Kids, Germs, and Gut Health

Home Life

There are few things harder on a parent than seeing your child sick. And yet, frequent colds and viruses seem to be the norm during those first few years of life, when your child’s immune system is still developing. I remember my pediatrician telling me not to worry, that babies, toddlers, and preschoolers get on average eight to 10 colds per year, plus two to three stomach viruses (vomit and diarrhea—fun!). According to her, my son’s frequent sniffles, fevers, and tummy bugs were all a normal part of his immune development.

To cope, I became the mom that I used to roll my eyes at—the one at the playground with the hand sanitizer always at the ready, who would ask you if your kids had runny noses or any other viral symptoms before getting together for a play date. I even avoided the public library for a time after a particularly bad spate of illness.

Fast forward to what I know now about immune health and the human microbiome, and I look back on those early days with new understanding. For starters, I’ve learned that gut health and immune health are very closely linked. Research indicates that 70-80% of your immune cells reside in the human gut.

I’ve also learned that the gut is home to literally trillions of bacteria, many of them beneficial. These bacterial colonies that live in the intestines, as well as on the surface of the skin, inside the mouth, and elsewhere in our bodies, make up what science calls the microbiome. And this microbiome, considered an “acquired organ” by some, plays an incredibly vital role in overall health and well-being throughout each person’s lifetime.

Your Child’s Microbiome

When your child is born, his or her microbiome is almost completely unformed. Passage through the birth canal, skin-to-skin contact with mom and dad, and early exposure to breastmilk or formula provide the building blocks for your child’s microbiome. The rest is acquired through your child’s diet and environment over time. By the time your child is three, his or her microbiome is as fully formed as an adult’s.


A healthy microbiome helps the body:

  • Digest food
  • Eliminate waste
  • Absorb nutrients and essential fats
  • Produce vitamins B12 & K
  • Produce serotonin, a mood transmitter
  • Fight off harmful bacteria


Although we all share some of the same types of bacteria, our individual microbiomes (the specific mix of bacteria, microbes, fungi, and viruses) are as unique to each of us as our fingerprints. Beyond our differences, though, what seems to matter most is maintaining a diverse, healthy balance of bacteria, where the good (beneficial and symbiotic) bacteria outnumber the bad (pathogenic).

A balanced gut microbiome can help the body digest certain foods; eliminate waste; absorb nutrients and fats; produce vitamins B12 and K; manufacture serotonin, a neurotransmitter that affects mood; and fight off harmful microorganisms. Conversely, a gut microbiome that falls out of balance—following a course of antibiotics, or a bout with diarrhea, for example—can make us more susceptible to illness.

The Role of Probiotics

Throughout history, people of every culture have incorporated fermented foods in their diets to help maintain a healthy gut. These fermented foods are one way we acquire the beneficial bacteria that helps keep us in balance. Yogurt, pickles, sauerkraut, cured olives, kimchi, miso, kefir, sourdough bread, soft cheeses, and buttermilk are all examples of fermented foods.

But as anyone with kids knows, getting them to eat the foods we parents consider good for them isn’t always easy. I’ve found through experience that it’s especially difficult to get picky eaters on board with fermented foods. This is where a high-quality probiotic supplement can be helpful.

Numerous studies have shown that probiotics can help support healthy respiratory and digestive function in children who attend daycare (who also tend to have two to three more infections per year than those who stay home).* A meta analysis of these same studies found that certain probiotic strains—such as the super strain, Lactobacillus rhamnosus GG—tend to be particularly effective for kids.

What else contributes to developing a healthy microbiome? Not surprisingly, exercise (found to foster beneficial microbe populations), high-fiber foods that serve as prebiotics (food for the beneficial microbes), and a diverse diet that incorporates fermented and organic whole foods all promote a healthy gut.

What may be even more surprising to parents is the revelation that playing in the dirt and directly interacting with animals and nature may be one of the best ways to help our kids develop a strong, protective microbiome. One more reason to ease up on the hand sanitizer, I say.

* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

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