When Cheryl Sew Hoy’s daughter developed eczema, allergies and food sensitivities, she began reading research on the infant gut microbiome. Her daughter had been born by C-section, while her younger son, born vaginally, had no similar conditions. The contrast made her wonder whether differences in their early microbial exposure played a role. While it did not give her a diagnosis for her daughter, it gave her an idea for a company.

“I learned that you can course-correct if you focus on the early life of the baby. If they’re missing certain beneficial bacteria, it can really cause a lot of issues for the infant,” Sew Hoy recalls. “I was reading all this literature and asked my doctors about it, and none of my doctors knew what I was talking about.”

Cheryl Sew Hoy, co-founder and CEO of Tiny Health. (Courtesy photo)

A week after her son’s birth in 2020, she incorporated Austin-based Tiny Health. Today, the company announced it has raised $33 million in a Series B funding round led by B Capital, it told Crunchbase News exclusively.

The financing brings Tiny Health’s total funding to $46 million, following a $4.5 million seed round in 2021 and an $8.5 million Series A in late 2023. Existing investors Spero Ventures, The Venture City and Overwater Ventures participated in the latest round, along with new investors including Black Opal Ventures and Alumni Ventures. B Capital’s Nick Whitehead will join the company’s board.

Demand for Tiny Health’s at-home microbiome tests is growing. The startup’s overall revenue has more than doubled each year, according to Sew Hoy. Its B2B arm, Powered by Tiny, which sells tests through healthcare providers and other companies, grew fourfold last year. Sew Hoy did not disclose revenue figures or the company’s valuation, though she said the valuation was “much higher” than in the Series A.

From baby gut tests to adult testing

Tiny Health spent two years developing its platform before launching an at-home baby gut test in 2022. Healthcare was new territory for Sew Hoy, whose previous startup, digital coupon company Reclip.It, was sold to Walmart Labs in 2013. Before raising a seed round, she put $50,000 of her own money into an initial study and spent about a year collecting stool samples and building the platform.

The baby test gave Tiny Health a focused entry point. In Sew Hoy’s view, parents of children with conditions such as eczema wanted more information as to the cause, while clinicians had few practical tools to apply emerging microbiome research. The company also offered pregnancy, vaginal microbiome and adult tests, but initially focused on infant testing. Adults have since become its larger testing segment, according to Sew Hoy.

So, how does it work? Customers collect a small stool sample with a swab. After sending in the swab, they receive a report on the microbes detected, along with explanations and suggested next steps. Tiny Health also sells a subscription called Tiny Plus that includes a baseline test and a retest.

Sew Hoy believes one of Tiny Health’s biggest differentiators is that its tests use shotgun metagenomic sequencing to analyze microbial DNA. The method provides a broader view of the organisms in a sample than tests that look for a limited set of microbes, she said. Chief science officer Kimberley Sukhum, who joined Tiny Health in 2021, leads its scientific work. The company’s other leaders include co-founder Donald Koo, who joined Sew Hoy two years after she started Tiny Health and leads its technology work, and chief medical officer Dr. Elisa Song, an integrative pediatrician who previously advised the company.

Tiny Health's PRO Gut Health Test kit. — Tiny Health’s PRO Gut Health Test kit. (Courtesy photo)

The reports examine what the detected microbes may be doing and suggest steps such as dietary changes, with links to supporting research.

“We are a wellness test,” Sew Hoy said. “We’re not a diagnostic … It’s very actionable, very evidence-backed.”

Insurance does not cover the tests, which can identify microbes in a sample, but cannot establish what caused a person’s symptoms.

Other startups are taking different approaches to digestive health. Austin-based Throne Science makes a device that attaches to a toilet and tracks stool patterns and hydration. Tiny Health analyzes microbial DNA from a collected sample. Throne recently raised $10 million in a Series A round led by Will Ventures.

Beyond direct-to-consumer testing

Tiny Health’s fastest-growing business is Powered by Tiny, which sells testing through healthcare providers and companies that incorporate it into their own services. Partners include Superpower, Fullscript and Mayo Clinic’s Executive Health and Longevity Programs, according to Tiny Health. It also works with supplement makers and academic partners that want to measure the microbiome in clinical studies.

Customers began taking their direct-to-consumer results to doctors, according to Sew Hoy. Some clinicians then approached Tiny Health for help interpreting the reports. Today, the startup serves more than 6,000 practitioners and offers training on using its tests in patient care.

Its enterprise business supplies testing to other health and wellness companies, including through technology integrations. As mentioned earlier, that B2B arm is growing fourfold. Expanding both, along with clinician training, is a priority for the new funding.

Nick Whitehead, senior principal at B Capital, told Crunchbase News that his firm sees an opportunity to make microbiome research more useful to consumers as interest in preventive health grows.

“We’re in the middle of a real shift in how people engage with their own health. Consumers are paying out of pocket for wearables, blood panels, and full-body scans because they want to understand what’s happening inside their bodies before something goes wrong,” he wrote via email. “The gut microbiome is one of the most important and least understood pieces of that picture … Tiny Health turns that science into something people can actually act on, and we believe the company that does this well will define the category.”

Whitehead also cited Tiny Health’s standing with clinicians the firm consulted during its diligence.

“Tiny Health was consistently the test they rated highest,” he said.

Another attractive feature, Whitehead added, is the company’s data from families tested beginning in infancy.

Putting its data to work

Tiny Health has collected nearly 200,000 microbiome samples over time, according to Sew Hoy. To make use of those samples, the startup is developing a tool called TinyAI that will draw on its data and research reviewed by its scientific staff to help people understand their results. The company also uses health information customers provide, with identifying details removed, to inform that work.

Long-term, Tiny Health aims to identify patterns that could help spot health risks before a condition develops. Research has associated gut microbiome imbalances with more than 100 diseases.

“We want to be able to predict disease before it happens and intervene before it happens,” Sew Hoy said in an interview with Crunchbase News.

Indeed, one pressing question is whether microbiome-guided interventions can improve health outcomes. Tiny Health says it has published four scientific papers, including a study involving infants, and plans to support further research involving adults.

Presently, the company has about 40 employees and plans to hire 30 more. It will use the new capital to expand its work with healthcare providers and other companies, and to fund research into whether changes in the microbiome can improve health outcomes. It plans to devote $5 million to a program that will give researchers and clinical partners access to its testing and data.

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From baby gut tests to adult testing

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Putting its data to work

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