'Period Blood Is in My Freezer': Why Biohacker Bryan Johnson Keeps Partner Body Fluids

Biohacker Bryan Johnson has revealed that he is storing his girlfriend Kate Tolo's menstrual blood in a laboratory freezer kept at −80°C, saying the samples will be used to investigate biomarkers linked to women's health and ageing.

Johnson, the 48-year-old entrepreneur behind the anti-ageing initiative Blueprint, shared the detail in a post on X on Thursday, describing menstrual blood as an 'underutilised' biological resource that could provide valuable health information.

The disclosure is the latest in a long series of highly public longevity experiments that Johnson has documented publicly, though this time the project involves another participant rather than his own body.

Bryan Johnson Says Menstrual Blood Is an Understudied Resource

According to Johnson, approximately 10 millilitres of menstrual blood have been preserved in an ultra-low-temperature freezer for future analysis.

He said the samples will be examined for markers including endocrine-disrupting chemicals, microplastics and other biological indicators that could provide insight into reproductive and overall health.

Johnson argued that menstrual blood offers researchers a non-invasive way to study the uterus and suggested the field remains significantly underexplored compared with other areas of medicine.

The entrepreneur also wrote that he enjoys conducting scientific experiments alongside Tolo, adding that she has actively participated in the project. Tolo later responded publicly, thanking Johnson for 'looking after"'her, indicating she is a willing participant in the ongoing research.

Part of Johnson's Blueprint Longevity Project

The menstrual blood study forms part of Johnson's wider Blueprint programme, an intensive health regimen aimed at slowing or reversing biological ageing.

For several years, Johnson has shared detailed information about his health routines, including strict dietary plans, extensive biometric monitoring and daily supplement protocols.

He has also attracted international attention for more controversial experiments, including plasma transfusions involving his teenage son and publishing unusually detailed physiological data online.

Supporters view his openness as an effort to accelerate personal health research, while critics argue many of his experiments lack independent scientific validation. The latest announcement has generated particular attention because it involves intimate biological data from another person rather than Johnson himself.

Kate Tolo Says the Project Focuses on Women's Health

Tolo has also discussed the project publicly, saying she hopes it contributes to improving understanding of women's health.

In an interview published earlier this year, she explained that she lives with polyendocrine metabolic ovarian syndrome and believes continuous health monitoring could eventually improve symptom management and research into female reproductive conditions.

According to Johnson, the couple collects an extensive range of physiological information throughout Tolo's menstrual cycle.

He has claimed the programme generates millions of data points through daily monitoring involving wearable devices, urine analysis, metabolic measurements and other health-tracking technologies.

Some aspects of the process remain unclear, however, including the technology Johnson has referred to as a 'techno tampon device,' which he has mentioned online without providing detailed technical information.

Women's Health Research Has Historically Been Underrepresented

Johnson has argued that his project highlights broader gaps in medical research. Historically, women have been underrepresented in clinical studies, particularly before US federal law required their inclusion in federally funded clinical trials in the early 1990s.

Researchers have also noted that menstrual health remains comparatively understudied despite its importance to reproductive medicine. Some scientific studies have highlighted shortcomings in menstrual product testing and reproductive health research, contributing to calls for greater investment in the field.

Those broader concerns provide context for Johnson's claim that menstrual blood deserves greater scientific attention.

However, experts generally caution that meaningful medical research requires rigorous study design, peer review and large participant groups rather than highly individualised self-experimentation.

Critics Question Scientific and Commercial Motivations

Not everyone is convinced by Johnson's latest project. Critics have questioned whether personal experiments involving a single participant can produce medically meaningful conclusions. Others have pointed to Johnson's commercial interests.

Johnson and Tolo are involved with Immortals, a wellness company reportedly developing products focused on longevity and women's health.

That overlap between research, personal branding and commercial activity has prompted questions about whether the experiments primarily serve scientific purposes or also function as marketing. There is also limited independent verification of many of Johnson's public claims.

Most information about the menstrual blood project comes directly from Johnson's own social media posts and interviews, and no peer-reviewed research arising from the work has yet been published.

As a result, the methods, data collection and conclusions remain difficult to evaluate independently. Even so, Johnson has built a global audience by publicly documenting experiments that many people would consider unusually personal or unconventional. His latest disclosure continues that pattern.

Whether freezing menstrual blood ultimately contributes to meaningful advances in women's health research or simply becomes another headline-grabbing chapter in Johnson's longevity journey will likely depend on what evidence, if any, emerges from the work in the years ahead.