Hypocholesterolemic effect of an enteric-coated garlic supplement

Alliaceae versus Brassicaceae for Dyslipidemia: State of the Art and Future Perspectives. Systematic Review and Meta-Analysis of Clinical Studies

Dyslipidemia is a risk factor for cardiovascular diseases. Preclinical studies have shown that organosulfur compounds from the Alliaceae and Brassicaceae plants, such as garlic (Allium sativum L.) and broccoli (Brassica oleracea L.), have potential lipid-lowering effects. However, their clinical efficacy is controversial, especially in "drug-free" patients. The aim of this work was to summarize evidence on the lipid-lowering properties of extracts containing organosulfur compounds in patients with dyslipidemia. Studies were searched in four databases (Medline, Scopus, Embase, and CENTRAL), from inception to October 11, 2023.Controlled clinical studies on patients with dyslipidemia receiving Alliaceae or Brassicaceae were included. The outcome was the change in lipid parameters from baseline. Random-effect meta-analysis of the extracted data was performed using R software. The effect size was expressed as mean difference (MD) and 95% confidence interval (CI). The certainty of evidence was assessed with the GRADE approach. Out of 28 studies that were reviewed, 22 were included in the meta-analysis (publication period: 1981-2022). Results showed that Alliaceae extracts significantly reduce total cholesterol [MD: -15.2 mg/dL; 95% CI: -21.3; -9.1] and low-density lipoprotein cholesterol levels [MD: -12.0 mg/dL; 95% CI: -18.1; -5.7], although with low certainty of evidence. Conversely, the lipid-lowering properties of Brassicaceae extracts are still unexplored. Our results support the use of Alliaceae extracts in patients with hypercholesterolemia, but future high-quality studies are needed. Our work suggests further exploration of the efficacy of Brassicaceae extracts, which may have high nutraceutical/phytotherapeutic potential, opening new perspectives in the management of dyslipidemia.

Oral aged garlic (Allium sativum) alleviates ulcerative colitis in mice by improving gut homeostasis

Aged garlic, obtained by heating raw garlic (Allium sativum) under high temperature and controlled humidity for a period, possesses a wide range of bioactivities, but its role in ulcerative colitis and its mechanism are not fully elucidated. We investigated the bioactive constituents in aged garlic (AG) and explored the effect of oral AG delivery on DSS-induced murine colitis. The results revealed that the aging process up-regulated anti-oxidative, anti-inflammatory and anti-microbial compounds such as dihydrocaffeic acid, 5-acetylsalicylic acid, verticine, S-allyl-L-cysteine and D-fucose. Oral AG obviously alleviated colitis, reducing colon damage and enhancing anti-oxidative and anti-inflammatory effects. Escherichia coli and Streptococcus equinus dramatically were enriched in the colon of mice with colitis that were strongly associated with Parkinson's disease, bacterial invasion of epithelial cells, aerobactin biosynthesis, and heme biosynthesis, but a distinct AG-mediated alteration in the colon due to increasing abundance of Akkermansia muciniphila, Lactobacillus sp. L-YJ, Bifidobacterium breve, Blautia wexlerae, Desulfomicrobium sp. P100A, and Lentilactobacillus hilgardii was observed. Next, we demonstrated that colonic microbiome reconstruction by oral AG significantly increased the production of short-chain fatty acids such as acetic acid, propionic acid, isobutyric acid, and isovaleric acid. This study provides the first data indicating that oral AG ameliorates colonic inflammation in a gut microbiota-dependent manner. Our findings provide novel insights into the AG-mediated remission of colitis and AG as a functional food for modulating the gut microbiota to prevent and treat colitis.

Garlic consumption can reduce the risk of dyslipidemia: a meta-analysis of randomized controlled trials

BACKGROUND AND PURPOSE

Garlic is used as an important medicinal food for treatment of many diseases, however, the association between garlic consumption and dyslipidemia have yielded inconsistent results. So we carried this meta-analysis to explore the blood lipid-lowering effects of garlic.

METHODS

Databases such as PubMed, Scopus, Web of science, Embase, Cochrane Library were systematically searched until June 2024. Heterogeneity among studies was examined using Q and I2 statistics. Also subgroup analysis were conducted to explore the potential heterogeneity. Combined weighted mean differences (WMD) with their 95% confidence interval (CI) were calculated using a random-effects model. The GRADE approach was used to evaluate the overall certainty of the evidence in the meta-analyses.

RESULTS

A total of 21 RCTs studies involved association between garlic consumption and blood lipids level of dyslipidemia patients were included in the meta-analysis. The pooled results showed that garlic consumption significantly reduced total cholesterol (TC)(WMD = -0.64mmol/L, 95%CI = -0.75 --0.54, P < 0.001), triglyceride (TG)(WMD = -0.17mmol/L, 95%CI = -0.26 --0.09, P < 0.001), low-density lipoprotein(LDL-C)(WMD = -0.44mmol/L, 95%CI = -0.57 --0.31, P < 0.001) while slightly increased high-density lipoprotein (HDL-C)(WMD = 0.04mmol/L, 95%CI = -0.00 - 0.08, P < 0.001). And subgroup analyses showed that TC, TG and LDL-C significantly decreased in patients aged > 50 years compared to those aged ≤ 50 years. And garlic oil greatly reduced TC and LDL-C compared with garlic power. Finally, sensitivity analysis and publication bias showed that the results were reliable.

CONCLUSIONS

Evidence from this meta-analysis suggested that garlic consumption could be effective in reducing the risk of dyslipidemia and preventing CVDs. Particularly the older people were more susceptible to the protective effects of garlic.

Therapeutic potentials of allicin in cardiovascular disease: advances and future directions

Cardiovascular disease (CVD) remains the predominant cause of mortality and disability worldwide. Against this backdrop, finding effective drugs for the pharmacological treatment of CVD has become one of the most urgent and challenging issues in medical research. Garlic (Allium sativum L.) is one of the oldest plants and is world-renowned for its dietary and medicinal values. Allicin (diallyl thiosulfinate) is one of the primary natural active ingredients in garlic, which has been proven to have powerful cardioprotective effects and mediate various pathological processes related to CVD, such as inflammatory factor secretion, myocardial cell apoptosis, oxidative stress, and more. Therefore, allicin holds a promising application prospect in the treatment of CVD. This review summarized the biological functions of allicin and its potential mechanisms in CVD, including antioxidation, anti-inflammation, and anti-apoptosis effects. Reckoning with these, we delved into recent studies on allicin's cardioprotective effects concerning various CVDs, such as atherosclerosis, hypertension, myocardial infarction, arrhythmia, cardiac hypertrophy, heart failure, and cardiotoxicity. Further, considering the tremendous advancement in nanomedicine, nanotechnology-based drug delivery systems show promise in addressing limitations of allicin's clinical applications, including improving its solubility, stability, and bioavailability. Through this review, we hope to provide a reference for further research on allicin in cardioprotection and drug development.

Advances in the study of vascular related protective effect of garlic (Allium sativum) extract and compounds

Garlic (Allium sativum) is a functional food containing multiple bioactive compounds that find widespread applications in culinary and medicinal practices. It consists of multiple chemical components, including allicin and alliin. This article offers a comprehensive review of the protective effects of garlic extracts and their active constituents on the vascular system. In vitro and in vivo experiments have shown that garlic extracts and their active ingredients possess various bioactive properties. These substances demonstrate beneficial effects on blood vessels by demonstrating anti-inflammatory and antioxidant activities, inhibiting lipid accumulation and migration, preventing lipid peroxidation, promoting angiogenesis, reducing platelet aggregation, enhancing endothelial function, and inhibiting endothelial cell apoptosis. In clinical studies, garlic and its extracts have demonstrated their efficacy in managing vascular system diseases, including atherosclerosis, diabetes, and high cholesterol levels. In summary, these studies highlight the potential therapeutic roles and underlying mechanisms of garlic and its constituents in managing conditions like diabetes, atherosclerosis, ischemic diseases, and other vascular disorders.

Effects of garlic supplementation on components of metabolic syndrome: a systematic review, meta-analysis, and meta-regression of randomized controlled trials

BACKGROUND

Garlic (Allium sativum), the underground bulb of the Allium genus, has been consumed on Earth for thousands of years. Many clinical trials of garlic supplementation on components of metabolic syndrome (MetS) have emerged in recent years, but there is no consensus on the effect. This meta-analysis aimed at systematically evaluating the effect of garlic supplementation on components of MetS.

METHODS

In this meta-analysis, we searched Pubmed, Embase, Cochrane, Medline, Web of Science databases, and clinical trials online sites from inception to November 1, 2022, with language restrictions to English. We engaged participants > 18 years and eligible for the clinical diagnosis of MetS or those with metabolic disorders and garlic was the only intervention. Outcomes included waist circumference, and body mass index, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, blood pressure, and fasting blood glucose. Meta-regression and subgroup analyses were conducted based on six covariates (total sample size, the mean age, the mean dose, the duration of intervention, the oral form of garlic, and the dietary intervention).

RESULTS

Results from 19 RCTs were included engaging 999 participants. Compared to placebo, garlic significantly reduced TG [SMD (95%CI) = -0.66 (-1.23, -0.09)], TC [SMD (95%CI) = -0.43 (-0.86, -0.01)], LDL [SMD (95%CI) = -0.44(-0.88, -0.01)], DBP [SMD (95%CI) = -1.33 (-2.14, -0.53)], BMI [SMD (95%CI) = -1.10(-1.90, -0.20)], and WC [SMD (95%CI) = -0.78(-1.09, -0.47)]. Meta-regression showed age and sample size are potential effect modifiers.

CONCLUSION

According to the results of meta-analysis, the modulatory effect of garlic on some MetS components is evident. More high-quality, large-scale RCTs are needed to confirm iat based on the high heterogeneity and potential publication bias of the current data.

TRIAL REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=373228 , ID: CRD42022373228.

Allicin and Capsaicin Ameliorated Hypercholesterolemia by Upregulating LDLR and Downregulating PCSK9 Expression in HepG2 Cells

Hypercholesterolemia is a common cause of cardiovascular diseases (CVDs). Although allicin and capsaicin possess hypolipidemic effects through several molecular mechanisms, their effects on LDLR and PCSK9 expression are still unknown. This study aimed to investigate the effects of allicin and capsaicin on LDLR and PCSK9 expression in HepG2 cells. The effects of allicin and capsaicin on cell viability were evaluated by MTT assay and trypan blue exclusion assay. Low-density lipoprotein receptor (LDLR) levels and LDL uptake were determined by flow cytometry and confocal laser scanning microscopy (CLSM), respectively. RT-qPCR and Western blot analyses were performed to evaluate the expression of PCSK9, LDLR, SREBP-2, and HNF1α. ELISA was used to measure PCSK9 levels in culture media. Allicin and capsaicin increased the protein expression levels of LDLR via activation of the transcription factor SREBP2. However, allicin and capsaicin decreased the expression of PCSK9 protein and the secretion of PCSK9 in culture media via the suppression of HNF1α. Moreover, allicin and capsaicin increased LDL uptake into HepG2 cells. The efficacies of the hypolipidemic effects of allicin (200 µM) and capsaicin (200 µM) were comparable to that of atorvastatin (10 µM) in this study. In conclusion, allicin and capsaicin possessed hypolipidemic effects via the upregulation of LDLR and downregulation of PCSK9 expression, thereby enhancing LDL uptake into HepG2 cells. This indicates that allicin and capsaicin should be used as potent supplements to ameliorate hypercholesterolemia.

Biological properties and therapeutic applications of garlic and its components

Garlic is one of the most widely employed condiments in cooking. It has also been used since ancient times in traditional plant-based medicine, largely based on its organosulfur compounds. The objective of this study was to provide updated information on the biological and therapeutic garlic properties. Garlic has been found to possess important biological properties with high therapeutic potential, which is influenced by the mode of its utilization, preparation, and extraction. It has been attributed with antioxidant, anti-inflammatory, and immunomodulatory capacities. Garlic, in particular its organosulfur compounds, can maintain immune system homeostasis through positive effects on immune cells, especially by regulating cytokine proliferation and expression. This may underlie their usefulness in the treatment of infectious and tumor processes. These compounds can also offer vascular benefits by regulating lipid metabolism or by exerting antihypertensive and antiaggregant effects. However, further clinical trials are warranted to confirm the therapeutic potential of garlic and its derivatives.

Virtual screening of functional foods and dissecting their roles in modulating gene functions to support post COVID-19 complications

COVID-19 has become the focal point since 2019 after the outbreak of coronavirus disease. Many drugs are being tested and used to treat coronavirus infections; different kinds of vaccines are also introduced as preventive measure. Alternative therapeutics are as well incorporated into the health guidelines of some countries. This research aimed to look into the underlying mechanisms of functional foods and how they may improve the long-term post COVID-19 cardiovascular, diabetic, and respiratory complications through their bioactive compounds. The potentiality of nine functional foods for post COVID-19 complications was investigated through computational approaches. A total of 266 bioactive compounds of these foods were searched via extensive literature reviewing. Three highly associated targets namely troponin I interacting kinase (TNNI3K), dipeptidyl peptidase 4 (DPP-4), and transforming growth factor beta 1 (TGF-β1) were selected for cardiovascular, diabetes, and respiratory disorders, respectively, after COVID-19 infections. Best docked compounds were further analyzed by network pharmacological tools to explore their interactions with complication-related genes (MAPK1 and HSP90AA1 for cardiovascular, PPARG and TNF-alpha for diabetes, and AKT-1 for respiratory disorders). Seventy-one suggested compounds out of one-hundred and thirty-nine (139) docked compounds in network pharmacology recommended 169 Gene Ontology (GO) items and 99 Kyoto Encyclopedia of Genes and Genomes signaling pathways preferably AKT signaling pathway, MAPK signaling pathway, ACE2 receptor signaling pathway, insulin signaling pathway, and PPAR signaling pathway. Among the chosen functional foods, black cumin, fenugreek, garlic, ginger, turmeric, bitter melon, and Indian pennywort were found to modulate the actions. Results demonstrate that aforesaid functional foods have attenuating roles to manage post COVID-19 complications. PRACTICAL APPLICATIONS: Functional foods have been approaching a greater interest due to their medicinal uses other than gastronomic pleasure. Nine functional food resources have been used in this research for their traditional and ethnopharmacological uses, but their directive-role in modulating the genes involved in the management of post COVID-19 complications is inadequately studied and reported. Therefore, the foods types used in this research may be prioritized to be used as functional foods for ameliorating the major post COVID-19 complications through appropriate science.

Pharmacotherapeutic Potential of Garlic in Age-Related Neurological Disorders

Age-related neurological disorders [ANDs] involve neurodegenerative diseases [NDDs] such as Alzheimer's disease [AD], the most frequent kind of dementia in elderly people, and Parkinson's disease [PD], and also other disorders like epilepsy and migraine. Although ANDs are multifactorial, Aging is a principal risk factor for them. The common and most main pathologic features among ANDs are inflammation, oxidative stress, and misfolded proteins accumulation. Since failing brains caused by ANDs impose a notable burden on public health and their incidence is increasing, a lot of works has been done to overcome them. Garlic, Allium sativum, has been used for different medical purposes globally and more than thousands of publications have reported its health benefits. Garlic and aged garlic extract are considered potent anti-inflammatory and antioxidants agents and can have remarkable neuroprotective effects. This review is aimed to summarize knowledge on the pharmacotherapeutic potential of garlic and its components in ANDs.

A Systematic Review and Meta-Analysis of Ayurvedic Herbal Preparations for Hypercholesterolemia

Background and Objectives: Cardiovascular disease (CVD) is the leading cause of death globally and hypercholesterolemia is one of the major risk factors associated with CVD. Due to a growing body of research on side effects and long-term impacts of conventional CVD treatments, focus is shifting towards exploring alternative treatment approaches such as Ayurveda. However, because of a lack of strong scientific evidence, the safety and efficacy profiles of such interventions have not been well established. The current study aims to conduct a systematic review and meta-analyses to explore the strength of evidence on efficacy and safety of Ayurvedic herbs for hypercholesterolemia. Methods: Literature searches were conducted using databases including Medline, Cochrane Database, AMED, Embase, AYUSH research portal, and many others. All randomized controlled trials on individuals with hypercholesterolemia using Ayurvedic herbs (alone or in combination) with an exposure period of ≥ 3 weeks were included, with primary outcomes being total cholesterol levels, adverse events, and other cardiovascular events. The search strategy was determined with the help of the Cochrane Metabolic and Endocrine Disorders Group. Two researchers assessed the risk of each study individually and discrepancies were resolved by consensus or consultation with a third researcher. Meta-analysis was conducted using the inverse variance method and results are presented as forest plots and data summary tables using Revman v5.3. Results: A systematic review of 32 studies with 1386 participants found randomized controlled trials of three Ayurvedic herbs, Allium sativum (garlic), Commiphora mukul (guggulu), and Nigella sativa (black cumin) on hypercholesterolemia that met inclusion criteria. The average duration of intervention was 12 weeks. Meta-analysis of the trials showed that guggulu reduced total cholesterol and low-density lipoprotein levels by 16.78 mg/dL (95% C.I. 13.96 to 2.61; p-value = 0.02) and 18.78 mg/dL (95% C.I. 34.07 to 3.48; p = 0.02), respectively. Garlic reduced LDL-C by 10.37 mg/dL (95% C.I. -17.58 to -3.16; p-value = 0.005). Black cumin lowered total cholesterol by 9.28 mg/dL (95% C.I. -17.36, to -1.19, p-value = 0.02). Reported adverse side effects were minimal. Conclusion: There is moderate to high level of evidence from randomized controlled trials that the Ayurvedic herbs guggulu, garlic, and black cumin are moderately effective for reducing hypercholesterolemia. In addition, minimal evidence was found for any side effects associated with these herbs, positioning them as safe adjuvants to conventional treatments.

Lego-Inspired Capsular Devices for the Development of Personalized Dietary Supplements: Proof of Concept With Multimodal Release of Caffeine

Dietary supplement companies have recently started to focus on the personalization of products and the improvement of the relevant performance. In this respect, a versatile, easy-to-handle capsular delivery platform with customizable content and release kinetics was here proposed and evaluated after filling with caffeine as a model dietary ingredient. In particular, capsular devices comprising 1 to 3 independent inner compartments were attained by Lego-inspired assembly of matching modular units with different wall compositions, manufactured by injection molding and fused deposition modeling 3D printing. Accordingly, one-, two- and three-pulse release profiles of the dietary ingredient were obtained from differently assembled devices following the breakup of the compartments occurring promptly (immediate-release), on pH change (delayed-release) or after tunable lag times (pulsatile-release). The latter release mode would enable the onset of the stimulating effect of caffeine at different times of the day after a single administration when convenient. The performance of each individual compartment only depended on the composition (i.e., promptly soluble, swellable/soluble or enteric soluble polymers) and thickness of its own wall, while it was not affected by the composition and number of joined modular units. Moreover, the delivery platform was extended to include an external gastroresistant shell enclosing previously assembled devices.

Combination Effect of Voluntary Exercise and Garlic (Allium sativum) on Oxidative Stress Biomarkers and Lipid Profile in Healthy Rats

Background: We evaluated the combination effect of voluntary exercise and garlic on serum oxidative stress biomarkers and lipid profile in healthy rats. Methods: The rats were randomly assigned to four groups (n=7): Control, Garlic, Exercise, and Garlic + Exercise. Rats were fed with raw fresh garlic homogenate by oral gavage (250 mg/kg) or were subjected to voluntary exercise using stainless steel running wheels alone or together for 6 weeks. The samples were collected at the end of the experiment. Results: After 6 weeks, total cholesterol, low-density lipoprotein (LDL), triglycerides (TG) and high-density lipoprotein (HDL) levels improved in both garlic and exercise group, compared with the control group. We also found that serum glutathione peroxidase (Gpx), Superoxide dismutase (SOD), Catalase (CAT), and Total antioxidant (TAC) levels enhanced significantly following the above-mentioned interventions. Furthermore, simultaneous treatment of rats with garlic and voluntary exercise had an additive effect on these parameters. However, malondialdehyde (MDA) level was not significantly different from control group during our protocol. Conclusion: The findings revealed that simultaneous treatment of rats with garlic and voluntary exercise improved antioxidant defense system and lipid profile in an additive manner in healthy rats.

Anti-hyperlipidemia of garlic by reducing the level of total cholesterol and low-density lipoprotein: A meta-analysis

BACKGROUND

This study aimed to understand the impact of garlic on improving blood lipids using a meta-analysis.

METHODS

A literature search of the PubMed, EMBASE, and Cochrane Library databases was performed using keywords such as "garlic" and "hypercholesterolemia," and the deadline "July 14 (th), 2017." After extracting relevant details, each selected literature was evaluated for quality according to the quality evaluation criteria of bias risk recommended by Cochrane Collaboration recommendations and heterogeneity tests were performed. Standardized mean difference (SMD) and 95% confidence interval (CI) were evaluated using R 3.12 software. The publication bias was assessed using Egger method.

RESULTS

A total of 14 eligible papers published from 1981 to 2016 were included. The quality of the literatures was of moderate to high qualities. The values of TC (SMD = -1.26, 95% CI, -1.86 to -0.66), low-density lipoprotein (LDL) (SMD = -1.07, 95% CI, -1.67 to -0.47), and high-density lipoprotein (HDL) (SMD = 0.50, 95% CI, 0.06-0.94) after taking garlic in the experimental group and the control group have statistical significance, while there was no significant difference of TG in the 2 groups (SMD = -0.16, 95% CI, -0.87-0.55). However, the result of HDL was reversed when removed some of the literatures. No significant publication bias among the eligible studies with values of TC (P = .0625), LDL (P = .0770), HDL (P = .2293), and TG (P = .3436).

CONCLUSION

Garlic can reduce the level of TC and LDL instead of HDL and TG, indicating the ability of anti-hyperlipidemia.

A Review on Promising Natural Agents Effective on Hyperlipidemia

Hyperlipidemia is a prevalent disease and a major component of the metabolic syndrome resulting from various factors. This disease increases morbidity and mortality when combined with other prevalent diseases such as diabetes mellitus, hypertension, and cardiovascular diseases. The side effects of the current lipid-lowering drugs have increased the tendency to move toward traditional and alternative treatments. Epidemiological observations indicate that using alternative treatments, consumption of medicinal plants, diet, and consumption of fruits have had satisfactory results on the effects of hyperlipidemia in many societies. It should be noted that in majority of societies, even developed countries, the tendency toward eating lipid-lowering medicinal plants has increased extensively. Using these plants especially when common remedies cannot control the disease is significant. Although consumption of medicinal plants by hyperlipidemic patients may show improvement in disease state, drug interaction and side effects may cause complications in disease control. Therefore, in this review, apart from introducing some of the reliable plants effective in inhibition and decrease of hyperlipidemia, the possibility of their intoxication and drug interaction is also presented.

Garlic powder intake and cardiovascular risk factors: a meta-analysis of randomized controlled clinical trials

BACKGROUND/OBJECTIVES

Although preclinical studies suggest that garlic has potential preventive effects on cardiovascular disease (CVD) risk factors, clinical trials and reports from systematic reviews or meta-analyses present inconsistent results. The contradiction might be attributed to variations in the manufacturing process that can markedly influence the composition of garlic products. To investigate this issue further, we performed a meta-analysis of the effects of garlic powder on CVD risk factors.

MATERIALS/METHODS

We searched PubMed, Cochrane, Science Direct and EMBASE through May 2014. A random-effects meta-analysis was performed on 22 trials reporting total cholesterol (TC), 17 trials reporting LDL cholesterol (LDL-C), 18 trials reporting HDL cholesterol (HDL-C), 4 trials reporting fasting blood glucose (FBG), 9 trials reporting systolic blood pressure (SBP) and 10 trials reporting diastolic blood pressure (DBP).

RESULTS

The overall garlic powder intake significantly reduced blood TC and LDL-C by -0.41 mmol/L (95% confidence interval [CI], -0.69, -0.12) (-15.83 mg/dL [95% CI, -26.64, -4.63]) and -0.21 mmol/L (95% CI, -0.40, -0.03) (-8.11 mg/dL [95% CI, -15.44, -1.16]), respectively. The mean difference in the reduction of FBG levels was -0.96 mmol/L (95% CI, -1.91, -0.01) (-17.30 mg/dL [95% CI, -34.41, -0.18]). Evidence for SBP and DBP reduction in the garlic supplementation group was also demonstrated by decreases of -4.34 mmHg (95% CI, -8.38, -0.29) and -2.36 mmHg (95% CI, -4.56, -0.15), respectively.

CONCLUSIONS

This meta-analysis provides consistent evidence that garlic powder intake reduces the CVD risk factors of TC, LDL-C, FBG and BP.

Potential therapeutic effects of functionally active compounds isolated from garlic

The medicinal properties of functionally active organosulfur compounds such as allin, diallyl disulfide, S-allylmercaptocysteine, and S-trityl-L-cysteine isolated from garlic have received great attention from a large number of investigators who have studied their pharmacological effects for the treatment of various diseases. These organosulfur compounds are able to prevent for development of cancer, cardiovascular, neurological, and liver diseases as well as allergy and arthritis. There have been also many reports on toxicities and pharmacokinetics of these compounds. The aim of this study is to review a variety of experimental and clinical reports, and describe the effectiveness, toxicities and pharmacokinetics, and possible mechanisms of pharmaceutical actions of functionally active compounds isolated from garlic.

A meta-analysis of randomized, double-blind, placebo-controlled trials for the effects of garlic on serum lipid profiles

BACKGROUND

Inconsistent results were obtained for the lipid-regulating effects of garlic in clinical trials. With increasing interest in complementary medicine for hyperlipoidemia, it is important to explore the real effects of garlic. This meta- analysis was performed to investigate the influence of garlic on serum lipid parameters.

RESULTS

A total of 26 studies were included into meta-analysis. Overall, garlic was superior to placebo in reducing serum total cholesterol (TC) and triglyceride (TG) levels. Compared with the placebo groups, serum TC and TG levels in the garlic group were reduced by 0.28 (95% CI, -0.45, -0.11) mmol L⁻¹ (P = 0.001) and 0.13 (95% CI, -0.20, -0.06) mmol L⁻¹ (P < 0.001), respectively. The effects of garlic were more striking in subjects with long-term intervention and higher baseline TC levels. Garlic powder and aged garlic extract were more effective in reducing serum TC levels, while garlic oil was more effective in lowering serum TG levels. In contrast, garlic did not influence other lipid parameters, including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), apolipoprotein B, and TC/HDL-C ratio.

CONCLUSION

Garlic could reduce serum TC and TG levels, and garlic therapy should benefit patients with risk of cardiovascular diseases.

Nutraceutical use of garlic sulfur-containing compounds

Garlic is one of the world's oldest medicines that has been employed not only for flavouring but also as a medical herb for its prophylactic and therapeutic actions. Most garlics' beneficial effects are due to the presence of the organosulphate molecule allicin. Allicin is a highly unstable molecule and, during processing, is rapidly transformed into a variety of organosulfur components. The enzyme alliinase, which is responsible for the conversion of alliin to allicin, is irreversibly destroyed at the acidic environment of stomach. This is the reason why most garlic supplements contain garlic powder or granules, but do not contain allicin itself. Garlic alliinase could be encapsulated and coated with materials which would protect it in the harsh conditions of the stomach. The objective of this chapter is to summarize the most important garlic health benefits and to discuss promising encapsulation/stabilization approaches.

The impact of garlic on lipid parameters: a systematic review and meta-analysis

In order to determine the impact of garlic on total cholesterol (TC), TAG levels, as well as LDL and HDL, and establish if any variables have an impact on the magnitude of this effect, a meta-analysis was conducted. A systematic literature search of MEDLINE, CINAHL and the Cochrane Database from the earliest possible date through to November 2007 was conducted to identify randomised, placebo-controlled trials of garlic that reported effects on TC, TAG concentrations, LDL or HDL. The weighted mean difference of the change from baseline (with 95 % CI) was calculated as the difference between the means in the garlic groups and the control groups using a random-effects model. Subgroup and sensitivity analyses were performed to determine the effects on type, brand and duration of garlic therapy as well as baseline TC and TAG levels, the use of dietary modification, and study quality on the meta-analysis's conclusions. Twenty-nine trials were included in the analysis. Upon meta-analysis garlic was found to significantly reduce TC ( - 0.19; 95 % CI - 0.33, - 0.06 mmol/l) and TAG ( - 0.11; 95 % CI - 0.19, - 0.06 mmol/l) but exhibited no significant effect on LDL or HDL. There was a moderate degree of statistical heterogeneity for the TC and TAG analyses. Garlic reduces TC to a modest extent, an effect driven mostly by the modest reductions in TAG, without appreciable LDL lowering or HDL elevation. Higher baseline line TC levels and the use of dietary modification may alter the effect of garlic on these parameters. Future studies should be conducted evaluating the impact of adjunctive garlic therapy with fibrates or statins on TAG concentrations.

Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects

BACKGROUND AND PURPOSE

Patients commonly take complementary medicines in conjunction with warfarin yet evidence supporting the safety or the risk of a herb-drug interaction is lacking. The aim of this study was to investigate the possible impact of two commonly used herbal medicines, garlic and cranberry, on the pharmacokinetics and pharmacodynamics of warfarin in healthy male subjects.

EXPERIMENTAL APPROACH

An open-label, three-treatment, randomized crossover clinical trial was undertaken and involved 12 healthy male subjects of known CYP2C9 and VKORC1 genotype. A single dose of 25 mg warfarin was administered alone or after 2 weeks of pretreatment with either garlic or cranberry. Warfarin enantiomer concentrations, INR, platelet aggregation and clotting factor activity were measured to assess pharmacokinetic and pharmacodynamic interactions between warfarin and herbal medicines.

KEY RESULTS

Cranberry significantly increased the area under the INR-time curve by 30% when administered with warfarin compared with treatment with warfarin alone. Cranberry did not alter S- or R-warfarin pharmacokinetics or plasma protein binding. Co-administration of garlic did not significantly alter warfarin pharmacokinetics or pharmacodynamics. Both herbal medicines showed some evidence of VKORC1 (not CYP2C9) genotype-dependent interactions with warfarin, which is worthy of further investigation.

CONCLUSIONS AND IMPLICATIONS

Cranberry alters the pharmacodynamics of warfarin with the potential to increase its effects significantly. Co-administration of warfarin and cranberry requires careful monitoring.

Neuroprotective effects of garlic a review

Garlic has been investigated extensively for health benefits, resulting in more than one thousand publications over the last decade alone. It is considered one of the best disease preventive foods, based on its potent and varied effects. Midlife risk factors for cardiovascular diseases, such as high serum total cholesterol, raised LDL, increased LDL oxidation, increased platelet aggregation, impaired fibrinolysis, hypertension and homocystinemia are important risk factors for dementia in later years. These risk factors play a major role in the genesis of atherosclerosis of vital arteries causing both cardiovascular and cerebrovascular disease. Garlic is best known for its lipid lowering and anti-atherogenic effects. Possible mechanisms of action include inhibition of the hepatic activities of lipogenic and cholesterogenic enzymes that are thought to be the genesis for dyslipidemias, increased excretion of cholesterol and suppression of LDL-oxidation. Oxidative stress caused by increased accumulation of reactive oxygen species (ROS) in cells has been implicated in the pathophysiology of several neurodegenerative diseases including Alzheimer's disease (AD). Several studies have demonstrated the antioxidant properties of garlic and its different preparations including Aged Garlic Extract (AGE). AGE and S-allyl-cysteines (SAC), a bioactive and bioavailable component in garlic preparations have been shown in a number of in vitro studies to protect neuronal cells against beta-amyloid (A) toxicity and apoptosis. Thus the broad range of anti-atherogenic, antioxidant and anti-apoptotic protection afforded by garlic may be extended to its neuroprotective action, helping to reduce the risk of dementia, including vascular dementia and AD.

Therapeutic actions of allylmercaptocaptopril and captopril in a rat model of metabolic syndrome

BACKGROUND

Hypertension often coexists with hyperlipidemia, insulin resistance, and glucose intolerance in metabolic syndrome. Allylmercaptocaptopril is a conjugate of the angiotensin-converting enzyme inhibitor captopril with allicin, an active principle in garlic with multiple beneficial actions on metabolic-syndrome abnormalities. We sought to test the hypothesis that the conjugation of allicin to captopril may confer additional therapeutic actions in metabolic disease.

METHODS

We compared allylmercaptocaptopril (53.5 mg/kg/day orally for 60 days) to an equimolar dose of captopril (40 mg/kg/day) in the spontaneously hypertensive, obese rat (SHROB) model.

RESULTS

Allylmercaptocaptopril prevented progressive weight gain, without a detectable effect on food intake. Both captopril and allylmercaptocaptopril lowered blood pressure, but allylmercaptocaptopril was more effective. Allylmercaptocaptopril, but not captopril, improved cardiac hypertrophy, as indicated by heart weight and ventricular-wall thickness. Allylmercaptocaptopril improved, whereas captopril impaired, oral glucose tolerance after a fast. Triglycerides were decreased by both captopril and allylmercaptocaptopril. Total cholesterol and non-HDL cholesterol were reduced by captopril but not by allylmercaptocaptopril. The SHROB rats developed severe glomerulosclerosis and renal failure. Allylmercaptocaptopril showed significant nephro-protection, as indicated by reductions in urinary protein loss, urinary protein-to-creatinine ratio, and plasma creatinine. Captopril showed the same trends and also prevented the decline of creatinine clearance. Finally, both allylmercaptocaptopril and captopril reduced the basal level of lipolysis in isolated abdominal adipocytes, and restored the response to catecholamine stimulation.

CONCLUSIONS

Both captopril and allylmercaptocaptopril are effective in attenuating multiple abnormalities of metabolic syndrome. Allylmercaptocaptopril may have additional effectiveness on improving glucose tolerance, further lowering blood pressure, reducing cardiac hypertrophy, preventing weight gain, and protecting against renal disease.

Dietary Supplements for The Prevention and Treatment of Coronary Artery Disease

PURPOSE

With the recent growth in the use of dietary supplements, it is increasingly important for clinicians to be familiar with the evidence for and against their efficacy. We set out to systematically review the dietary supplements available for the prevention and treatment of coronary artery disease.

METHODS

Between May 2004 and May 2006, we searched MEDLINE, the Cochrane Library, and Pro-Quest using the MeSH terms hypertension, hypercholesterolemia, myocardial infarction, dietary supplements, and herb-drug interactions. The MeSH terms of individual supplements identified were then added to the search. Reference lists of pertinent papers were also searched to find appropriate papers for inclusion. We included randomized controlled trials published in English of at least 1 week's duration that studied the efficacy of supplements in the treatment of hypercholesterolemia, or hypertension, or in the prevention of cardiac events. Qualifying papers were identified and assigned a Jadad quality score. In areas of uncertainty, a second investigator independently scored the trial.

RESULTS

Fifteen (15) supplements were identified. Of these, most had little data available and most of the data were of poor quality. The supplements with the most supporting data were policosanol and garlic, both for hyperlipidemia.

CONCLUSIONS

A growing body of literature exists for numerous supplements in the prevention of coronary artery disease, but much of these data are inconclusive. Clinicians should become familiar with the extent and limitations of this literature so that they may counsel their patients better.

Complementary and alternative therapies for the management of dyslipidemia

OBJECTIVE

To review the literature on select alternative therapies for the management of dyslipidemia.

DATA SOURCES

Searches of MEDLINE and PubMed (1965-March 2006) were conducted using the key terms omega-3-fatty acids, policosanol, plant stanols and sterols, flaxseed, red yeast rice, guggulipid, garlic, fiber, almonds, and cholesterol and/or lipids.

STUDY SELECTION AND DATA EXTRACTION

Meta-analyses, published in English and involving adults, that incorporated randomized, controlled trials on alternative therapies for dyslipidemia were reviewed. Additionally, trials published subsequent to the meta-analyses were reviewed. Articles deemed relevant were included in this review.

DATA SYNTHESIS

Of the aforementioned alternative therapies, randomized controlled trials were found for omega-3-fatty acids, policosanol, plant stanols and sterols, flaxseed, red yeast rice, guggulipid, garlic, fiber, almonds, and soy. Studies for each of these agents report varying degrees of lipid reduction. Based on published data, effective therapeutic options for lipid-lowering include intake of fiber, intake of plant stanols/sterols, replacement of animal protein with soy protein, and substitution of foods high in saturated fat with those with monounsaturated fatty acids (eg, dry roasted almonds). Adding omega-3-fatty acids is effective for reducing triglycerides in patients with hypertriglyceridemia. Well-designed studies with long-term outcome data are necessary to further define the role for guggul, red yeast rice, policosanol, garlic, and flaxseed in the management of dyslipidemia.

CONCLUSIONS

Alternative therapeutic approaches with complementary therapies are becoming increasingly popular among patients. It is important for healthcare providers to be familiar with the safety and efficacy of these agents to facilitate optimal outcomes for patients with dyslipidemia.

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.

Composition, stability, and bioavailability of garlic products used in a clinical trial

In support of a new clinical trial designed to compare the effects of crushed fresh garlic and two types of garlic supplement tablets (enteric-coated dried fresh garlic and dried aged garlic extract) on serum lipids, the three garlic products have been characterized for (a) composition (14 sulfur and 2 non-sulfur compounds), (b) stability of suspected active compounds, and (c) availability of allyl thiosulfinates (mainly allicin) under both simulated gastrointestinal (tablet dissolution) conditions and in vivo. The allyl thiosulfinates of blended fresh garlic were stable for at least 2 years when stored at -80 degrees C. The dissolution release of thiosulfinates from the enteric-coated garlic tablets was found to be >95%. The bioavailability of allyl thiosulfinates from these tablets, measured as breath allyl methyl sulfide, was found to be complete and equivalent to that of crushed fresh garlic. S-Allylcysteine was stable for 12 months at ambient temperature. The stability of the suspected active compounds under the conditions of the study and the bioavailability of allyl thiosulfinates from the dried garlic supplement have validated the use of these preparations for comparison in a clinical trial.

Use of alternative medicine by patients with stage 5 chronic kidney disease

The use of complementary and alternative medicine (CAM) in the United States is growing at a remarkable speed. Herbal products and dietary supplements are CAM therapies that have grown faster than any other CAM treatments. Little information is available about herbs and dietary supplement use in the stage 5 chronic kidney disease population. These products contain a myriad of pharmacologically active compounds that, when used by people with kidney disease, may be hazardous. Members of the renal dietitian listserv were queried about herbs and dietary supplements reportedly used by dialysis patients. Up-to-date information on the use, safety, efficacy, adverse effects, and recommended dosages in the nondialysis population are presented for 24 products. In the dialysis population, Noni juice should be avoided because of its high potassium content. In addition, bulk-forming laxatives such as flaxseed should be used with caution because of the need for increased fluid intake. Dialysis practitioners should include specific questions about herbs and dietary supplement use in medical and nutrition histories, and they should increase their knowledge about these products to advise patients appropriately. A list of reliable sources of information for the health care provider on herbs and dietary supplements is also presented.

Effect of garlic (Allium sativum) powder tablets on serum lipids, blood pressure and arterial stiffness in normo-lipidaemic volunteers: a randomised, double-blind, placebo-controlled trial

Recent studies have cast doubt on the proposed lipid-lowering and blood pressure-lowering effects of garlic. We tested the effect of dried garlic (Allium sativum) powder on blood lipids, blood pressure and arterial stiffness in a 12-week randomised, double-blind, placebo-controlled trial. Seventy-five healthy, normo-lipidaemic volunteers (men and women aged 40-60 years) were assigned to dried garlic powder tablets (10.8 mg alliin (3-(2-propenylsulfinyl)-L-alanine)/d, corresponding to about three garlic cloves) or placebo. Sixty-two subjects were eligible for the per-protocol analysis. The primary outcome measure was serum total cholesterol concentration. Secondary outcome measures were LDL-cholesterol, HDL-cholesterol and triacylglycerol concentrations, blood pressure and arterial stiffness (assessed by pulse wave velocity). No significant differences between the garlic and placebo groups were detected for any of the outcome measures. However, garlic powder was associated with a near-significant decrease (12 %) in triacylglycerol concentration (P=0.07). In conclusion, garlic powder tablets have no clinically relevant lipid-lowering and blood pressure-lowering effects in middle-aged, normo-lipidaemic individuals. The putative anti-atherosclerotic effect of garlic may be linked to risk markers other than blood lipids.

Soy, garlic, and ginkgo biloba: Their potential role in cardiovascular disease prevention and treatment

There are hundreds of foods, nutrients, herbs, and botanicals that have "bioactive" constituents with potential human health benefits. Three of these are discussed in this review: soy, garlic, and ginkgo biloba. Each of these three choices involves an ingestible item composed of a complex mixture of bioactive agents. For each of these three, there is a large and growing body of research suggesting potential cardiovascular health benefits. And for each there is at least some level of disagreement or controversy. The focus of this review is on results from recent human clinical trials.

Garlic and aging: new insights into an old remedy

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

Effects on the human serum lipoprotein profile of beta-glucan, soy protein and isoflavones, plant sterols and stanols, garlic and tocotrienols

The effects of beta-glucan, soy protein, isoflavones, plant sterols and stanols, garlic and tocotrienols on serum lipoproteins have been of great interest the last decade. From a critical review of the literature, it appeared that recent studies found positive as well as no effects of beta-glucan from oats on serum LDL cholesterol concentrations. These conflicting results may suggest that the cholesterol-lowering activity of products rich in oat beta-glucan depends on factors, such as its viscosity in the gastrointestinal tract, the food matrix and/or food processing. The effects of beta-glucan from barley or yeast on the lipoprotein profile are promising, but more human trials are needed to further substantiate these effects. It is still not clear whether the claimed hypocholesterolemic effects of soy can be attributed solely to the isoflavones. Several studies found no changes in serum LDL cholesterol concentrations after consumption of isolated soy isoflavones (without soy protein), indicating that a combination of soy protein and isoflavones may be needed for eliciting a cholesterol-lowering effect of soy. Therefore, the exact (combination of) active ingredients in soy products need to be identified. The daily consumption of 2-3 g of plant sterols or stanols reduces LDL cholesterol concentrations by 9-14%. It has been demonstrated that functional foods enriched with plant sterols and stanols are effective in various population groups, and in combination with cholesterol-lowering diets or drugs. Whether garlic or garlic preparations can be used as a lipid-lowering agent is still uncertain. It is important to characterize the active components in garlic and their bioavailability after ingestion. It is not very likely that tocotrienols from palm oil or rice bran oil have favorable effects on the human serum lipoprotein profile.