Cheryl Sew Hoy: The Engineer Who Ran the Trial Nobody Would

Every founder says their company exists to answer a question. Cheryl Sew Hoy’s actually does, and the question was asked over a crib: her first child was struggling — eczema, broken sleep, food sensitivities — and when she went looking for what was happening inside her baby’s gut, she found that no test for it existed. Most parents stop at the Googling. Sew Hoy, a Cornell-trained engineer who had already built and sold a startup and run a government innovation agency, did the other thing: she spent two years in R&D and built the test herself. Five years on, Tiny Health is the most scientifically serious company in consumer microbiome testing — a bar it raised itself, by running the trial nobody else would.

The resumeAn engineer, twice over, with receipts

Sew Hoy holds no medical degree and has never claimed one — her training is engineering: a bachelor’s in operations research and industrial engineering and a master’s in engineering management, both from Cornell, both on full scholarships. The career before Tiny Health explains the execution since. She co-founded Reclip.It, a shopping-list startup acquired by Walmart Labs in 2013. A year later, Malaysia’s government recruited her home as founding CEO of MaGIC, a $30 million national innovation agency, where she launched the country’s flagship accelerator and struck partnerships with Stanford and Techstars. She is, in other words, that specific Silicon Valley type — the operator who builds institutions — pointed, since 2020, at infant guts.

The reckoningThe other institution she helped fix

One more chapter belongs in any honest profile, because she put it on the record herself. In 2017, Sew Hoy published a detailed account of being assaulted by one of Silicon Valley’s most powerful investors, 500 Startups co-founder Dave McClure — “It’s not just inappropriate, it’s assault,” she wrote — and he resigned within days. Rather than leave it there, she co-launched #MovingForward the following year, pushing venture firms to adopt the formal anti-harassment policies and reporting lines she herself had lacked. It is the same pattern as the company: encounter a system with a missing piece, build the piece, make it public.

The workWhat Tiny Health became

The company reads like an engineer’s answer to a scientific credibility problem. Where the adult gut-test market sells sprawling wellness dashboards, Tiny Health narrowed to the window where microbiome science is strongest — the first 1,000 days — and then did the unheard-of thing: it randomized 54 C-section infants and published the result in Pediatric Allergy and Immunology, with eczema — a real clinical endpoint — at 6 percent in the program group versus 29 percent in controls. The business has compounded alongside: past $10 million in 2025 revenue and on pace to nearly triple, per Inc., with NutraIngredients-USA’s Start-up of the Year award in 2025. The trial’s honest limits — small, company-run, a bundled program — are sized properly in our Gut Check audit of Tiny Health, which is the independent document this profile is not trying to be.

The disclosure mapWhere her interests sit

Sew Hoy is founder and chief executive of Tiny Health with the full financial stake that implies; she is an engineer, not a clinician, and her company’s reports say themselves that they inform conversations with a pediatrician rather than replace them. Both facts are printed here for the same reason we print them about everyone: the reader who knows the frame can trust what sits inside it. What sits inside this one is a founder who keeps responding to broken systems by building the missing piece in public — and who, when her industry’s credibility problem needed an answer, answered with a randomized trial. This profile is educational, is not medical advice, and was prepared with no input from Tiny Health.