Why Kids Need Dirt

Why kids and adults need dirt

Thanks to modern hygiene and sanitation, we have seen lower rates of many diseases and health problems. Unfortunately, too much of a good thing can have its problems. I’ve talked before about how gardeners (statistically) live longer, and it turns out that the dirt itself can play a role in this:

The Problem

We have antibacterial soap, antibacterial spray, antibacterial cleaning wipes and a myriad of disinfecting cleaning products. Kids are growing up in clean, disinfected, sterile environments. We go to great lengths to make sure we are protected from germs. At the same time, we have rising rates of allergies, autoimmune problems and gut related disorders (especially in children).

Could there be a connection?

Some research says yes… In fact, some research says that widespread use of disinfecting and antibacterial products (and removal/avoidance of dirt) is preventing proper formation of healthy gut bacteria and that restoring this beneficial bacteria could be the key to boosting immune function, reducing rates of allergies or digestive problems and even improving mood.

So where are these healthy bacteria and how can we benefit from them? Probiotic rich foods and supplements are a great start, but they are missing an important factor: Soil-Based Organisms (SBOs). These soil based organisms have stronger strains of beneficial bacteria that can survive through the digestive system and provide the most benefit. While fermented foods and probiotic supplements can also be very beneficial, some of these strains do not survive through the digestive system.

Just as the name suggests, soil based organisms are microorganisms found in soil.

Various cultures have known the health benefits of dirt for centuries and there is an old saying that “You have to eat a peck of dirt before you die.” It seems there is wisdom in this old saying…

As this article explains:

“In studies of what is called the hygiene hypothesis, researchers are concluding that organisms like the millions of bacteria, viruses and especially worms that enter the body along with “dirt” spur the development of a healthy immune system. Several continuing studies suggest that worms may help to redirect an immune system that has gone awry and resulted in autoimmune disorders, allergies and asthma.

These studies, along with epidemiological observations, seem to explain why immune system disorders like multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma and allergies have risen significantly in the United States and other developed countries.”

As I’ve written about before when I talked about our experience with the GAPS protocol, we’ve known about a link between gut health and mental health for a long time, and it turns out that certain soil based organisms play an important role here too:

Mary O’Brien, an oncologist at Royal Marsden Hospital in London, first stumbled upon these findings while inoculating lung cancer patients with a strain of M. vaccae (pronounced “emm vah-kay”) to see if their symptoms improved. She noticed that in addition to fewer cancer symptoms, patients also demonstrated an improvement in emotional health, vitality, and even cognitive function.

Heather (from Mommypotamus) talked about the benefits of these types of organisms for people with IBS or digestive disorders in this post:

Plus, in this double-blind, placebo controlled study researchers found that IBS patients who took a soil-based probiotic experienced a significant reduction in symptoms after two weeks. A follow-up study found that the patients were still experiencing these benefits one year after discontinuing the probiotic, presumably because the beneficial bacteria stays in the gut and continues to function.

Why Dirt is Important for Kids

So what does it mean for our kids? It means that all of our cleaning, disinfecting and sterilizing could be doing more harm than good at times.

Much to the chagrin of their mothers (and my husband!), babies have a natural desire to play in the dirt and put dirty objects in their mouth. Turns out, this could have an important immune developing purpose:

What a child is doing when he puts things in his mouth is allowing his immune response to explore his environment,” Mary Ruebush, a microbiology and immunology instructor, wrote in her  book, Why Dirt Is Good: “Not only does this allow for ‘practice’ of immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored.

After a study found that kids who grew up on farms or with a dog in the house had fewer allergies, research started to explore the importance of the organisms found in these less-than-sanitized environments and how they impacted health.

“One leading researcher, Dr. Joel V. Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston, said in an interview that the immune system at birth “is like an unprogrammed computer. It needs instruction.”

He said that public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they “also eliminated exposure to many organisms that are probably good for us.”

“Children raised in an ultra clean environment,” he added, “are not being exposed to organisms that help them develop appropriate immune regulatory circuits.”

Studies he has conducted with Dr. David Elliott, a gastroenterologist and immunologist at the University of Iowa, indicate that intestinal worms, which have been all but eliminated in developed countries, are “likely to be the biggest player” in regulating the immune system to respond appropriately, Dr. Elliott said in an interview. He added that bacterial and viral infections seem to influence the immune system in the same way, but not as forcefully.”


“In the June 2012 issue, The Journal of Allergy and Clinical Immunology published a study that demonstrated that Amish children who grew up on farms in northern Indiana had significantly lower rate of allergies than non-farm populations (5.2% for Indiana Amish populations, 11.3% for non-farm Swiss populations). This is called “the farm-effect” and has been documented in farm populations across North America and Europe, with a 50% reduction in allergic occurrence in farm children.

In the United States, the third National Health and Nutrition Examination Survey found 54.3% of the study population to have evidence of allergic sensitization to at least one thing.

A recent study shows that the Amish have a lower incidence of asthma and allergies than non-farm populations.

Add to that the results of a study American Journal of Respiratory and Critical Care Medicine published in 2007 that shows the use of cleaning sprays 4 times a week caused an increase in asthma and you can start to see the problem. Sprays that were included in the increase in asthma were glass-cleaning, furniture and air freshening sprays.”

Why Dirt is Especially Important for Babies

The natural organisms in dirt serve an important purpose for people of all ages, but babies have a specific and additional need for interaction with dirt.

Breast milk lacks Iron and with important reason. Pathogens like E.Coli (which can cause severe digestive problems in newborns) needs Iron to thrive, as do other pathogens. These low iron levels can help protect newborns from these bacteria.

Around 6 months, a baby’s  need for Iron and other nutrients increases, but breast milk doesn’t increase its levels of these nutrients and with good reason. At this stage in life, babies spend more time on the ground. In the past, this meant they spent more time interacting with dirt, which is a good source of Iron and minerals like Zinc, magnesium, etc.

As Science of Mom explains:

  • “Most babies are born with enough iron stores to meet their needs for about the first 6 months of life [1].
  • Breast milk contains very little iron (~0.35 mg/liter). The Institute of Medicine recommends that infants 6-12 months old get 11 mg of iron per day [1]. By this age, most babies’ iron stores have been depleted, so this iron needs to come from complementary foods, in addition to breast milk or formula. If you try to meet your infant’s iron requirement on breast milk alone, she would have to consume between 4 and 13 liters of breast milk per day, depending on your baby’s efficiency of iron absorption from breast milk (estimates range from 15-50% absorption). Most exclusively breastfed babies don’t consume much more than 1 liter of milk per day.
  • Iron deficiency during infancy increases the risk of cognitive, motor, and behavioral deficits that may last into the teens, even with iron treatment. Specific deficits that have been identified include impaired motor development at 18 months [2], mental retardation at 10 years old [3], increased need to repeat a grade, and increased behavioral and attention problems [4]. When I hear parents say that they declined the test for anemia at their baby’s 9 or 12-month check-up, I have to assume that they don’t know how serious iron deficiency can be for their child’s future.”

So is breastmilk inadequate? Hardly…

This study shows that babies are capable of absorbing Iron from soil (which they are naturally in contact with at this age if playing on the ground). Other mammals have breast milk that is naturally low in Iron at the same developmental times and these mammals are also capable of absorbing Iron and other nutrients from the soil, indicating that there is a biological reason for this.

In the past, the umbilical cord also wasn’t clamped immediately after birth (and there is good reason to delay clamping it these days too) which allowed more of the umbilical cord blood (the baby’s blood) to flow in to the baby. This resulted in higher blood levels and higher Iron levels, which would also help baby maintain Iron levels for a longer time.

I also give liver as one of baby’s first foods to help with iron levels, but that is another post for another day.

How to Make Sure We Get Enough Dirt

Step 1: Go outside. Step 2: Eat some dirt…. Just kidding!

We don’t actually need to make an effort to consume dirt to get the benefits of soil based organisms and nutrients in soil, we just need to make an effort to come in contact with it and to have our babies and children come in contact with it.

I take the following steps to make sure we get the health benefits of dirt:

  • Encourage my kids (including crawling babies) to play outside barefoot in the dirt as long as I know it is an area that hasn’t been sprayed with chemicals or contaminated in some other way. I garden and walk outside barefoot (which has other benefits too).
  • At the recommendation of this post, I also let my babies have an outside play area with organic dirt once they are 3-4 months or old enough to sit up or crawl. Yes, they get dirty. Yes, they put it in their mouths (that is the point). Usually, this area is just a small kiddie pool or pot or organic dirt with some toys in it to encourage play.
  • I let my older kids help my in the garden, let them play in the dirt, make mud pies and otherwise get dirty. If they’ve been playing in clean dirt, I also let them eat outside without washing their hands so they can transfer small amounts of these soil based organisms to their digestive systems.
  • We also all consume probiotic rich foods and drinks like water kefir, homemade sauerkraut, kombucha, and other fermented foods to make sure we are exposed to a wide variety of naturally occurring beneficial bacteria.
  • I supplement with a high quality probiotic/prebiotic blend that contains many of these same organisms. I also sprinkle these on the foods I feed my little ones and even dump a capsule in to the play dirt. (This brand has been clinically studied, especially in patients with IBS or digestive problems)

Did you know that kids need dirt? Do you let yours get dirty? Do you have any contact with dirt yourself? Think I’m crazy? Share below!

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Reader Comments

  1. Katie, I love it! Thanks so much for sharing. We live in a townhouse complex and have a small fenced in backyard but it really doesn’t have much dirt as its xeriscaped. I try to let my 18 month old get out into nature as much as possible, and we take excursions on the path that connects to our complex. I need to try to get a baby pool with some dirt as soon as I can! 🙂

  2. I love this article. I let my daughter play in the dirt and rocks all the time (and plan to let my 3month old son as well when it warms up) because i firmly believed it was good for the immune system. People looked at me like i was crazy. Now i have studies to back up this belief! Thanks so much. I love reading your blog!

  3. My son is going to be 6 months in December, but its freezing any suggestions?

    • If you are brave… a small pot of dirt or a dirt play station inside. I have a friend who has this in the corner of her kitchen and says it isn’t really that hard to keep it contained.

      • Yeah people are going to think I have really lost it lol. But I saw some organic soil on amazon, does it have to be anything fancy?

      • Really interested in having a “dirt box” for my toddler. I can’t seem to find simple organic dirt. It seems to have bat or chicken poop! Help

        • I’ve found that local organic farmers sometimes have a good stockpile of dirt and out local nursery also had some last time I checked

  4. Thanks so much for this article. You mentioned BioKult in your other posts (I think!) – did you switch or do you alternate between the two?

  5. This is great. I have heard people say that walking around outside barefoot is good for us but haven’t researched it myself. I do know that being barefoot in nature is an amazing feeling and that has to mean it is good for us! If I have kids, I will definitely let them get dirty!

  6. Love this! I rarely wash my 2 year old’s hands… He gets his dirt, it makes my life easier 🙂

  7. I understand where you are coming from in theory, but you might want to do a little reading up on parasites found in soil and how easily they are transmitted to humans. It is interesting to see how many things like intestinal problems, fatigue, skin rashes, joint aches and pains, sleep disturbances, and allergies are caused by these.

    • she did state that it is organic soil. meaning it isn’t your average everyday backyard stuff, she purchases it

  8. I agree that we shouldn’t over-sterilize, but wanted to point out that farm kids are also not as exposed to the car and factory fumes, and other city-smog in general, which could also contribute to fewer cases of asthma.

  9. Hi Katie, would I be able to give this type of probiotic to my 20 month old baby? Thanks so much for sharing.

  10. Thank you so much! Now…where does one get organic dirt for the kids to play in?

  11. I do NOT think you’re crazy… I completely agree! When I was growing up, my dad always said (about dirt, germs, cuts, injuries, etc.) “it teaches your body how to heal.” He was right, and I share that same philosophy with my own son now that I’m a parent!

  12. Amen sister. One of my “pet peeves” so to speak is parents treating their children like fragile flowers. The over “protection” is breeding a society of dependent and entitled individuals. Children should explore, skip, jump, run, and should be discovering new things every day!

  13. People often ask why I don’t use gardening gloves when I’m working in the yard. My answer has always been that I like playing in the dirt. 🙂 In all honesty I love getting my hands in the warm soil and working bare handed. I’ve long been a believer that we do ourselves more harm than good with the outrageous abundance of anti-bacterial products. You’re right people need dirt!

  14. I love this post!! My kids (ages 4, 2 and 1) are healthy, and we have done similar things (although I had no idea about all the research you included!). My babies have been eating dirt in my garden, playing outside barefoot, and occasionally eating with dirty hands. So glad to know maybe I’m not such a bad mama after all. 😉

  15. Do you buy your dirt? If so, where do you get it?

  16. I grew up in the countryside in Wisconsin and played in the dirt every day surrounded by cats, dogs, birds, cows, and dirt. As a kid, I had NO allergies. At age 24, they all hit me like a ton a bricks. I am now allergic to nearly everything outside – oak, maple, cedar, milkweed, ragweed, cats, dogs, bunnies…pretty much everything I came into contact with as a kid. How does this fit into this theory?

  17. My baby is 10.1 iron, doctor told me is low. How bad it is Katy and what can I do to help my baby. She is 13 months she never crawls. she walks But she is always afraid of walking by herself! Thank you for your help.

  18. This is a great article. My kids are now 2 & 4. We live in Australia and its very common for kids to go barefoot. I’m from the UK and kids never went barefoot there when I was growing up so it was hard for me to go along with this. My husband insisted though. I now feel reassured, so thanks. My husband hardly ever wears shoes in his leisure time. He goes barefoot walking anywhere and everywhere, it used to bother me but perhaps now I’ll join him. Thanks!

  19. Love it, but at some point, we need to get cleaned up. Curious about what you use for kid’ baths.

  20. I grew up in the 60’s. We never wore shoes while playing outside. We never got sick! Except for the usual childhood diseases (ie..Chicken Pox). When I had kids, I never insisted they wear shoes outside. They did get Pin Worms once and the entire family had to be treated with one pill each. It wasn’t until I became a homemaker and began to live most of my days indoors with carpeted floors that I developed allergies to dust mites. What took so long for this realization of the benefits of nature when it should be common sense. In the old days people were closer to nature and there was no such thing as auto-immune diseases.

  21. I really like this theory and believe it now!! I have 2 kids 5 and 3 years , they are always sick unfortunately !! And I’m tired of this! I’m obsessed with cleaning and clean environment !! This was my mistake , I tried to protect them but actually I did the oppisite !! I don’t know what to do now after this time! I really need an advice if I can correct the situation and what I did 🙁
    What may help them now to make a better body better immune ??

  22. I love this! We have always allowed our kids to run around barefoot outside. We barely ever wear shoes when it’s warm enough so I’m glad to hear there’s some scientific benefit to it!

  23. I was wondering if you will be posting any recipe ideas for babies? Mine is almost 6 months and would like to make my own food instead of canned. Thanks for all you do!!

  24. Such a great article!!! I grew up in the country and I loved it!!! Our bodies are nature,so makes Alot of sense to get out in nature,as a mother to boys I never minded them getting dirty cuz I played in the dirt as a child…..thankfully they are healthy happy boys,I’m sharing this with my sister whom thinks that bleaching everything is beneficial for her and her families health!!

  25. Do you take these sbo probiotics when you are pregnant?

    • I do but ask your midwife or doctor to be sure.

  26. All my nurseries in the area sell organic dirt but it has small wooden bits and splinters in it. I live in a large city and all 8 nurseries don’t sell anything without tree compost in it.

    Help! Is there a product on Amazon I can buy for my 9 month old, like a small amount of organic dirt? His iron levels are low because of being purely breastfed up to this point.

  27. I’m not sure if you know the answer to this, but I know soil is one place that young babies can get botulism. In the spring when we are out more I want to let her get dirty for sure, but right now we live in an appartment and would love to get some organic soil for her to play it is 7 months passed that stage they should be more wary of the honey and soil bacteria ? I’m not going to feed honey until after a year but outing her in soil daily would be great except that part I wonder? Ahh first time mom worries! Who knew, as I love getting in the dirt outside but now worry more than I thought! And for the inside soil… Could I just ask and organic farmer for some or should it not be fertilized. Thanks!

  28. I loved reading your article and I absolutely agree to all the points =) Kids benefit tremendously with the time spent playing in the garden and dirt. Our germaphobic, hyper hygienic society has actually placed us and our kids in a weaker state. It not only boosts their immune system but it also lets them connect with life on the most fundamental level.

  29. would the organic soil, or even regular soil help a much older kid who has allergies/asthma most of his life and get sick much more than a regular kid?
    He is going to be 10 year old.

  30. This was a great read, thank you. Unwittingly I’ve done exactly what you outlined with my own children…not because I knew it to be healthy but just because that is how I grew up. (Imagine my delight to find that going barefoot, something I never stopped as I grew up, had wonderful health benefits!) My first born struggled with mild asthma like symptoms a few times a year which I partly attribute to mold in our apartment. When he was 5 we moved out to the country and built a house (so no more mold) along with running around for hours in the sunshine and dirt and fresh air (not to mention playing in the barn) and he gradually had fewer episodes to where it’s hardly an issue now. Wish I could post a picture of my dirty little children 🙂