Tech entrepreneur Bryan Johnson says he keeps his girlfriend, Kate Tolo’s, menstrual blood in a freezer at -80°C. In posts shared online, Johnson indicates the samples are stored at that temperature and that the amount is about 10 mL. Multiple outlets describe Johnson as a prominent “longevity” biohacker who tracks extensive health measurements and conducts unconventional experiments to better understand aging and improve health.
Both sources report that Johnson’s stated rationale is to study women’s reproductive health using menstrual blood, which he believes may contain information relevant to uterine cells and stem cells. They also place the storage within his broader approach—collecting and analyzing biological data alongside dietary changes, supplements, and frequent biomarker monitoring as part of his long-running effort to reverse biological age.
While the outlets present different contextual framing—one focusing on the unusual storage practice and the other adding commentary on skepticism—they agree on the core claims: Johnson has publicized the storage of menstrual blood at -80°C for study.
