Relationship between Blood Glucose and Lipid Levels and Intestinal Bifidobacterium in Middle-Aged and Older Adults in Chengdu

  Objective  To explore characteristics of the species structure of the genus Bifidobacterium at different levels of blood glucose and lipid in middle-aged and older adults in Chengdu so as to provide research basis for applying bifidobacteria in the prevention and treatment of hyperglycemia and dyslipidemia.

  Methods  A total of 289 middle-aged and older adults of 45 and older were recruited in Chengdu between April and August 2018. They were divided into the healthy group, the dyslipidemia group, the hyperglycemia group, and the combination group (of subjects with both dyslipidemia and hyperglycemia). The levels of their fasting blood glucose (GLU), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were examined. In addition, stool samples were collected and real-time fluorescence quantitative PCR was used for quantitative analysis of the genus Bifidobacterium and the 8 bifidobacteria most commonly found in human intestines, the results of which were then examined to identify their correlation to blood glucose and lipid levels.

  Results   A total of 289 samples were collected and findings of inter-group comparison of the species structure of Bifidobacterium were as follows: 1) findings regarding the Bifidobacterium species examined--there was no significant difference between groups in the detection rate and the number of species detected; the quantity of B. angulatum was significantly higher in the dyslipidemia group than that in the healthy group and that in the combination group, the quantify of B. catenulatum was significantly higher in the hyperglycemia group than that in the healthy group, and the quantity of B. dentium was significantly higher in the dyslipidemia group than that in the combination group. 2) Findings regarding the correlation between the quantity of bifidobacteria and blood glucose and lipid--at the genus level, only the dyslipidemia group showed negative correlation (r=−0.346) between Bifidobacterium and TC. At the species level, B. bifidum was negatively correlated with TG (r=−0.761), B. breve was negatively correlated with GLU, TC, and LDL-C (r=−0.256, r=−0.261, and r=−0.362), B.dentium was positively correlated with GLU (r=0.206), and B. infantis was negatively correlated with TC (r=−0.334) in the healthy group. In the hyperglycemia group, B. catenulatum and B. infantis were both positively correlated with HDL-C (r=0.307 and r=0.525). In the combination group, B. bifidum was negatively correlated with HDL-C (r=−0.828), while B. breve was positively correlated with TG and HDL-C (r=0.427 and r=0.375).

  Conclusion   Middle-aged and older adults with dyslipidemia and/or hyperglycemia were significantly different from healthy subjects in their testing results for Bifidobacterium. Compared with the structure of Bifidobacterium species, the changes in the number of Bifidobacterium species detected were more closely correlated to the levels of blood glucose and blood lipid, showing unique characteristics in different situations, which may indicate potential application as indicators for glucose and lipid metabolism.