Bryan Johnson keeps his girlfriend’s menstrual blood in a -112°F freezer for his longevity research

Biohacker Bryan Johnson has built a reputation for pushing the limits of health tracking. From documenting his strict longevity routine to sharing intimate medical data, he rarely keeps his experiments private. Now, one of his latest revelations has left many people both surprised and curious.

This time, the focus is on his girlfriend, Kate Tolo. Johnson revealed that he has stored a sample of her menstrual blood in an ultra-cold freezer as part of an ambitious research project. While the announcement sparked online reactions, he insists the decision is driven by science rather than shock value.

The project is part of a much larger effort to better understand women’s reproductive health, the New York Post reported. Johnson believes collecting detailed biological data could uncover health issues earlier and help improve treatments for conditions that often go undiagnosed for years.

This might be the most unexpected health experiment he’s shared yet

Johnson recently revealed on X that “Kate’s period blood is in my -80°C freezer.” He explained that the roughly 10 mL sample, collected during her last menstrual cycle, offers a non-invasive look into the uterus without requiring surgery.

Johnson said the sample will be examined for diseased tissue, microplastics, endocrine disruptors and PFAS, also known as “forever chemicals.” He believes menstrual blood offers direct insight into the uterine environment without requiring a surgical biopsy. It can also be collected repeatedly during each cycle, making long-term monitoring possible.

The announcement comes as Tolo, 30, completes a 100-day research project designed to collect 14 million data points from her menstrual cycle. As reported by The Wall Street Journal, her routine includes saliva collection, cheek swabs and a high-tech tampon that gathers additional biological information. The project is estimated to cost $2.6 million.

Tolo has said the research aims to close long-standing gaps in female reproductive health studies. The project also follows her diagnosis with endometriosis, a condition that causes tissue similar to the uterine lining to grow outside the uterus. Johnson noted that many women wait seven to 10 years before receiving a diagnosis.

Tolo has also been diagnosed with polyendocrine metabolic ovarian syndrome, formerly known as PCOS. Johnson recently shared that he is living with autoimmune gastritis and said his mission is to use AI and biotechnology to improve treatment options. He said his goal is to cure his own AIG and Kate’s endometriosis as well.

Johnson has previously shared other personal health findings involving Tolo. Earlier this year, he claimed testing from a Tiny Health vaginal health test showed she ranked in the top 1% for bacterial composition. He added that her sample showed an unusually high level of Lactobacillus crispatus, a bacteria linked to vaginal health.

The couple has been together for three years and made their relationship public in December. Johnson later wrote that he likes having Kate as a science experiment with him, to which Tolo replied, “Thanks for looking after me bby.”

Johnson’s willingness to turn his own life into a longevity experiment has repeatedly pushed him into unusual territory. In another controversial project, he previously claimed to have created a “newborn clone” of himself, adding to the long list of unconventional ideas he has explored while chasing the future of human health.