Clean Living

The Hygiene Hypothesis: How Clean is Too Clean?

The Hygiene Hypothesis: How Clean is Too Clean?

If you’re like many busy parents, the thought of rushing around to clean your house at the end of a long day ranks right up there with maintaining your car’s engine—necessary, but not at the top of your “want to do” list! Fortunately, recent research on the microbiome may encourage all of us to put the sponge down and learn to live a little (more) dirty.

Don’t worry—we aren’t talking about giving up cleaning altogether. Letting a week’s worth of dishes pile up in the sink or ignoring the grime threatening to take over your bathroom may do more harm than good when it comes to your well-being...and your social life. But, researchers are discovering one very important health reason to stop “over-cleaning” and sanitizing every surface in your home: your kids’ microbiome.

Our Microbiome, Our Immune Health

Our microbiome is the collection of all of the teeming colonies of bacteria living in and on our body. Composed of trillions of bacteria, the microbiome is involved in a plethora of essential health functions in our body—such as supporting digestion, helping us absorb nutrients, supporting blood sugar levels already within a healthy range, and encouraging positive emotions—but one of its most significant tasks is keeping our immune system in tip top shape.

Why are microbes so crucial for immune system health? A staggering 80% of our immune system resides in the gut, where the vast majority of our body’s microbes live and work. Here, friendly flora (also called probiotics) help to crowd out bad guy bacteria, produce immune-supporting vitamins and antibodies, and help seal the gut barrier so toxins and inhospitable invaders can’t get through to the bloodstream. Without these helpful microbes working hard on our behalf, our immune system can become under or overstimulated, both of which can make us feel less than our best.

Clearly, a healthy, balanced microbiome (with about 85% beneficial bacteria) is critical to maintain immune function and overall health, but what makes a strong microbial community especially important for the developing systems of children?

Immune System Development

It may come as a surprise that we aren’t born with a fully mature immune system. In the womb, babies are exposed to their moms’ antibodies via the placenta and after birth, breast milk provides loads of antibodies for baby’s developing body. This “passive” immunity from mom is an amazing (and very necessary) feat of nature, but it doesn’t last forever—your baby must develop their own antibodies and immune system over their first several months of life.

So, how does a baby’s immune system prepare for their long-term health? Once again, the answer lies in the microscopic world of the microbiome. As your child is exposed to a variety of microorganisms, their immune system learns how to react appropriately to microbes in the environment. Much like an athlete’s body needs exposure to various training regimens to get stronger, a child’s immune system must encounter different bacteria to develop properly.

But what happens if there aren’t enough microbes around to adequately “train” the immune system?

The Hygiene Hypothesis

In 1989, epidemiologist David Strachan discovered that the number of children in a household directly influenced the kids’ immune reactions.1 In other words, kids growing up in large families with multiple siblings showed less overstimulation of their immune system than children in smaller families. In addition to small family size, Strachan also theorized that increased personal and household cleanliness played a significant role in immune system imbalance—a theory widely known as the Hygiene Hypothesis.

Here’s how it works: the fewer the kids bringing home microorganisms from school and the environment, and the cleaner the home, the less exposure to microbes and the less “training” a baby’s developing immune system gets. According to Strachan, this Hygiene Hypothesis helps to explain the epidemic of increasing immune hypersensitivity we’ve seen in the last 50 years.

Wondering where cleaning fits in the puzzle? Overzealous cleaning (especially with harsh ingredients) wipes out bacteria, both good and bad. A home environment stripped of a vast majority of helpful microbes lacks the necessary bacteria for your child’s immune system development. So, while your uber-clean and sanitized house may be the envy of all the neighbors, it could actually be impeding your child’s immune system, setting them up for a lifetime of less than optimal health.

Fortunately, researchers are discovering that, even in our clean-obsessed culture, we can take steps to make sure our children are exposed to the microbes they need for long-term health and proper immune function.

Living a Microbe-Rich Life

The good news is that you can have it all—a tidy, clean home and kids with balanced, healthy immune systems. Here are our five tips for living a clean, gut-healthy life:

1. Get dirty. Newly published research indicates that direct exposure to a variety of microbes (particularly during childhood) can help teach your immune system how to react appropriately to different bacteria in the environment. 2 So, don't be afraid of a little dirt! Go camping, spend time gardening, or make a muddy mess in the backyard with your kids. Your bolstered immune system will thank you!

2. Hand wash your dishes. It turns out that hand washing dishes is preferable to using a dishwasher when it comes to a balanced microbiome and healthy immune system. Scientists surveyed over one thousand Swedish children and found that those whose families hand washed dishes had fewer over-the-top immune reactions than kids from families who used dishwashers.2 Why? Dishwashers sanitize and disinfect dishes, destroying good microbes in the process, while hand washing enables some valuable microbes to stick around.

3. Don’t be afraid to share! Sharing kisses and snuggles with your baby is one of the most rewarding parts of parenting, but it turns out the bacteria you’re swapping may be reason alone to partake—especially when it comes to pacifiers. We all know that dreaded moment when our baby’s beloved “binky” careens to the ground in a blaze of glory. From rinsing or boiling in water to dusting off with a diaper wipe, well-meaning parents usually try to clean the pacifier after it takes a tumble.

Interestingly, researchers have found that children of parents who “cleaned” their babies’ pacifiers by putting them into their own mouths had lower white blood cell counts at 18 months (a marker of immune function), as well as increased protection from developing hypersensitive immune systems later in childhood. This immune protection is most likely due to the increased exposure to microbes from their parents’ oral microbiome.3 So, resist the impulse to disinfect an errant binky—giving it a little suckle instead can make your baby (and maybe even you) healthier!

4. Live near (or with) animals. Research shows that exposure to dogs or farm animals during the first year of life is associated with healthier immune system development.4 That’s because animals, just like humans, carry microbes that can help to train immature human immune systems. In one study, children raised on Amish farms had significantly fewer problems with immune oversensitivity than children raised on more modern Hutterite farms.5 The difference, according to researchers, seems to be in the extensive use of horses in Amish farms and the microbial-rich house dust from farm animals. If you can’t bring animals into your home, consider routinely visiting local farms for a good dose of healthy microbes.

5. Skip the antibacterial products. Designed to kill all bacteria, antibacterial cleaners and sanitizers don’t just target the bad guy microbes, they indiscriminately wipe out all the probiotics, too—the very bacteria your child’s gut needs to teach their immune system how to react. So stick with simple cleaners like water, apple cider vinegar, baking soda and natural soap whenever possible. Don’t forget to look for toxins and antimicrobial chemicals in hygiene products as well—these can deplete the vital good guys.

6. Incorporate probiotics. Because an abundant population of friendly flora is critical to properly maintain your immune function, it makes sense to include plenty of these beneficial microbes in your entire family’s diet. If you’re breastfeeding, a high-quality, daily probiotic formula like Hyperbiotics PRO-Moms supports your baby's immune health along with your own as the good guy bacteria travel through your milk to nourish your baby’s gut and immune system. If your child is beyond breastfeeding, PRO-Kids is the perfect probiotic supplement for children of safe chewing age and up. As your child begins to eat solid foods, you can also expand their repertoire with tasty fermented fare. In one study, kids who routinely ate probiotic-rich fermented foods and microbe-friendly farm produce displayed more balanced immune function than kids who didn’t have access to these foods.1

We now know that early exposure to microbes is the foundation of health a child’s immune system needs to support lifelong vitality. So, next time you feel like double-disinfecting your entire abode, throw out the cleaner and take your kids outside to play in the dirt instead—their microscopic friends will thank you with the gift of health for many years to come.

1. Strachan, D. P. (1989). Hay fever, hygiene, and household size. BMJ, 299(6710), 1259-1260.
2. Arrieta, M., Stiemsma, L. T., Dimitriu, P. A., Thorson, L., Russell, S., Yurist-Doutsch, S., . . . Finlay, B. B. (2015). Early infancy microbial and metabolic alterations affect risk of childhood asthma. Science Translational Medicine, 7(307). doi:10.1126/scitranslmed.aab2271
3. Virant, F. S. (2015). Allergy in Children in Hand Versus Machine Dishwashing. Pediatrics, 136(Supplement).
4. Hesselmar, B., Sjoberg, F., Saalman, R., Aberg, N., Adlerberth, I., & Wold, A. E. (2013). Pacifier Cleaning Practices and Risk of Allergy Development. Pediatrics, 131(6).
5. Fall, T., Lundholm, C., Örtqvist, A. K., Fall, K., Fang, F., Hedhammar, Å, . . . Almqvist, C. (2015). Early Exposure to Dogs and Farm Animals and the Risk of Childhood Asthma. JAMA Pediatrics, 169(11).
6. Stein, M. M., Hrusch, C. L., Gozdz, J., Igartua, C., Pivniouk, V., Murray, S. E., . . . Sperling, A. I. (2016). Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children. New England Journal of Medicine, 375(5), 411-421.


Emily Courtney is a Writer and Editor at Hyperbiotics and mom to two fun and active boys. Emily is passionate about natural wellness and helping others learn about the power of probiotics for vibrant health! For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter.