Philosophy is not the first thing that comes to mind when we think about microbiome research. Yet, there is more philosophy at work in microbiome research than we tend to think, while philosophical research may open new perspectives, that we should address to avoid bigger problems in the future.

It is likely that scientific insights will allow humans to become stewards of their own health in an evidence-based manner, resulting in improved lifestyles and prevention of disease.  A range of microbiome-based tools to support people’s health is already on the market, such as advice on lifestyle or food supplements. While such tools promise to empower citizens to manage their health, there are several unsolved questions. First of all: are claims made by researchers, or by producers of microbiome products trustworthy? Nowadays, many tools seem to promise more than they can actually offer, for instance because the advice provided is quite general rather than personalised. As the evidence for self-management tools is often fragile, there is a strong need to bring expertise from various disciplines into the debate and to consider the experiences of citizens using these tools.

Self- what?

Microbiome research generates interesting insights even on a more fundamental level. While the phrase “self-management” suggests that humans are in control of their microbiome, research challenges this idea. We are part of nature, embedded in and dependent on our external environment. At the same time, we are ecosystems, inhabited by millions of organisms who are part of us. We have a microbiome, but at the same time our microbiome is part of what we are.

Microbiome research fosters an interactive and symbiotic view of human existence, seeing human beings as holobionts, a term coined by biologist Lynn Margulis to emphasise interconnectedness and interdependence of all living beings. The microbes inhabiting us not only orchestrate digestion, but also influence mood and cognition.

“Love is a microbe too”

The realization that humans are not insulated entities, but the outcome of multiple interactions with microorganisms, both indigenous and external, has consequences beyond biology. Our traditional self-image is challenged. To some extent humans have always been aware of this, but current research makes our knowledge more precise.

While Vincent van Gogh being a patient in a mental hospital in France, he wrote a letter to his sister Wilhelmina in 1889: “When I suffer from attacks of melancholy and atrocious remorse, I tell myself that all these things might possibly be caused by microbes too, like love”. Apparently, a physician had informed him that “love is a microbe too”. For Van Gogh, this was a consolation, enabling him to make sense of mood swings. He would probably have been interested to hear about the gut-brain axis, linking emotional and cognitive centres of the brain with what happens inside the human gut.

The “forgotten” organ

The human microbiome has been named our “forgotten” organ, to which microbiome research calls attention. It is an “estimate” part of ourselves: both intimate and external, both “us” and “other”. This calls for stewardship and self-care, rather than “microbiome management”. We cannot control the health and wellbeing of our microbiome by adding specific components. We should see it more as a relationship.

Microbiome research fosters self-care by increasing awareness for instance concerning the use of antibiotics. But microbiome research also urges us to rethink what we already know about our gut. Rather than defining microbiome health in terms of the presence or absence of “good” and “bad” microbes, we should adopt a relational and interactive attitude towards the living beings that inhabit us.

From practical experience to participatory research

Initially, practices of selfcare were based on experiences. Subsequently, laboratories produced reliable, evidence-based knowledge, resulting in a tension between lifeworld experience (practical knowledge) and laboratory findings (validated knowledge). In the current situation, although labs remain prolific producers of validated knowledge claims, it is important to find out how these results work out in practice, in the messy, complex lifeworld outside the lab. All citizens may become citizen scientists, participatory researchers, sharing their samples and their experiences. This offers opportunities for participatory research, seeing citizens as life-world experts, using public intelligence as a decisive source of information. Insights from single individuals may provide insights about the dynamics of the microbiome in a particular societal context.

In this way, microbiome research may alter the traditional relationship between researchers and research subjects, affording a more active and participatory role to bio-citizens.