It turns out that getting messy and playing outside isn’t just good for kids’ spirits – it’s good for their health. A growing body of research suggests that animal contact, time in soil and nature, and a healthy gut microbiome all contribute to immune resilience and emotional regulation and may even reduce the risk of conditions like allergies, eczema, and asthma.
In this article, I’ll walk you through what the research says and why it matters.
How Early Microbial Exposure Shapes the Immune System
Children have lived alongside animals for most of human history, and that relationship may have shaped our biology in ways we are only beginning to understand. Research suggests that exposure to animals, particularly in early life, may support healthy immune development, gut microbiome diversity, and social and emotional growth.
Pets and the Microbiome
A 2013 study found that household pets such as dogs and cats increase infant exposure to environmental microbes, promoting diversity within the infant gut microbiota, and that the net effect of both pets and siblings is to support healthy immune development and may help protect against atopic disease (1). A separate analysis found that dog ownership at three months of age was associated with a reduced risk of food allergy development, an effect researchers believe may be partly mediated through the infant’s developing microbiome (2).
What seems to be happening is that animals bring a wider variety of microbes into the home environment – on their fur, their paws, and in the air around them. For a baby whose immune system is still in its critical formation window, that microbial variety appears to act like a kind of education, helping the immune system learn to distinguish between genuine threats and harmless substances.
A Note on Pets and Existing Allergies
The research above focuses on early life exposure during the window when a child’s immune system is still being formed. This is quite different from introducing a pet into a home where a child has already developed sensitivities. For children who are already sensitized to pet dander, animal exposure can worsen eczema flares and asthma rather than help them.
If your child has existing allergies, eczema, or asthma, bring this conversation to your healthcare provider before making any decisions about a new pet.
The Case for Dirt & Messy Play
The breadth and richness of microbial exposure in early life appears to play a critical role in training the immune system to respond proportionately rather than overreact. Research has consistently shown lower rates of asthma, hay fever, and eczema in children raised in rural environments and on farms, an effect researchers largely attribute to richer and more varied microbial exposure in those environments (3).
Put simply: kids who grow up around more diverse environments tend to have better-trained immune systems. And one of the easiest ways to increase microbial diversity in everyday life is to spend time outside, particularly in contact with soil and plants.
Why Gardening is Good for Gut Health
Gardening combines physical activity, sensory engagement, and direct soil contact all at once. A cohort study found that during the active gardening season, gardening families showed higher gut microbial diversity and richness compared to non-gardening families (4). A human intervention study also found that introducing forest floor materials and gardening facilities into daycare environments diversified children’s skin microbiota and produced measurable changes in immune regulation markers (5). Even short-term contact with soil and plants has been show to immediately increase the diversity of skin microbiota (6).
A Note on Access
Not every family has a yard, a pet, or easy access to green space. The immune system is shaped by many factors. Small and frequent exposures count, too! Consider a windowsill herb garden and simply stop to pet friendly dogs at the park.
Probiotics & What the Gut Microbiome Does for Your Child
Research increasingly shows that a well-balanced, diverse gut microbiome may play a role in reducing the risk of conditions like allergies, eczema, and asthma, and in supporting how children handle stress (7, 8, 9).
Probiotics are live beneficial bacteria that help populate and diversify the gut microbiome. For families with limited access to outdoor space or animals, they offer one of the most practical and accessible ways to support this system. And even for children who spend plenty of time in nature, probiotics can be a useful complement because supplements offer a way to select specific strains that have been studied for particular benefits.
To learn more about probiotic supplementation, read this article: Understanding The Differences Between Prebiotics & Probiotics
To learn more about increasing gut diversity, read this article: The Vast Health Benefits of Probiotics
Summary
Children’s immune systems are shaped by the world around them, and the research increasingly points in the same direction: diverse microbial exposure in early life matters. Animal contact, time in soil and nature, and a healthy gut microbiome all appear to support immune resilience; reduce the risk of allergies, eczema, and asthma; and even influence how children handle stress and emotion.
References:
- Azad MB, et al. Infant gut microbiota and the hygiene hypothesis of allergic disease: impact of household pets and siblings on microbiota composition and diversity. Allergy Asthma Clin Immunol. 2013. PMID: 23607879.
- Marrs T, et al. Dog ownership at three months of age is associated with protection against food allergy. Allergy. 2019. PMID: 31077604.
- Lynch SV, Boushey HA. The microbiome and development of allergic disease. Curr Opin Allergy Clin Immunol. 2016. PMID: 26859355.
- Brown L, et al. Fecal and soil microbiota composition of gardening and non-gardening families. Sci Rep. 2022. PMID: 35102166.
- Roslund MI, et al. Biodiversity intervention enhances immune regulation among daycare children. Sci Adv. 2020.
- Gronroos M, et al. Short-term direct contact with soil and plant materials increases diversity of skin microbiota. MicrobiologyOpen. 2019. PMC6436432.
- Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integr Med. 2018. PMC6469458.
- Ansari F, et al. The role of probiotics and prebiotics in modulating of the gut-brain axis. Front Nutr. 2023. PMID: 37565035.
- Acuna-Gonzalez A, et al. The Impact of Bioactive Molecules from Probiotics on Child Health. Nutrients. 2024. PMC11547800.
