Aged garlic extract improves endothelial function in men with coronary artery disease

Anti?atherosclerotic effect of aged garlic extract: Mode of action and therapeutic benefits (Review)

Atherosclerosis, a chronic inflammatory disease characterized by plaque buildup within the arteries that obstructs blood flow and significantly increases the morbidity and mortality rates associated with cardiovascular diseases caused by impaired blood flow due to vascular stenosis or occlusion, such as angina and myocardial infarction. The development of atherosclerosis involves a complex interplay of endothelial dysfunction, accumulation of oxidized low-density lipoprotein and macrophage-driven inflammation. The risk factors for atherosclerosis include chronic inflammation, hyperlipidemia and hypertension. Effective management of these risk factors can prevent and delay the onset and progression of atherosclerosis. Garlic and its processed preparations have previously been utilized to mitigate cardiovascular risk factors and continue to be used in traditional medicine in several countries. Among these preparations, aged garlic extract (AGE) has been shown to improve atherosclerosis in clinical trials and animal studies. AGE contains various compounds with potential anti-atherosclerotic properties, such as S-1-propenylcysteine, S-allylcysteine and other sulfur-containing constituents, which may help prevent the development and progression of atherosclerosis. The present manuscript reviewed and discussed the anti-atherogenic effect of AGE and its constituents by highlighting their mode of action and potential benefits for prevention and therapy in the management of atherosclerosis.

Effects of aged garlic extract on blood pressure in hypertensive patients: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

There is no consensus based on the existing literature regarding the effect of aged garlic extract (AGE) on blood pressure. The present systematic review and meta-analysis was conducted to synthesize existing data from randomized clinical trials (RCTs) concerning the impact of AGE supplementation on blood pressure in hypertensive patients.

METHODS

We searched English web databases including, PubMed, Scopus, Embase, Web of Science until August 2024. Random-effects meta-analysis was used to pool weighted mean differences (WMD) and 95 % CI for the outcomes.

RESULTS

Overall, nine RCTs with584 participants met inclusion criteria. AGE tea supplementation reduces systolic blood pressure (SBP) (WMD: -4.03; %95CI: -6.87, -1.20; I2: 57.1 %) and diastolic blood pressure (DBP) (WMD: -1.44; 95 % CI= -2.87, -0.02; P = 0.052; I2: 36.8 %; P: 0.105). Moreover, subgroup analysis indicated that higher doses of AGE supplementation in hypertensive patients significantly decreased DBP, and SBP.

CONCLUSION

The results of this study suggest that AGE supplements may be beneficial for improving blood pressure in hypertensive patients, but significant effects are observed only at doses over 1200 mg/day. To confirm these results, well-designed future trials will be needed.

Effect of Encapsulated Purple Garlic Oil on Microvascular Function and the Components of Metabolic Syndrome: A Randomized Placebo-Controlled Study-The ENDOTALLIUM Study

Endothelial dysfunction (ED) is associated with progressive changes contributing to clinical complications related to macro- and microvascular diseases. Garlic (Allium sativum L.) and its organosulfur components have been related to beneficial cardiovascular effects and could improve endothelial function. The ENDOTALLIUM Study aimed to evaluate the effect of the regular consumption of encapsulated purple garlic oil on microvascular function, endothelial-related biomarkers, and the components of metabolic syndrome (MetS) in untreated subjects with cardiometabolic alterations. Fifty-two individuals with at least one MetS component were randomized (1:1) in a single-center, single-blind, placebo-controlled, parallel-group study. The participants received encapsulated purple garlic oil (n = 27) or placebo (n = 25) for five weeks. Skin microvascular peak flow during post-occlusive reactive hyperemia significantly increased in the purple garlic oil group compared to the placebo group (between-group difference [95%CI]: 15.4 [1.5 to 29.4] PU; p = 0.031). Likewise, hs-CRP levels decreased in the purple garlic group compared to the control group (-1.3 [-2.5 to -0.0] mg/L; p = 0.049). Furthermore, we observed a significant reduction in the mean number of MetS components in the purple garlic group after five weeks (1.7 ± 0.9 vs. 1.3 ± 1.1, p = 0.021). In summary, regular consumption of encapsulated purple garlic oil significantly improved microvascular function, subclinical inflammatory status, and the overall MetS profile in a population with cardiometabolic alterations.

Effect of garlic on the components of metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Metabolic diseases are the major causes of macrovascular and microvascular complications which lead to morbidity and mortality. Traditionally, garlic has been used as food and medicine for more than 5000 years. However, efficacy studies have shown conflicting results regarding the garlic effect.

AIM OF THE STUDY

This study aims to evaluate the efficacy of garlic on the components of metabolic syndrome (MetS) in metabolic disease patients.

MATERIALS AND METHODS

This study was a systematic review and meta-analysis of randomized controlled trials (RCTs). Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), and Google scholar were searched till December 25, 2021 for identifying the relevant studies that have shown the effects of garlic on components of metabolic syndrome in metabolic disease patients. The mean difference with 95% CI was calculated using fixed-effect or random-effect models.

RESULTS

The effect of garlic has shown significant changes on waist circumference (p-value= <0.0001), total cholesterol (p < 0.0001), low density lipoprotein (p = 0.01), high density lipoprotein (p < 0.00001), triglycerides (p < 0.00001), systolic blood pressure (p < 0.00001), diastolic blood pressure (p < 0.00001), glucose (p < 0.00001), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (p = 0.04), C-reactive protein (p < 0.00001), tumor necrosis factor (TNF)-α (p = 0.002), interleukin (IL)-6 (p = 0.0001). Subgroup analysis has shown the favorable effects of garlic in metabolic disease patients.

CONCLUSION

Our meta-analysis results confirm the findings that garlic could be useful as an anti-hyperlipidemic, anti-hyperglycemic, anti-hypertensive and anti-inflammatory drug.

Effect of Black Garlic Consumption on Endothelial Function and Lipid Profile: A Before-and-After Study in Hypercholesterolemic and Non-Hypercholesterolemic Subjects

BACKGROUND

Black garlic is obtained from raw garlic (Allium sativum L.), by a fermentation process, under humidity and heat treatment, showing a high concentration of organosulfur compounds, which have been related to benefits in the prevention or delay of cardiovascular diseases (CVDs). The objective of the research was to evaluate whether long-term consumption of black garlic improves endothelial function and lipid profile in subjects with hypercholesterolemia.

METHODS

Single center, controlled clinical trial with two branches: Hypercholesterolemia vs. Healthy condition. Sixty-two subjects of both sexes were distributed in two groups, the hypercholesterolemia group (n = 31) (total cholesterol (TC) range 200-300 mg/dL and low-density lipoprotein (LDL)-cholesterol range 135-175 mg/dL) and the healthy group (n = 31). The intervention consisted of the ingestion of 4 cloves of black garlic (12 g) daily for 12 weeks.

RESULTS

significant increases in Apolipoprotein (Apo)A1 occurred in both groups: Hypercholesterolemia (Δ 11.8 mg/dL p < 0.001) vs Healthy (Δ 11.1 mg/dL p < 0.001). Besides, significant reductions for endothelial adhesion molecules monocyte chemoattractant protein-1 (MCP-1) (Δ -121.5 pg/mL p = 0.007 vs. Δ -56.3 pg/mL p = 0.015), intracellular adhesion molecule-1 (ICAM-1) (Δ -39.3 ng/mL p < 0.001 vs. Δ 63.5 ng/mL p < 0.001), and vascular cyto-adhesion molecule-1 (VCAM-1) (Δ -144.4 ng/mL p < 0.001 vs. Δ -83.4 ng/mL p = 0.061) were observed, for hypercholesterolemic and healthy subjects, respectively.

CONCLUSIONS

These data show that black garlic consumption could improve some parameters related to endothelial function and lipid profile, which may have a favorable impact on the risk of CVDs, although more long-term studies are necessary to confirm.

L-arginine and aged garlic extract for the prevention of migraine: a study protocol for a randomised, double-blind, placebo-controlled, phase-II trial (LARGE trial)

Background

Migraine is a common and distressing neurological condition characterised by recurrent throbbing headaches, nausea and heightened sensitivity to light and sound. Accumulating evidence suggests that cerebral arteries dilate during migraine, causing distal microvessels to constrict, which could activate nociceptors and cause onset of headache pain. If so, preventing or attenuating chronic microvascular constriction, and promoting a dilatory phenotype, may reduce frequency and/or severity of migraines. The primary aim of the L-Arginine and Aged Garlic Extract (LARGE) trial is to investigate whether oral treatment with dietary nutraceuticals, L-arginine and aged garlic extract (AGE), both systemic vasodilatory agents, will alleviate migraine frequency, duration and severity in adults with chronic frequent episodic migraines.

Methods

The study is a randomised double-blind placebo-controlled phase-II single-site clinical trial conducted in Perth, Australia. The target sample is to recruit 240 participants diagnosed with chronic frequent episodic migraines between 18 and 80 years of age. Participants will be randomised to one of four treatment groups for 14 weeks (placebo induction for 2 weeks, followed by 12 weeks on one of the respective treatment arms): placebo, L-arginine, AGE, or a combination of L-arginine and AGE. The doses of L-arginine and AGE are 1.5 g and 1 g daily, respectively. The primary outcome is to assess migraine response using change in migraine frequency and intensity between baseline and 12 weeks. Secondary outcomes include the impact of L-arginine and/or AGE on photosensitivity, retinal vessel changes, and blood biomarker concentrations of vascular tone, following a 12-week intervention.

Discussion

The protocol describes the oral administration of 2 nutraceutical-based interventions as possible prophylactic treatments for chronic frequent episodic migraines, with potential for direct clinical translation of outcomes. Potential limitations of the study include the fixed-dose design of each treatment arm and that in vivo neuroimaging methods, such as magnetic resonance imaging (MRI), will not be conducted to determine putative cerebro-vasodilatory changes to coincide with the outcome measures. Dose-response studies may be indicated.

Trial registration

The trial was retrospectively registered with the Australian New Zealand Clinical Trials Registry ACTRN12621001476820 (Universal Trial Number: U1111-1268-1117) on 04/08/2021. This is protocol version 1, submitted on 25/11/2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-023-03149-y.

Effect of garlic extract on markers of lipid metabolism and inflammation in coronary artery disease (CAD) patients: A systematic review and meta-analysis

Several preclinical studies have focused on the beneficial effects of garlic on cardiovascular diseases, but the results were inconsistent. We performed a systematic review and meta-analysis on the effect of garlic powder tablets and aged garlic extract (AGE) in CAD patients, mainly focusing on blood pressure, coronary artery calcification, lipid profile, and inflammatory markers. We searched PubMed, Cochrane CENTRAL, and Google Scholar to identify randomized controlled trials which examined garlic's effect on CAD patients. The standardized mean difference with 95% CI was calculated using fixed-effect or random-effect models. Garlic has shown statistically significant changes of HDL (SMD = 0.18; 95% CI = -0.00 to 0.37; p = .05); LDL (SMD = -0.27; 95% CI = -0.46 to -0.08; p = .004), apolipoprotein-A (SMD = 0.68; 95% CI = 0.24 1.13; p = .002), C-RP (SMD = -0.59; 95% CI = -0.92 to -0.25; p = .0007), IL-6 (SMD = -1.08; 95% CI = -2.17 to 0.01; p = .05), homocysteine (SMD = -0.66; 95% CI = -1.04 to -0.28; p = .0007) and CAC score (SMD = -1.61; 95% CI = -2.66 to -0.57; p = .003). In the case of subgroup analysis, the overall effect was significantly effective in reducing TC, LDL levels and improving HDL levels in CV risk patients. Our study findings provide consistent evidence that intake of garlic reduces CVD risk factors. However, garlic could be considered a safe natural medicine to debilitate inflammation in CAD patients.

Roles and mechanisms of garlic and its extracts on atherosclerosis: A review

The prevention and treatment of cardiovascular diseases (CVDs) have achieved initial results, but the number of CVDs patients will increase rapidly in the next 10 years. Atherosclerosis (AS) is a significant risk factor for CVDs. The impact of lifestyle and daily diet varies considerably between different countries and continents and has been shown to affect the development of various diseases such as diabetes and CVDs. Primary and secondary prevention using alternative supplements and methods to avoid or reduce the use of traditional pharmacological drugs have also become popular. One of the reasons for this is that pharmacological drugs with lipid-lowering, and blood pressure-lowering effects cause many side effects that may negatively impact the quality of life. Patients are now emphasizing reliance on lifestyle changes to reduce cardiovascular risks. Garlic is a medicinal and edible plant that has been used for a long time. In order to reveal garlic application in the prevention and treatment of AS, reviewing the latest domestic and international studies through searching databases. The result shows that the antiatherogenic role of garlic is eximious. And the mechanisms are mainly related to hypolipidemic, antioxidant, antithrombotic, inhibiting angiogenesis, protecting endothelial cells, anti-inflammatory, anti-apoptotic, inhibiting vascular smooth muscle proliferation, and regulating gut microbiota. The main signaling pathways involve AMPK/TLRs, Keap1/Nrf2, PI3K/AKT, PPARγ/LXRα, GEF-H1/RhoA/Rac, etc. The antiatherogenic actions and molecular mechanism of garlic were reviewed in this study to obtain a robust evidence basis for the clinical application and mechanistic study and provide a theoretical basis for further utilization of garlic.

Improved microvascular reactivity after aged garlic extract intake is not mediated by hydrogen sulfide in older adults at risk for cardiovascular disease: a randomized clinical trial

PURPOSE

This study aimed to investigate the effects of AGE on microvascular reactivity, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in older individuals at high risk for cardiovascular disease (CVD). Urinary thiosulfate was also investigated as an indirect marker of endogenous hydrogen sulfide (H₂S) synthesis. The study was conducted in a randomized, double-blind, crossover, and placebo-controlled way.

METHODS

Twenty-eight participants (14 male), 67 ± 6 years old with CVD risk factors, ingested 2.4 g of AGE or placebo (PLA). Near-infrared spectroscopy evaluated tissue oxygen saturation (StO₂) during a vascular occlusion test (30 s baseline, 5 min occlusion, and 2 min reperfusion). The upslope of StO₂ signal after cuff release was calculated to measure microvascular reactivity. Urinary thiosulfate levels were measured using a high-performance liquid chromatography system.

RESULTS

The upslope of StO₂ was significantly faster after AGE (1.01 ± 0.37% s^-1) intake compared to PLA (0.83 ± 0.35% s^-1; P < 0.001; d = 0.50). Relative changes in Δ% SBP from pre- to post-AGE intake (- 5.17 ± 5.77%) was significantly different compared to Δ% PLA (0.32 ± 5.99%; P = 0.001; d = 0.93). No significant changes in urinary thiosulfate concentrations were observed between interventions. Moreover, no significant gender effect in any parameter assessed was found.

CONCLUSION

This study demonstrated that a single dose of AGE improved microvascular reactivity in older adults at risk of CVD despite such an effect was not linked with urinary thiosulfate levels. This trial was registered at clinicaltrials.gov as NCT04008693 (May 19, 2020).

In Vitro Colonic Fermentation of (Poly)phenols and Organosulfur Compounds of Fresh and Black Garlic

The beneficial properties associated with garlic consumption have been related to the presence of bioactive compounds including (poly)phenols and organosulfur compounds (OSCs). This study aims to assess the effect of in vitro colonic fermentation on fresh and black garlic by determining the transformation of these compounds through ultrahigh-performance liquid chromatography coupled to mass spectrometry with a linear ion trap (uHPLC-LIT-MS). Colonic fermentation had a similar influence on the phenolic content of fresh and black garlic, with total respective decreases of 43.8% and 41.7%. Meanwhile, fermentation resulted in a significant decrease (33%) in OSCs in black garlic. Compounds such as 4-hydroxybenzoic acid, S-allylcysteine (SAC), and methionine sulfoxide were the phenolic compounds and OSCs with the highest concentration in fresh and black garlic after the in vitro fermentation. These compounds, potentially present at the colonic level, might be responsible for the systemic health benefits associated with the consumption of black and fresh garlic.

Effects of garlic extract on lipid profile in patients with coronary artery disease: A systematic review and meta-analysis of randomised clinical trials

This meta-analysis was conducted to evaluate the effects of garlic extract on total cholesterol (TC), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-c) and high-density lipoprotein-cholesterol (HDL-c), among the patients with coronary artery disease (CAD). Literature searches were conducted in EMBASE, Scopus, PubMed, Web of Science and Cochrane Library until Sep18th, 2020. Inter-study heterogeneity was examined using Cochrane's Q and I² tests. The random-effect models were utilised to pool the weighted mean differences (WMDs) and the corresponding 95% confidence intervals (CIs). Six articles were enrolled in the current meta-analysis. Garlic consumption significantly reduced TC levels (WMD -16.32 mg/dL; 95% CI -31.22, -1.43; P = .032). We found no significant effects on TG (WMD -10.93 mg/dL; 95% CI -26.19, 4.32; P = .160), HDL-c (WMD 4.55 mg/dL; 95% CI -1.13, 10.23; P = .116) and LDL-c concentrations (WMD -3.65 mg/dL; 95% CI -13.21, 5.92; P = .455). Significant heterogeneity was observed for HDL-c (I²  = 76.8%). However, the findings of sensitivity analysis revealed that upon exclusion of the potential heterogeneity source, the pooled WMD on HDL-c levels were stable. Garlic supplementation may result in a decrease in TC, but will not affect TG, HDL-c and LDL-c levels among CAD patients.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Traditional plants with antioxidant properties in clinical trials-A systematic review

There is a trend toward the use of natural substances present in plants and vegetables. In general, foods rich in antioxidants are complex matrices; therefore, understanding its absorption effects is extremely relevant to know its bioactive potential. Thus, this systematic review focused on clinical trials involving plants (or compounds) registered on the National List of Medicinal Plants of Interest to the Unified Health System (RENISUS) with antioxidant properties. Following the reporting guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyzes studies of interest indexed in the PubMed and ClinicalTrials.gov databases were analyzed. Of the 59 clinical trials found, Allium sativum and Curcuma longa are the plant species with the highest percentage of clinical research. Prevention/attenuation of oxidative stress was one of the main antioxidant mechanisms indicated in the studies. The most tested compounds of the RENISUS plants in clinical trials were curcumin and soy isoflavone. In this review, we selected studies in advanced stages that highlight plants' value in optimizing antioxidant status; however, even with high-quality studies, it is not prudent to overstate the clinical efficacy of these plants.

S-1-propenylcysteine improves TNF-α-induced vascular endothelial barrier dysfunction by suppressing the GEF-H1/RhoA/Rac pathway

Background

Vascular endothelial barrier function is maintained by cell-to-cell junctional proteins and contributes to vascular homeostasis. Various risk factors such as inflammation disrupt barrier function through down-regulation of these proteins and promote vascular diseases such as atherosclerosis. Previous studies have demonstrated that aged garlic extract (AGE) and its sulfur-containing constituents exert the protective effects against several vascular diseases such as atherosclerosis. In this study, we examined whether AGE and its sulfur-containing constituents improve the endothelial barrier dysfunction elicited by a pro-inflammatory cytokine, Tumor-necrosis factor-α (TNF-α), and explored their mode of action on TNF-α signaling pathway.

Methods

Human umbilical vein endothelial cells (HUVECs) were treated with test substances in the presence of TNF-α for various time periods. The endothelial permeability was measured by using a transwell permeability assay. The localization of cell-to-cell junctional proteins and actin cytoskeletons were visualized by immunostaining. RhoA and Rac activities were assessed by using GTP-binding protein pulldown assay. Gene and protein expression levels of signaling molecules were analyzed by real-time PCR and western blotting, respectively.

Results

We found that AGE and its major sulfur-containing constituent, S-1-propenylcysteine (S1PC), reduced hyperpermeability elicited by TNF-α in HUVECs. In addition, S1PC inhibited TNF-α-induced production of myosin light chain (MLC) kinase and inactivation of MLC phosphatase through the suppression of the Rac and RhoA signaling pathways, respectively, which resulted in the dephosphorylation of MLC2, a key factor of actin remodeling. Moreover, S1PC inhibited the phosphorylation and activation of guanine nucleotide exchange factor-H1 (GEF-H1), a common upstream key molecule and activator of Rac and RhoA. These effects of S1PC were accompanied by its ability to prevent the disruption of junctional proteins on the cell–cell contact regions and the increase of actin stress fibers induced by TNF-α.

Conclusions

The present study suggested that AGE and its major constituent, S1PC, improve endothelial barrier disruption through the protection of junctional proteins on plasma membrane.

Effects of garlic supplementation on oxidative stress and antioxidative capacity biomarkers: A systematic review and meta-analysis of randomized controlled trials

Evidence suggests that garlic supplementation may have an effect on oxidative stress by augmenting the rate of enzymatic and non-enzymatic antioxidants and diminishing pro-oxidant enzymes. Given inconsistencies across studies, we aimed to systematically review the current literature and quantify the effects of garlic supplementation on oxidative stress. We conducted a systematic search with multiple databases (Scopus, PubMed, and Web of Science) to find relevant articles published prior to October 2020. Results were reported as bias-corrected standardized mean difference (Hedges' g) with 95% confidence intervals (CI) using random-effects models. Cochrane's Q and I squared (I² ) tests were used to determine heterogeneity among the studies included. Twelve randomized controlled trials (RCTs) were included. Garlic doses ranged from 80 to 4,000 mg/day, and intervention duration varied between 2 and 24 weeks. Garlic supplementation increased serum level of total antioxidant capacity (TAC) (Hedges' g: 2.77, 95% CI: 1.37 to 4.17, p < 0.001) and superoxide dismutase (SOD) (Hedges' g: 13.76, 95% CI: 4.24 to 23.29, p = 0.004), while it reduced the malondialdehyde serum level (MDA) (Hedges' g: -1.94, 95% CI: -3.17 to -0.70, p = 0.002). Due to limited data available, glutathione (GSH) was not considered for the current meta-analysis. The nonlinear dose-response effect of garlic supplementation was not observed with regard to serum TAC and MDA levels (TAC: p-nonlinearity = 0.398; MDA: p-nonlinearity = 0.488). Garlic supplementation appears to improve serum levels of TAC, MDA, and SOD. Garlic supplementation may be useful to reduce oxidative stress and related diseases. Future studies with large sample sizes and longer duration are required to confirm these findings.

Bioaccessibility of Bioactive Compounds of 'Fresh Garlic' and 'Black Garlic' through In Vitro Gastrointestinal Digestion

Numerous studies have reported health benefits associated with the consumption of fresh and black garlic, which are characterized by the presence of polyphenols and organosulfur compounds (OS). This study aims to analyze the bioaccessibility of the bioactive compounds in fresh and black garlic after in vitro gastrointestinal digestion by monitoring the individual profile of these compounds by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). Polyphenols decreased from the beginning of the digestive process, is mainly affected during intestinal digestion. Regarding the OS, the S-alk(en)yl-L-cysteine (SACs) derivatives were more influenced by the acidic conditions of the gastric digestion, while the γ-glutamyl-S-alk(en)yl-L-cysteine (GSAk) derivatives were more susceptible to intestinal digestion conditions in both the fresh and black garlic samples. In conclusion, after in vitro gastrointestinal digestion, the compounds with the highest bioaccessibility were vanillic acid (69%), caffeic acid (52%), γ-glutamyl-S-methyl-L-cysteine sulfoxide (GSMCS) (77%), and S-allylmercapto-L-cysteine (SAMC) (329%) in fresh garlic. Meanwhile, in black garlic, the main bioaccessible compounds were caffeic acid (65%), GSMCS (89%), methionine sulfoxide (262%), trans-S-(1-propenyl)-L-cysteine (151%), and SAMC (106%). The treatment (heating + humidity) to obtain black garlic exerted a positive effect on the bioaccessibility of OS compounds, 55.3% of them remaining available in black garlic, but only 15% in fresh garlic. Polyphenols showed different behavior regarding bioaccessibility.

Effects of garlic supplementation on serum inflammatory markers: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Previous studies have indicated that garlic consumption may be beneficial in improving inflammation. This systematic review and meta-analysis aimed to examine the effect of garlic supplementation on inflammatory biomarkers.

METHODS

PubMed/Medline, Scopus and ISI web of science were searched up to February 2019. Random effects model was used to calculate the overall effects on C-reactive protein (CRP), Interleukin-6 (IL-6), and Tumor necrosis factor- α (TNF-α).

RESULTS

17 randomized controlled trials (RCTs) were included in the meta-analyses. Garlic supplementation significantly reduced the level of circulating CRP (P < 0.05), whereas it did not have any significant effect on IL-6 level (p > 0.05). Sub-group analysis showed that aged garlic extract (AGE) was able to reduce CRP and TNF-α significantly (P < 0.05).

CONCLUSIONS

This meta-analysis showed that supplementation with garlic could reduce the level of circulating CRP and AGE could reduce the level of TNF-α and CRP, whereas it had no significant effect on the IL-6 level.

A Paradoxical Vasodilatory Nutraceutical Intervention for Prevention and Attenuation of Migraine-A Hypothetical Review

Studies suggest that migraine pain has a vascular component. The prevailing dogma is that peripheral vasoconstriction activates baroreceptors in central, large arteries. Dilatation of central vessels stimulates nociceptors and induces cortical spreading depression. Studies investigating nitric oxide (NO) donors support the indicated hypothesis that pain is amplified when acutely administered. In this review, we provide an alternate hypothesis which, if substantiated, may provide therapeutic opportunities for attenuating migraine frequency and severity. We suggest that in migraines, heightened sympathetic tone results in progressive central microvascular constriction. Suboptimal parenchymal blood flow, we suggest, activates nociceptors and triggers headache pain onset. Administration of NO donors could paradoxically promote constriction of the microvasculature as a consequence of larger upstream central artery vasodilatation. Inhibitors of NO production are reported to alleviate migraine pain. We describe how constriction of larger upstream arteries, induced by NO synthesis inhibitors, may result in a compensatory dilatory response of the microvasculature. The restoration of central capillary blood flow may be the primary mechanism for pain relief. Attenuating the propensity for central capillary constriction and promoting a more dilatory phenotype may reduce frequency and severity of migraines. Here, we propose consideration of two dietary nutraceuticals for reducing migraine risk: L-arginine and aged garlic extracts.

Potential Health Benefit of Garlic Based on Human Intervention Studies: A Brief Overview

Garlic is a polyphenolic and organosulfur enriched nutraceutical spice consumed since ancient times. Garlic and its secondary metabolites have shown excellent health-promoting and disease-preventing effects on many human common diseases, such as cancer, cardiovascular and metabolic disorders, blood pressure, and diabetes, through its antioxidant, anti-inflammatory, and lipid-lowering properties, as demonstrated in several in vitro, in vivo, and clinical studies. The present review aims to provide a comprehensive overview on the consumption of garlic, garlic preparation, garlic extract, and garlic extract-derived bioactive constituents on oxidative stress, inflammation, cancer, cardiovascular and metabolic disorders, skin, bone, and other common diseases. Among the 83 human interventional trials considered, the consumption of garlic has been reported to modulate multiple biomarkers of different diseases; in addition, its combination with drugs or other food matrices has been shown to be safe and to prolong their therapeutic effects. The rapid metabolism and poor bioavailability that have limited the therapeutic use of garlic in the last years are also discussed.

The effect of garlic on vascular function: A systematic review of randomized clinical trials

BACKGROUNDS AND AIMS

Atherosclerosis and its associated cardiovascular disease (CVD) represent a major global health problem worldwide and vascular dysfunction is important in its pathogenesis. Clinical trials investigating the effect of garlic on vascular function measured by several non-invasive methods and their results are inconsistent. This study aimed to summarize the current evidence regarding the effectiveness of garlic as one of the world's most ancient medicines on measures of vascular reactivity and/or stiffness in adults.

METHODS

All published RCTs in English were systematically searched on PubMed, Scopus and Google Scholar search engines up to Oct 2019. The exposure and outcome variable of interest were garlic and vascular function measurements. Ten trials which met inclusion criteria were included in this study.

RESULTS

A total of 45 studies were found through search databases. After excluding duplicates, the 25 remaining studies were screened by title and abstract which 15 of them excluded. Finally, ten trials were included in this review study, which were published between 2004 and 2018.

CONCLUSIONS

Findings were inconsistent. However, garlic has the potential to improve vascular function, particularly in subjects with cardiovascular risk factors. Additional human studies on garlic and its constituents should consider the population and the specific type of garlic preparation.

Effect of garlic intake on inflammatory mediators: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Garlic is a species in the onion genus, Allium. Data have shown that garlic has anti-inflammatory activity; however, the findings are inconclusive and inconsistent. We aimed to evaluate the impact of garlic intake on inflammatory mediators through systematic review and meta-analysis of existing data.

METHODS

Electronic databases were completely investigated using databases of ISI Web of Science, Medline, Scopus, Cochrane Library and EMBASE until October 2019. A random effects model and the generic reverse variance procedure were used for quantitative data production. Sensitivity analyses and prespecified subgroup were done to evaluate potential heterogeneity. Random effect meta-regression was conducted to investigate the effects of possible confounders on the assessed effect size.

RESULTS

Ten trials with one observational study, including 530 participants, met the eligibility criteria. The findings showed reduction in the tumour necrosis factor alpha (TNF-α) (-0.31 pg/mL, 95% CI -1.07 to 0.46) and C reactive protein (CRP) levels (-0.20 mg/L, 95% CI -1.4 to 1.05) following supplementation with garlic, although it had no marked impact on the interleukin 6 (IL-6) level (0.37 pg/mL, 95% CI -0.58 to 1.33). In the subgroup analysis, we found that garlic supplementation significantly decreased TNF-α, highly sensitive CRP and IL-6 levels in subgroups of >8, >6 and ≥4 weeks of intervention duration, respectively, and dose of garlic consumption between 2 and 2.4 g/day.

CONCLUSION

These findings suggested that current evidence may support garlic as an adjunct to pharmacological management of metabolic diseases.

PROSPERO REGISTRATION NUMBER

CRD42018108816.

Short-term impact of aged garlic extract on endothelial function in diabetes: A randomized, double-blind, placebo-controlled trial

Impaired endothelial function portends an increased risk of cardiovascular disease. Vascular oxidative stress and systemic inflammation play a critical role in the pathogenesis and progression of vascular disease. Aged garlic extract (AGE) may improve impaired vascular endothelial function, while decreasing the progression of atherosclerotic plaque. We hypothesized that AGE may improve endothelial function, and in this study, we examined this hypothesis to determine whether this can be achieved over a period of 3 months, measured by the cardio-ankle vascular index (CAVI), by reducing intracellular oxidant stress and stimulating nitric oxide generation in endothelial cells. We conducted a double-blinded placebo controlled, randomized clinical trial to investigate the effects of AGE on CAVI in subjects with type 2 diabetes mellitus. A total of 65 individuals (38 men and 27 women) with a mean age of 58.8±11.1 years were enrolled and randomized to the AGE or placebo group in a double-blind placebo controlled trial. An ANOVA model with treatment as the main effect was used to compare changes in CAVI from baseline to follow-up between groups. The primary objective of this study was reduction in CAVI over a 3-month period. In the AGE group, CAVI was reduced on average by 0.71±1.27 vs. a mean reduction of 0.13±0.94 in the placebo group (P=0.04). On the whole, this study demonstrates that AGE has a positive impact on endothelial function in patients with T2DM and may play a role in the primary prevention of cardiovascular disease.

Relation of Fruits and Vegetables with Major Cardiometabolic Risk Factors, Markers of Oxidation, and Inflammation

Noncommunicable diseases (NCDs) are considered to be the leading cause of death worldwide. Inadequate fruit and vegetable intake have been recognized as a risk factor for almost all NCDs (type 2 diabetes mellitus, cancer, and cardiovascular and neurodegenerative diseases). The main aim of this review is to examine the possible protective effect that fruit and vegetable consumption or their bioactive compounds may have on the development of NCDs such as atherosclerosis. The accumulated evidence on the protective effects of adequate consumption of fruits and vegetables in some cases, or the lack of evidence in others, are summarized in the present review. The main conclusion of this review is that well-designed, large-scale, long-term studies are needed to truly understand the role fruit and vegetable consumption or their bioactive compounds have in atherosclerosis.

Garlic Supplementation Reduces Circulating C-reactive Protein, Tumor Necrosis Factor, and Interleukin-6 in Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Conflicting findings on the effects of garlic supplementation on inflammatory biomarkers have been observed in randomized clinical trials (RCTs).

OBJECTIVES

The aim of this study was to summarize study results regarding the effects of garlic supplementation on serum inflammatory biomarkers in adults.

METHODS

We searched Scopus, PubMed, Google Scholar and Cochrane library databases for relevant papers published until April 2018, using keywords such as "garlic" and "inflammatory biomarker." We included RCTs that 1) were conducted in adults, 2) examined the effects of garlic supplementation on inflammatory biomarkers compared to a control group, and 3) reported sufficient data on inflammatory biomarkers. Results were reported as weighted mean differences (WMD) with 95% CI using random effects models. Cochrane's Q and I-squared (I2) tests were used to determine heterogeneity among studies. Funnel plots and Egger's regression test were used to assess publication bias.

RESULTS

Sixteen RCTs were included. Garlic doses ranged from 12 to 3600 mg/d, and intervention duration ranged from 2 to 52 wk. Garlic administration significantly reduced serum C-reactive protein (CRP) (n = 13) (WMD: -0.61 mg/L, 95% CI: -1.12, -0.11, P = 0.018, I2 = 76.9%), IL-6 (n = 5) (WMD: -0.73 ng/L, 95% CI: -1.06, -0.40, P < 0.001, I2 = 0%), and TNF (n = 7) (WMD: -0.26 ng/L, 95% CI: -0.41, -0.12, P < 0.001, I2 = 0.0%), compared to controls. However, the effect of garlic supplementation on serum adiponectin (n = 3) (WMD: 0.18 µg/L, 95% CI: -0.21, 0.57, P = 0.35, I2 = 60.7%) and leptin (n = 2) (WMD: -1.25 µg/L, 95% CI: -2.64, 0.14, P = 0.07, I2 = 0.0%) concentrations were not significant.

CONCLUSION

In this meta-analysis of RCTs, we found that garlic supplementation reduced serum concentrations of CRP, TNF, IL-6, but did not affect serum adiponectin and leptin in adults. More RCTs are needed to test the effects of garlic supplementation on inflammation.

The effect of garlic on lipid profile and glucose parameters in diabetic patients: A systematic review and meta-analysis

PURPOSE

Several studies have been published about the effect of garlic on lipid profile and blood glucose in diabetic patients. Which, the results mostly contradict with each other. This study aimed to investigate the effect of garlic on lipid profile and serum glucose levels in diabetic patients using a systematic review and meta-analysis.

METHODS

This study was a systematic review and meta-analysis of articles published between 1988 and 2016. For this purpose, two independent researchers searched SID medical information databases including MagIran, Irandoc, Medlib, Iran Medex, Science Direct, Scopus, Google and PubMed using keywords. Data were analyzed using STATA software.

RESULTS

After the initial search, 23,000 articles were found, of which 33 had the required criteria for the meta-analysis. In the present study, the total sample under review was 1273 individuals, with a mean of 39 samples per study. Overall, the garlic was more influential than placebo in reducing the levels of lipid parameters including triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), and fasting blood sugar (FBS) and HbA_1C. In the meta-analysis, the concentration of serum TC, LDL, TG, and HDL in the group receiving garlic compared with the placebo showed a significant decreased for 16.87mg/dl (95% CI, -21.01, -12.73) (P=0.001), 9.65mg/dl (95% CI, -15.07, -4.23) (P=0.001), 12.44mg/dl (95% CI, -18.19, -6.69) (P=0.001), and increased for 3.19mg/dl (95% CI, 1.85, 4.53) (P=0.001), respectively. Also, the concentration of serum FBS and HbA_1C serum showed a significant decreased for 10.90mg/dl (95% CI, -16.40, -5.40) (P=0.001) and 0.60mg/dl (95% CI, -0.98, -0.22) (P=0.001), respectively.

CONCLUSION

Garlic can reduce lipid profile as well as glucose parameters and be therapeutically effective in patients suffering from cardiovascular diseases and diabetes.

Medicinal plants in treatment of hypertriglyceridemia: A review based on their mechanisms and effectiveness

BACKGROUND

Hypertriglyceridemia (HTg) defines as high amounts of triglyceride (TG) in the blood which can lead to serious complications over time. HTg is usually a part of metabolic disorders such as diabetes mellitus, metabolic syndrome, and dyslipidemia. Different medications have been used to treat HTg but experimentally, many herbs have been recommended for treating HTg as an adjuvant therapy. In most cases, the recommendations are based on animal studies and limited evidences exist about their mechanisms and clinical usefulness.

PURPOSE

This review focused on the herbs which have been shown TG lowering effect.

METHOD

The search was done in PubMed, Science Direct, Scopus, Web of Science and Google Scholar databases a 20-year period between 1997 to 2017 with keywords search of medicinal plant, plant extract, hypertriglyceridemia, dyslipidemia, hyperlipidemia, lipoprotein lipase and apolipoprotein.

RESULTS

According to the results, many plants showed positive effects but Allium sativum, Nigella sativa, Curcuma longa, Anethum graveolens and Commiphora mukul had the best TG lowering effect with exact mechanisms of action.

CONCLUSION

It seems that use of these plants as complementary therapeutics or extraction of their active ingredients along with currently available drugs will improve the management of HTg in patients.

Effect of garlic supplementation on serum C-reactive protein level: A systematic review and meta-analysis of randomized controlled trials

The present study was designed to systematically review randomized controlled trials (RCTs) that report on the effects of garlic supplementation on serum C-reactive protein (CRP) levels. We conducted a literature search of Scopus, PubMed, Cochrane Library, and Google Scholar up to January 2018. Weighted mean differences (WMD) were estimated for net change in serum CRP. Subgroup analyses were also performed by duration of study, dose of supplementation, baseline CRP level, and the quality of studies. From 438 articles found and screened in our initial search, nine RCTs with the sum of total sample size of 363 were included in the meta-analysis. Compared with the controls, garlic intake significantly reduced the concentrations of serum CRP by 0.8 mg/L (95% CI [-1.5, -0.1], p = 0.02) with the evidence of heterogeneity among studies. Subgroup analyses showed that garlic significantly lowered CRP by 0.82 mg/L (95% CI [-1.02, -0.62], p < 0.001) among studies with a daily garlic dose ≥1,200 mg/day and by 2.44 mg/L (95% CI [-4.02, -0.87], p = 0.002) among studies with baseline CRP ≥2 mg/L. Current data confirmed that garlic supplementation would reduce serum CRP levels. However, the changes were related to the supplemental doses and baseline levels of serum CRP.

Nutritional Supplements for the Treatment of Hypertension: A Practical Guide for Clinicians

Nutraceuticals are dietary components with pharmacologic properties that can be used to treat various disease states. There is growing interest among patients in the use of nutraceuticals for the management of hypertension; as such, it is important that clinicians are prepared to engage in meaningful discussions with their patients about these substances. Flavonoids, beetroot, garlic, and unsaturated fats have garnered significant attention for their blood pressure lowering properties. We review the clinical evidence and reported mechanisms of action for these substances in an attempt to offer a practical guide for clinicians to engage with patients who are highly motivated to seek out nutraceutical therapies to manage their hypertension.

Effects of garlic on brachial endothelial function and capacity of plasma to mediate cholesterol efflux in patients with coronary artery disease

Objective:

This study investigated the effects of garlic on brachial endothelial function and THP-1 macrophage cholesterol efflux (CE) and examined whether garlic modulates ATP-binding cassette (ABC) A1 and ABCG1 mRNA expressions in peripheral blood mononuclear cells (PBMCs) isolated from patients with coronary artery disease (CAD).

Methods:

In this randomized, placebo-controlled trial, patients with CAD were randomly divided into two groups: those receiving garlic powder or placebo tablets twice daily for 3 months. Brachial flow-mediated dilation (FMD) was assessed using ultrasound. Fasting blood samples were collected before and after period and PBMC and plasma were isolated. Human THP-1 monocytes were differentiated into macrophages, labeled with 3H-cholesterol, and incubated with plasma samples, and CE was assessed. ABCA1 and ABCG1 mRNA expressions were determined in PBMCs.

Results:

After 3 months, brachial FMD values significantly improved (50.7%) in the garlic group compared with those in the placebo group (p=0.016). High-sensitive C-reactive protein (hs-CRP) levels significantly decreased in the garlic group, but the difference between the two groups was not statistically significant. No significant difference was observed with regard to CE and ABCA1 and ABCG1 mRNA expressions in PBMCs. CE was negatively correlated with hs-CRP levels.

Conclusion:

Short-term treatment with garlic may improve the endothelial function and may affect hs-CRP levels; however, it could neither significantly improve THP-1 macrophage CE nor affect ABCA1 or ABCG1 expressions in PBMCs.

A Review of the Efficacy, Safety, and Clinical Implications of Naturally Derived Dietary Supplements for Dyslipidemia

Dyslipidemia is recognized as a major cause of cardiovascular disease. A number of evidence-based guidelines recommend conventional synthetic drugs as standard therapy for dyslipidemia in clinical practice. However, antihyperlipidemic drugs have some serious side effects. Naturally derived dietary supplements are becoming attractive as an alternative strategy because of their high efficacy and safety, as supported by numerous data. Moreover, they could be considered an initial treatment for dyslipidemia. The aims of this literature review were to demonstrate the efficacy, safety, and clinical implications of dietary supplements for treating dyslipidemia. We reviewed the literature, including data from in vitro, in vivo, and human studies, and clinical guideline recommendations. We classified dietary supplements by their proposed mechanisms of action on lipid metabolism and also collected daily dosage recommendations, interactions with concurrent drugs and/or foods, dosage forms, and examples of commercially available products. Various types of naturally derived dietary supplements exhibit lipid-improving properties. Efficacy and safety are acceptable; however, their use in clinical practice will require further well-designed investigations and the support of scientific data.

Complementary and Alternative Medicine Use in Hypertension

Thirty six percent of people in USA and Canada regularly use complementary and alternative medicine (CAM) for the prevention and treatment of different diseases, including hypertension. Generally, majority of the hypertensive patients do not disclose the use of such remedies, and also health care providers do not usually ask their hypertensive patients if they use CAM. The widespread consumption of CAM in hypertension requires clear understanding of their underlying mechanism of action, efficacy and safety. This chapter will provide a comprehensive list of CAM commonly used by Americans for the prevention and treatment of hypertension as well as their postulated mechanism of action. Modulation of drug metabolizing enzymes and their safety will also be covered along with the clinical consequences, i.e. drug-herb or herb-disease interactions. patients and healthcare providers should also be careful with using CAM therapies, because not only is there minimal evidence that several CAM products work to treat hypertension, but their safety hasn't been well-established.

The effects of garlic extract upon endothelial function, vascular inflammation, oxidative stress and insulin resistance in adults with type 2 diabetes at high cardiovascular risk. A pilot double blind randomized placebo controlled trial

BACKGROUND AND AIMS

Endothelial dysfunction, vascular inflammation and oxidative stress have been integrally linked to the pathogenesis of both type 2 diabetes and cardiovascular disease. Aged Garlic Extract (AGE), a potent antioxidant, has been shown in previous studies to attenuate these novel risk factors in a non-diabetic population.

AIMS

This study tested the hypothesis that AGE may improve endothelial function, oxidative stress, vascular inflammation and insulin resistance in high risk cardiovascular subjects with type 2 diabetes.

METHODS

A double blind, placebo controlled crossover pilot study was performed in 26 subjects with type 2 diabetes who received 1200 mg of AGE or placebo daily for 4 weeks with a 4 week washout period. Plasma HsCRP was measured as a marker of inflammation. Plasma TAOS, blood GSH/GSSG and plasma LHP were measured as markers of oxidative stress/anti-oxidant defense. Insulin resistance was measured using the HOMA-IR method. Endothelial function was measured using change in the reflective index (RI) post-salbutamol using digital photoplethysmography and urinary albumin/creatinine ratio was measured as a biochemical surrogate. Measurements were taken at baseline and after intervention with AGE or placebo.

RESULTS

Of the 26 patients studied (male 17, female 9), age was 61 ± 8 years (mean ± 1 SD), HbA1c 7.2 ± 1.1%, BP 130/75 ± 15.9/9.8 mmHg, total cholesterol 4.2 ± 0.81 mmol/l, triglyceride 2.11 ± 1.51 mmol/l, and HDL cholesterol 1.04 ± 0.29 mmol/l. The majority of patients were being treated with metformin (59%), aspirin (50%) and statin (96%) therapy. 36% were treated with an ACEI. There were no changes in these therapies throughout the study. Treatment with AGE had no significant effect upon the above metabolic parameters including insulin resistance. Treatment with AGE also had no significant effect on markers of endothelial function (plethysmography), oxidative stress (TAOS, GSH/GSSG, LHP) or inflammation (HsCRP).

CONCLUSION

In this group of type 2 diabetic patients at high cardiovascular risk, 4 weeks treatment with AGE did not significantly improve endothelial function, vascular inflammation, oxidative stress or insulin resistance.

Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review

BACKGROUND

Garlic has been shown to have cardiovascular protective and immunomodulatory properties.

OBJECTIVES

We updated a previous meta-analysis on the effect of garlic on blood pressure and reviewed the effect of garlic on cholesterol and immunity.

METHODS

We searched the Medline database for randomized controlled trials (RCTs) published between 1955 and December 2013 on the effect of garlic preparations on blood pressure. In addition, we reviewed the effect of garlic on cholesterol and immunity.

RESULTS

Our updated meta-analysis on the effect of garlic on blood pressure, which included 20 trials with 970 participants, showed a mean ± SE decrease in systolic blood pressure (SBP) of 5.1 ± 2.2 mm Hg (P < 0.001) and a mean ± SE decrease in diastolic blood pressure (DBP) of 2.5 ± 1.6 mm Hg (P < 0.002) compared with placebo. Subgroup analysis of trials in hypertensive subjects (SBP/DBP ≥140/90 mm Hg) at baseline revealed a larger significant reduction in SBP of 8.7 ± 2.2 mm Hg (P < 0.001; n = 10) and in DBP of 6.1 ± 1.3 mm Hg (P < 0.001; n = 6). A previously published meta-analysis on the effect of garlic on blood lipids, which included 39 primary RCTs and 2300 adults treated for a minimum of 2 wk, suggested garlic to be effective in reducing total and LDL cholesterol by 10% if taken for >2 mo by individuals with slightly elevated concentrations [e.g., total cholesterol >200 mg/dL (>5.5 mmol/L)]. Garlic has immunomodulating effects by increasing macrophage activity, natural killer cells, and the production of T and B cells. Clinical trials have shown garlic to significantly reduce the number, duration, and severity of upper respiratory infections.

CONCLUSIONS

Our review suggests that garlic supplements have the potential to lower blood pressure in hypertensive individuals, to regulate slightly elevated cholesterol concentrations, and to stimulate the immune system. Garlic supplements are highly tolerated and may be considered as a complementary treatment option for hypertension, slightly elevated cholesterol, and stimulation of immunity. Future long-term trials are needed to elucidate the effect of garlic on cardiovascular morbidity and mortality.

Garlic and Heart Disease

BACKGROUND

Thousands of studies have been published based on animal and human studies evaluating garlic's effects and safety.

OBJECTIVE

We reviewed the available literature investigating the effects of garlic supplements on hypertension, hypercholesterolemia, C-reactive protein (CRP), pulse wave velocity (PWV), and coronary artery calcium (CAC), as well as available data on side effects.

METHODS

We searched PubMed for all human studies using medical subject heading words through 30 May 2013 and assessed relevant review articles and original studies. Only double-blind, randomized, controlled trials and meta-analyses of double-blind, randomized, controlled trials were included. The review of articles and data extraction were performed by 2 independent authors, with any disagreements resolved by consensus.

RESULTS

Garlic supplementation reduced blood pressure by 7-16 mm Hg (systolic) and 5-9 mm Hg (diastolic) (4 meta-analyses and 2 original studies). It reduced total cholesterol by 7.4-29.8 mg/dL (8 meta-analyses). The most consistent benefits were shown in studies that used aged garlic extract (AGE). A few small studies that used AGE also showed favorable effects on CAC, CRP, and PWV. Although garlic is generally safe, rare adverse reactions have been documented with limited causality established.

CONCLUSION

We conclude that garlic supplementation has the potential for cardiovascular protection based on risk factor reduction (hypertension and total cholesterol) and surrogate markers (CRP, PWV, and CAC) of atherosclerosis. Larger studies are warranted to evaluate these effects further.

A review on the effects of Allium sativum (Garlic) in metabolic syndrome

The metabolic syndrome is a common problem world-wide and includes abdominal obesity, hypertension, dyslipidemia, and hyperglycemia disorders. It leads to insulin resistance and the development of diabetes mellitus or cardiovascular disease. Allium sativum (garlic) has been documented to exhibit anti-diabetic, hypotensive, and hypolipidemic properties. This suggests a potential role of A. sativum in the management of metabolic syndrome; however, more studies should be conducted to evaluate its effectiveness. In this review, we discussed the most relevant articles to find out the role of A. sativum in different components of metabolic syndrome and cardiovascular disease risk factors. Because human reports are rare, further studies are required to establish the clinical value of A. sativum in metabolic syndrome.

Salivary antioxidants of male athletes after aerobic exercise and garlic supplementation on: A randomized, double blind, placebo-controlled study

PURPOSE

Production of reactive oxygen species and reactive nitrogen species is a natural biological event in metabolism. However, the presence of antioxidants can highly reduce the negative effect of free radicals. Thus, the efficiency of antioxidant system in the physiology of exercise is very important.

DESIGN

Considering the known antioxidant capacity of garlic, the purpose of this study was to evaluate the effect on combining 14 days aerobic exercise till exhaustion with garlic extract supplementation on the antioxidant capacity of saliva.

METHODS

Sixteen young men volunteered to participate in this randomized, double blind, placebo-controlled study and were randomly placed into two groups, placebo (Group I) and garlic extract (Group II). The participants performed exhaustive aerobic exercise on a treadmill before and after supplementation. Their unstimulated salivary samples were collected before, immediately after, and 1 h after the activity. The antioxidant activity in terms of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) was then measured in the collected samples using their specific substrates.

RESULTS

A significant increase in salivary antioxidant activity of SOD, POD, and CAT was observed in saliva of the supplement group compared to the placebo group (P ≤ 0.05).

CONCLUSION

The findings from this study suggest that increased activity of antioxidant enzymes could possibly decrease exercise-induced oxidative damage in male athletes.

Dehydrodiconiferyl alcohol suppresses monocyte adhesion to endothelial cells by attenuation of JNK signaling pathway

Several clinical studies have shown that the intake of aged garlic extract improves endothelial dysfunction. Lignan compounds, (+)-(2S,3R)-dehydrodiconiferyl alcohol (DDC) and (-)-(2R,3S)-dihydrodehydrodiconiferyl alcohol (DDDC), have been isolated as antioxidants in aged garlic extract. There is evidence showing the importance of oxidative stress in endothelial dysfunction. In the present study, we examined whether DDC and DDDC enhance endothelial cell function in vitro. Cell adhesion assay was performed using THP-1 monocyte and human umbilical vein endothelial cells (HUVECs) which were activated by lipopolysaccharide (LPS) or advanced glycation end products (AGEs)-BSA. Cellular ELISA method was used for the evaluation of vascular cell adhesion molecule 1 (VCAM-1) expression on HUVECs. DDC and DDDC suppressed the adhesion of THP-1 to HUVECs which was activated by LPS or AGEs-BSA. DDC and DDDC also inhibited VCAM-1 expression induced by LPS or AGEs-BSA, but DDDC was less effective than DDC. In addition, the inhibitory effect of DDC on VCAM-1 expression involved suppressing JNK/c-Jun pathway rather than NF-κB pathway. DDC has an inhibitory effect on VCAM-1 expression via JNK pathway in endothelial cells and therefore may serve as a novel pharmacological agent to improve endothelial dysfunction.

A Systematic Review of the Efficacy of Bioactive Compounds in Cardiovascular Disease: Carbohydrates, Active Lipids and Nitrogen Compounds

Background/Aims: The prevalence of cardiovascular diseases (CVD) is rising and it is the prime cause of death in all developed countries. Bioactive compounds (BACs) can play a role in CVD prevention and treatment. To examine the scientific evidence supporting BACs groups' efficacy in CVD prevention and treatment, we conducted a systematized review. Methods: All available information on Medline, LILACS and EMBASE; all randomized controlled trials (RCTs) with prospective, parallel or crossover designs in humans in which the BACs effect was compared with that of placebo/control. Vascular homeostasis, blood pressure, endothelial function, oxidative stress and inflammatory biomarkers were considered primary outcomes. Results: We selected 26 articles, verifying their quality based on the Scottish Intercollegiate Guidelines Network, establishing diverse quality levels of scientific evidence according to the design and bias risk of a study. Grades of recommendation were included, depending on the evidence strength of antecedents. Conclusions: Evidence shows that certain BACs' derivative from active lipids and nitrogen compounds, mainly from horse chestnut seed extract, sterol plants, allium derivatives, and certain doses of beta-glucans, can be helpful in decreasing the prevalence of CVD risk factors. However, further rigorous evidence is necessary to support and prove BACs' effect on CVD prevention and treatment.

The effects of acute garlic supplementation on the fibrinolytic and vasoreactive response to exercise

Background

The purpose of this project was to examine the effects of acute garlic supplementation on fibrinolysis and vasoreactivity both at rest and following maximal exercise.

Methods

Eighteen healthy trained males (20.9 ± 2.2 years, 178 ± 7.7 cm, 75.5 ± 9.6 kg, VO₂max = 59.8 ± 6.7 ml • kg⁻¹ • min⁻¹) performed a graded treadmill test to volitional exhaustion. Blood samples were taken at rest, within two minutes post-exercise, and one hour post-exercise. Eleven of the subjects also had a brachial vasoreactivity test performed immediately after the blood sample to assess flow-mediated dilation (FMD) of the brachial artery. Participants were randomly assigned to ingest either 900 mg of powdered garlic or a placebo three hours before the exercise session. The supplement was distributed in a double-blind, crossover fashion. Participants repeated the protocol with the other treatment after a 14-day washout period. Paired t-tests were used to compare VO₂max between the two trials. A two-factor (treatment and time) repeated measures analysis of variance (ANOVA) was used to assess changes in FMD, tPA activity, tPA antigen, and PAI-1 activity. A priori statistical significance was set at P <0.05.

Results

VO₂max was greater for the garlic treatment trial vs. placebo (Placebo = 59.8 ± 6.7 ml • kg⁻¹ • min⁻¹; Garlic = 61.4 ± 6.6 ml • kg⁻¹ • min⁻¹). There was no main effect for treatment and no treatment x time interaction for FMD or any fibrinolytic variables examined.

Conclusion

Acute garlic supplementation does not alter vasoreactivity, fibrinolytic potential or the fibrinolytic response to exercise in young healthy trained males. Acute garlic supplementation does, however, cause a small but statistically significant increase in VO₂max. It remains unclear if this increase in VO₂max is of functional importance.

Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In the past decade, garlic has become one of the most popular complementary therapies for blood pressure (BP) control used by hypertensive patients. Numerous clinical studies have focused on the BP-lowering effect of garlic, but results have been inconsistent. Overall, there is a dearth of information available to guide the clinical community on the efficacy of garlic in hypertensive patients.

AIM

To systematically review the medical literature to investigate the current evidence of garlic for the treatment of hypertension.

METHODS

PubMed, the Cochrane Library and EMBASE were searched for appropriate articles from their respective inceptions until August 2014. Randomized, placebo-controlled trials comparing garlic vs. a placebo in patients with hypertension were considered. Papers were independently reviewed by two reviewers and were analyzed using Cochrane software Revman 5.2.

RESULTS

A total of seven randomized, placebo-controlled trials were identified. Compared with the placebo, this meta-analysis revealed a significant lowering effect of garlic on both systolic BP (WMD: -6.71 mmHg; 95% CI: -12.44 to -0.99; P = 0.02) and diastolic BP (WMD: -4.79 mmHg; 95% CI: -6.60 to -2.99; P < 0.00001). No serious adverse events were reported in any of the trials.

CONCLUSION

The present review suggests that garlic is an effective and safe approach for hypertension. However, more rigorously designed randomized controlled trials focusing on primary endpoints with long-term follow-up are still warranted before garlic can be recommended to treat hypertensive patients.

Effect of garlic on blood pressure: a meta-analysis

Garlic supplements are thought to reduce blood pressure (BP). The authors performed a meta-analysis to investigate garlic's effect on BP. Ovid Medline, Cochrane Library, and PubMed (1946 to November 2013) were used to search for randomized controlled trials. Seventeen trials were included. Pooled analysis showed that garlic intake caused a 3.75-mm Hg reduction (95% confidence interval [CI], -5.04 to -2.45, I(2) =30.7%; P<.001) in systolic BP and a 3.39-mm Hg reduction (95% CI, -4.14 to -2.65, I(2) =67%; P<.001) in diastolic BP compared with controls. Meta-analysis of subgroups showed a significant reduction in systolic BP in hypertensive (-4.4 mm Hg; 95% CI, -7.37 to -1.42, I(2) =0.0%; P=.004) but not normotensive patients. No significant reduction in diastolic BP was seen. After sensitivity analysis, heterogeneity disappeared and significant diastolic BP reduction (-2.68 mm Hg, 95% CI, -4.93 to -0.42, I(2) =0.0%; P=.020) was shown in hypertensive patients. This meta-analysis suggests that garlic supplements are superior to controls (placebo in most trails) in reducing BP, especially in hypertensive patients.

Improvement of symptoms of aging in males by a preparation LEOPIN ROYAL containing aged garlic extract and other five of natural medicines - comparison with traditional herbal medicines (Kampo)

"LEOPIN ROYAL®" (LER), a non-prescription health-promoting medication in Japan, is a preparation containing six natural medicines, namely, aged garlic extract, ginseng, oriental bezoar, velvet antler, cuscuta seed and epimedium herb. To determine the effect of LER on symptoms of aging in males, we conducted an open-labeled, randomized clinical trial using Kampo (mainly kamishoyosan) as a control. Forty-nine male patients (age, 62.7 (SD 11.8) years) with mild or more pronounced symptoms of aging were enrolled and randomly assigned to the LER (n = 24) or Kampo group (n = 25) for 6 months. The Aging Males' Symptoms (AMS) scale and the International Index of Erectile Function with 5 questions (IIEF-5) were tested at baseline, and after 3 and 6 months of administration of the medications. In the AMS scale, the somatic and psychological sub-scores and total score decreased depending on the time course in both groups. However, the decrease in the slope of the LER group was greater than that of the Kampo group. There was a significant difference between the groups and the group and month interaction (G × M), as revealed by a linear mixed model analysis (p < 0.05). The IIEF-5 score increased in the LER group (p = 0.02 with regard to G × M). In conclusion, the present results indicate that LER is possibly superior to mainly kamishoyosan on the rate of improvement of symptoms of aging, including erectile dysfunction, in males.