A controversial tech millionaire says his father, 70, is now biologically 46 thanks to injections of his 'super blood'

• Bryan Johnson says he's slowed his father's rate of aging using his "super blood."
• Johnson's 70-year-old father saw his rate of aging slow by about 25 years, he said on X.

Tech entrepreneur Bryan Johnson claims he has slowed his father's rate of aging by 25 years by giving him transfusions of his "super blood."

"My super blood reduced my Dad's age by 25 years," Johnson said Wednesday in a post on X, formerly Twitter.

The multi-millionaire, who is known for his controversial anti-aging treatments, said his father was injected with one liter of his plasma, which is the liquid part of the blood.

Since then, he said, his 70-year-old Dad, who had been aging at the rate of a 71-year-old before the injection, has been aging like a 46-year-old.

"I am my dad's blood boy," Johnson said on X.

Johnson was careful to frame his own findings. In the post on X, he noted that he based his assessment of his father's aging on one biomarker, which is a medical sign that can be picked up by tests. Johnson didn't state which marker he was using.

Though biomarkers are a useful tool to hint at what's going on in the body, they aren't an accurate measure of the body's aging on their own, lead physician, Oliver Zolman, previously told Insider.

It is also not possible to know from one intervention if it is the injection that led to the change in the rate of aging, or whether there could be something else going on, Johnson noted.

Johnson passed his plasma to his father about six months ago, he said on X. On the same day, Johnson himself received plasma from his 17-year-old son, though he later said he personally saw no benefit from the procedure.

Johnson, who considers himself a "professional rejuvenation athlete", has been trying dozens of interventions on himself to see if he can slow aging. These range from a carefully controlled diet and strict exercise regimen to fat injections and laser treatments.

Some clinics in the US are offering injections of plasma from young donors as an antiaging treatment, but there is "there is no compelling clinical evidence on its efficacy," the FDA said in 2019.

In some circumstances like wound healing, it may make sense to use a person's own plasma. That science is quickly evolving, but even then, there's no solid evidence that it could reduce aging, per a post from John Hopkins University