Assessing Relationships Between Dietary Intake, Gut Microbiota and Weight Among a Diverse Cohort of College Freshmen
Authors: Journey Elizabeth , Hotz Ricci‐Lee , Bruening Meg , Whisner Corrie M 
Published: November 2023

Obesity is a growing problem in the United States, and the transition to college has been identified as a vulnerable period for weight gain and the onset of obesity. The intestinal microbiota have been shown to change with obesity and dietary factors, playing a role in energy harvesting from the host's diet as well as the metabolism of nutrients. The purpose of this study was to characterize the intestinal microbiome in order to explore associations between the intestinal microbiome, weight status, and diet in healthy college students living on‐campus. A total of 90 racially and ethnically diverse students participated in this cross‐sectional study by providing 24‐hour dietary recalls, anthropometric measurements, and one fecal sample collected within a week of completing all other measurements. Fecal samples were analyzed by high‐throughput bacterial 16S rRNA gene sequencing. Gut microbial abundance values were assessed statistically at phylum and genus levels. Phylum‐related analyses included the use of the Firmicutes:Bacteroidetes (F:B) ratio with genus‐level assessments performed using multivariate regression following data reduction by principal components analysis. Additional statistical analyses included Pearson and Spearman correlations. Participants were racially and ethnically diverse with 31.1%, 41.1%, 7.8%, 10% and 8.9% self‐identifying as Hispanic/Latino/Spanish, non‐Hispanic White, non‐Hispanic Black, non‐Hispanic Asian and mixed race/ethnicity, respectively. Anthropometric measurements showed a mean BMI of 24.4 ± 5.3 kg/m2 and dietary analysis showed a mean caloric intake of 1684 ± 947 kcals/day within the sample population. Analysis of bacterial communities revealed four predominant phyla and 12 predominant families accounting for 99.3% and 97.1% of overall microbial communities, respectively. Bacteroidetes (57.2 ± 11.4%), Firmicutes (24.3 ± 9.9%), Proteobacteria (6.0± 3.9%) and unassigned (11.8 ± 5.4%) microbes with the four most abundant phyla. Principal components analysis revealed that one principal component, impacted most heavily by 23 microbial genera (primarily from the phylum Firmicutes), was significantly associated with BMI (R2=0.053, p=0.0301). Among the 23 genera, Lactococcus, Parvimonas, and varying Clostridiales were identified as important contributors. Lactococcus and Clostridiales have been associated with fermentation and substrate utilization which may limit the availability of energy‐yielding substrate to the host. Parvimonas has been shown to have pathogenic effects which may increase inflammation and obesity risk. No significant correlations were observed when assessing the F:B ratio in relation to BMI or habitual dietary intake. Results from this study provide a baseline for intestinal microbiome research in college students and suggest that specific microbial genera may contribute to obesity. Further longitudinal research is needed to assess these associations over time. Pre‐ and probiotic interventions could also be implemented as a possible means to moderate weight gain during this vulnerable life stage.

Support or Funding Information

Project number 1DP5OD017910‐01 (PI: Bruening) was funded by the NIH Office of the Director and the Office of Behavioral and Social Sciences Research.