The Farm Effect: How Dirt Makes You Happy and Healthy

7 Ways Dirt Is A Powerful Immune System Booster

by Christiane Northrup, M.D.

Dirt is not just good for children. We all need a little need dirt in our lives! — Christiane Northrup, M.D.

When was the last time you had dirt embedded under your fingernails or mud oozing between your toes? If it was recently, then good for you! Research over the last decade or so has shown that the microbes and bacteria in dirt can help boost your immune system and make you healthier and even happier.

Unfortunately, most people today have become germaphobic, using germ-killing wipes, hand sanitizers, and even strong chemicals to clean their homes. But, it turns out that dirt has an important immune strengthening purpose.

How Dirt Strenthens Our Immune System

A study published in the June 2012 issue of The Journal of Allergy and Clinical Immunology shows that Amish children who live on farms have about a 50% reduction in asthma, allergies, and gut-related disorders compared to children who grow up in more sterile environments.

This is known as “the Farm-Effect.” What’s interesting to note is that seasonal hay fever was first described in the United States in the 1890’s, and by 1920 it was quite common. However, hay fever was rarely diagnosed in the working class population, particularly those living on farms.

The Farm Effect is the corollary — or positive proof — of the “Hygiene Hypothesis,” which states that a lack of early childhood exposure to infectious agents, microorganisms and parasites increases our susceptibility to allergic diseases by suppressing the natural development of our immune systems. (The Hygiene Hypothesis has also been called the “Biome Depletion Theory” and the “Lost Friends Theory.”)

This makes perfect sense. As humans we have co-evolved for millions of years with microbes and parasites, both around and within our bodies. From the time a child is able to crawl, she intuitively knows to get dirty and to put dirty objects in her mouth — it’s a natural way of allowing her immune system to explore her environment. 

The Farm Effect: How Dirt Makes Us Happy and Healthy by Christiane Northrup, M.D. #immune #system #kids

This routine exposure to harmless microorganisms in the environment, such as soil bacteria, trains her immune system to ignore benign molecules, such as pollen. (By the way, the Farm Effect works the same way for children who grow up with a dog or other pets in the house.)

But, dirt is not just good for children. We all need a little need dirt in our lives!

In fact, doctors are now handing out “park prescriptions” for a range of conditions including heart disease, obesity and ADD.

Dirt Has Been Called the New Prozac

Soil microbes called Mycobacterium vaccae are proven to have a natural antidepressant effect on the brain.

Lack of serotonin has been linked to disorders such as depression, anxiety, obsessive compulsive disorder (OCD), bipolar and more. Studies show that Mycobacterium vaccae actually mirror the effect that drugs, such as Prozac, have on the brain without the side effects or chemical dependency.

In one study, lung cancer patients injected with Mycobacterium vaccae reported a better quality of life and less stress. This may mean that Mycobacterium vaccae works by stimulating serotonin production, which makes you feel relaxed and happy.

Another interesting bit of research suggests that the brain actually releases dopamine when we harvest food from the garden! This is known as “Harvest High.” Harvest High most likely evolved over 200,000 years ago when hunting and gathering was a means of survival.

When our ancestors found food, a flush of dopamine would release in the reward center of their brains. This means our primitive brains were originally wired to crave healthy foods from the soil. By the way, that same dopamine high – which is similar to the high some people get from drugs or shopping (“retail therapy,”) but is actually healthy for you and your wallet — can be triggered simply by seeing or smelling fresh produce!

6 More Reasons to Get Dirty

If getting dirty makes you happy, what else might it do? Well, it turns out dirt is good for you in more ways than one. Here are some reasons to get dirty:

  1. Being “dirt happy” lowers your blood pressure and stress hormones.
  1. Mycobacterium vaccae in soil can improve cognitive function, as well as symptoms associated with Crohn’s disease and even rheumatoid arthritis.
  1. Bacteria on your skin can help manage inflammatory skin conditions such as psoriasis, and can even heal wounds.
  1. Gardening (and other dirty outdoor activities) engages your senses. Research shows that when multiple senses are stimulated, the brain is more likely to remember things and is better able to solve problems.
  1. If you’re playing in the dirt, chances are you’re outside (unless you have a kiddie pool full of dirt in your living room.) This means you are getting sunshine, which is full-spectrum light. Full-spectrum light stimulates production of Vitamin D and serotonin. It also regulates the production of melatonin, helping you get a good night’s sleep.
  1. Children who play outside become more adventurous and self-motivated and use their imagination more. They are also better able to understand and assess risk because playing in nature lets them explore in ways that they can ask questions, make observations and see outcomes. For example, “What if I put water on a pine cone?” “What changes if I put the pine cone in the hot sun?”

How You Can Create The Farm Effect Anywhere

While many of us don’t live on farms or large plots of land these days, there are ways you can create a modified Farm Effect in your body and in your home, no matter where you live.

  1. Stop using antibacterial soaps and detergents. These kill healthy bugs off and can actually produce a breeding ground for antibiotic-resistant and disease-causing bacteria. Try using natural cleaning solutions.
  1. Clean Up Your Diet. It sounds counterintuitive when I am talking about getting dirty, but getting clean in your diet means getting rid of the harmful chemicals and additives (including sugar!) that children, especially, get in massive amounts.  Learn to read labels, including the labels and side-effect profiles on any medications you and your children are taking. Read the game-changing book, The Dirt Cure, by integrative pediatric neurologist Maya Shetreat-Klein, M.D. for a nutrition plan that can help your kids and your entire family prevent chronic disease.
  1. Purchase organic, seasonal fruits and vegetables from your local farmer’s market. Rinse your food, but don’t scrub off all of the healthy dirt. If you can’t get to farmer’s market regularly, invest in a weekly organic community-supported agriculture (CSA) box.
  1. Garden with your kids. If your child is very young, you don’t even need to plant anything. She will love just having some dirt to play in. If you live in an apartment or have a small lot, create an organic window garden. You can actually grow more than you realize in really small areas by using one-pot containers. Strawberry pots are also great. You could even try hanging pots by your windows.
  1. Use the best soil you can afford. Buy or create healthy soil with organics before planting and avoid using chemicals in your garden. Studies show that glyphosate (the active ingredient of Roundup,) depletes serotonin and dopamine levels in mammals. Glyphosate and other Roundup ingredients stay in the environment, including our soil and water, the plants we eat, and ultimately in our cells. Glyphosate residues have even been found in clothes made from Roundup-ready GM cotton.  This can absorb directly into your skin, nervous and circulatory systems! Read Farmacology: Total Health from the Ground Up by Daphne Miller, MD, which explores the idea that it’s the farm where food is grown that offers us the real medicine.
  1. Explore nature. Go walking or hiking. Put your bare feet in the earth and in streams. If you have children or grandchildren, you can have a great time studying nature. You could even start a collection of rocks or leaves. Make each outing about adding to your collection. Read The Last Child In the Woods by Richard Louv, to learn more about what he calls “Nature-Deficit Disorder,” and how the health of our children and the health of the Earth are inseparable.
  1. Take Up A Mud Sport. Playing in the mud allows you to feel a sense of freedom and it’s an opportunity to act like a child again. Mud runs, mountain biking, and hiking are a few good options.  If sports aren’t your thing, consider a “mud pack” with organic soil.  You can go to a day spa or do this at home.
  1. Eat Fermented Foods and Take a Daily Probiotic. Even if you are eating food from healthy soil, in today’s hyper-hygienic and chemically-ridden world it’s important to continually restore beneficial gut bacteria.

How has getting dirty improved your health? Please share your comments with me in the comments section below!

Last Updated: March 1, 2016

Christiane Northrup, M.D.

Christiane Northrup, M.D., is a visionary pioneer and a leading authority in the field of women’s health and wellness. Recognizing the unity of body, mind, and spirit, she empowers women to trust their inner wisdom, their connection with Source, and their ability to truly flourish.


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  1. Aidan
    2 years ago

    Hi Dr. Christiane. As a kid who played in mud, I was so glad to hear that science now backs up what many of us normally clean people knew. My kids also have no allergies and sat in sand a me dirt all their childhood.

    Could I ask where your citations are or are they all from those books you quoted.

    Also, I’ve lost my job recently and started dishwashing. My hands hurt and are fragile dry, crispy and painful. Would dirtyjng them on days off help repopulate the good stuff that’s been lost on my hands.

    Shame about covid and sanitizers overkill. I always said door handles thar automatically soap with regular soap would have dissolved the phospholipid bylarer around the virus cells and people should just wipe their soapy hands on their pants.
    Lol. Perhaps I’m mad.

  2. Bea
    4 years ago

    Thank you so much for this article. I would like to share this on my Facebook page if that’s ok. I believe you also had written an article in regards to a ‘backyard’ garden, through the the connection you make with the plants and the soil, providing the nutrients the gardener needs for their body. If you have written or spoken about this could you please share the link. Thank you Bea

    1. Shannon
      4 years ago

      I think I’m looking for the same information. I heard that if you use your bare hands in the soil while planting, the plant somehow detects deficiencies in your cells/dna and compensates for that. Then, when you eat that plant, it helps to heal your ailments. Is that correct? Can someone point me to the information on this topic, please?

      1. Ede
        3 years ago

        I hope that’s true that sounds awesome

    4 years ago

    My wife thinks that you are the source of this quote; is she correct? I want to quote it in my book on adobe….

    “Recent international research from the Netherlands verified that those early MUD PIES we made as children, with hands and dirt are part of the chemistry for mental and visual stimulation, and counter stress hormones like cortisol and roadblock serious illnesses. It stimulates positive attitudes, energy, breathing and our vitality overall. We also know mud baths work, now we know why.” From The Farm Effect: How Dirt Makes You Happy and Healthy, by Christiane Northrup, MD.

    1. Coulson Duerksen
      4 years ago


      I am Dr. Northrup’s editor. Thank you for your request. However, the quote you ask about is not from Dr. Northrup’s blog and therefore should not be attributed to her.

      Coulson Duerksen

  4. Tracy Martinez
    6 years ago

    I know this thread is old but I’m hoping Dr. Northrup might still read the comments. As a 45 year old adult I have a severe allergy related auto immune disorder (AERD). I grew up in that sterile house without pets and didn’t play outside much. Now I’m allergic to every tree and grass and have asthma. I also seem to catch every cold going around. Would taking up gardening and getting dirty in midlife retrain my immune system or is my haywire system set?

  5. Janie
    8 years ago

    I wondered why I often felt compelled to work in the yard, especially so if I missed a week. It was like I needed a “fix” to feel right. It definitely helps with mood, emotions, and solving problems. Glad this has been researched!

  6. B Halleron
    8 years ago

    You are so right about dirt. I feel the best when I am outside, and especially when I am working in the yard. It’s also true when I go to the beach or kayak. I love the water on my body and sand between my toes. I do not use antibacterial products because I know that I need some bacteria to fight bacteria. I am bipolar, manic depressive and add. This therapy outside works for my mood. I know I can change my “negative” mood by being in nature. That’s another reason why I love to swim and bask in the sun while completely naked. IT JUST FEELS GOOD AND RIGHT!

  7. Lisa
    8 years ago

    Lover this… we took the kids camping in April… a first this early….it was MUDDY… my daughter and the other kids she was with put the mud on their face like war paint… they had so much fun, almost as if their bodies were called to it. Good article to promote to all parents! A

  8. Nancy Tossell
    8 years ago

    As a former Microbiology lab tech, I’m amazed at the germ phobia we have these days. The lab where I worked had a candy drawer where we kept occasional treats. When one of us took and break (and did wash our hands), we’d get some and even feed others who were still working on the bench. This practice was banished years ago but at the time, infections, including colds, were little to no problem!
    As a gourmet mud pie maker in my early years, and one who continues to enjoy yard work, I thoroughly enjoyed your article and will follow up on some of the references you mentioned.

  9. Vivian Franck
    8 years ago

    Dear Christiane,

    Oh how great it is to read about the benefits of dirt! Who would’ve thunk? I was brought up in a home where we were never allowed to go barefoot either inside or outside, where the kitchen floor was so clean (even in a family of eleven!) that people told me as I grew older “We could eat on Mrs. Franck’s floor!”
    Thank you for this enlightening information. Am I going to ‘play’ in my garden this summer!!

  10. Angela
    8 years ago

    I am such a huge advocate of this. I had allergies to all nuts, milk, eggs, all seafood, horses, cats, dogs, and some seasonal allergies as well as eczema since I was an infant.

    Then I fell in love with my husband, who lives on a farm. Over the past 15 years that we have been together on the farm, and 11 years of organic gardening, my allergies have dwindled to only peanuts, walnuts & salmon. All else is fine. I do not get seasonal allergies, I am no longer allergic to animals, I get sick less, since using homemade kefir, my eczema is gone.

    Studies of Blue Zones (areas of the longest lived populations) consistently reveal gardening as a lifestyle and in my own family, all those who gardened lived in to their 90’s and one until 105.

    Healthy soil is integral to wellness, but it is also a resource that we are quickly losing.

    1. Christiane
      8 years ago

      Oh how I love hearing your story!! thank you SO much for this!!

  11. Lisa Henderson
    8 years ago

    Thank you, Dr. Northrop, for continually providing such relevant and useful information for optimal health and well-being! This year I joined forces with an amazing, innovative early childhood educator to found Grow, Bloom & Thrive ( and open the first of many to come Farm and Forest Kindergarten – a primarily outdoor, child-led, play-based preschool program on a CSA farm in Millis, MA. Our mission is to partner with CSA farms and communities and reframe the concept of ‘kindergarten’ in the US to emphasize child-led, outdoor, play as the standard for programming for ages 3 through 6. We provide monthly opportunities for the whole family to join us on the farm and play in the mud!! Our 3 and 4 year olds have been known to provide a detailed explanation of what compost is as how the farmer uses it to grow her vegetables. It’s an amazing thing to be a part of. Thank you for helping to beat the drum and guide more families to #getoutsideandplay!!

    1. Christiane
      8 years ago

      As the grandmother of a baby girl, you can be sure I’m going to let my daughter know about your Farm and Kindergarten movement. I am just thrilled with this venture!! thank you.

  12. Joy Nissley
    8 years ago

    Such great information! Thank you!! I run a program for children called Natural Learning Alternative and we have been called the “barefoot school.” Our focus is on getting children back to playing outside learning through real experiences and discoveries! Thanks for helping parents realize dirt is actually good for children and adults too. Love your work!

  13. Kirstie
    8 years ago

    This is a fantastic article and touched on every point I make when explaining a healthy lifestyle. As a culinary gardener, I’m always preaching the benefits of growing our own food. Thank you for this!

  14. Jean S.
    8 years ago

    Dr. Northrup, Thank you for this great article! I’m 58 and as kids we lived outside…..those are the happiest days of my life!! I remember eating spoonfuls of dirt, making the mud pies, playing in the sun!!! Even though I have precancerous spots on my face, have had Lymes disease two times, and many other co-infections from ticks, nothing will ever keep me from my big beautiful garden. We live out in the country and grown lots of our own food including raspberries & strawberries. I love walking through the woods…it calms my soul. I simply cannot let fear rule my outdoor activities. I wear sunscreen everyday,
    especially on my face, check for ticks when going in the house for the evening and pray to God for His protection so that I may enjoy many more years of the outdoors… favorite place to be! I love you Dr. Northrup!!!!!

    1. Ann Marie Gambino
      8 years ago

      Wow! You said it all Jean! Ditto! You brought tears to my eyes! Thank you.

      1. Christiane
        8 years ago

        I so agree. I never worry about ticks, dirt, germs, or anything else. And I plan to go barefoot in the woods more, not less. I love what you said Jean. You nailed the genius of nature. And I thank you. Nice comment Ann Marie!!!

  15. Katherine Richardson
    8 years ago

    Keep it coming, Dr. Northrop! We need more like-minded docs to help get our world healthy again.

  16. Great information! I read the info. about the Amish children and the farm effect. I am pretty sure they also do not have vaccinations….and that has likely positively effects their immune systems as well. With modern electronics, vehicles and lifestyle, I suspect their stress levels are lower too.

    1. Christiane
      8 years ago

      You are correct. Amish children aren’t vaccinated. One more reason why they stay so healthy.

  17. Marilyn Harding
    8 years ago

    My sweetheart was born in Greece before his family moved to Canada when he was nine. He and his brother were sickly as children and the mom asked the doctor why her children weren’t as healthy as the Gypsy children that played in the dirt. Her response to his question of don’t your children play outside, was “Of course not!” after which he prescribed a large sandbox and daily dose of dirt play to which my guy attributes his vibrant health. We now live in Greece where we enjoy a more natural lifestyle and access to simple nutritional foods.

    I love the term “Nature-Deficit Disorder,” and totally agree that our children need communion with nature. Mine got plenty of that and I believe that is why they are such accomplished and creative musicians today.

    Thanks for this great sharing!

  18. Joan Vernikos
    8 years ago

    Fantastic!! I grew up in Egypt and whether liked it or not the flies that landed on us brought with them all kinds of visitors. Though vaccinated for everything including cholera, we grew up with incredible resistance that has served me well. When part of the US/USSR joint working group in 1976, all my US colleagues routinely came down with diarrhea except me which I attributed to those very early exposures that stood the test of time. Great article.

    1. Christiane
      8 years ago

      Are you the same amazing Joan Vernikos who was head of NASA Life Sciences and wrote about your work with the astronauts and the health dangers of weightlessness? you are one of my heros!! Thank you so much for this fantastic comment.

  19. Leann Chaney
    8 years ago

    Is there any benefit of smelling dirt? I make a handmade soapscented with a blend of natural oils that smells like dirt.

    1. Christiane
      8 years ago

      Hi Leann, What a great question. I think there really is a benefit. I personally have craved the smell of certain kinds of dirt since I was a child. There was a concrete building in the back of a school I attended as a child that has a certain smell I couldn’t get enough of. Aromatherapy is as old as time. And smell activates the most primitive and primal areas of our brains– perhaps reminding us that we are literally made from the Earth herself. I’m all about the good smell of dirt. Thanks for asking.

    2. Christiane
      8 years ago

      Hi Yvette, perhaps you can plan some good dirt- friendly vacations with your grandkids. Complete with beach walks and mud pies!!

  20. Ursula Banks
    8 years ago

    Thank you, Dr Northrup! this information is something I truly believe. I love gardening and though my GP has advised that I do less because of asthma, I actually feel better and breathe better during and after a session in the garden.

  21. My wonderful midwife, Sister Pearl, when my kids were born in the ’80s said that all children should ‘eat a peck of dirt by the time they are five’. An American peck is nearly 9 litres volume! I”m not sure mine ate that much but thankfully I did take her at her word. And they all three garden passionately as adults – producing their own food to eat.

  22. Yvette Robinson
    8 years ago

    As a child we practically lived in the parks of New York City. I developed a love for gardening and nature in general.
    Now I’m watching my grands grow in a sterile environment and frankly it concerns me that they until recently they had never been in a sandbox or are frightened by an insect.
    I want them to be stewards of this Earth, that is their inheritance.

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