Does gut microbiome profile differ in obese individuals?

In a study published in The American Journal of Gastroenterology, researchers examined the variation in small bowel microbiome profiles between obese individuals and those of normal weight.

Obesity is associated with increased risks of a wide variety of diseases, including cardiovascular diseases, metabolic syndrome, type 2 diabetes (T2D), and certain cancers. Worldwide, obesity contributes to an estimated 2.8 million deaths annually.

Imbalances in gut microbial populations have repeatedly been reported in patients with obesity-related diseases. Recent research has indicated that individuals with lower bacterial richness and gene content tend to have a higher inflammatory phenotype, along with conditions like obesity and insulin resistance. Little is known about differences in the small bowel microbiome between obese and non-obese individuals, despite previous research. Understanding this link is vital for understanding the gut microbiome's role in obesity and developing targeted interventions.

In the study, subjects aged 18-80, undergoing upper endoscopy were categorized by BMI: normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), and obese (BMI >30), following Centers for Disease Control and Prevention guidelines. A post-screening step excluded those with diabetes, gastric bypass history, weight control medication use, or recent antibiotics. Samples were collected from duodenal aspirates and serum, along with assessments of microbial metabolic functions and serum biomarkers.

Direct analysis of the duodenal microbiome identified key genera associated with overweight and obesity, including some previously identified in stool, e.g., Bifidobacterium and Lactobacillus. Specific species and strains that exhibit differing associations with overweight and obesity were also identified.

The findings revealed microbial species associated with overweight and obesity. "Escalation" features from normal weight to obesity included reduced Bacteroides pyogenes and Staphylococcus hominis, and decreased biogenic amine metabolism potential. "De-escalation" features from normal weight to overweight and overweight to obesity involved changes in Lactobacillus acidophilus, Lactobacillus hominis, and Bifidobacterium dentium, potentially impacting obesity.

"We identify small bowel microbial species associated with overweight and obesity, as well as escalation and de-escalation features that could potentially be selected as therapeutic targets. These findings illustrate that, although stool studies can and have provided very valuable data, direct analysis of the small bowel has yielded specific targets for further study," said the authors.

Reference: Leite, Gabriela PhD; Barlow, Gillian M. PhD; Characterization of the Small Bowel Microbiome Reveals Different Profiles in Human Subjects Who Are Overweight or Have Obesity. The American Journal of Gastroenterology ():10.14309/ajg.0000000000002790, April 22, 2024. | DOI: 10.14309/ajg.0000000000002790