Butyric acid concentration is associated with Firmicutes bacteria abundance after dairy intake among hyperinsulinemic individuals

Karine Greffard, Mickael Leclercq, Arnaud Droit, Jean-François Bilodeau, Iwona Rudkowska

Endocrinology and Nephrology Unit, CHU de Québec-Laval University Research Center, Québec (QC), Canada; Endocrinology and Nephrology Unit, CHU de Québec-Laval University Research Center, Québec (QC), Canada; Endocrinology and Nephrology Unit, CHU de Québec-Laval University Research Center, Québec (QC), Canada; Endocrinology and Nephrology Unit, Centre de recherche du CHU de Québec – Université Laval ; Endocrinology and Nephrology Unit, Centre de recherche du CHU de Québec – Université Laval

Objective/hypothesis: To investigate the association between short-chain fatty acids (SCFA) and gut microbiota after consumption of a high-dairy compared to an adequate-dairy intake among individuals with hyperinsulinemia.

Methods: Participants were randomized in a two-phase crossover study according to high-dairy (≥4 servings/day (Canada’s Food Guide for Healthy Eating (2007)) or adequate-dairy intake (≤2 servings/day) for 6 weeks. SCFA concentrations were measured in stool samples by headspace gas chromatography-mass spectrometry using a HP-Innowax column. Gut microbiome was measured by high-throughput sequencing of the 16S-rRNA gene fragments. Paired-T test and machine learning (ML) analyses were performed on the data.

Results: Ten individuals with hyperinsulinemia were included in this study (mean± SD: BMI 31.9 ±2.9 kg/m2; age 58 ±13 years). Gut microbiome composition did not change significantly between high- and adequate-dairy intakes; however, the abundance of Firmicutes was positively correlated to insulin sensitivity. Results showed that SCFA including acetic acid (162 ±134 versus 132±170 mmol/kg), propionic acid (11±6 versus 8±4 mmol/kg) and butyric acid (9 ±4 versus 9±6 mmol/kg) did not change after high-dairy compared to adequate intake, respectively. ML analysis (which included age, sex, and BMI as features before feature selection) found that butyric acid concentration can be predicted by the abundance of Firmicutes phylum bacteria including Clostridium-sensu, Turicibacter, Romboutsia, Tyzzerella, Lachnospiracea, Incertae-sedis, and Faecalitalea.

Conclusion: Results showed that butyric acid concentration could be linked to the abundance of Firmicutes bacteria which may modify insulin sensitivity in hyperinsulinemic individuals. Registration number: NCT02961179. (Financial support: Canadian Institutes for Health Research).