Function Health

Function Health has scaled consumer access to comprehensive lab and imaging data faster than anyone in longevity, and its November 2025 $298M Series B led by Redpoint Ventures at a $2.5B valuation — with a16z, Battery Ventures, and Nat Friedman and Daniel Gross's NFDG participating, bringing total funding to roughly $350M — made it one of the category's most valuable companies. The product is a genuinely differentiated wedge: a membership giving 100+ biomarker lab tests run twice yearly, advanced whole-body MRI and CT imaging, and AI-assisted interpretation, all in one longitudinal member record. Co-founded in 2022 by Jonathan Swerdlin with functional-medicine celebrity physician Mark Hyman as chief medical officer, Function has hundreds of thousands of members and reports members have completed 50 million lab tests since 2023 — real scale and a proprietary longitudinal dataset that compounds in value. Crucially, alongside the raise Function lowered membership pricing and launched a Medical Intelligence Lab to build a generative "medical intelligence" model on its data, a strategy that widens the funnel while deepening the data moat that AI interpretation depends on. In a world shifting toward continuous, data-driven preventive health, Function has the members, the data flywheel, the capital, and the brand to define the category.

A $2.5B valuation on a consumer diagnostics subscription demands enormous future growth, and the model faces the same structural doubts that have humbled blood-testing startups before it — Forbes and others have openly questioned whether these businesses are sustainable. Function resells lab tests and imaging it does not own, so its gross margins depend on third-party lab and MRI capacity, and lowering membership pricing to chase growth compresses the very economics that must eventually justify the valuation. The clinical value is contested at both ends: over-testing asymptomatic people generates false positives and incidental findings that cascade into anxiety, unnecessary follow-up, and cost, while the medical establishment questions whether frequent broad biomarker panels improve outcomes — a regulatory and liability exposure that grows with scale. Retention is the quiet risk: novelty-driven consumers may not renew once initial curiosity is satisfied, and a subscription whose core loop is "get tested twice a year" must fight churn continuously. Competition is fierce and well-funded — Fountain Life, Superpower, Neko Health, Prenuvo, and traditional labs like Quest and Labcorp moving downstream all contest the same buyers. And heavy reliance on Mark Hyman's personal brand ties the company to a figure whose functional-medicine positioning draws scientific skepticism. The bear case is a richly valued reseller in a category that has repeatedly failed to prove durable.