While breast milk offers many health benefits for babies, some adults claim that the benefits don’t stop once you are too old for a crib.

Men who consume breast milk were interviewed recently by New York Magazine about the questionable practice. The men report significant health benefits from their breast milk habit, such as boosting energy levels and strengthening the immune system. One father stated that breast milk eased the nausea he experienced while receiving chemotherapy.

This is not a new fad. Men in China, especially those in ill health, have been partaking of breast milk for quite some time, according to The Telegraph.

The American Pregnancy Association states that breast milk contains fats, proteins, carbohydrates and special immune-boosting cells. Scientists hope to be able to take the beneficial qualities of breast milk and create a treatment for adults who suffer from a wide variety of maladies, including chronic conditions like Crohn’s disease.

The sale of bodily fluids, including breast milk, is banned on mainstream websites like Craigslist, but there is a growing underground market seeking to meet the increased demand. Buying breast milk online from strangers comes with significant risks, as breast milk can be contaminated with disease-causing bacteria, such as staph and strep.

Mainstream medical experts are skeptical about the practice. So far, there is only anecdotal evidence that adults gain health benefits from drinking breast milk.