Samples and techniques highlighting the links between obesity and microbiota.

Area of Science:

• Microbiology
• Human Health
• Metagenomics

Background:

• Gut microbiota composition is linked to human health and obesity.
• Current methods using stool samples and next-generation sequencing can yield contradictory results.
• Nutrient absorption primarily occurs in the stomach and small intestine, areas often overlooked in gut microbiota studies.

Purpose of the Study:

• To address the challenges in studying the gut microbiota and its relation to obesity.
• To highlight the limitations of current methodologies, particularly the reliance on stool samples.
• To advocate for a comprehensive approach combining molecular and culture-dependent techniques.

Main Methods:

• Comprehensive review of nutrient absorption processes.
• Analysis of bariatric surgery outcomes related to weight loss and intestinal resections.
• Discussion of biases in metagenomics studies (e.g., extraction, primer, depth biases).
• Evaluation of culturomics as a complementary high-throughput culture-dependent technique.

Main Results:

• Nutrient absorption occurs mainly in the stomach and small intestine.
• Bariatric surgery affecting the upper intestine leads to weight loss, unlike colonic surgery.
• Metagenomics studies face inherent biases, and stool samples may not fully represent the gut environment.

Conclusions:

• Accurate analysis of gut microbiota in obesity requires studying both small intestine and stool samples.
• Combining metagenomics with culture-dependent methods like culturomics is essential for comprehensive insights.
• Large-scale studies are needed to elucidate the complex gut microbiota-obesity relationship.