The gut-immune connection: 4 back-to-school tips every parent should know

Discover how the gut microbiome shapes your child’s immunity, and 4 expert tips to stay healthy this back-to-school season.

Back-to-school season is upon us. Time for sharpened pencils, fresh uniforms, and….runny noses. Parents everywhere know the drill. Your child comes home with more than just homework; they bring a backpack of germs to share with the whole family. But it’s not all bad news. In fact, those very germs might actually be helping your child build a stronger immune system. And the secret link between the playground and immunity? The gut microbiome.

Study buddies for life: how the gut and immune system learn together

The gut microbiome is a bustling community of bacteria, fungi, viruses, and archaea living throughout your gastrointestinal system. Most people think the gut microbiome’s job ends with digestion. But in reality, it plays a far bigger role in your child’s health.

One of its most important partnerships is with the immune system. From birth, the gut microbiome and the immune system develop together, constantly “talking” to each other¹. In fact, around 70-80% of your immune cells are located in the gut. This relationship trains the immune system to distinguish between harmless substances (like food or friendly bacteria) and genuine threats (like viruses and harmful bacteria)². Think of it like a school for the immune system: exposure to a variety of microbes is part of the curriculum. Without these early lessons, the immune system can overreact to harmless stimuli, which may increase the risk of allergies or autoimmune conditions later in life. This means that early microbial encounters children have - from exposure to the outdoors, to diet, to playing with friends - all shape the diversity and resilience of their gut microbiome and in turn, their immune system responses. 

From mud fights to microbes: how early exposure builds immunity

This is where the “hygiene hypothesis” comes in. This idea suggests that children growing up in an environment that’s too clean or sanitised may be more susceptible to allergies and autoimmune diseases compared with those exposed to a wider range of microbes³. A nice example of this is the “mini-farm” effect, where research has shown children who live with pets (a dog or cat) in their first year of life are less likely to develop allergies later on⁴. Spending time outdoors, playing with other children, and even getting a bit muddy all help broaden microbial diversity and strengthen immune defences.

That said, balance is key. Some germs are dangerous, and good hygiene still prevents serious infections. The challenge for parents is finding that sweet spot between healthy exposure and over-sanitisation. Overuse of antibacterial wipes, constant hand sanitiser, and reduced social contact can inadvertently narrow the diversity of microbes your child is exposed to, and potentially impact their immune resilience in the long run.

4 ways to support your child’s gut-immune connection this school year

So how do we strike a balance between keeping our kids safe from infection, yet harnessing the power of the gut-immune connection? Here are our top 4 tips:

1. Prioritise a plant-based diet

You don’t have to go fully vegan to get the benefits of plants, but variety is key. The single most important dietary habit for gut microbiome health is eating a diverse range of plants. Fruits, vegetables, legumes, nuts, seeds, and whole grains all contain fibre, which acts as the only food source for our beneficial gut bacteria.

When these bacteria digest fibre, they produce something called short-chain fatty acids (SCFAs) which help regulate immune responses and reduce inflammation.

SMART snacks for your kids:

• Vegetable sticks with hummus
• Apple slices with peanut butter 
• Avocado on wholegrain toast, sprinkled with nuts and seeds

2. Play outdoors

Swap some screen time for green time. Outdoor play exposes children to a greater diversity of microbes from soil, plants, and animals, all of which contribute to a balanced microbiome⁵. Parks, gardens, and muddy puddles are all part of nature’s immune-building toolkit. 

3. Regular handwashing

Handwashing before meals and after using the toilet is one of the simplest, most effective ways to prevent harmful infections. But there’s no need to scrub every 15 minutes or rely on antibacterial gels unless soap and water aren’t available.

4. Take a live bacterial supplement

A high-quality live bacterial supplement can offer an extra layer of immune support, especially during peak cold and flu season⁶. A review publication of 23 studies from the Cochrane Library⁷ found that live bacterial supplements

• Likely reduce the recurrence of upper respiratory tract infections (URTIs) by 41%
• May shorten the duration of URTIs by more than a day 
• Likely reduce the need for antibiotics by 42%

Clinically studied strains such as Lactobacillus rhamnosus LGG® and Bifidobacterium lactis BB-12® have been shown to reduce both the number and severity of respiratory infections^8-9. Remember, not all probiotics are created equal. Look for products containing the right strain, at the right dose, supported by strong clinical evidence.

Takeaway

Back-to-school germs are inevitable. But instead of fearing them, we can see them as part of the training programme for your child’s immune system. By supporting a healthy gut microbiome through diet, outdoor activity, sensible hygiene, and evidence-based live bacterial supplements, you can help your child not only survive but thrive during the school year.

References

1. Mowat, A.M. and Agace, W.W., 2014. Regional specialization within the intestinal immune system. Nature Reviews Immunology, 14(10), pp.667-685.

2. Fujimura, K.E. and Lynch, S.V., 2015. Microbiota in allergy and asthma and the emerging relationship with the gut microbiome. Cell host & microbe, 17(5), pp.592-602.

3. H Okada, C Kuhn, H Feillet, J-F Bach, The ‘hygiene hypothesis’ for autoimmune and allergic diseases: an update, Clinical and Experimental Immunology, Volume 160, Issue 1, April 2010, Pages 1–9, https://doi.org/10.1111/j.1365-2249.2010.04139.x

4. Hesselmar B, Hicke-Roberts A, Lundell AC, Adlerberth I, Rudin A, Saalman R, Wennergren G, Wold AE. Pet-keeping in early life reduces the risk of allergy in a dose-dependent fashion. PLoS One. 2018 Dec 19;13(12):e0208472. doi: 10.1371/journal.pone.0208472.

5. Marja I. Roslund et al., Biodiversity intervention enhances immune regulation and health-associated commensal microbiota among daycare children.Sci. Adv.6,eaba2578(2020).DOI:10.1126/sciadv.aba2578

6. Wang, X., Li, Y., Zhang, Z. et al. (2021) 'Probiotics Regulate Gut Microbiota: An Effective Method to Improve Immunity' Molecules, 26, p.6076.

7. Zhao, X., et al. (2022). Cochrane Database of Systematic Reviews, Issue 8, Art. No. CD006895. Probiotics for preventing acute upper respiratory tract infections - PubMed

8. Rautava, S., et al. (2009) ‘Probiotics and the immune system’, British Journal of Nutrition, 101, pp. 1722–1726.

9. Smith, T.J., et al. (2013) ‘Effects of probiotics on immune function’, British Journal of Nutrition, 109, pp. 1999–2007.