Ben Greenfield. Image: Screenshot via YouTube

Ben Greenfield is a cult figure among fitness fanatics, a guru to the sort of nerds who devote themselves to meticulously monitoring their own biometric data for insight into their personal health. He has more than 50,000 Twitter followers, 60,000 Facebook fans, and 30,000 YouTube subscribes. Now he may become known for something else entirely: Injecting himself with stem cells in hopes that it will make his dick bigger.



“I want to take care of my body in the best way possible,” Greenfield said during a webinar earlier this month, in which he spoke to listeners while walking on a treadmill. Part of that, he said, means “having fun with using what science has given us to make the body better.”

Greenfield is something of a human science experiment, who’s willing to try almost anything in the name of getting ripped and some publicity. He has subjected himself to platelet-rich plasma injections, stem cell injections, and even sound wave therapy, all in search of bodily enhancement and better health.

“I live my life as an N=1,” he told Gizmodo, referencing research studies with just one subject.

In November, Greenfield visited U.S. Stem Cell, a controversial clinic in Florida, to have his penis injected with his own stem cells. If the name of the clinic seems familiar, that’s because it’s the same Florida clinic that last year unintentionally blinded three patients in a clinical trial of an unproven stem cell therapy. In August 2017, the Food and Drug Administration sent U.S. Stem Cell and its chief scientific officer Kristin Comella (who appears in the webinar video with Greenfield) a warning letter for “marketing stem cell products without FDA approval and for significant deviations from current good manufacturing practice requirements, including some that could impact the sterility of their products, putting patients at risk.” U.S. Stem Cell Clinic, the FDA said, even tried to interfere the FDA’s investigation by denying agency employees access to facilities. (U.S. Stem Cell did not respond to repeated requests for comment.)



“I wanted to go from good to great, and to get a bigger dick,” he told Gizmodo. “I’m not going to lie, that’s why guys without erectile dysfunction would do this.”

In the webinar, Greenfield and Comella explain how the procedure worked. Greenfield had U.S. Stem Cell isolate stem cells from his body’s fat cells. Then, said Greenfield, those stem cells were injected into the “meat of the tissue” of his penis. (“You don’t feel a thing other than a little bit of pressure,” he said in the webinar.)

Several early-stage studies have shown that stem cells do show promise in treating erectile dysfunction in men. A press release from U.S. Stem Cell cites one such study from 2016, in which adipose-derived stem cells were used to treat 17 men who suffered from erectile dysfunction after undergoing a radical prostatectomy for prostate cancer. The stem cells were injected at the base of their penis. The men experienced limited side effects, and eight of the 17 men were able to successfully get erections and have sex again. Greenfield, though, was seeking to enhance his manhood, rather than to fix any medical problem. The evidence that such a treatment could help treat erectile troubles is still nascent. Evidence that it could enhance a man without any such issues is even more tenuous.

Kiki Sanford, a molecular physiologist and host of The Stem Cell Podcast, told Gizmodo that while the study cited in the press release suggests the injections might not be harmful, it was also too small of a study to really indicate whether they might actually work, even in men with erectile issues.



“You can’t say that since a study might have enhanced function in deficient tissue it will do the same in normal tissue,” Sanford said. “The body doesn’t necessarily work that way.”

And, she said, even if the procedure is “safe” there is still risk of complications like infection—all for a procedure that has little chance of working.

Nonetheless, Greenfield said in the webinar that the procedure had made him “noticeably better hung.”

Three or four days after the procedure, he said, it was “almost like it grew.” His erections were also bigger, his penis got harder, and his orgasms were better, he said. The better orgasms, he said, might be a placebo effect, but the anatomical changes in size “cannot be denied.”

“I haven’t taken out a ruler. When inside of my wife, she can tell.”

Gizmodo asked Greenfield whether he had measured his change in size.

“I haven’t taken out a ruler,” he said, explaining that he felt the size fluctuates too much to get a consistent measurement. But he thinks it looks noticeably larger.

“When inside of my wife, she can tell,” he added.

Greenfield, who considers himself a “biohacker,” is a big believer in stem cells. He’s had them in his knee and hip to help him recover from an injury, which he said was successful. He’s also injected them into his own arm as a performance enhancer at home. With the help of stem cells, he said, by the time he is 40 in a few years, he hopes to have attained a biological age of 25.

He told Gizmodo that he thoroughly researches any new therapy he plans to undertake, and he felt confident that this one was safe.

“There is still a risk,” he said. “But the payoff in terms of health is very big. You can’t always wait for things to be thoroughly studied.”

Stem cells do have lots of therapeutic promise. But while most of those treatments are still little more than theoretical, clinics offering stem cell procedures have flourished because FDA regulations allow clinics to inject patients with their own stem cells as long as those cells meet criteria including “minimal manipulation” and are intended to just perform their normal function. Some treatments, including some of those offered by U.S. Stem Cell, seem to flout those rules, but so far the FDA has had difficulty cracking down. That may change, with a new regulatory initiative announced last fall.

Several US clinics market better sex through stem cell injections to both men and women, for price tags that run more than $1,000.

“Stem cell therapies are all very exciting for their potential to help people, but very few have been shown to work well enough in clinical trials to gain FDA approval,” said Sanford. “We are still very much in the age of snake-oil with respect to many of the therapies that are being marketed, which is too bad because the potential is there. “

But why would Greenfield, a fitness guru who says he has no problems with getting it up, want to try a risky, unproven procedure on himself?

“It’s not normal,” he said in the webinar. “I don’t think ancient man injected stem cells, especially into his nether region.”

Then he rattled off a laundry list of “modern assailants,” including cellphones, and a list of problems including autism and erectile dysfunction that he believes may be related.

“We’re fighting an uphill battle,” he said.

Injecting his penis with stem cells, he continued, is just one way to combat the perils of modern life.

Update, 3:35 p.m., May 5, 2020: This post has been updated to remove a broken video embed .