Celebrating Tiny Health's Series B: A Letter From Cheryl Sew Hoy

I’m thrilled to share that Tiny Health has closed $33 million in Series B funding, led by B Capital. New investors include Black Opal Ventures, Denver Ventures, Pave Health Ventures, Alumni Ventures, Gaingels and Pari Passu Ventures, alongside continued support from Spero Ventures, TheVentureCity, Overwater Ventures and others. Altogether, this brings our total funding to $46 million. 

Four years ago, we launched the first at-home gut microbiome test built specifically for moms and babies, with every kit hand-packed by my mom out of my garage.

Today, Tiny Health is a gut and vaginal microbiome intelligence platform for everyone — from newborns to centenarians. We’ve served nearly 200,000 customers and more than 6,000 healthcare practitioners across independent practices, hospital systems, longevity clinics and precision medicine organizations, including Mayo Clinic’s Executive Health and Longevity Clinic, Atria, Superpower and Fullscript.

The numbers keep growing, and so do the messages I read every week: from a parent who finally feels like they understand what may be behind their baby’s symptoms, from a woman who spent 15 years searching for answers to chronic digestive issues and finally found a path forward, or from a practitioner who tells us Tiny Health has changed how they think about their patients.

We’re building Tiny Health for you.

What started as a solution for my own family — for my daughter’s eczema and all the questions I couldn’t get a straight answer on — has become a platform used by families, practitioners, health systems and researchers. We’re building toward a future where we can identify microbiome risk earlier, predict disease before symptoms worsen, and intervene early enough to meaningfully change the trajectory of someone’s health.

That’s why this funding round matters.

Investing in the future of microbiome science

From day one, we’ve believed that if microbiome science is going to become a meaningful part of healthcare, we can’t just consume the research — we have to contribute to it.

In 2025, we published a randomized controlled trial in Pediatric Allergy and Immunology showing that infants in our personalized microbiome program had 83% lower odds of developing eczema and allergic conditions. That’s now one of four papers we’ve published, with another RCT underway and new research extending into IBD, menopause, GLP-1 response and oncology.

With this round, we’re committing $5 million to the Tiny Health Microbiome Research Program to give researchers, clinicians and scientific partners access to our testing, data, bioinformatics pipeline and microbiome expertise.

Microbiome research is still hard and expensive to do well. It requires the right sequencing depth, validated methodology, good study design, specialized expertise and, of course, funding. For many clinicians and researchers, that’s a steep hill to climb. We want to lower those barriers, accelerate the pace of research and help generate more rigorous clinical data.

We’re also introducing TinyAI, the world’s first AI trained on Tiny Health’s proprietary dataset of nearly 200,000 microbiome profiles. TinyAI is designed to turn a person’s microbiome results into personalized, science-backed guidance, and because it’s built directly on our own dataset and science, its guidance can become more precise as that dataset grows.

We’re extending that same intelligence into longevity and healthy aging through new metrics like Gut Microbiome Age and Gut Resilience. The future of microbiome testing isn’t about generating longer lists of bacteria. It’s about understanding what those microbes are doing, what they may mean for someone’s health, and what we can actually do with that information.

Why we’re building this

I founded Tiny Health because I wanted better answers for my own family. Four years later, that mission hasn’t changed — the scale has.

None of this happens without our team, who show up every day for a mission bigger than any one of us, or without the practitioners, researchers, partners and families who have trusted us along the way. Thank you to B Capital for leading this round, to our existing investors for continuing to believe in us, and to the new investors joining this next chapter.

The funding itself isn’t the destination. It gives us the ability to make microbiome science more rigorous, more useful and more accessible — and ultimately help more people get better answers about their health.

And we’re just getting started.

If you’re compelled by our mission, come join us!