Behind the Tantrum: How the Toddler Microbiome Influences Behavior

Parents calm crying girl on walk in summer garden. Girl sits in lap at father.

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Toddlers are marvelous creatures. They live in the present, express themselves freely, and are almost completely fearless. But did you know the adorable and creative expression of their emotions could actually stem from the bacteria in their gut?

According to recent findings, the next time your toddler throws themselves on the floor in protest, lovingly cuddles up to you for a snuggle, or screams uncontrollably about well, anything, you can consider attributing this behavior to the microbes in his or her gut environment.

A study conducted by Dr. Lisa Christian at Ohio State’s Institute for Behavioral Medicine Research found that specific abundances of bacteria in the gut appear to influence how small children tend to behave. While toddler behavior wasn’t necessarily the goal of the study (they were originally looking at maintaining optimal physical health in early childhood), scientists gleaned key insight into how intestinal bacteria interact with stress hormones and the human brain. It all starts with the microbiome.

The Toddler Microbiome

The human microbiome is ignited beginning at birth when an infant inherits their mother’s bacteria. The microbiome establishes the foundation of health as we know it as it’s made up of an astronomical array of coexisting microorganisms that comprise 90% of our body.

It’s our naturally-occurring beneficial bacteria that reside in this world beneath the microscope that become the building blocks for budding immune systems, affect how well we absorb nutrients from our food, promote digestive health, and, according to new research, may even influence how our little ones think and feel.

The adolescent microbiome changes significantly in the first two years of life due to factors like mode of delivery, skin-to-skin contact, exposure to breast milk and first foods, antibiotic intervention, stress, and environmental exposure, leading to fluctuations in the diversity and number of our helpful gut microbes.

Scientists agree that many of our western practices have a way of wiping out our good bacteria, which is why so many are keen to research this fascinating topic – particularly as it pertains to the health consequences for our children.

The Gut-Brain Association

Understanding the dynamics of the gut-brain association in early childhood is important because the gut microbiome, while changeable throughout your lifetime, is particularly malleable in the first two years of life. In fact, by the age of 2, most human microbiota resemble the profile of an average adult, which is why researchers in Ohio were specifically interested in studying the gut microbiota of children between the ages of 18-22 months.

Dr. Christian worked with a leading microbiologist to study fecal samples collected from 77 girls and boys whose parents were asked to assess the behavior of their children based on a scale of emotional reactivity that measured 18 different personality traits. The team looked at various things like the diversity of the microbes in each sample, the presence of certain strains, genera and families of bacteria, and how rich and evenly spread these microbes appeared to be based on the resulting temperament.

They found that children who frequently acted with more positivity, curiosity, sociability, and impulsivity tended to have a greater variety of strains from different genera (or groups) of microscopic organisms present in their gut environments than their shyer, more restrained, and more focused peers. This correlation appears to exist even when considering factors known to influence the type of bacteria found in the gut such as diet, history of breastfeeding, and method of childbirth. That said, there is much that remains to be learned from this introductory research.

For example, one conclusion from the study might be that outgoing toddlers have a lower number of stress hormones affecting their gut than quieter, more reserved children. However, it’s also possible that the production of stress hormones is mitigated by the presence of certain bacteria when a child encounters something or someone new. Identifying these resident microbes and understanding how they interact with stress hormones will help give us better insight into what exactly throws certain children into an immediate tailspin while others are more reserved with their expressions of stress.

While the research continues, for Dr. Christian and her associates, one thing is clear – there is definitely communication happening between the gut bacteria and the brain through the enteric nervous system. Which one starts the conversation? Well, that’s the next gap to fill in the understanding of exactly how the microbiome affects toddler temperament and mental health during childhood.

While we may not be able to change our child’s temper or throwing of an outright tantrum, observing toddler temperaments can indicate how well they’ll handle stress later in life. It’s important to keep in mind, however, that just about every toddler will throw a temper tantrum at some point – similar to the inevitability of a thunderstorm.

This new research gives us insight into the importance of nutrition and the critical role that our gut flora play in communicating with and affecting the health of the mysterious toddler brain (as well as our own).

Probiotics and the Gut-Brain Axis

An expert in the the field of how our gut microbes affect the brain is Dr. David Perlmutter, the author of the best-selling book Brain Maker, who denotes diet and lifestyle as our two main routes to obtaining the microbes that we need for healthy brain function.

In his book, Dr. Perlmutter recommends taking probiotics in addition to consuming whole fruits, vegetables, and grains rich in prebiotics that help feed the right bacteria in our GI tract – positively influencing what’s known as the gut-brain axis. The gut-brain axis describes the biochemical signals that are exchanged by your gut flora and your brain through the nervous system. For Dr. Perlmutter, having plentiful and diverse microbes in the gut can only help ensure that these biochemical signals are working optimally.

So, what is it exactly that affects the diversity of the gut microbes, and how can we ensure our children are being continuously seeded with the right ones?

During early childhood, alterations in the diversity of gut flora can be caused by stress, the presence of antibiotics, toxins in the air and water, and other lifestyle and environmental factors. Probiotic supplementation can help restore this bacterial balance and even make sure that the many nutrients from our foods are being properly absorbed into the body so that these nutrients can effectively interact with the brain and other critical organs.

If you’re in toddler territory right now, the best place to start for your child’s microbial health is with a premium supplement designed with small children in mind. Hyperbiotics PRO-Kids was formulated to be impeccably tiny; small enough for even a preschooler to swallow. PRO-Kids is made with natural ingredients and zero sugar – we choose only the best for our kids!

Because infants are sterile in the womb until birth, the first step any nursing or expecting mother can take to ensure their child is inoculated by plentiful and diverse bacteria is to take a probiotic during pregnancy like Hyperbiotics PRO-Moms. Taking a high-quality supplement with a variety of strains can offer unmatched prenatal support to both you and your child before they ever make their entrance into the world.

As additional research emerges on the gut-brain axis, we look forward to learning more about the impact our gut flora has on our lifelong physical and mental health.

Writer, health-nut and mama of two little girls, Julie Hays is on a mission to empower others to live natural, healthy lives free from the continual microbiome depletion that many of us face today. You can find more of her work (and more information about gut health) by heading over to

5 thoughts on “Behind the Tantrum: How the Toddler Microbiome Influences Behavior”

  1. very good information — but lacking in that it only recommends taking a probiotic supplement, rather than also encouraging the consumption of the myriad of naturally occurring probiotics in foods such as kefir, kombucha, sauerkraut, and other fermented foods. So much more needs to be said about lifestyle & diet choices, and how they affect our gut flora, and how we can better care for our gut flora, by encouraging/ reseeding the good bacteria, and starving the bad (which feed on sugars).

    1. I totally agree with you and that’s exactly what made me wonder if it isn’t one of those paid articles advertising for the probiotics company.

    2. Hi Erin, thanks so much for your comment – and we could NOT agree more! One of the biggest keys to regaining optimal gut health lie in making small changes – and diet is a HUGE piece of this.

      There are so many lifestyle factors that have led to this place where compromised gut health is the norm. From our modern diet, stress, the overuse of antibiotics as well as the frequent use of medicines like birth control, acid suppressants (PPIs), antacids, steroids, hormone replacement therapy and NSAIDs, many of us have damaged the very system that is in place to protect and sustain us: our microbiome. We’ve got some great information on our website that you might be interested in checking out, and if you have any specific questions, we’d love to chat about them, so please do not hesitate to reach out to us directly!

      Thank you again for checking out the article! Your passion for healthy living is evident, and it seems like something we definitely have in common. We look forward to hopefully connecting with you in the future! 🙂

  2. I have to second the comment about only recommending a supplement. Verbatum “the best place to start for your child’s microbial health is with a premium supplement designed with small children in mind.” No, not really. The best place to start would have been getting your own microbiome healthy and passing it on to your child. Supplementing is second best. It is always better to try for a diverse and healthy food intake. Cultured foods are everywhere. Find what you like and invest in them. Supplements are fine, but should be the back up solution, not the first thing tried. Same with any nutritional supplements.

    As well, infants are NOT sterile in the womb before birth. It matters what you eat. It matters how you eat. Be informed.

  3. Hi Arielle- thanks so much for your comment – we appreciate your feedback! We completely agree with you that the food you eat is paramount to health, and it’s the most direct way to ensure your diet is teeming with the beneficial microbes that support a healthy gut microbiome both during pregnancy and throughout your life.

    As well, we absolutely believe that the maternal microbiome is key to influencing the health and immunity of your child as they enter this world.

    We are riveted by the recently published work of Dr. Sharon Meropol, and we look forward to learning more about her findings as to exactly when and how infants are seeded with maternal bacteria. Until just weeks ago, as I’m certain you’re aware, most scientists were in agreement with the fact that infants are sterile until birth, which is why we too are intrigued by the Times article you included in your post. We’re moms ourselves, and we pride ourselves on staying at the forefront of the leading research.

    The truth is that whether seeded in utero or during the birthing process, it’s critical to ensure that mothers are getting the proper probiotic and prebiotic supplementation that may be missing from their diets to help ensure a healthy microbiome for their child in the face of many intervening factors that can negatively impact beneficial bacteria. Increasing your intake of fermented foods and whole fruits and veggies during pregnancy is an excellent suggestion in regard to achieving improved gut health and a great number of beneficial good guys. It’s also why we created a probiotic with specific strains targeted for expecting mothers – because we understand just how important the maternal microbiome truly is for the health of mother and child.

    However, if you’re no longer pregnant and have a toddler that might not be getting all he or she needs from their diet (or due to an array of other factors) to support their microbial balance, a natural probiotic supplement designed for children can help even out microbial imbalances and positively influence the physical and mental health of our children.

    We’ve got some great information on our website surrounding gut health during pregnancy and throughout childhood that you might be interested in checking out, and if you have any specific questions, we’d love to chat about them, so please do not hesitate to reach out to us directly! Thank you again for checking out the article! 🙂

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