We all enter this world with an inexperienced immune system. The first 5 years is really the most important time for our immunity. Building our immunity in childhood is very important, educated by our environment and shaped by our lifestyles, creating our own unique fingerprint for future health. So, given that strong immunity is made, not born, unfortunately, in some ways, getting sick when you’re a kid is simply part of the job description.
You might feel that the never-ending colds and flus are a “natural” part of childhood. Perhaps you have even heard that they are vital for toughening up a developing immune system. But children prime and educate their immunity not just by battling an ongoing series of germs, it’s also educated by their environment and shaped by lifestyle habits, creating a unique fingerprint for future health (1).
But we seem to have forgotten how to build a tiny strong immune system, building immunity in childhood is very important. Rates of allergy, autoimmunity and inflammatory disease are skyrocketing (2).
Now, whether you have children, you plan on having children, or you know children, the wonderful fact is that you have the ability to enable any kids in your life to be tiny superhumans by building their immunity in childhood, and many of these things can be helpful for adult immunity too.
Research shows that up to 80% of immune cells are located in the gut and this is the predominant site of childhood immune education. While the cultivation of gut bacteria starts at birth, it’s vital that they can flourish as your child grows (3). While there is no scientific definition of a healthy gut microbiome, we know that the diversity of the microbes in your gut matters (4).
The birthing process sets off the most radical transformation – a tsunami of good gut microbes colonises the (relatively) sterile baby as it enters the world. So receiving foundational microbes with the potential to educate immunity, starts with your mother (5).
These initial microbes were inherited from her mother, and so on. The maternal microbiome has among the most powerful input into this incredible ecological event with the potential to shape our health decades down the line. Research indicates that caesarean deliveries can distort or inadequately populate the microorganisms in a baby’s gut. Babies born by caesarean section are more likely to collect hospital-acquired bacteria when they are born, while those born vaginally collect microbes from their mother (6).
These differences in the gut microbiota were found to persist in children until at least 7 years of age (7). Showing the importance of building immunity in childhood. Researchers think this may have an impact on health further down the line but sometimes women often need or choose a caesarean and at the moment this should not deter women from having a caesarean section.
After the route of entry into the world, what’s the next thing to influence the microbiota of a newly born baby? You guessed it: it happens through the gut with food! And the best way to start is breast milk. Human milk is a particular microbial marvel.
For many decades considered sterile, breast milk is, in fact, a creamy bacterial soup. Breast milk even contains microbes from the mother’s gut that travel to the breast in preparation for seeding the baby’s gut (8). Breast milk also conveniently comes packed with a food source, not just for baby, but for their microbes too. Human milk oligosaccharides, or HMOs, found only in breast milk are the third-most plentiful ingredient in human milk after lactose and fat (9).
There is no doubt that the gastrointestinal microbiota of breast-fed babies differs from classic standard formula-fed infants. While standard infant formula doesn’t contain these natural prebiotics HMOs, Some formulas now have different prebiotic oligosaccharides such as galacto-oligosaccharides (GOS), and fructo-oligosaccharide (FOS) added. There is evidence that the addition of prebiotics in infant formula alters the gastrointestinal (GI) microbiota resembling that of breastfed infants (10).
Dietary fibre is crucial because digestion of fibre produces some of the key metabolites that shape our immunity and inflammatory set-point. Cultivating diverse gut bugs requires diverse dietary fibre (it’s not just about the amount) (11). Good sources of fibre tend to be found in ‘whole plant foods’ which are close to their natural form, think whole fruits and veggies, whole grains, nuts, seeds, and legumes. Aim for a diverse range of fibres. Try to boost your child’s fibre intake gradually to avoid upsetting their tummy and give those gut bugs time to adapt.
Apart from our mothers, and our diets, we also obtain our microbes from our environment. In a world of hand sanitizer and wet wipes, we can scarcely imagine the preindustrial lifestyle that resulted in the daily intake of trillions of helpful organisms.
When we’re building immunity in childhood, you need to learn that dirt is good. Disconnection from nature not. Compared to green rural environments, the microbiota of modern built environments is not only different but less diverse. The air we breath carries a load of bacteria (12) that gets deposited in our mouth and airways, together with organisms that come mostly from soil and plants. As we swallow, these enter our gut ecosystem.
For kids growing up in cities and spending much of their time indoors, their immune system may be missing out on those environmental microbes. And since immunity is built in childhood, we need to maximise their childhood as a time to build up defence systems. How can we restore these natural inputs that the immune system evolved to require? It’s surprisingly remarkably simple.
Expanding our thinking of the microbiome to encompass natural environments means cultivating a connection with them by breathing it, playing in it and digging in it regularly. The more we contact dirt and natural environments, the more we let its microbiome infiltrate our systems and nurture our own. You might also want to try getting your veggies from a farm shop or vegetable box company, which usually come with a helping of soil (just don’t forget to wash this off).
Now don’t get me wrong, the suggestion that we should embrace dirt in the sense that we are disconnected from natural environments does not immediately imply that we are inviting more bad germs too. Playing in dirt might be good once in a while but good personal hygiene is essential – e.g. washing hands with good old soap and water. Just remember, what won’t kill you — and 99% of the germs surrounding us at any one time won’t kill you — makes you stronger and may bring balance to your immune system.
About the Author
Immunologist Dr. Jenna Macciochi unravels the science underlying strong immunity and teaches us how to be well in a modern world. Currently a lecturer at the University of Sussex, she specialises in understanding how nutrition, lifestyle, and gut health interact with the immune system in health and disease. Jenna is a Brighton (UK) based mum to twins, a perpetual kitchen experimenter with a passion for movement and exercise.
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