Aged garlic extract ameliorates fatty liver and insulin resistance and improves the gut microbiota profile in a mouse model of insulin resistance

Abstract

Aged garlic extract (AGE) produced by the aging process has various beneficial pharmacological effects. In this study, the effects of AGE on fatty liver, insulin resistance and intestinal microbiota were compared between ddY-H mice, an insulin resistance mouse, and ddY-L mice, normal mice. Mice were fed an AGE-supplemented diet (4% w/w) for 7 weeks. The administration of AGE had no effect on the body weight and dietary intake of both types of mice. In the ddY-H mice, the serum levels of glucose and insulin were increased and glucose tolerance was impaired; however, the administration of AGE ameliorated these abnormal conditions. AGE did not have these effects in ddY-L mice. Triglyceride (TG) accumulation in the liver and fat absorption from the digestive tract were increased in the ddY-H mice; however, the administration of AGE reduced this increase. On the other hand, AGE exerted no such effects in the ddY-L mice. In addition, the gut microbiota has been shown to be closely associated with obesity, diabetes, dyslipidemia and non-alcoholic fatty liver disease in human and animal models. The bacterial composition of the gut microbiota in the feces of the ddY-H mice did not differ from that of the ddY-L mice at 5 weeks of age; however, it was altered in the mice at 9 and 12 weeks of age even when the mice were fed a standard diet. In the ddY-H mice, the relative presence of Lactobacillales was increased, while that of Bifidobacterium, Clostridium cluster XVIII and Prevotella was decreased. The alteration of the bacterial composition in the ddY-H mice was reversed by the administration of AGE; however, this effect of AGE was not observed in the ddY-L mice. On the whole, the findings of this study indicate that AGE improves abnormal fat accumulation and insulin resistance, and also alters the intestinal flora in ddY-H mice, suggesting the possibility that these effects of AGE may be related.

Synergistic effects of black ginseng and aged garlic extracts for the amelioration of nonalcoholic fatty liver disease (NAFLD) in mice

“…Owing these effects, increased attention is being given to ginsenosides for long‐term glycemic control. In another study when AGE was administered, the serum glucose levels were found to be lowered in hyperglycemic mice (Maeda et al., 2019). In addition, Seo et al., (2012) suggested that intake of AGE lowered homocysteine levels in postmenopausal women.…”

“…The serum level of TG in HFD mice was higher than that of other groups ( p <.05). BGE (Park et al., 2020) and AGE (Maeda et al., 2019) have been reported to exhibit profound effect on the regulation of lipid metabolism. This could be attributed to the increased carnitine content in BGE and AGE.…”

“…Garlic, a well‐known medicinal food, possess various biological activities that include antimicrobial, antitumor, antithrombotic, and antioxidant (Maeda et al., 2019). Aged black garlic extract (AGE) is produced by extraction process using water–ethanol mixture followed by aging at room temperature.…”

“…Aged black garlic extract (AGE) is produced by extraction process using water–ethanol mixture followed by aging at room temperature. During processing, molecules that cause undesirable flavors (allicin) are converted to compounds (S‐allylcysteine (SAC), S‐allylmercaptocysteine (SAMC), and S‐1‐propenylcysteine (S1PC)) that not only have higher stability but also improved antioxidant activity (Maeda et al., 2019; Miki et al., 2017). Particularly, SAC has been shown to ameliorate NAFLD in rats with diabetes (type 2) (Takemura et al., 2013).…”

Effects of garlic powder supplementation on metabolic syndrome components, insulin resistance, fatty liver index, and appetite in subjects with metabolic syndrome: A randomized clinical trial

“…Garlic improves atherosclerosis and hypertension, inhibits platelet aggregation, and increases fibrinolytic activity (Chan, Yuen, Chan, & Chan, 2013). Research findings suggest that garlic has beneficial effects on dyslipidemia and insulin resistance (Heidarian, Jafari‐Dehkordi, & Seidkhani‐Nahal, 2011; Maeda, Miki, Morihara, & Kagawa, 2019). Garlic as a prebiotic increases the growth and activity of health‐promoting bacteria in the gut (Filocamo, Nueno‐Palop, Bisignano, Mandalari, & Narbad, 2012; Ried, Travica, & Sali, 2018).…”