The Microbiota Unveiled: 5 Common Myths Debunked

The Microbiota Unveiled: 5 Common Myths Debunked

Kevin Meza Achahue, Scientist - R&D Specialist at Bifidice. 2 minutes reading.

Despite its importance, a significant percentage of people fail to be informed about the microbiota. For example, a survey conducted in the United States showed that two-thirds of Americans are not familiar with the concept of "gut microbiota." In fact, the same survey mentions that 71% of Americans do not know that antibiotics can kill beneficial bacteria for health, in addition to pathogenic ones, and that 60% of respondents do not know that food sensitivities are not the same as food allergies [1]. What are other common myths about the microbiota? Here are some of them.

1. The microbiota is limited to the gastrointestinal tract.

Although the largest concentration of human microbiota is found in the colon, this is just one of several populations of microorganisms in the human body [2][3]. Other populations of microbiota include those found on the skin, in the mouth, and in the urogenital tract, encompassing approximately 1013 to 1014 cells [4].

2. The bacteria in our body outnumber human cells by over 10 times.

The belief that bacteria in the body's microbiota outnumber human cells by 10 times arises from a widely cited but no longer accurate estimate from a 1972 study by microbiologist Thomas Luckey [5]. Recent research shows that, in reality, the number of bacteria in the body is nearly on the same order as human cells, in a range of 1:1 [6].

3. All bacteria are "bad."

It is a common mistake to think that all bacteria are pathogens. In reality, the majority of bacteria are harmless, and in some cases, they can provide health benefits. According to the Agency for Healthcare Research and Quality, "less than one percent of the different types (of bacteria) cause diseases in people" [7]. Many types of bacteria are essential for our body's functions, aiding in food digestion, competing against pathogenic organisms [8], and promoting tissue repair [9].

4. The microbiota changes slowly.

Recent studies have shown that the microbiota can exhibit rapid changes both autonomously and in response to external factors [10]. For example, a study published in Nature found that it takes only 3 or 4 days for diet changes to have effects on the intestinal microbiota [11]. Other factors, such as age, can also lead to changes in the microbiota, although they have variable timelines and can be influenced by environmental factors, both personal and external [12].

5. Only diet can change the microbiota.

Despite the importance of diet in the characteristics of the intestinal microbiota, there are other factors that can influence its composition, such as antibiotic use, age, geographic location, lifestyle, among others [13]. There is consensus that the administration of probiotics can be important for the modulation of the intestinal microbiota [14][15].

As Bifidice, we are committed to the teaching and communication of the latest scientific advances on microorganisms. Understanding these myths and realities is crucial to promote accurate information about the microbiota and overall health.


[1] MDVIP (2023), Two-Thirds of Americans Are Living With Gut Issues, Unaware of the Health Consequences. Cision Pr Newswire. 

[2] Dieterich, W., Schink, M., & Zopf, Y. (2018). Microbiota in the Gastrointestinal Tract. Medical Sciences (Basel), 6(4), 116.

[3] Thursby, E., & Juge, N. (2017). Introduction to the human gut microbiota. Biochemical Journal, 474(11), 1823–1836.

[4] Hou, K., Wu, Z.-X., Chen, X.-Y., Wang, J.-Q., Zhang, D., Xiao, C., Zhu, D., Koya, J. B., Wei, L., Li, J., & Chen, Z.-S. (2022). Microbiota in health and diseases. Signal Transduction and Targeted Therapy, 7(1), 135.

[5] Abbott, A. (2016). Scientists bust myth that our bodies have more bacteria than human cells. Nature. 

[6] Sender, R., Fuchs, S., & Milo, R. (2016). Revised Estimates for the Number of Human and Bacteria Cells in the Body. PLoS Biology, 14(8), e1002533. 

[7] Effective Health Care Program (2022). Bacterial Infections. Agency for Healthcare Research and Quality. 

[8] Milani, C., Duranti, S., Bottacini, F., Casey, E., Turroni, F., Mahony, J., Belzer, C., Palacio, S. D., Montes, S. A., Mancabelli, L., Lugli, G. A., Rodriguez, J. M., Bode, L., de Vos, W., Gueimonde, M., Margolles, A., van Sinderen, D., & Ventura, M. (2017). The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota. Microbiology and Molecular Biology Reviews, 81(4), e00036-17. 

[9] Lukic, J., Chen, V., Strahinic, I., Begovic, J., Lev-Tov, H., Davis, S. C., Tomic-Canic, M., & Pastar, I. (2017). Probiotics or Pro-healers: The Role of Beneficial Bacteria in Tissue Repair. Wound Repair and Regeneration, 25(6), 912–922. 

[10] Schlomann, B. H., & Parthasarathy, R. (2019). Timescales of gut microbiome dynamics. Current Opinion in Microbiology, 50, 56–63. 

[11] David, L. A., Maurice, C. F., Carmody, R. N., Gootenberg, D. B., Button, J. E., Wolfe, B. E., Ling, A. V., Devlin, A. S., Varma, Y., Fischbach, M. A., Biddinger, S. B., Dutton, R. J., & Turnbaugh, P. J. (2014). Diet rapidly and reproducibly alters the human gut microbiome. Nature, 505(7484), 559-563. 

[12] Ghosh, T. S., Shanahan, F., & O'Toole, P. W. (2022). The gut microbiome as a modulator of healthy ageing. Nature Reviews Gastroenterology & Hepatology, 19(9), 565-584. 

[13] Hasan, N., & Yang, H. (2019). Factors affecting the composition of the gut microbiota, and its modulation. PeerJ, 7, e7502. 

[14] Wang, X., Zhang, P., & Zhang, X. (2021). Probiotics Regulate Gut Microbiota: An Effective Method to Improve Immunity. Molecules, 26(19), 6076. 

[15] Hemarajata, P., & Versalovic, J. (2013). Effects of probiotics on gut microbiota: mechanisms of intestinal immunomodulation and neuromodulation. Therapeutic Advances in Gastroenterology, 6(1), 39–51.
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