The Roles of Garlic on the Lipid Parameters: A Systematic Review of the Literature

Allyl methyl disulfide (AMDS) prevents N,N-dimethyl formamide-induced liver damage by suppressing oxidative stress and NLRP3 inflammasome activation

N,N-dimethylformamide (DMF), a widely consumed industrial solvent with persistent characteristics, can induce occupational liver damage and pose threats to the general population due to the enormous DMF-containing industrial efflux and emission from indoor facilities. This study was performed to explore the roles of allyl methyl disulfide (AMDS) in liver damage induced by DMF and the underlying mechanisms. AMDS was found to effectively suppress the elevation in the liver weight/body weight ratio and serum aminotransferase activities, and reduce the mortality of mice induced by DMF. In addition, AMDS abrogated DMF-elicited increases in malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels and decreases in glutathione (GSH) levels in mouse livers. The increase in macrophage number, mRNA expression of M1 macrophage biomarkers, and protein expression of key components in the NF-κB pathway and NLRP3 inflammasome induced by DMF exposure were all suppressed by AMDS in mouse livers. Furthermore, AMDS inhibited DMF-induced cell damage and NF-κB activation in cocultured AML12 hepatocytes and J774A.1 macrophages. However, AMDS per se did not significantly affect the protein level and activity of CYP2E1. Collectively, these results demonstrate that AMDS effectively ameliorates DMF-induced acute liver damage possibly by suppressing oxidative stress and inactivating the NF-κB pathway and NLRP3 inflammasome.

The nutritional value, bioactive availability and functional properties of garlic and its related products during processing

Garlic, a common culinary spice, is cultivated and used around the globe. Consumption of garlic and its supplements reduces the risk of diabetes and cardiovascular disease and boosts the immune system with antibacterial, antifungal, anti-aging, and anti-cancer properties. Diallyl sulfide, diallyl disulfide, triallyl trisulfide, phenolics, flavonoids, and others are the most commercially recognized active ingredients in garlic and its products. In recent years, global demand for medicinal or functional garlic has surged, introducing several products such as garlic oil, aged garlic, black garlic, and inulin into the market. Garlic processing has been demonstrated to directly impact the availability of bioactive ingredients and the functionality of products. Depending on the anticipated functional qualities, it is also recommended that one or a combination of processing techniques be deemed desirable over the others. This work describes the steps involved in processing fresh garlic into products and their physicochemical alterations during processing. Their nutritional, phytochemical, and functional properties are also reviewed. Considering the high demand for functional food, this review has been compiled to provide guidance for food producers on the industrial utilization and suitability of garlic for new product development.

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.

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.

The association of garlic intake and cardiovascular risk factors: A systematic review and meta-analysis

Garlic is a common cooking ingredient and used in traditional medicine in Asian countries. There is a growing attention on garlic due to its preventive characteristics in cardiovascular diseases (CVDs). Many studies have reviewed the association between garlic intake and CVDs; however, no consistent conclusions have been drawn. New clinical trials have also been conducted and could contribute to more solid statements. In order to systematically review the reliability of previous studies regarding the implication of garlic in the management of CVDs, we performed in-depth meta-analysis using the most up-to-date randomized clinical trials (RCTs) data with more systematic controls. According to the 22 studies included, the effects of garlic intake on lowering total cholesterol (TC) and low-density lipoprotein (LDL) are more noticeable with lower dosage and longer duration, especially in patients with CVDs. In addition, subgroup analysis indicated that appropriate diet intervention could be an important control factor that should be taken into consideration in any future study designs.

Hepatoprotective effect of diallyl trisulfide against lipopolysaccharide and D-galactosamine induced acute liver failure in mice via suppressing inflammation and apoptosis

Acute liver failure (ALF), characterized by the quick occurrence of disorder in liver, is a serious liver injury with extremely high mortality. Therefore, we investigated whether diallyl trisulfide (DATS), a natural product from garlic, protected against ALF in mice and studied underlying mechanisms. In the present study, lipopolysaccharide (LPS) (10 μg·kg^-1)/D-galactosamine (D-gal) (500 mg·kg^-1) was intraperitoneally injected to ICR mice to induce ALF. The mice were orally administered 20-, 40-, or 80-mg·kg^-1 DATS) 1 h before LPS/D-gal exposure. Serum biochemical analyses and pathological study found that DATS pretreatment effectively prevented the ALF in LPS/D-gal-treated mice. Mechanistically, pretreatment of DATS inhibited the increase of the numbers of CD11b⁺ Kupffer cells and other macrophages in the liver, the release of tumor necrosis factor-α into the blood, and Caspase-1 activation induced by LPS/D-gal treatment in mice. Furthermore, DATS inhibited the activation of Caspase-3, downregulation of Bcl-2/Bax ratio, and increase of TUNEL positive staining. Altogether, our findings suggest that DATS exhibits hepatoprotective effects against ALF elicited by LPS/D-gal challenge, which probably associated with anti-inflammation and anti-apoptosis.

Garlic oil blocks tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis by inducing phase II drug-metabolizing enzymes

Lung cancer caused one-quarter of all cancer deaths that was more than other cancers. Chemoprevention is a potential strategy to reducing lung cancer incidence and death, and the effective chemopreventive agents are needed. We investigated the efficacy and mechanism of garlic oil (GO), the garlic product, in the chemoprevention of tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung cancer in A/J mice and MRC-5 cell models in the present study. As a result, it was demonstrated that GO significantly inhibited the NNK-induced lung cancer in vivo and protected MRC-5 cells from NNK-induced cell damage. GO could induce the expressions of the phase II drug-metabolizing enzymes, including NAD(P)H: quinone oxidoreductase 1 (NQO-1), glutathione S-transferase alpha 1 (GSTA1), and antioxidative enzymes heme oxygenase-1 (HO-1). These results supported the potential of GO as a novel candidate agent for the chemoprevention of tobacco carcinogens induced lung cancer.

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.

Effect of garlic powder supplementation on hepatic steatosis, liver enzymes and lipid profile in patients with non-alcoholic fatty liver disease: a double-blind randomised controlled clinical trial

Non-alcoholic fatty liver disease (NAFLD) includes a range of disorders from simple steatosis to non-alcoholic steatohepatitis. There is no proven drug treatment for NAFLD, and diet modification is considered part of the main line of treatment for this disease. The aim of this study was to investigate the efficacy of garlic supplementation in NAFLD patients. The effect of garlic powder supplementation on hepatic steatosis, liver enzymes and lipid profile was investigated in NAFLD patients. Ninety NAFLD patients were randomly assigned to take either a garlic powder supplement or a placebo for 12 weeks. The treatment group received four tablets of garlic daily (each tablet contained 400 mg garlic powder). The control group received four tablets of placebo (each placebo contained 400 mg starch). At the end of the study, hepatic steatosis was significantly reduced in the treatment group compared with the control group (P = 0·001). In addition, a significant decrease was seen in the serum concentration of alanine transaminase (P < 0·001), aspartate transaminase (P = 0·002), γ-glutamyltransferase (P = 0·003) as well as total cholesterol (P = 0·009), TAG (P < 0·001), HDL-cholesterol (P < 0·001) and LDL-cholesterol (P = 0·01) in the treatment group compared with the control group. No significant difference was seen between the two groups in serum concentration of alkaline phosphatase. Overall, garlic powder supplementation improved hepatic features and lipid profile among NAFLD patients.

Allium Jesdianum Extract Improve Acetaminophen-Induced Hepatic Failure through Inhibition of Oxidative/Nitrosative Stress

Objectives

Allium jesdianum (Aj) is a medicinal plant that has highlighted pharmacological features. In this study, the effects of Aj extract were examined on acetaminophen (APAP)-induced hepatic failure in rats.

Methods

Methanolic fraction of hydro-alcoholic extract of Aj was obtained by silica gel column chromatography method. Animals were randomly divided into four groups each containing six rats and treated by gavage as follows: the first and second groups received normal saline, the third and fourth groups were received with 50 and 100 mg/kg of Aj extract, respectively. After two consecutive weeks, the groups 2–4 were given a single dose of APAP (2 g/kg). After 48 hours, blood and liver samples were collected for biochemical and histological examinations.

Results

The findings of the study demonstrated that APAP caused a significant increase in ALT (P < 0.001), AST (P < 0.001), LDH (P < 0.001), ALP (P < 0.001) serum levels, hepatic lipid peroxidation (LPO; P < 0.001) and nitric oxide (NO; P < 0.001). In this regard, APAP led to the depletion of the total antioxidant capacity (TAC; P < 0.001), glutathione and total thiol groups (TTGs; P < 0.001), and structural change in the liver. In the Aj extract groups, a considerable improvement was found in the hepatic function alongside the histopathologic changes.

Conclusion

This investigation indicated that the influential effects of Aj extract in APAP-induced hepatic failure might depend on its effect on improving oxidant/antioxidant balance in hepatic tissue.

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 Consumption and All-Cause Mortality among Chinese Oldest-Old Individuals: A Population-Based Cohort Study

In vitro and in vivo experimental studies have shown garlic has protective effects on the aging process; however, there is no evidence that garlic consumption is associated with all-cause mortality among oldest-old individuals (≥80 years). From 1998 to 2011, 27,437 oldest-old participants (mean age: 92.9 years) were recruited from 23 provinces in China. The frequencies of garlic consumption at baseline and at age 60 were collected. Cox proportional hazards models adjusted for potential covariates were constructed to estimate hazard ratios (HRs) relating garlic consumption to all-cause mortality. Among 92,505 person-years of follow-up from baseline to September 1, 2014, 22,321 participants died. Participants who often (≥5 times/week) or occasionally (1–4 times/week) consumed garlic survived longer than those who rarely (less than once/week) consumed it (p < 0.001). Participants who consumed garlic occasionally or often had a lower risk for mortality than those who rarely consumed garlic at baseline; the adjusted HRs for mortality were 0.92(0.89–0.94) and 0.89(0.85–0.92), respectively. The inverse associations between garlic consumption and all-cause mortality were robust in sensitivity analyses and subgroup analyses. In this study, habitual consumption of garlic was associated with a lower all-cause mortality risk; this advocates further investigation into garlic consumption for promoting longevity.

Allyl methyl trisulfide protected against acetaminophen (paracetamol)-induced hepatotoxicity by suppressing CYP2E1 and activating Nrf2 in mouse liver

In order to investigate the protective effects of allyl methyl trisulfide (AMTS) on acetaminophen (APAP)-induced hepatotoxicity, 75 KM mice were randomized into 5 groups, i.e. a control group, an APAP group, and three AMTS/APAP groups.

Biomarkers of food intake for Allium vegetables

Allium vegetables are widely consumed around the world and are known for their potential bioactive components improving human health. These effects have been extensively investigated; however, the results were inconsistent in human studies. Biomarkers of food intake (BFIs) could provide objective measurements of food intake in observational studies and assess compliance in intervention studies. Therefore, the discovery and application of BFIs for Allium vegetables would facilitate the exploring and understanding of the health benefit of Allium vegetables. In this manuscript, we reviewed the currently used and potential candidate BFIs for Allium vegetables and evaluated their levels of validation. S-Allylmercapturic acid (ALMA), allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO), allyl methyl sulfone (AMSO2), and S-allylcysteine (SAC), which are derived from organosulfur compounds, were shown to be promising candidate BFIs for garlic consumption. Further validation is needed to assess their robustness and concordance with other measures. Their applicability for the whole food group should be evaluated as well. N-Acetyl-S-(2-carboxypropyl)cysteine (CPMA) was detected in high levels in urine after both garlic and onion intake, suggesting that it may be used for the assessment of intake of Allium food group. The available information regarding its kinetics, robustness, and analytical performance is limited and needs to be assessed in further studies. No candidate BFIs specific to intake of onion, leek, chives, shallots, or ramsons were found. Untargeted metabolomics studies and further validation studies should be performed to discover more reliable BFIs for individual Allium vegetables and the whole food group. This paper serves as an example of Biomarker of Food Intake Reviews (BFIRev) and biomarker of food intake validation procedures.

Targeting Nrf-2 is a promising intervention approach for the prevention of ethanol-induced liver disease

Alcoholic liver disease (ALD) remains to be a worldwide health problem. It is generally accepted that oxidative stress plays critical roles in the pathogenesis of ALD, and antioxidant therapy represents a logical strategy for the prevention and treatment of ALD. Nuclear factor erythroid-derived 2-like 2 (NFE2L2 or Nrf-2) is essential for the antioxidant responsive element (ARE)-mediated induction of endogenous antioxidant enzymes such as heme oxygenase 1 (HO-1) and glutamate-cysteine ligase [GCL, the rate-limiting enzyme in the synthesis of glutathione (GSH)]. Activation of Nrf-2 pathway by genetic manipulation or pharmacological agents has been demonstrated to provide protection against ALD, which suggests that targeting Nrf-2 may be a promising approach for the prevention and treatment of ALD. Herein, we review the relevant literature about the potential hepatoprotective roles of Nrf-2 activation against ALD.

Allicin Bioavailability and Bioequivalence from Garlic Supplements and Garlic Foods

Allicin is considered responsible for most of the pharmacological activity of crushed raw garlic cloves. However, when garlic supplements and garlic foods are consumed, allicin bioavailability or bioequivalence (ABB) has been unknown and in question because allicin formation from alliin and garlic alliinase usually occurs after consumption, under enzyme-inhibiting gastrointestinal conditions. The ABB from 13 garlic supplements and 9 garlic foods was determined by bioassay for 13 subjects by comparing the area under the 32-h concentration curve of breath allyl methyl sulfide (AMS), the main breath metabolite of allicin, to the area found after consuming a control (100% ABB) of known allicin content: homogenized raw garlic. For enteric tablets, ABB varied from 36–104%, but it was reduced to 22–57% when consumed with a high-protein meal, due to slower gastric emptying. Independent of meal type, non-enteric tablets gave high ABB (80–111%), while garlic powder capsules gave 26–109%. Kwai garlic powder tablets, which have been used in a large number of clinical trials, gave 80% ABB, validating it as representing raw garlic in those trials. ABB did not vary with alliinase activity, indicating that only a minimum level of activity is required. Enteric tablets (high-protein meal) disintegrated slower in women than men. The ABB of supplements was compared to that predicted in vitro by the dissolution test in the United States Pharmacopeia (USP); only partial agreement was found. Cooked or acidified garlic foods, which have no alliinase activity, gave higher ABB than expected: boiled (16%), roasted (30%), pickled (19%), and acid-minced (66%). Black garlic gave 5%. The mechanism for the higher than expected ABB for alliinase-inhibited garlic was explored; the results for an alliin-free/allicin-free extract indicate a partial role for the enhanced metabolism of γ-glutamyl S-allylcysteine and S-allylcysteine to AMS. In conclusion, these largely unexpected results (lower ABB for enteric tablets and higher ABB for all other products) provide guidelines for the qualities of garlic products to be used in future clinical trials and new standards for manufacturers of garlic powder supplements. They also give the consumer an awareness of how garlic foods might compare to the garlic powder supplements used to establish any allicin-related health benefit of garlic.

Calcification of the heart: mechanisms and therapeutic avenues

INTRODUCTION

Coronary artery calcification (CAC) is reflective of atherosclerotic disease and incrementally predictive of future cardiovascular events (CVE), independent of traditional risk factors. Extra coronary calcium such as aortic valve calcification, which can be identified and quantified by computed tomography (CT) imaging, has shown to predict future CVE in both asymptomatic and symptomatic (i.e. stable angina and acute coronary syndrome [ACS]) settings. It has hence been a vital tool in studies involving new therapies for cardiovascular disease. Areas covered: In this review, promising therapies on the horizon are reviewed, along with the role of cardiac CT and coronary calcification in these studies. A Medline search for peer-reviewed publications using keywords related to coronary calcium score, aortic valve calcium, and therapies targeting the same was carried out. Expert commentary: CT scanning provides a distinct means of detecting and quantifying coronary plaque as well as valvular calcification with excellent reproducibility. Based on voluminous data available, the absence of coronary calcium serves as a factor to de-risk patients for cardiovascular risk stratification and management algorithms. Newer therapies have shown to lower progression of coronary calcification, thus being beneficial in slowing progression of atherosclerotic disease. As British Epidemiologist Geoffrey Rose states, the best predictor of a life-threatening disease is the early manifestation of that disease. As CAC represents the early manifestation of atherosclerosis, it is the best-known stratifier of risk today, and its clinical use will continue to rise.

Diallyl trisulfide attenuated n-hexane induced neurotoxicity in rats by modulating P450 enzymes

Chronic exposure to n-hexane can induce serious nerve system impairments without effective preventive medicines. Diallyl trisulfide (DATS) is a garlic-derived organosulfur compound, which has been demonstrated to have many beneficial effects. The current study was designed to evaluate whether DATS could restrain n-hexane induced neurotoxicity in rats and to explore the underlying mechanisms. Rats were treated with n-hexane (3 g/kg, p.o.) and different doses of DATS (10, 20 and 30 mg/kg, p.o.) for 8 weeks. Behavioral assessment showed that DATS could inhibit n-hexane induced neurotoxicity, demonstrated by the improvement of the grip strength and decline of gait scores. Toxicokinetic analysis revealed that the C_max and AUC_0-t of 2,5-hexanedione (product of n-hexane metabolic activation) and 2,5-hexanedione protein adducts in serum were significantly declined in DATS-treated rats, and the levels of pyrrole adducts in tissues were significantly reduced. Furthermore, DATS activated CYP1A1 and inhibited n-hexane induced increased expression and activity of CYP2E1 and CYP2B1. Collectively, these findings indicated that DATS protected the rats from n-hexane-induced neurotoxicity, which might be attributed to the modulation of P450 enzymes by DATS.

An umbrella review of garlic intake and risk of cardiovascular disease

PURPOSE

To gain further insight into the strength of evidence and extent of possible biases in the scope of studies investigating the impact of garlic and garlic supplement intake on biomarkers of cardiovascular disease, we performed an umbrella review of all published meta-analyses synthesizing data from both observational studies and randomized controlled trials.

METHODS

Electronic database PubMed (between 1966 and June 2015) was searched for systematic reviews and meta-analyses using following search terms: ("garlic" OR "allium sativum" OR "allicin" OR "organosulfur") AND ("cardiovascular" OR "coronary" OR "cholesterol" OR "triglyceride" OR "atherosclerosis" OR "blood pressure" OR "hypertension" OR "blood glucose") AND ("systematic review" OR "meta-analysis"), with no restriction to calendar data and language. Hand-search of reference lists and relevant clinical guidelines was performed as well.

RESULTS

Nine systematic reviews investigated the effects of garlic on lipid parameters and eight systematic reviews analyzed the effects on blood pressure parameters were identified. Eight of nine meta-analyses synthesizing the effect of garlic on blood lipids reported significantly decreased total cholesterol levels. Inconsistent results could be detected for HDL-cholestrol, LDL-cholesterol, and triacylglycerols. The effect of garlic on systolic blood pressure showed consistent results across publications with 7 out of 8 meta-analyses demonstrating a substantial decrease in systolic blood pressure. Similar results could be reported regarding the effect of garlic on diastolic blood pressure, i.e. 6 out of 8 meta-analyses detected significant reductions in diastolic blood pressure levels following interventions with garlic.

CONCLUSION

According to the data summarized in the present umbrella review, garlic preparations as well as garlic exerted some positive effects on indicators and biomarkers of cardiovascular disease, typically without causing any serious side effects. However, with regard to the substantial heterogeneities between the different trials enrolled in the various meta-analyses of this review, a conservative interpretation of the outcome seems to be appropriate.

Diallyl trisulfide protects the liver against hepatotoxicity induced by isoniazid and rifampin in mice by reducing oxidative stress and activating Kupffer cells

Background & Aim: Diallyl trisulfide (DATS) has been verified to ameliorate hepatotoxicity induced by many drugs, but the protective actions of isoniazid (INH) and rifampicin (RFP) have not been reported. We attempted to elucidate the potential effects and mechanisms of DATS against INH&RFP-caused hepatotoxicity. Methods: Male Kunming mice weighing 18-22 g were divided into 6 groups. For the hepatic-protective study, DATS (10 mg per kg, 20 mg per kg, and 40 mg per kg bw, respectively) was orally administered two hours before the INH&RFP (100 mg per kg, 100 mg per kg bw, respectively) treatments. After 11 days of treatment, 10 mice in each group were taken for the carbon clearance test, while the other 10 mice were sacrificed for the collection of serum and livers for further measurements, including the levels of serum alanine aminotransferase (ALT), aspartate transaminase (AST) and total bilirubin (T.Bili), the liver index, and liver histopathological examination. Malondialdehyde (MDA), glutathione (GSH), and the level of interleukin 1-β (IL-1-β) were measured, the carbon clearance test was performed and the immunohistochemistry of F4/80 marker for activated Kupffer cells (KCs) was analyzed to investigate potential mechanisms. Results: DATS co-administration significantly inhibited the increase of liver index and elevation of serum ALT, AST and T.Bili levels induced by INH&RFP, as well as improved the hepatocellular structure. The further mechanistic studies demonstrated that DATS co-administration counteracted INH&RFP-induced oxidative stress in mice, which was illustrated by the restoration of GSH levels, and the reduction of MDA levels in the liver. Furthermore, DATS co-administration reactivated the KCs inhibited by INH&RFP, which was illustrated by the increase of carbon phagocytosis, and the restoration of the number of activated KCs and IL-1-β levels in the liver. Conclusion: DATS effectively protected the liver against INH&RFP-induced hepatotoxicity, which might be due to its antioxidant effect and enhancement of KCs' activities.

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.

Garlic Oil Suppressed Nitrosodiethylamine-Induced Hepatocarcinoma in Rats by Inhibiting PI3K-AKT-NF-κB Pathway

To explore the underlying mechanisms for the protective effects of garlic oil (GO) against nitrosodiethylamine (NDEA)-induced hepatocarcinoma, 60 male Wistar rats were randomized into 4 groups (n=15): control group, NDEA group, and two GO plus NDEA groups. The rats in GO plus NDEA groups were pretreated with GO (20 or 40 mg/kg) for 7 days. Then, all rats except those in control group were gavaged with NDEA for 20 weeks, and the rats in GO plus NDEA groups were continuously administered with GO. The results showed that GO co-treatment significantly suppressed the NDEA-induced increases of alpha fetal protein (AFP) level in serum, nuclear atypia in H&E staining, sirius red-positive areas and proliferating cell nuclear antigen (PCNA) expression. The molecular mechanisms exploration revealed that the protein levels of phosphatidylinositol 3 kinase (PI3K)-p85, PI3K-p110, total AKT, p-AKT (Ser473) and p-AKT (Thr308) in the liver of NDEA group rats were higher than those in control group rats. In addition, NDEA treatment induced IκB degradation and NF-κB p65 phosphorylation, and up-regulated the protein levels of downstream pro-inflammatory mediators. GO co-treatment significantly reversed all the above adverse effects induced by NDEA. These results suggested that the protective effects of GO against NDEA-induced hepatocarcinoma might be associated with the suppression of PI3K- AKT-NF-κB pathway.

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.

The role of phytochemicals as micronutrients in health and disease

PURPOSE OF REVIEW

Intake of dietary phytochemicals has frequently been associated with health benefits. Noninfectious diseases including cardiovascular disease (CVD), cancer and diabetes are major causes of death, whereas dementia cases are also increasing to 'epidemic' proportion. This review will focus on recent progress on mechanisms underlying the potential role of dietary phytochemicals in CVD, diabetes, cancer and dementia, with consideration of the latest clinical data.

RECENT FINDINGS

The association of tea (Camellia sinensis), particularly catechins, with reported mechanistic effects for CVD, diabetes, cancer and cognition contributes to our understanding of the suggested benefits of tea consumption on health from limited and inconclusive clinical trial and epidemiological data. Resveratrol, which occurs in grapes (Vitis vinifera) and wine, and curcumin, a component of turmeric (Curcuma longa), are also emerging as potentially relevant to health, particularly for CVD and dementia, with some promising data also concluded for curcumin in cancer. Other phytochemicals mechanistically relevant for health include anthocyanins, isoflavones and glucosinolates, which are also discussed.

SUMMARY

Evidence for the role of phytochemicals in health and disease is growing, but associations between phytochemicals and disease need to be more firmly understood and established from more robust clinical data using preparations that have been phytochemically characterized.

Protective effects of garlic oil on hepatocarcinoma induced by N-nitrosodiethylamine in rats

To investigate the protective effects and the possible mechanisms of garlic oil (GO) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinoma in rats, Wistar rats were gavaged with GO (20 or 40 mg/kg) for 1 week, and then were gavaged with GO and NDEA (10 mg/kg) for the next 20 weeks. The changes of morphology, histology, the biochemical indices of serum, and DNA oxidative damage of liver were examined to assess the protective effects. Lipid peroxidation (LPO), antioxidant defense system, and apoptosis-related proteins were measured to investigate potential mechanisms. At the end of the study (21 weeks), GO administration significantly inhibited the increase of the nodule incidence and average nodule number per nodule-bearing liver induced by NDEA, improved hepatocellular architecture, and dramatically inhibited NDEA-induced elevation of serum biochemical indices (alanine aminotransferase , aspartate aminotransferase, alkaline phosphatase and gamma-glutamyl transpeptidase) and hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in a dose-dependent manner. The mechanistic studies demonstrated that GO counteracted NDEA-induced oxidative stress in rats illustrated by the restoration of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) levels, and the reduction of the malondialdehyde (MDA) levels in liver. Furthermore, the mRNA and protein levels of Bcl-2, Bcl-xl, andβ-arrestin-2 were significantly decreased whereas those of Bax and caspase-3 were significantly increased. These data suggest that GO exhibited significant protection against NDEA-induced hepatocarcinogenesis, which might be related with the enhancement of the antioxidant activity and the induction of apoptosis.