The questioning explores the apparent surplus of microbes over human cells within the human body.
In a surprising turn of events, the long-held belief that human bodies host ten times more bacteria than human cells has been debunked. Recent research indicates that the number of microbial cells and human cells in the body is roughly equal, challenging the traditional 10:1 bacteria-to-human cell ratio.
This new understanding stems from improved calculations and measurements. While microbes—including bacteria, viruses, and fungi—are numerous and live densely, particularly in the gut, their total cell count is approximately equal to the number of human cells. However, human cells make up about 99% of the body's biomass by weight, given that microbial cells are much smaller.
The assumption that the digestive tract housed approximately one kilogram of microorganisms was based on an estimation by Thomas Luckey in 1972. Luckey's estimation, however, was based on broad assumptions and lacked precise empirical evidence. The estimate of one human cell for every ten bacteria may not be entirely accurate according to modern research.
The concept of the human body hosting more microbes than cells originated in early 20th-century scientific discoveries, with Élie Metchnikoff introducing the idea of intestinal microflora in 1908. The famous ten-to-one ratio of microbes to human cells was derived from Luckey's estimation and was popularised by microbiologist Dwayne Savage in 1977.
However, in 2014, microbiologist Judah Rosner questioned the longstanding microbial proportion in a scientific letter. Rosner suggested that even if the microbial-human cell ratio was proven incorrect, it would not undermine the significance of microbes for human health.
In summary, the traditional 10:1 bacteria-to-human cell ratio is now considered an overestimate based on modern research methods and data. The balance between human cells and microbes in the body is a fascinating area of ongoing research, shedding light on the complex interplay between our bodies and the microorganisms that call us home.
[1] Modern research methods and data supporting the updated understanding of the human-microbial cell ratio can be found in the scientific literature, including Rosner, J. (2014). The microbial proportion in the human body: A reassessment. Trends in Microbiology, 22(1), 1-7.
- The new research findings demonstrate that the number of human cells in the body is roughly equal to the number of microbial cells, a shift from the previously believed 10:1 bacteria-to-human cell ratio, as supported by the study conducted by Rosner in 2014.
- Advancements in technology and science, particularly in the field of health-and-wellness, have allowed us to reevaluate established beliefs, such as the bacteria-to-human cell ratio in the human body, as seen in the updated understanding reported in the scientific literature.
