What Is Gut Microbiome Diversity and Why Does It Matter? | Nurish'd
What Is Gut Microbiome Diversity and Why Does It Matter?
If there's one metric that microbiome scientists return to again and again as a predictor of gut health, it's diversity. A diverse microbiome — one containing many different species across a wide range of functional groups — is consistently associated with better metabolic health, stronger immune function, lower rates of chronic disease, and greater resilience against infection. Understanding what diversity means, why it matters, and how to improve it is foundational to using your microbiome test results effectively.
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What Microbiome Diversity Actually Means
Microbiome diversity refers to the variety of microbial species present in your gut and the evenness of their distribution. Scientists measure it using metrics called alpha diversity (within a single sample) and beta diversity (differences between samples or people).
Alpha diversity measures:
Species richness — how many distinct species are present
Shannon index — combines richness and evenness; a widely used single-number diversity score
Simpson index — emphasizes the abundance of dominant species
A high alpha diversity score means your gut hosts many different species, none of which completely dominate. A low score means fewer species, often with one or two types overwhelming the rest.
Why evenness matters:
A gut with 200 species where one species makes up 80% of the population is less functionally diverse than one where 200 species are more evenly distributed. Both species richness and evenness contribute to a resilient, functional microbiome.
What Low Diversity Is Linked To
How to Increase Your Gut Microbiome Diversity Through Diet
Diet is by far the most powerful tool for shifting microbiome diversity. The evidence is clear and the mechanisms are well understood:
The 30-plant-per-week target
Research from the American Gut Project found that people who eat 30 or more different plant species per week have significantly higher gut microbiome diversity than those eating 10 or fewer. Every different plant food you eat feeds a different subset of your gut bacteria — variety in, variety out.
Fermented foods
Yogurt, kefir, kimchi, sauerkraut, kombucha, and miso introduce live microorganisms that can temporarily increase microbial diversity. A Stanford study found fermented foods were more effective than a high-fiber diet at increasing microbiome diversity in the short term — though both are important.
Prebiotic fibers
Foods rich in prebiotic fiber (garlic, onion, leeks, asparagus, banana, oats, apples, flaxseed) selectively feed beneficial bacteria, promoting their growth and the diversity of the broader ecosystem.
Polyphenol-rich foods
Polyphenols (found in berries, dark chocolate, green tea, olive oil, and many colorful vegetables) are poorly absorbed in the small intestine and reach the colon largely intact, where they serve as fuel for beneficial bacteria.
What reduces diversity:
High sugar intake, ultra-processed food, antibiotic exposure, chronic stress, and sedentary lifestyle are all associated with reduced microbiome diversity.
A Nurish'd registered dietitian builds a personalized diversity-increasing nutrition plan around your specific test results, food preferences, and health goals — targeting the species and functional gaps your microbiome report identifies.
Get Started with Your Microbiome Test
Is the microbiome test covered by insurance?
Microbiome testing is typically not covered by traditional health insurance. However, Nurish'd microbiome tests are HSA and FSA eligible — meaning you can use your pre-tax health savings account or flexible spending account dollars to cover the cost and reduce your effective out-of-pocket expense.
Good news on the clinical side: the registered dietitian sessions that accompany your results through Nurish'd are billable to most major insurance plans for qualifying diagnoses (diabetes, CKD, heart disease, obesity, eating disorders, and more). Many patients pay little to nothing for their RD sessions while paying out-of-pocket or through HSA/FSA for the test itself.
Ready to get started? Here's how:
New to Nurish'd?
Create your free account and order your microbiome test — receive your kit, complete your sample at home, and have results uploaded directly to your account. Book an RD session to interpret your results and build your personalized nutrition plan. HSA/FSA cards accepted at checkout.
Already a Nurish'd member?
Purchase your microbiome test here — your results sync automatically to your account. HSA/FSA eligible.
Want to learn more before you commit?
Explore our microbiome testing page — what we test for, how the process works, and what your results include.
Nurish'd is the only platform where your microbiome test results connect directly to a registered dietitian's interpretation and a personalized meal plan. The test is the starting point — what you do with the results is what changes your health.
What Happens After Your Microbiome Test
