Peyton Manning has done it. So has baseball pitcher Bartolo Colon. Ditto Argentine soccer star Angel Di Maria. And just last month, tennis great Rafael Nadal had it done too.

Sports stars from all over the world are turning to stem cell therapies in order to fix nagging injuries and to speed their return to competition. It has been estimated, for example, that hundreds of NFL players have pursued various kinds of stem cell therapies.

Media coverage of these treatments is often substantial. News of Nadal’s procedure was ubiquitous: there were mentions in the New York Times, the Globe and Mail and the Toronto Star. And, no surprise, there was heavy coverage in sports media, from Sports Illustrated and to Tennis magazine. But one thing all the coverage shared was an uncritical approach to the treatment. The value of the procedure seems to be taken for granted. Usually, the only ”œexpert” quoted is the physician providing the treatment, and that is usually an individual who appears to lack expertise in the area of stem cells.

Nadal’s treatment is presented as cutting-edge medicine, similar to the treatment received by other sports stars and, by implication, efficacious. For example, the Guardian of November 10, 2014, reported that Nadal’s treatment ”œis meant to repair his cartilage” and that ”œhe is expected to return to training in early December.”

Some of the online stories are particularly problematic. They come off as more marketing than journalism. For example, the November 10 Washington Times piece on Nadal’s treatment, like virtually all the stories, provides no informed commentary on the possible efficacy (or, more likely, lack of efficacy) of the treatment and notes that ”œseveral NFL players and baseball players have received stem cell treatment.” Immediately under the paragraph that contains this sentence there is an advertisement for ”œtreatment breakthroughs using stem cell technology.” Clicking on that advertisement takes you to the website for a clinic that offers completely unproven stem cell therapies for everything from aging ($3,900) to Alzheimer’s disease ($15,000) to cerebral palsy (”œcost begins around $13,500”).

The social media magnify the problem. I skimmed about a thousand tweets on the Nadal stem cell therapy. Most of the tweets simply repeat the headline that Nadal is getting stem cell therapy for his ailing back. A few wondered if stem cell therapy should be considered cheating " which implies that it is so powerful and effective that it will give him a competitive advantage. (Do these people suspect Nadal will have some kind of stem-cell-enhanced super-back?) But I found only one tweet that questioned the efficacy of the treatment. It was sent by me.

This uncritical portrayal appears to be the norm. In a September 2012 article in Molecular Therapy Amy -McGuire and I analyzed how the popular press covered the use of stem cell therapies by professional athletes and found that 10”ˆpercent explicitly state the therapy worked and 73 percent of the articles did not touch on the issue of efficacy " which, given the topic of the article, could certainly be interpreted as implying efficacy.

And that is what I find so worrisome about the trend. To be honest, I am not terribly concerned about rich athletes using unproven treatments. I understand that these professionals are under intense pressure to perform at the highest level. But the uncritical reporting of the use of these therapies may help to fuel a market for unproven and potentially dangerous stem cell products. It is no surprise that the clinics offering these services leverage the media coverage to market products. If selling unproven stem cell therapies is your core business, a headline like ”œPeyton Manning: Poster Child for Stem Cell Treatment,” which appeared on the front page of the Washington Times Communities in September 2013, is a promotional gift.

Given all this uncritical coverage, desperate patients may be led to believe that if a therapy is good enough for Peyton Manning or Rafael Nadal, perhaps a similar treatment can help cure a debilitating or life threatening disease. Perhaps it can be used to treat a sick or disabled child.

But while the field of stem cell research is incredibly promising, there are, in fact, very few stem cell therapies that are ready for the clinic. The treatment these athletes are receiving has not been established to be effective in well run clinical trials. And this is also true for the alleged stem cell ”œtherapies” for cerebral palsy, Alzheimer’s disease and almost every other condition mentioned on these clinics’ websites.

I hope that patients and parents are not swayed by the actions of professional athletes. But given the viral spread of all the ”œthis stuff works” messages, they may be difficult to ignore. Thankfully, there are many useful and scientifically informed resources that can be easily accessed to help inform patients about stem cell therapies. The International Society for Stem Cell Research has a wonderful website and provides advice on how to evaluate clinic claims. And our team at the Health Law Institute recently published a patient booklet entitled ”œWhat You Need to Know about Stem Cell Therapies,” which is aimed at explaining both the basic science and how clinical translation happens.

Stem cell research is a genuinely exciting area of research. I believe that a host of beneficial therapies for a range of diseases are on the horizon. But we aren’t there yet, no matter what you hear about Manning and Nadal.

Timothy Caulfield holds the Canada Research Chair in Health Law and Policy at the University of Alberta where he is also a member of the Health Law Institute; he is a Trudeau Fellow and is the author of The Cure for Everything: Untangling the Twisted Messages about Health, Fitness and Happiness (Penguin 2012).