Tech mogul Bryan Johnson says he stores girlfriend's menstrual blood and closely monitors her cycle for health study #
Bryan Johnson has stunned the internet again after revealing he is storing his girlfriend Kate Tolo's menstrual blood in a -80°C freezer as part of a $2.6 million (£1.94 million) women's health experiment.
The tech entrepreneur and anti-ageing obsessive posted the revelation on X on 31 July, alongside a photo of Tolo.
'Kate's period blood is in my -80 °C freezer. Around 10 mL,' Johnson wrote.
He said the sample was collected during Tolo's last cycle and is being kept for health analysis, not shock value. Still, the post quickly went viral, with many users saying the project felt invasive and unsettling, even as others argued that menstrual health remains badly under-researched.
Johnson, who became widely known for his intense longevity routine and Netflix documentary 'Don't Die: The Man Who Wants to Live Forever,' has built a public brand around turning his body into a data project. This time, however, the subject is his girlfriend.
Why Johnson Says Menstrual Blood Matters #
Johnson defended the experiment by saying menstrual blood can offer a direct window into the uterus.
'Menstrual blood is valuable and underutilized,' he wrote.
According to Johnson, the sample could be used to look for diseased tissue and measure exposure to microplastics, PFAS and endocrine-disrupting chemicals. He said it also contains endometrial cells, immune cells and stem cells.
For him, the appeal is that the testing is non-invasive. Instead of relying on surgery or standard blood tests, he argued that menstrual blood allows repeated, cycle-by-cycle monitoring of the uterine environment. 'This is great because you get the data without surgical biopsy,' Johnson wrote, adding that it can be measured directly rather than inferred from a regular blood draw.
Kate Tolo's Day Becomes a Data Project #
The freezer post is part of a much larger project involving Tolo, 30, and Johnson's company Immortals.
Johnson has said Tolo is helping collect 14 million data points linked to her menstrual cycle, calling it a major step for women's health. He said that 'women are not well understood medically' and claimed Tolo would provide one of the most detailed datasets ever gathered on a menstrual cycle.
The schedule he shared online is extreme. From 6am to nearly 10pm, Tolo's day is packed with blood draws, urine samples, sleep tracking, metabolism tests, body photos, vaginal microbiome swabs, exercise, red light therapy and the use of a so-called 'techno tampon' to monitor blood flow. A 12-person medical team and around 50 devices are involved in the process.
Johnson joked: 'I like that Kate is a science experiment with me.'
Tolo replied: 'Thanks for looking after me bby.'
Online Reaction Turns Uneasy #
That exchange did little to calm the backlash. Some users were less concerned with the science and more uncomfortable with the image of a boyfriend keeping his girlfriend's period blood in a freezer. Others focused on the scale of Tolo's daily routine, arguing that consent does not make the schedule any less bizarre to watch from the outside.
The reaction fits a familiar pattern for Johnson. His experiments often start as health optimisation and end up as viral debates about money, control, ageing and the limits of self-experimentation.
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