Men are drinking human breast milk to grow muscle and beat cancer. It's unproven, and it could have dangerous downsides.

• Episode three of the new Netflix series "(Un)well" features people using breast milk in unconventional and unproven ways, like to build muscle and beat cancer.
• Anecdotal reports suggest the substance may benefit athletes, and some research has shown components of it may kill cancer — in the lab.
• But experts say donor milk can contain harmful bacteria, is high in sugar and saturated fat, is meant only for babies, and is unethical to drink when there's a shortage.

Jameson "JJ" Ritenour doesn't just want to get back in shape — he wants to be ripped.

"I wanna be like, 'Give him a Band-Aid 'cause he's cut," the amateur body builder in Goose Creek, South Carolina, said on episode three of the Netflix series "(Un)well."

To get there, Ritenour isn't just cleaning up his diet and spending more time in the gym. He's not taking steroids. His supplement of choice? Human breast milk.

"If I wanna grow and be the best that I can, I'm going to eat like a baby, I'm going to sleep like a baby, and if drinking breast milk is a part of that, than it's definitely an edge I'm going to take advantage of," Ritenour said.

He's one of several adults featured in the episode who swear by human breast milk as a miracle supplement for building muscle, defeating cancer, and more.

While their anecdotal reports suggest breast milk may have benefits to adults, experts say the substance is intended for infants. It's also likely ineffective or counterproductive in athletes, they say, and that some black market products are as densely packed with bacteria as sewer water.

There's no evidence breastmilk is good for athletes

There's not solid research on how human breastmilk affects adults, but Ritenour, who pays a donor he met through Facebook, says it's helped him cut down on body fat while maintaining muscle mass.

After measuring progress before and after Ritenour started supplementing, his trainer agreed. "I would say the vitamins from the breastmilk have really helped him," the trainer said on "(Un)Well."

Some professional wrestlers in Mongolia, where breastfeeding is encouraged until the child loses interest, also support the theory that breast milk's nutrients give them an edge in training.

But experts on the show say there's no evidence, or even rationale, as to why it would do so.

The substance adapts to a baby's needs as he or she develops, taking on some of the flavors of the mom's diet and boosting immunity , but "it's not particularly valuable for athletes," Bruce German, a professor of food and chemistry at the University of California-Davis, said on the show.

In fact, he said, the nutritional profile of human milk is "rather poor" for athletes: low in protein, high in saturated fat, and very high in lactose, a sugar many people can't digest.

Plus, the anabolic factors in breast milk, which athletes may seek to build muscle, are quickly digested and eliminated in mature digestive systems, he said.

Some studies show components of breastmilk kills cancer cells — in the lab

Howard Cohen, a prostate cancer survivor featured on the episode, says he's been drinking breast milk for about 20 years. He began after reading an article in 1999 on a study showing that a component of breast milk known as HAMLET killed cancer cells in the lab.

"The only problem [with drinking breastmilk] is it's a protein, and usually proteins are digested in the gastrointestinal tract," Anders Hakansson, a professor of experimental infection medicine at Lund University in Sweden, who conducted the study, said. "So whether it would actually reach the tumor out in the body somewhere ... we don't know."

But Cohen found drinking the substance decreased his PSA levels, a measure of prostate cancer risk. Stopping the regimen when his original source, a neighbor, weaned her baby, elevated it again. After convincing doctors to give him a prescription to acquire it from a local milk bank, his PSA dropped again. His cancer has been undetectable for years, he said.

While Cohen is a case study of one, Pauline Sakamoto, the executive director of Mother's Milk bank, where Cohen gets the milk, is intrigued. He's "definitely convinced me there is something there," she said.

Since the 1999 article, other research has shown patients with bladder cancer who were treated with HAMLET excreted dead cancer cells in their urine afterwards.

There are ethical and health reasons not to drink human breastmilk

But Sakamoto said Cohen is near the bottom of the list of those who need breast milk. NICUs in the US need 8 million ounces; last year, milk banks sent 5.7 million ounces, Sakamoto said.

"There is not enough donor breast milk for babies in intensive care unites that desperately need it, so it's not an ethically grounded nutritional source for an adult," Katie Hinde, a professor at Arizona State University's Center for Evolution and Medicine, said on the show.

It's also potentially quite dangerous. In work evaluating over 100 samples of breast milk sold online (rather than through banks, which carefully screen and package donations), scientists found most had disease-causing bacteria, some so much it resembled sewer water.

"That was really alarming," Sarah Keim, an epidemiologist at Nationwide Children's hospital in Columbus who conducted the research, said during the episode.

Some breast milk also had infectious disease and environmental contaminants, and the products varied widely — from pristinely-packaged and chilled to leaky bags that had been diluted with cow's milk or infant formula.

"I don't think there's really any circumstance where one can recommend breast milk sharing," Keim said.

• Read more:
• People are undergoing 'bee sting therapy' to treat everything from Lyme disease to wrinkles, even though it could be deadly
• Netflix's '(Un)Well' delves into the dark side of fasting, essential oils, tantric sex, and other popular 'wellness' trends
• A woman had to seek medical attention after eating essential oils for weeks on end, triggering full-body swelling and rashes
• New moms who've recovered from the coronavirus appear to have a 'strong immune response' to the disease in their breast milk