A voyage into the entrails of humanity: the microbiome

The human microbiome term refers to microbial communities living in symbiosis in or on different organs throughout our bodies. Our intestines, mouth, nostrils, skin, sexual organs, and others profit from this lively win-win collaboration. In recent years, the scientific community has put a lot of efforts into understanding these ‘invisible’ associations and their impact on people’s health. It appears, for instance, that if the intestinal bugs aren’t there in quite the right proportions, this imbalance may favor obesity, allergies, gut disorders or even diabetes – and this list is far from exhaustive. Overall, scientists agree that bacterial diversity is a key parameter in a healthy microbiome.

We humans have around 10 times more bacterial cells than eukaryotic cells that build our muscles, organs and body, adding up to trillions of little companions. This means we are made of a mix of eukaryotic and bacterial cells; the latter accounts for 2 kg in average on the body of a 100-kg adult. Their relationship is dictated by such factors as our own diet, medication intake, hygiene, disease state, genetic profile and so on. As hosts of microbes, we profit from their presence – first benefitting from their role as bodyguards, and second because we obtain essential elements we wouldn’t otherwise. However, research suggests our current societies’ excessive intake of medication, obsession with hygiene, Western high fat and low fiber diets and the rise in C-sections may threaten this much needed cooperation.

One of the signs these actions are unhealth, is the rise of allergies worldwide. Professor Cathryn Nagler from University of Chicago opened up the conference in Rotterdam last March by elegantly pointing out the fact that two kids in each American school have a food allergy nowadays. This is definitely surprising when we take into consideration that decades ago, kids in the United States ate peanut butter and jelly in school every day. What could possibly have gone wrong? Well, C-section may be one of the parameters in this equation. Scientists have been closely studying the development of a child’s gut microbiome, which becomes stable only by the age of three or so – and stunning discoveries have already been made. For instance, babies born from natural delivery get colonized from the mom’s rich vaginal microbiota as well as her skin, whereas C-section babies get colonized mostly by the bacteria present in the environment and on the caregiver’s skin. Children in the latter group may be more vulnerable to allergies later in life. The ultimate take home message here is that C-section should be a choice only if there are risks to the mom to-be and/or baby from a vaginal birth.

Additionally, researchers noted that kids overall are less inclined to get exposed to infections these days as a result of living in highly sanitized environments. Their immune systems get less of a workout. In nature, whenever a limb is no longer essential for the specimen survival, evolution gradually rules it out. However, this shouldn’t be the fate of a person’s immune system since it is very much required to allow us to thrive in all sorts of hostile environments.

Fortunately, we can make changes to our medical systems and choose healthier habits that will result in a more vigorous microbiome. We can discourage C-sections unless there are risks to a mother or baby. We can work on balancing, whenever possible, medicine intake with probiotics -- and only take medication when needed. Additionally, to promote the positive development of our children’s immune system, research shows we should let them play with dirt, which contains a lot of other funny-looking microscopic creatures. This will not only allow them to grow healthier, but happier!

The microbiome research domain is still only in its infancy, as speaker after speaker of the 5th Microbiome R&D and Business Collaboration Forumand 2nd Probiotics Congress repeated, and many more discoveries will come into the spotlight soon. This said, keep in mind that you should nourish your microbes well, starting with a healthy diet, because they will accompany you until the end of your story… for good or for ill!

After hearing all day long about microbes and probiotics, in between sessions, I find myself dozing off… “The interior of the cockpit was filled with essential supplies for an unprecedented scientific journey. I had butterflies in my stomach and was plagued by uneasy thoughts: ‘What if they hold weapons of mass destruction’? ‘What if they don’t understand my peaceful chemical pathway responses and try to acidify me to death’? I recalled the adorable little slimy creatures I’d observed several times under the microscope. How could they be evil? Excitement took me over. The first-ever microencapsulated scientist was about to propel herself inside a tiny transparent all-proof vehicle into the mouth of Humana.

Suction cups were activated and the capsule was about to anchor to a mucosa-ground when a wave of saliva was suddenly released near the landing zone. I lost position and let the vehicle drift in the darkness. My staring eyes sought for a landmark to restore localization when light entered through Humana’s open mouth. ‘Oh my god! Ice cream is on the way’. At this very instant, I spotted an army of tiny objects rushing for the feast. They were different sizes and shapes and had very specific appetites. The diverse communities, identified by their morphological discrepancies, seemed to cooperate well altogether. Among them, I could detect cavity-provoking germs, yet they seemed to get along with the other microbes without causing any harm.

Before I got the chance to pack a sample of these microbes to take home, the capsule was sucked down the drain. As in an aquatic park slide, I found myself screaming holy terror going through free fall until I reached safety in a mystic pond containing vapor on its surface and small live specimens. The stomach seemed indeed a very hostile environment, I thought. It was so acidic that there weren’t many bugs, but I knew that right at the entrance of the gut, the scenario should change dramatically. The time was too short to explore the zone any further, yet the most anticipated moment of the adventure was about to start. ‘Holy shit, the intestines!’ I shouted joyfully.

Sure enough, at the entrance of the intestines, I spotted a dense population of all sorts of funny tiny creatures. Somehow, I did not feel in danger, but welcome. They kept working frenetically without noticing my presence. I figured my capsule was neither tasty enough nor was I sending molecular signals to disturb their usual activities. Such a beautiful diversity of bugs. Some kept close to their preferred habitat zone, which was right next to the epithelial cells of the host – that is, the gut wall. Others tried to infiltrate this sticky barrier but got repelled by assertive molecules coming from their rivals. Humana was having a bowel movement, and as it continued, the capsule floated onward and the tiny inhabitants kept increasing in density and dancing with the loud – and sometimes creepy song – of digestion.

The further I advanced in the intestines, the fewer individuals I was able to count. Some new ones arrived on the scene while others started becoming less abundant. The beauty of a healthy microbiome was flourishing right there in front of my own eyes: I couldn’t help but laugh. Suddenly, a cyclone hit my capsule – I figured I must be spinning wildly in a WC whirlpool by this time. I woke up, and indeed, a storm was announcing itself from the skies. My scientific exploration came to an end too soon, but I was still thrilled with such a vivid microdream.”

Text by Fernanda Haffner

Illustration by Emilie Schmidt