Johnson underwent six monthly one-liter plasma exchanges, one using plasma donated by his teenage son, under the supervision of what Fortune (13 July 2023) reported as his team of 30 doctors. On 5 July 2023 he announced on social media, reproduced in the same Fortune report, that a biomarker evaluation across biofluids, devices, and imaging found ‘no benefits detected,’ and discontinued the therapy. The FDA’s 2019 safety communication on young-donor plasma infusions, issued before Johnson’s experiment, had already stated there was no proven clinical benefit for anti-aging use of this kind. This is the clearest example in the case of a claim disconfirmed by the practitioner’s own subsequent testing rather than by outside investigators.