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Variations in bacterial genera in the small bowel of those spanning normal weight to obesity suggest a correlation between the gut microbiome and weight.

According to a study published in The American Journal of Gastroenterology, variations exist in specific bacterial genera in the small bowels of individuals of normal weight, individuals who are overweight, and individuals with obesity. The findings suggest a correlation between gut microbiome composition and weight.

For this study, participants were recruited from the Revealing the Entire Intestinal Microbiota and its Associations with the Genetic, Immunologic, and Neuroendocrine Ecosystem (REIMAGINE) study. REIMAGINE comprised individuals 18 to 80 years old undergoing standard-of-care upper endoscopy without colon preparation who provided serum and duodenal aspirate samples.

Researchers investigated the duodenal microbiome and serum biomarkers in 214 study participants. The participants were stratified by BMI into three groups: normal weight (n=105), overweight ( n=67), and obesity (n=42). The researchers examined small bowel microbiomes, employing specimens obtained from esophagogastroduodenoscopies, blood samples, and patient questionnaires.

Small Bowel Microbial Species Associated With Weight

Key findings reported by the authors include:

• Compared with normal weight, the duodenal microbiome is meaningfully transformed in overweight and obesity.
• Specific microbial alterations are overweight specific or obesity specific; others are escalation or de-escalation features.
• Bifidobacterium dentium is a de-escalation feature in harmony with recognized antiobesity effects.
• Variations in Lactobacillus gasseri and decreased L reuteri are obesity specific, but L acidophilus and L hominis are de-escalation features.
• Specific Lactobacillus species are associated with type IIa dyslipidemia, and Alloprevotella rava is associated with type IIb and IV dyslipidemias.

“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,” the researchers wrote.

Importance of Microbiome Changes

“A key finding was that one bacterial population, Lactobacillus, in the duodenum exhibited differing and highly species-specific associations in subjects classified as overweight or having obesity,” Gabriela Leite, PhD, lead author of the study and lead project scientist for Cedars-Sinai’s Medically Associated Science and Technology (MAST) Program, said in a press release. “These microbiome changes related to weight gain may be of particular importance because many people regularly consume Lactobacillus-containing products, including dairy-based foods, probiotics, and certain vegan cuisine such as fermented tempeh.”