“I haven’t been sick since 2019,” said a patient of mine recently.
No one likes getting sick, and you may think that this is something to celebrate. However, this is actually something I worry about hearing. I don’t believe that our immune system is healthy if we don’t get sick every once in a while. Getting sick is an innate part of being human, and our immune system has evolved to account for this. My patient’s statement has me thinking about the downstream consequences of avoiding illness.
An Epidemic of Absence by Moises Vasquez-Manoff provides an insightful exploration of the hygiene hypothesis: that the modern-day sanitization practices may be causing immune dysfunction underlying the current rise in allergies, asthma, and autoimmune conditions.¹ Considering that the immune system has tight links with the endocrine and nervous systems, this discussion also begs an even bigger question...
What exactly does illness do to us as humans – physically, mentally, and developmentally?
While there’s still so much we don’t yet understand about immunity, it’s worth exploring how extreme attempts to protect ourselves from pathogens may have big-picture consequences.
The Human Microbiome and Immunity
As human beings, we tend to think of ourselves as separate from other species – especially from the microscopic world of viruses, bacteria, funguses, spirochetes, and parasites responsible for getting us sick. This mentality is being turned on its head, as we’re beginning to understand more and more about the human microbiome.
Growing up, you may have thought that all “germs” are bad, but there are actually many friendly microbes. We now know that there are ecosystems of trillions of bacteria, viruses, and fungi living within our GI tract and on our skin that make up the human microbiome. We can no longer think of ourselves as isolated from the microbial world.
Research strongly supports that a healthy immune response has strong ties with a diverse microbiome. Inflammation and immune dysfunction often occur when there’s an imbalance of any microorganism in and on our body – whether initially thought of as good or bad. It actually doesn’t matter anymore. One of my favorite physicians once said to me... “anything in an overgrowth state is a pathogen”. Indeed, much of what ails us can be put into the very broad category of dysbiosis.²
Our microbiome health begins at birth with the colonization of gut bacteria upon exposure to the mother’s microbial flora in the birth canal. Babies who are born by C-section tend to have a less healthy microbiome and are more likely to develop immune-related disorders, such as allergies and asthma. Breastmilk is also rich in beneficial bacteria and prebiotics (the food for beneficial bacteria). It also contains our friend, colostrum, which contains antibodies to support the baby’s immune system for the first 6 months of life while it is still developing its own immune system to defend against the world outside of the womb. .³
From day one, we can see evidence of the importance of microbial exposure. In fact, our understanding of babies and their immune system building directly reflects what we know about our internal milieu. We have many cells in our body that mature in our tissues – only after exposure to their specific internal environment. This makes sense, that each cell should learn to specialize in how they react, specifically to the environment they are in. As our modern world becomes more sanitized, we have to wonder about the potential consequences of removing stressors to the immune system and what new stressors we may be introducing.
The Hygiene Hypothesis: Is Our Sterile World Causing a Rise in Autoimmune Conditions?
High-income countries like the United States have taken many steps toward building a more sterile environment. After the Industrial Revolution, sanitization practices took off with water purification, antibiotic use, and improved hygiene measures. In our attempts to avoid pathogens, we’ve also eliminated many of the microorganisms that we need in order to keep a balanced milieu. As we have less and less exposure to certain microbes on a daily basis, it seems highly likely that this has disrupted the microbiome and immune system to a tipping point of dysbiosis on all levels – the GI, the skin, and the oral microbiome….
Our adaptive immune system evolved to protect the body from pathogens and learn how to respond better in the future. We have specialized immune cells that not only protect our bodies from pathogens, but they learn how to mount a better response the next time they encounter the same microbe. When the immune system doesn’t experience this process of education and refinement, it’s unsurprising that dysfunction would result.
Research at Brigham and Women’s looked at immunity in mice raised in a “germ-free” environment compared with mice who had normal microbial exposure. The germ-free mice showed inflammation of the lungs and GI tract (resembling asthma and colitis).⁴ While we can only draw so many conclusions from animal studies, this supports the argument that a well-functioning immune system is dependent upon microbial interaction.
The Relationship Between Illness and Human Behavior
I recently had a patient who described caring for her 13-year-old daughter who was sick with mono for four months. After her daughter had recovered, she seemed to become “a different person”, seeming more responsible, mature, and independent. I noticed something similar when my own daughter got sick with the flu. She seemed as though she had gone through something on her own and came out on the other side stronger and more mature.
Beyond the scope of the immune response, I believe there may be other facets to illness that we don’t yet understand. It seems as though getting sick may lead to behavioral change and maturity. This makes sense when you think about the bidirectional communication between the brain and immune system, meaning that they’re both constantly influencing each other.⁵ Our immune function may very well play a role in how we develop as humans.
The inverse seems to be true as well. Our social experiences, or lack thereof, can influence immunity. You’ve likely heard of the evidence of the harmful impact that chronic stress and isolation can have on immunity.⁶ This is not just in our minds only. There is a biological piece to how we are interacting with our world and being influenced by it.
Oxytocin is a prime example of this interplay between human connection, neurology, and immunity. Oxytocin is a neurotransmitter and hormone that has anti-inflammatory and immunosupportive properties. Research on NICU babies shows that skin-to-skin contact causes a release of oxytocin in both the parents and babies.⁷ It’s possible that our skin is a transmitter and receiver of information in ways that we don't fully understand. Human touch and connection may have an even greater physiological and biochemical role than we realize.
An Ecosystems Approach to Immunity
As human beings, we are an ecosystem living within an ecosystem. We’re not meant to be living in our isolated bubbles, living in fear and avoidance of other humans and the microbial world. While there’s so much we don’t yet understand about immunity, we do know that this is an incredibly complex system that seems to be malfunctioning more and more in today’s world of isolation and sanitization.
Rather than trying to avoid germs at all costs, efforts should be redirected towards supporting a robust immune response. This doesn’t necessarily mean that you’ll never get sick. Rather, your body will respond efficiently to pathogens and become stronger. This comes down to healthy lifestyle practices and supporting the microbiome, through:
Healthy nutrition
Consuming probiotic-rich foods
Daily movement
Spending time in nature and getting enough sunlight
Managing stress levels
Getting enough sleep
Spending time with loved ones
Decreasing exposure to toxins from food, cleaning products, bath, and beauty products.