Good and bad dirt

In this episode, Greg Dickens and I talk about how heat affects children’s development and how the effects depend on what they are eating. We discuss mineral intake during pregnancy, why baby microbiomes don’t have much overlap with their mother’s microbiomes, and we discuss what affects a boy’s testosterone health as he develops. And finally, we explore how we can tell whether dirt is likely to make children sick, and how that should affect what we do about it.

This episode relates to this article (and references are here):

Topics covered

* Why we should minimise heat stress in children [01:16]

* How maternal exposure to trace elements influence a baby’s risk of infection [06:10]

* Why baby microbiomes don’t have much in common with their mother’s vaginal microbiome [08:35]

* What affects a boy’s ability to balance his testosterone levels [16:35]

* What we should know about good and bad dirt: [21:48]

These other podcast episodes cover overlapping topics:

Notes

Mice that have a single episode of heat stress show long-term effects: https://www.nature.com/articles/s42003-025-07484-3

Maternal selenium exposure may have protective effects on Streptococcus infection among children: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0319356

Babies don’t get their microbes from their mother’s vagina: https://link.springer.com/article/10.1186/s12884-025-07358-w

Childhood and adolescent BMI and early childhood infection alter boys’ ability to regulate testosterone throughout life: https://onlinelibrary.wiley.com/doi/full/10.1111/andr.70091