A recent study in Nature Microbiology debunks several myths about the human microbiome, emphasizing the importance of evidence-based research. Key misconceptions include the age of the field, the origin of the term “microbiome,” and exaggerated figures about bacterial cell counts and microbiota weight. Correcting these inaccuracies is crucial for scientific progress and public trust.
The human microbiome, the vast collection of microorganisms living in and on our bodies, has been a hot topic in scientific research for the past two decades. However, a recent study published in Nature Microbiology highlights that this surge in interest has also led to the spread of several myths and misconceptions. These inaccuracies can undermine both scientific progress and public trust in microbiome research.
Myth: Microbiome Research is a New Field
One of the most persistent myths is that microbiome research is a new field. While it’s true that the pace of research has accelerated in the past 15 years, the field itself is far from new. Studies on human-associated microorganisms date back to the late 19th century. For instance, Escherichia coli was first isolated in 1885, and bifidobacteria were described in 1899. The concept of beneficial gut microorganisms was even speculated by Metchnikoff in the early 1900s. This rich history is often overshadowed by the advent of high-throughput DNA-sequencing technologies, but acknowledging these early contributions is crucial for a comprehensive understanding of the field.
Myth: Joshua Lederberg Coined the Term “Microbiome”
Another common misconception is the claim that Nobel laureate Joshua Lederberg coined the term “microbiome.” This myth has been thoroughly debunked, with evidence showing that the term was used in its modern context more than a decade before Lederberg first used it in 2001. This serves as a reminder of how easily falsehoods can become entrenched in scientific literature.
Myth: 1012 Bacterial Cells per Gram of Human Feces
The study also debunks the widely cited figure that there are 1012 bacterial cells per gram of human feces. This number is often mentioned but is incorrect. The actual figure, determined through various methods like direct cell counts and quantitative polymerase chain reaction (qPCR), is typically between 1010 and 1011 microbial cells per gram of wet-weight feces. This discrepancy highlights the importance of verifying data before it becomes widely accepted.
Myth: Human Microbiota Weighs 1 to 2 Kilograms
Similarly, the claim that the human microbiota weighs between 1 to 2 kilograms is also unfounded. Despite being frequently mentioned in literature, the study found no original source for this claim. More accurate estimates place the weight closer to 200 to 500 grams. This correction is crucial for understanding the true scale and impact of the microbiome on human health.
Implications of These Myths
These myths are not just trivial inaccuracies; they have real implications for how we understand and study the microbiome. For example, the belief that the microbiome outnumbers human cells by a ratio of 10:1 originated from a simplistic 1972 paper. More recent estimates place the ratio at approximately 1:1. This correction is important for accurately assessing the microbiome’s role in human health.
Myth: Probiotics Universally Prevent Antibiotic-Associated Diarrhea
Moreover, the idea that probiotics can universally prevent antibiotic-associated diarrhea is another oversimplification. While probiotics are often marketed for this purpose, specific effective strains and dosages are not yet determined. This underscores the need for more rigorous, evidence-based research to substantiate health claims related to the microbiome.
Complexity of the Microbiome’s Relationship with Diseases
The study also highlights the complexity of the microbiome’s relationship with diseases. While changes in the microbiome are associated with various conditions, they are not definitively proven to cause them. Most diseases are not caused solely by microbiome disturbances; their exact relationships are complex and poorly understood. This nuanced understanding is essential for developing effective treatments and interventions.
Dynamic Nature of the Microbiome
Interestingly, the study also points out that the diversity of the microbiome changes over a person’s lifetime, increasing until adulthood and declining with age. This dynamic nature of the microbiome further complicates efforts to link it directly to specific health outcomes.
The recent study in Nature Microbiology serves as a critical reminder of the importance of evidence-based claims in microbiome research. By debunking these myths, the study aims to foster a more accurate and nuanced understanding of the human microbiome. As the field continues to grow, it is essential to base knowledge on solid evidence to ensure both scientific progress and public trust. For more detailed insights, you can read the full study here.