increased popularity, more publications are warning about the potential harmful effects of some of these products.

OBJECTIVE

To present scientific evidence of the benefits and surgical risks of herbal products.

METHODS

A Medline search and review of the literature was performed.

RESULTS

Many herbal medicines are relevant in dermatologic surgery since Ginkgo biloba, garlic, ginger, ginseng, feverfew, and vitamin E may increase the risk of bleeding, and ephedra may potentiate the side effects of epinephrine.

CONCLUSION

Dermatologists should be aware of these herbal products and their uses. Many of these products prescribed by alternative medicine physicians or purchased over the counter should be discontinued prior to dermatologic surgery to minimize the risk of surgical complications.

Reducing the personal risk of perceived disease: the chiropractic patients' self-care endeavor

OBJECTIVE

It has been suggested that clinicians should be looking at new ways to enhance the self-care of their patients. Patient education is one strategy that primary providers may use. This study investigates the behavior of chiropractic patients to identify whether they are using widely published community health information messages to reduce their personally perceived risk of various diseases.

METHODS

An exploratory study of chiropractic patients was undertaken to investigate the health-relevant behaviors of patients. Purposive sampling of 9 Australian chiropractic clinics was undertaken. Convenience sampling of patients attending these clinics resulted in the participation of 102 patients. All participants completed a questionnaire, and data were collected and collated into a series of case studies that described some behaviors of participants that might have influenced their risk of acquiring disease. The study was limited to diseases for which participants believed they were at risk.

RESULTS

A substantial number of participants had undergone a screening procedure as recommended by health authorities. The 67 participants who believed they were at risk for one or more of the conditions listed were more likely to have complied. In addition, all participants made certain healthy lifestyle choices. However, implementation of those lifestyle choices that would reduce the personal risk of perceived diseases was sporadic.

CONCLUSION

The behavior of participants in this study suggests that many chiropractic patients would benefit from additional personalized health information messages. The use of information brochures in chiropractic clinics may not alone lead to a lifestyle change.

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.

Postoperative stroke after stopping warfarin for cutaneous surgery

BACKGROUND

Two patients undergoing cutaneous surgery had thromboembolic strokes within 1 week after surgery. Both patients had been taking warfarin for prevention of thromboembolism and warfarin was stopped 3-7 days prior to surgery.

OBJECTIVE

To examine the rationale and problems associated with preoperative warfarin discontinuation.

METHODS

Review of the medical literature.

RESULTS

When warfarin is stopped prior to surgery and restarted soon after surgery, the patient is at increased risk for thromboembolism. Although it is commonly believed that continuing warfarin during surgery is associated with an increased bleeding risk, for cutaneous surgery, this risk is extremely low and can be easily managed.

CONCLUSION

Warfarin should not be discontinued prior to cutaneous surgery because of the risk of thromboembolic stroke.

Effects of allyl mercaptan and various allium-derived compounds on cholesterol synthesis and secretion in Hep-G2 cells

The present study was undertaken to compare the effects of allyl mercaptan (AM), a major metabolite of garlic, with several garlic constituents and extracts on cytotoxicity, cholesterol synthesis and its secretion in Hep-G2 cells. The cells were grown in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS), and treated with 5, 25, 50, 125, 250 and 500 microg/ml of AM, diallyl disulfide (DD), diallyl trisulfide (DT), steam-distilled garlic oil (SD) or vinyl-dithiin oil of garlic (VD) for 4 h. At concentrations up to 50 microg/ml, no significant cytotoxic effect was found in any group, but at concentrations above 250 microg/ml, the cell viability decreased drastically in all groups compared to the control. The treatment of cells with 25 microg/ml (non-cytotoxic concentration) of AM, DD, DT, SD for 4 h significantly inhibited [3H]acetate incorporation into cholesterol compared to that of the control (P < 0.05). The secretion of cholesterol into the medium was also significantly decreased in all groups except for VD. The treatment of cells with those allium constituents had no effect on either [3H]acetate incorporation into fatty acids or [3H]glycerol incorporation into triglyceride or phospholipid.

Circulating platelet aggregates in glaucoma

PURPOSE

The aim of the study was to assess the role of circulating platelet aggregates (CPA) in advanced glaucoma.

METHOD

CPA was determined in vivo in 32 patients with advanced open-angle glaucoma accompanied by visual field loss, and in 20 healthy volunteers. The platelet aggregate ratio in glaucoma patients was significantly higher than those of normal controls (p = 0.002).

CONCLUSIONS

Our study indicates that measurement of platelet aggregate ratio might be used as an exploratory tool to assess the role of atherothrombotic events in glaucoma.

Effect of a garlic derivative (alliin) on peripheral blood cell immune responses

The in vitro effect of the garlic derivative alliin, on the mitogen induced peripheral blood mononuclear cell (PBMC) proliferation and cytokine production was examined. In addition, its effect on the engulfing capacity of phagocyting cells was evaluated. The results showed an increase in pokeweed mitogen (PWM) induced cell proliferation, IL-1beta and TNF-alpha production, as well as in the engulfing capacity of both percentage of phagocyting cells and number of latex particles phagocytized by each individual cell. The Con-A induced cell proliferation and IL-6 production decreased following incubation with alliin, whereas PHA-induced cell proliferation, IL-2 and superoxide anion generation remained unchanged. It is concluded that alliin in vitro exerts an immunomodulatory effect on certain functions of the peripheral blood cells.

Clinical trials of herbs

Consumers, clinicians, and corporations are taking an interest in botanical medicine. Although large gaps remain in research, many clinical trials of herbs exist. This article reviews these trials.

Effects of garlic on atherosclerosis

This review discusses the use of garlic and garlic preparations as agents for prevention and treatment of atherosclerosis and atherosclerosis-related diseases. Garlic indirectly effects atherosclerosis by reduction of hyperlipidemia, hypertension, and probably diabetes mellitus and prevents thrombus formation. In addition, in animal models, garlic causes direct antiatherogenic (preventive) and antiatherosclerotic (causing regression) effects at the level of artery wall. Garlic's direct effect on atherosclerosis may be explained by its capacity to reduce lipid content in arterial cells and to prevent intracellular lipid accumulation. This effect, in turn, is accompanied by other atherosclerotic manifestations, i.e., stimulation of cell proliferation and extracellular matrix synthesis. Clinical trials are currently being carried out to reveal the possible effect of garlic therapy on human atherosclerosis. Positive results of these trials may open a new era in the use of garlic for prevention and treatment of many atherosclerosis-related diseases.

Surgically significant nutritional supplements

This is not an exhaustive study of all nutritional supplements that patients may be taking. The most frequently used and those potentially most detrimental or most beneficial for surgical patients have been chosen for review of pertinent effects. It is essential to ask patients specifically about supplements or unusual dietary habits that may affect their surgical outcome prior to their invasive procedure and to keep in mind the supplements that may improve their outcome.