Gut Microbiome

Your Gut Microbiome — The 38 Trillion Microbes Running Your Digestive System

Inside your gut right now, roughly 38 trillion bacteria, fungi, viruses, and other microorganisms are working — digesting fiber, producing vitamins, training your immune system, and communicating with your brain.

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What is the gut microbiome?

The gut microbiome is the collective community of microorganisms living in your gastrointestinal tract — primarily the large intestine. Each person's microbiome is unique, shaped by genetics, early-life exposures, diet, medications, and environment. A healthy microbiome is diverse — containing hundreds of different bacterial species. Low diversity is consistently associated with IBS, IBD, obesity, type 2 diabetes, and depression.

What your microbiome actually does

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    Breaks down fiber your body can't digest alone, producing short-chain fatty acids that fuel the gut lining
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    Produces vitamins — including vitamin K and several B vitamins
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    Trains your immune system (70% of immune cells live in the gut)
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    Communicates with your brain via the vagus nerve and gut-brain axis
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    Influences mental health — gut bacteria produce ~90% of your body's serotonin

Signs of an unhealthy gut

Chronic Bloating & Gas

Excess fermentation by an imbalanced microbiome produces more gas than a healthy gut. Persistent bloating after meals is a common sign of dysbiosis.

Irregular Bowel Movements

Chronic constipation, chronic diarrhea, or unpredictable alternation can all reflect a microbiome out of balance. Gut bacteria influence transit speed and stool consistency significantly.

Fatigue & Brain Fog

Poor microbiome health is linked to systemic inflammation and disrupted serotonin production — manifesting as persistent fatigue and difficulty concentrating.

New Food Intolerances

A dysbiotic gut lining becomes more permeable, allowing food proteins to trigger immune reactions. Developing new food sensitivities as an adult can be a sign of compromised gut integrity.

Probiotics, prebiotics & postbiotics — what's the difference?

Type What it is Examples Evidence
Probiotics Live beneficial bacteria you consume Lactobacillus acidophilus, Bifidobacterium; yogurt, kefir, kimchi, sauerkraut Moderate — strain-specific. Best evidence for IBS-D and antibiotic-associated diarrhea prevention.
Prebiotics Fiber that feeds beneficial gut bacteria Inulin (chicory), FOS, GOS, resistant starch (oats, green bananas) Strong — consistently improve microbiome diversity and short-chain fatty acid production.
Postbiotics Beneficial compounds produced by gut bacteria Short-chain fatty acids (butyrate, acetate), certain vitamins, antimicrobial peptides Emerging — butyrate shows promise for IBD and gut barrier integrity.

How to improve your gut microbiome

Eat diverse plants

Aim for 30+ different plant foods per week — the strongest predictor of microbiome diversity in population studies. Variety matters more than volume.

Eat fermented foods daily

A 2021 Stanford study found that eating fermented foods (kefir, kimchi, yogurt, kombucha) daily for 10 weeks significantly increased microbiome diversity and reduced inflammatory markers.

Use antibiotics carefully

Antibiotics are necessary and important, but they disrupt the microbiome significantly. Always take them when medically needed — discuss whether a shorter or narrower-spectrum course is appropriate.

Prioritize sleep & stress

Poor sleep and chronic stress directly alter gut bacterial composition. The microbiome is sensitive to the same lifestyle factors that affect mood, energy, and immune function.

Related Guides

FODMAP & Diet Guide
The Low-FODMAP Diet for IBS
Stool Color Guide
What the Color of Your Poop Means
Women's Gut Health
Hormones, Cycles & Your Gut

Gut Microbiome FAQs

Leaky gut (intestinal hyperpermeability) refers to a condition where the tight junctions of the gut lining become more permeable, potentially allowing bacteria and food particles to pass into the bloodstream. It is associated with IBD, celiac disease, and is being studied in relation to IBS, autoimmune conditions, and other disorders. It is a real physiological phenomenon, though the term 'leaky gut syndrome' as a standalone diagnosis is not formally recognized in mainstream medicine.
Consumer microbiome tests (like Viome, Zoe, Thryve) sequence bacterial DNA from stool samples and provide species-level breakdowns. They are fascinating but currently have limited clinical utility — we do not yet know enough about 'normal' microbiome composition to translate most results into specific actions. They are more useful for tracking changes in response to dietary interventions than for one-off diagnosis.
Plop tracks the observable outputs of microbiome health — stool consistency, frequency, gas, bloating, and food responses — over time. While it does not sequence your bacteria, it captures the functional picture: how your gut is actually behaving, and whether dietary changes or new foods are improving or disrupting that pattern.
Probiotic supplements are heavily marketed, but the evidence is more nuanced than most products suggest. Benefits are highly strain-specific — what works for one condition will not necessarily work for another. Food-based sources (fermented foods) may be more effective at actually colonizing your gut than capsule supplements for most healthy people. A varied, fiber-rich diet does more to support your microbiome than any single probiotic product.

Understand your unique health patterns.

Plop learns what's normal for you — not population averages. Establish your personal baseline, track bowel movements and symptoms, and discover the patterns that matter to your health. Get insights your doctor can actually use.

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