I ate dirt as a kid so I have a better immune system then you...maybe

     I think most of us have heard people say, “Oh, I ate dirt as a kid, so I won't get sick”. But what is the extent of this “protection” from illnesses? Well, I was one of those kids; I used to play all the time outside, digging in the dirt and ruling the playground (if I didn't like you, you didn't come on the playground when I was on it 🙂). From time to time, I'll accidentally lick my fingers full of dirt and not think much about it. But as I grew up, I heard people say, “If you ate dirt as a kid, you should be fine”. Per the Environmental Protection Agency, children in the U.S. consume about 200–800 mg of dirt per day (Hauptman &Woolf, 2017). This seems like a lot, and it also gives my mom reason to ground me anytime I end up with dirt on my clothes (because I always wore white for some reason).

However, when looking at the literature, studies on animals raised in sterile environments, such as rabbits, mice, guinea pigs, and rats, have shown failure of proper immune system development (Gerald, 2003). It is said that their lymph nodes and Gut-associated lymphoid tissue (GALT) did not achieve the right shape or composition and could not initiate a normal immune response (Gerald, 2003). Furthermore, exposure to certain microbiomes causes lymph nodes and GALT to enlarge and reorganize, and develop T/B lymphocytes. Germ-free mice had increased inflammation of the lungs and colon, which was the result of hyperactivity of T cells linked to these disorders in both mice and humans (Brigham and Women's Hospital, 2012). The overall literature points out that exposing the germ-free mice to microbes during their first weeks of life, but not when exposed later in adult life, led to a normal immune system (Brigham and Women's Hospital, 2012).

Now, as a graduate student, I understand why people say they will not get sick because they “ate dirt”. Of course, kids should just shove a handful of dirt in their mouth (I might have), but it overall points to the bigger idea of the development of children and how nature and environment can shape not only our experiences, but also our biological and metabolic functions. Now I open the discussion…with the recent global pandemic  and years of restrictions, reduced social interaction, and increased hygiene measures, how might the immune systems of today’s children develop differently? Of course, not EVERY plays in the mud or “eats dirt”, but what could the implications be for their health?

References

Brigham and Women’s Hospital. (2012). Getting the dirt on immunity: Scientists show evidence for hygiene hypothesis | ScienceDaily. https://www.sciencedaily.com/releases/2012/03/120322142157.htm?utm_source=chatgpt.com

  Callahan, G. N. (2003). Eating Dirt. Emerging Infectious Diseases, 9(8), 1016. https://doi.org/10.3201/EID0908.030033

  Hauptman, M., & Woolf, A. D. (2017). Childhood Ingestions of Environmental Toxins: What Are the Risks? Pediatric Annals, 46(12), e466. https://doi.org/10.3928/19382359-20171116-01

 Olszak, T., An, D., Zeissig, S., Vera, M. P., Richter, J., Franke, A., Glickman, J. N., Siebert, R., Baron, R. M., Kasper, D. L., & Blumberg, R. S. (2012). Microbial exposure during early life has persistent effects on natural killer T cell function. Science, 336(6080), 489–493. https://doi.org/10.1126/SCIENCE.1219328