Bryan Johnson, the tech entrepreneur and self-described biohacker, has revealed that he is keeping a sample of his girlfriend’s menstrual blood in a freezer as part of a project on women’s health. In a post on X, Johnson shared a photo of Kate Tolo, his 30-year-old girlfriend, with the caption: «Kate’s period blood is in my -80 °C freezer. Around 10 mL.»
Johnson has built a public identity around extreme longevity. The 48-year-old says he wants to reverse his biological age and has organised his daily life around that ambition, eating a highly controlled diet, taking dozens of supplements and measuring every biomarker he can. He has described himself as «certainly the most biologically measured person ever» and shares much of his health data online. The latest disclosure fits that pattern: even the contents of his freezer have become part of the content he posts.
Johnson and Tolo have said the menstrual blood is being kept for research into women’s health, arguing that this area of medicine has been neglected for too long. According to the couple, their aim is to generate better data and, eventually, products that help women track their bodies. In line with that, Johnson has teased the launch of a «techno tampon» designed to monitor Tolo’s period. Separate reports have described Tolo as turning her body into a $2.6 million science experiment, with her health data becoming part of Johnson’s wider longevity project.
The unusual presentation has invited both curiosity and skepticism. Arwa Mahdawi, a Guardian columnist, has written that studying women’s health is a worthy goal but that some skepticism is in order. She noted that Johnson’s disciplined lifestyle leaves little room for frozen treats, yet his freezer apparently has space for a small sample of his girlfriend’s menstrual blood. Mahdawi describes Johnson as a chronic oversharer whose posts routinely blur the line between health experiment and public performance.
Johnson is one of the most recognisable faces of biohacking, a culture that encourages individuals to seize control of their own biology. He has spent years posting about his sleep, diet, blood work and daily protocols, and has made clear that he regards data as essential to living longer. Tolo’s involvement suggests that he wants to apply the same quantified approach to women’s health.
So far, the public explanation for the frozen sample is limited to the couple’s comment that they are studying women’s health. No further research plan has been outlined in the posts that prompted the latest discussion. What the episode has done is force another conversation about the limits of biohacking and the right way to draw attention to understudied areas of medicine.
Johnson has regularly said he wants to live longer and treats every part of his body as a potential source of data. The menstrual blood post is consistent with that worldview, however unusual it may seem. Whether it leads to scientific progress is unclear, but it has already made one thing apparent: the boundaries of Johnson’s experiments now extend well beyond his own body.
