Increased species richness in the oral microbiome by a 13-week protein and combined lifestyle intervention in older adults with obesity and type 2 diabetes: abstract

Rationale: While combined lifestyle interventions have multiple health benefits, their impact on the oral microbiome is not known. We explored the effects of a lifestyle intervention including protein drink on the oral microbiome in older adults with obesity and type 2 diabetes (T2D). Methods: In a post-hoc analysis of the PROBE study, 87 subjects (66.5±6.1 years, 33% female) with tongue dorsum samples at baseline and week 13 were included. All subjects participated in a 13-week lifestyle intervention with exercise (3x/week) and hypocaloric diet (-600 kcal/day), and had been randomized to receive a test product (21g whey protein enriched with leucine and vitamin D) or isocaloric control (0g protein) 10x/week. T2D was subtyped as muscle insulin resistance (MIR, n=34) or no-MIR (n=36) based on available muscle insulin sensitivity index. Microbiome was analysed by V4 16s rDNA sequencing. Diversity, measured as species richness and Shannon diversity index, was statistically analysed with paired (within group) and independent (between groups) samples t-test. Results: In the MIR subgroup, species richness (baseline 73.1±19.1, wk13 88.1±24.9; p<0.001) and Shannon diversity index (baseline 2.8±0.3, wk13 3.0±0.3; p=0.01) increased significantly over time, and change in species richness was significantly different between test (+15.0±11.5) and control (+0.7±18.2) (p=0.01). On the whole group level, diversity did not change over time and did not differ between study groups. Change in species richness significantly correlated with change in BMI (r=-0.25, p=0.02) and change in fasting glucose (r=-0.28, p=0.01). Conclusion: Consuming a whey protein drink enriched with leucine and vitamin D during a combined lifestyle intervention increased species richness of the oral microbiome in obese T2D subjects with muscle insulin resistance.