Investigation into the effects of dietary emulsifiers on gut microbiota, mucus layer and metabolism

• Main Authors: Chih-Ting Chang, 張芷婷
• Other Authors: 沈立言
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/8ced49

碩士 === 國立臺灣大學 === 食品科技研究所 === 107 === Emulsifiers are common food additives used in various kinds of food product. Recent studies reported that two emulsifiers (carboxymethylcellulose, CMC; polysorbate 80, P80) could cause intestinal inflammation and metabolic syndrome by attenuation of intestinal mucus layer as well as increased the gut epithelial permeability to increase the lipopolysaccharide level. Once the high level of lipopolysaccharides in GI tract may induce the inflammation of intestinal cell. One of possible reasons progress the metabolic syndrome and colitis. However, we do not know if other commonly used emulsifiers such as mono- and diglycerides, lecithin and sucrose fatty acid esters could lead to similar health concerns. Thus, the current study is to investigate the effects of emulsifiers on gut microbiota and whether the intervention of the emulsifiers could cause the gut microbiota dysbiosis and via the mucus layer has the impact to host. Because of the property of emulsifiers, the study was divided into two parts. Based on the hydrophile-lipophile balance (HLB) value. In first part, mice experiment was conducted by using fifteen-week-old male C57BL/6 mice fed with chow diet and supplemented by lecithin (7523 mg/kg bw/day), sucrose fatty acid esters (1110 mg/kg bw/day), and carboxymethylcellulose (1853 mg/kg bw/day) in water for 12 weeks. The dosages of intervention are based on human daily exposure of these emulsifiers reported in the literature. The results of the first part showed the body weight of mice treated with emulsifiers were slightly increased without significant difference. There was no significant finding on fat mass, intestinal permeability, colon length and histopathology analysis as compared with the control group. It means no clue for inducing symptom of colitis. Observation the bacteria localization and measurement the mucus layer thickness, there is no microbiota encroachment and mucus layer thinning. However, emulsifier treatments (excluding lecithin) impaired glycemic control as assessed by fasting blood glucose concentration and serum insulin concentration. Our data suggest that sucrose fatty acid esters and CMC might induce metabolic disorder. In addition, 16S rRNA metagenomic analysis showed the gut microbiota compositions were altered by emulsifiers in cecum content. Significantly, we found that Akkermansia spp. Are much higher in sucrose fatty acid esters group. However, no significant differences were observed in alpha diversity. Another part of experiment was supplementation with mono- and diglycerides (40 mg/kg) in customized feeding. After intervention for 12 and 24 weeks, mice were sacrificed. Organs and blood were collected for subsequent analysis. In this part, the body weight and fat mass in the mono- and diglycerides group were significantly decreased. The results of gut permeability test, colon length and OGTT test which were no significant differences were observed between groups. Our data suggested there is no potential for colitis and metabolic syndrome. Analyzed bacteria localization at the surface of the intestinal mucosa and measured the thickness of mucus layer. The emulsifier-treated mice did not show microbiota encroachment and mucus layer thinning. The 16S rRNA metagenomics analysis revealed that mono- and diglycerides dramatically altered microbiota composition, which assessed by principal coordinate analysis. However, mono- and diglycerides administration did not reduced the alpha diversity. Our results suggest that common dietary emulsifiers can shape the microbiome composition, but did not cause mucus layer thinning, not necessarily cause metabolic disorder or intestinal inflammation in mouse model but exist potential risk for glucose metabolic disorder.