Human gut microbiome research and diversity

Scientific research has increasingly focused on the human gut microbiome, specifically regarding its role in disease and its evolutionary history. Studies have explored the ‘microbiome–gut–lung axis,’ which suggests that intestinal microbiota can influence immune responses in the lungs and affect conditions such as asthma, COPD, cystic fibrosis, and pneumonia. However, researchers note that clinical observations have not yet established definitive causal relationships.

Comparative studies between traditional groups, such as the Hadza of Tanzania and the Tsimane of Bolivia, have identified over 1,200 shared bacterial species. These findings suggest that high microbial diversity may have been a long-standing human trait, as approximately 60 percent of these species are rare or absent in industrialized populations. Lower microbial diversity in urbanized societies is often associated with increased rates of obesity, type 2 diabetes, and autoimmune diseases.

Additionally, analysis of DNA sequences from hundreds of thousands of microbiome samples has revealed the presence of the Epulopiscium genus, known as ‘giant bacteria.’ While these bacteria typically comprise only 1-2 percent of identified sequences, they can reach up to 20 percent in certain cases. Their exact role in humans is unknown, but their presence may serve as an indicator of gut flora imbalance.