The tiny world inside you

Bacteria Aren't the Only Residents of Your Gut

This is well-established science, though a newer, less-studied part of it than the bacterial story.

Bacteria get most of the attention when people talk about the microbiome, but they share the gut with several other kinds of life entirely.

Viruses, fungi, and even single-celled organisms called archaea all live there too, each doing their own distinct job.

The gut's virus population mostly attacks its own bacteria

A single gram of stool contains an estimated 1 to 10 billion virus-like particles, and the overwhelming majority of them are bacteriophages, viruses that specifically infect and hunt bacteria rather than human cells.

This viral population, called the virome, is even more individual than the bacterial community. Studies tracking the same person's gut viruses over years found they evolve rapidly and remain largely unique to that one person, more so than their bacteria do.

Rather than being purely destructive, phages appear to help shape which bacteria thrive and which don't, acting almost like a natural population control system that keeps any single bacterial species from taking over entirely.

Source: Gut virome dynamics: from commensal to critical player in health and disease

Fungi and single-celled archaea round out the ecosystem

Beyond bacteria and viruses, the gut hosts a community of fungi, collectively called the mycobiome, along with archaea, single-celled organisms that are neither bacteria nor a form of animal or plant life, despite superficially resembling bacteria.

These groups have been studied far less than gut bacteria simply because the tools to detect and analyse them properly are newer, not because they matter less. Early research already links shifts in the mycobiome to inflammatory gut conditions.

Bacteria still account for the vast majority of the gut's total genetic material, but the fact that several other kingdoms of life share the same small ecosystem is a reminder of how much more complex this system is than the bacteria-only picture most people carry around.

Source: Gut Microbiota beyond Bacteria: Mycobiome, Virome, Archaeome, and Eukaryotic Parasites in IBD

This viral population is even more unique to you than your bacteria

Studies comparing identical twins, who share nearly all their DNA and often much of their childhood environment, found their gut viruses were still distinctly different from one another, more different than their bacterial communities were.

This makes the virome something close to a biological fingerprint. Where bacterial community types are shared, in broad strokes, across many people, the specific viruses someone carries appear to be substantially their own.

Diet appears to shape this hidden layer too. Research has found that certain dietary patterns, including higher fructose intake, can increase how actively some gut bacteria produce new phages, linking something as simple as what's eaten to a population of organisms most people don't know they're carrying.

Source: The human gut phageome: composition, development, and alterations in disease

What this means for you

There's no specific action needed to manage this hidden layer of the gut directly, since research on it is still developing far behind the bacterial story. What is clear is that a healthy, diverse bacterial community likely supports a healthier balance among these other residents too, since they all interact within the same shared ecosystem. A varied, plant-rich diet supports that same underlying diversity. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.