Natural Garlic Organosulfur Compounds Prevent Metabolic Disorder of Lipid and Glucose by Increasing Gut Commensal Bacteroides acidifaciens.

A number of reports of the effects of garlic on gut microbiota revealed that the active garlic organosulfur compounds (OSCs) are destabilized by the action of alliinase during garlic preparation. In this study, garlic alliinase was deactivated to obtain stable garlic OSCs. Experiments with C57BL/6J mice fed with lipid and glucose metabolic disorder-inducing Western diet (WD) revealed that stable garlic OSCs prevented the disorder by increasing the relative abundance of gut Bacteroides acidifaciens. Molecular analysis indicated that garlic OSCs inhibited dyslipidemia and fatty liver by increasing taurine and subsequently promoting hepatic fatty acid ß-oxidation. In parallel, garlic OSCs could meliorate glucose homeostasis by inhibiting dipeptidyl peptidase-4 (DPP-4) and hepatic gluconeogenesis. In vitro bacterial culture experiments revealed that garlic OSCs directly increased the growth of gut Bacteroides acidifaciens. The results of this study demonstrate that the molecular mechanism of the preventive effect of garlic OSCs on the WD-induced metabolic disorder is attributed to the enhanced growth of Bacteroides acidifaciens and the consequent increase in taurine.

Modulation of Allicin-Free Garlic on Gut Microbiome.

The allicin diallyldisulfid-S-oxide, a major garlic organosulfur compound (OSC) in crushed garlic (Allium sativum L.), possesses antibacterial effects, and influences gut bacteria. In this study, we made allicin-free garlic (AFG) extract and investigated its effects on gut microbiome. C57BL/6N male mice were randomly divided into 6 groups and fed normal diet (ND) and high-fat diet (HFD) supplemented with or without AFG in concentrations of 1% and 5% for 11 weeks. The genomic DNAs of feces were used to identify the gut microbiome by sequencing 16S rRNA genes. The results revealed that the ratio of p-Firmicutes to p-Bacteroidetes increased by aging and HFD was reduced by AFG. In particular, the f-Lachnospiraceae, g-Akkermansia, and g-Lactobacillus decreased by aging and HFD was enhanced by AFG. The g-Dorea increased by aging and HFD decreased by AFG. In addition, the ratio of glutamic-pyruvic transaminase to glutamic-oxaloacetic transaminase (GPT/GOT) in serum was significantly increased in the HFD group and decreased by AFG. In summary, our data demonstrated that dietary intervention with AFG is a potential way to balance the gut microbiome disturbed by a high-fat diet.

Preventive Effects and Mechanisms of Garlic on Dyslipidemia and Gut Microbiome Dysbiosis.

Garlic (Allium sativum L.) contains prebiotic components, fructans, antibacterial compounds, and organosulfur compounds. The complex ingredients of garlic seem to impart a paradoxical result on the gut microbiome. In this study, we used a mouse model to clarify the effects of whole garlic on the gut microbiome. C57BL/6N male mice were fed with or without whole garlic in normal diet (ND) or in high-fat diet (HFD) for 12 weeks. Supplementation with whole garlic attenuated HFD-enhanced ratio of serum GPT/GOT (glutamic-pyruvic transaminase/glutamic-oxaloacetic transaminase), levels of T-Cho (total cholesterol) and LDLs (low-density lipoproteins), and index of homeostatic model assessment for insulin resistance (HOMA-IR), but had no significant effect in the levels of serum HDL-c (high density lipoprotein cholesterol), TG (total triacylglycerol), and glucose. Moreover, garlic supplementation meliorated the HFD-reduced ratio of villus height/crypt depth, cecum weight, and the concentration of cecal organic acids. Finally, gut microbiota characterization by high throughput 16S rRNA gene sequencing revealed that whole garlic supplementation increased the α-diversity of the gut microbiome, especially increasing the relative abundance of f_Lachnospiraceae and reducing the relative abundance of g_Prevotella. Taken together, our data demonstrated that whole garlic supplementation could meliorate the HFD-induced dyslipidemia and disturbance of gut microbiome.

Intake of black-vinegar-mash-garlic enhances salivary release of secretory IgA: A randomized, double-blind, placebo-controlled, parallel-group study.

Several previous studies have provided evidence that suggests the beneficial effects of garlic and black vinegar on human health, including benefits to immune function. The preliminary study indicated that the intake of black-vinegar-mash-garlic-containing food, created from aged garlic pickled in the mash of black vinegar, enhanced the release of secretory immunoglobulin A (sIgA) in the saliva. The aim of the present study was to evaluate the effect of the food in a randomized, double-blind, placebo-controlled, parallel-group trial. The trial was conducted in subjects aged between 30 and 60 years whose rate of salivary sIgA release was moderately low. Subjects consumed 2.49 g of placebo or black-vinegar-mash-garlic-containing food (active food) daily for 8 weeks. The data obtained with 54 eligible subjects (n=28 and 26 for placebo and active, respectively) were analyzed for efficacy. The rates of salivary sIgA release in the active food group (35.9±84.6 and 47.9±123.4 µg/min at weeks 4 and 8 of intake; changes from pretrial value) were higher compared to the respective rates in the placebo food group (-12.3±72.1 and -3.2±85.9 µg/min, P=0.028 and 0.082, respectively). These findings indicate that intake of black-vinegar-mash-garlic-containing food enhanced the intraoral immune response. There was no adverse event associated with the intake of active food.

Inhibitory effects and molecular mechanisms of garlic organosulfur compounds on the production of inflammatory mediators.

SCOPE: Garlic is used for both culinary and medicinal purposes by many cultures. The garlic organosulfur compounds (GOSCs) are thought to be bioactive components. This study aims to clarify the antiinflammatory effects and molecular mechanisms of GOSCs in both cell and animal models. METHODS AND RESULTS: RAW264.7 cells were treated with six kinds of GOSCs to screen their influence on cyclooxygenase-2 and inducible nitric oxide synthase expression by Western blotting. Prostaglandin E2 and nitrite were measured by ELISA and Griess reaction, respectively. Cytokines in culture medium were assayed by the multiplex technology. Proteins were detected by Western blotting. Mouse paw edema was induced by LPS. The results revealed that diallyl trisulfide (DATS) was a strongest inhibitor for cyclooxygenase and inducible nitric oxide synthase among GOSCs, and reduced the levels of LPS-induced IL-6, IL-10, IL-12(p70), KC, MCP-1, and TNF-α. Cellular signaling analysis revealed that DATS downregulated AKT1/TGF-ß-activated kinase-mediated mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. Furthermore, DATS activated Nrf2-mediated expression of HO-1 and NQO1 and reduced LPS-induced intracellular reactive oxygen species, which may contribute to suppress inflammatory mediator production. Finally, in vivo data demonstrated that DATS attenuated LPS-induced mouse paw edema. CONCLUSION: DATS as a potential inhibitor revealed antiinflammatory effect in both cell and animal models by downregulating AKT1/TGF-ß-activated kinase-mediated NFκB and MAPK signaling pathways.

Effect of a traditional Japanese garlic preparation on blood pressure in prehypertensive and mildly hypertensive adults.

Numerous clinical studies have used differing garlic preparations leading to controversial results with regard to the hypotensive effect of garlic. This randomized, double-blind, placebo-controlled study was designed to determine the effect of a traditional Japanese garlic homogenate-based supplementary diet (GH diet) product on blood pressure (BP) in subjects with prehypertension and in those with mild hypertension. In total, 34 eligible subjects with prehypertension and 47 with mild hypertension were treated with a daily dose of GH diet (300 mg as dried garlic homogenate; n=16 and 23, respectively) or placebo (n=18 and 24, respectively) for 12 weeks. Of these, 32 prehypertensive subjects (15 on the GH diet and 17 on the placebo) and 40 mildly hypertensive subjects (19 on the GH diet and 21 on the placebo) completed the study and were subjected to efficacy analyses. Systolic and diastolic BPs were monitored at weeks 4, 8 and 12 during the treatment and at post-week 4 following the termination of the treatment. The GH diet induced significant reductions of systolic BP (of between 6.6 and 7.5 mmHg) and diastolic BP (of between 4.6 and 5.2 mmHg) compared with the placebo subsequent to 8 and 12 weeks of treatment. A 12-week intake of the GH diet did not cause any clinically problematic side-effects. We conclude that the GH diet was well tolerated, and had a clinically relevant hypotensive effect in adults with mild hypertension, but not in those with prehypertension.

Effect of a glucosamine-based combination supplement containing chondroitin sulfate and antioxidant micronutrients in subjects with symptomatic knee osteoarthritis: A pilot study.

In the present study, we aimed to investigate the potential effect of a glucosamine (1,200 mg/day)-based dietary supplement combined with chondroitin sulfate and three antioxidant micronutrients, namely methylsulfonylmethane, guava leaf extract, and vitamin D (test supplement) on osteoarthritis (OA) of the knee. A 16-week, randomized, double-blinded, placebo-controlled trial was conducted involving 32 subjects with symptomatic knee OA. Clinical outcomes were measured using the Japanese Knee Osteoarthritis Measure (JKOM) for symptoms and a study diary-based visual analog scale (diary VAS) for pain at baseline and at weeks 4, 8, 12 and 16 during the 16-week intervention period. Furthermore, biomarkers for cartilage type II collagen degradation (C2C) and synovitis hyaluronan (HA) were measured. As compared with the baseline, the JKOM pain subscale was significantly improved at all of the four assessment time points in the test group, but was not at any time point in the placebo group. On the other hand, all of the four symptom subscales and the aggregated total symptoms were significantly improved in the two groups at one or more time points. However, all of these clinical improvements were greater in extent in the test group than in the placebo group, and there were significant differences between groups in the magnitude of changes from baseline for one subscale 'general activities' and the aggregated total symptoms at week 8 (P<0.05). The results of efficacy assessments with the diary VAS showed that all of the three pain subscales were significantly improved only in the test group at almost all the time points. Moreover, serum levels of C2C and HA were decreased by 10 and 25%, respectively, at week 16 in the test group, albeit not statistically significant, without any detectable changes in the placebo group. In conclusion, although the results obtained in this study were not conclusive, the tested glucosamine-based combination supplement is likely to have a beneficial effect on pain and other symptoms associated with knee OA.