Our bodies are home to an abundance of tiny organisms, collectively called the microbiome, which are essential to human health and longevity. But not all microbiomes are equal, according to an essay published on Tuesday in PLOS Biology that spotlights how access to healthy microbes is profoundly interlinked with social and economic inequities.

A team led by Suzanne Ishaq, an assistant professor at the University of Maine and an expert in animal microbiomes, outlines examples of the human microbiome’s sensitivity to discrepancies in healthcare, nutrition, and safe environmental standards. This “microbial inequality,” as the essay calls it, raises the question of whether a healthy microbiome should be a “right” or a “legal obligation” for governments to pursue on behalf of people.

“The diet that you eat and your lifestyle can have dramatic impacts on the gut microbes that you recruit and the benefits or the negatives that you derive from them,” said Ishaq in a call. “If you don’t even have access to a good quality diet, you might be suffering the effects of not having those beneficial microbes and products in ways you might not have imagined.”

Gaps in microbial health can emerge before a person is even born, because some of the most important microbes are fostered in utero. The fetal microbiome is influenced by the mother’s access to healthy foods as well as her stress levels, which can be amplified by economic inequities. The availability of maternity leave or social support also affects the amount of time that new mothers can devote to breastfeeding their babies, which is another critical factor in the establishment of a healthy microbiome.

These microbial patterns play out over our entire lifetimes. Populations with access to quality nutrition will have better physical and mental health outcomes than those that do not, and that is reflected on a gut microbial level. The environmental quality of the buildings where we live and work also influence what lifeforms are inside us, as does our general proximity to greenspace, on the positive side, or polluting industrial and agricultural facilities, on the negative end.

Ishaq had been ruminating about these connections in her research for years, and decided to teach a special course on the subject at the University of Oregon over the summer. Fifteen undergraduate students with a wide variety of majors participated in the class, and are now co-authors on the new paper. Because the majority of the class were not science majors, the essay has an interdisciplinary approach that concludes with legal and political implications of microbial inequality, in addition to the medical dimensions.

“They were actually much more familiar with the social policies than I was, given their background, which was really cool,” Ishaq said of her students.

One of the questions the team explored is whether a healthy microbiome can be considered a human right or a legal obligation. One 2011 paper touched on this issue through the lens of biobanking, or archiving of human tissue, but there has never been a major legal case that establishes who owns an individual’s microbiome, or if people are legally entitled to a healthy microbiome.

From the perspective of Ishaq and her colleagues, the dynamic nature of the microbiome suggests that legal arguments should emphasize access to healthy microbes, rather than ownership over one’s microbiome.

“You’re picking up and putting off hundreds of thousands of microbial cells every day so to think that what’s in your gut is completely yours is probably the wrong way to think about it,” Ishaq explained. “They are more like passengers than things that you own.”

In other words, healthy microbes could potentially be categorized as an essential resource or common good, like clean water, safe environments, and quality public health. Ishaq hopes the essay will encourage researchers across disciplines to think about the human microbiome as both a metric of social inequities, and a roadmap to more effectively bridge those divides.

“It tends to be people that weren’t even involved with polluting water or growing too much food or pouring chemicals everywhere that end up being the ones that have to deal with these microbial-related problems,” she said.