Human Biology, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Universiteitssingel 40, 6229 ET Maastricht, the Netherlands.
Benef Microbes. 2021 Jun 15;12(3):259-266. doi: 10.3920/BM2020.0179. Epub 2021 Apr 21.
The gut microbiota may affect host metabolic health through microbial metabolites. The balance between the production of microbial metabolites by saccharolytic and proteolytic fermentation may be an important determinant of metabolic health. Amongst the best-studied saccharolytic microbial metabolites are the short-chain fatty acids acetate, propionate and butyrate. However, human data on the role of other microbial fermentation by-products in metabolic health are greatly lacking. Therefore, we compared in a cross-sectional study the faecal microbial metabolites (caproate, lactate, valerate, succinate, and the branched-chain fatty acids (BCFA) (isobutyrate, isovalerate)) between insulin sensitive (homeostatic model assessment of insulin resistance (HOMA-IR), HOMA-IR<1.85, IS) and insulin resistant (HOMA-IR>1.85, IR) individuals. Additionally, we assessed the relationships between faecal metabolites and markers of metabolic health including fasting glucose, insulin, free fatty acids, insulin resistance (HOMA-IR) and fasting substrate oxidation in 86 individuals with a wide range of body mass index. Faecal metabolite concentrations did not significantly differ between IS and IR. Furthermore, there were no associations between microbial metabolites and metabolic health markers, except for a slight positive association of isovalerate with carbohydrate oxidation (E%, 0.194, =0.011) and fat oxidation (E%, -0.075, =0.047), also after adjustment for age, sex and BMI. In summary, faecal caproate, lactate, valerate, succinate, and BCFA (isobutyrate, isovalerate) were not different between IR and IS individuals, nor was there any association between these faecal metabolites and parameters of metabolic health. Further human intervention studies are warranted to investigate the role of these microbially-derived fermentation products and their kinetics in metabolic health and insulin sensitivity.
肠道微生物群可能通过微生物代谢物影响宿主的代谢健康。糖分解和蛋白分解发酵产生的微生物代谢物之间的平衡可能是代谢健康的一个重要决定因素。在研究最充分的糖分解微生物代谢物中，有短链脂肪酸（乙酸盐、丙酸盐和丁酸盐）。然而，人类关于其他微生物发酵副产物在代谢健康中的作用的数据非常缺乏。因此，我们在一项横断面研究中比较了胰岛素敏感（稳态模型评估的胰岛素抵抗（HOMA-IR），HOMA-IR<1.85，IS）和胰岛素抵抗（HOMA-IR>1.85，IR）个体之间粪便微生物代谢物（己酸盐、乳酸盐、戊酸盐、琥珀酸盐和支链脂肪酸（BCFA）（异丁酸、异戊酸））。此外，我们评估了粪便代谢物与代谢健康标志物之间的关系，包括 86 名个体的空腹血糖、胰岛素、游离脂肪酸、胰岛素抵抗（HOMA-IR）和空腹底物氧化，这些个体的体重指数范围很广。IS 和 IR 之间粪便代谢物浓度没有显著差异。此外，微生物代谢物与代谢健康标志物之间没有关联，除了异戊酸与碳水化合物氧化（E%，0.194，=0.011）和脂肪氧化（E%，-0.075，=0.047）之间有轻微的正相关，调整年龄、性别和 BMI 后也是如此。总之，IR 和 IS 个体之间粪便己酸、乳酸盐、戊酸盐、琥珀酸盐和 BCFA（异丁酸、异戊酸）没有差异，这些粪便代谢物与代谢健康参数之间也没有关联。需要进一步的人体干预研究来研究这些微生物衍生的发酵产物及其在代谢健康和胰岛素敏感性中的动力学作用。
