If the new testing regime in MLB, along with the New Times scoop, leads to a renewed interest in stamping out HGH abuse, this cycle may begin anew. Further research in the last five years has not brought much more clarity about the drug, in terms of its benefits or its risks.
The most dramatic recent study of how HGH affects athletic performance came out in 2010, and found that regular dosing could improve a sprinter's time by almost 4 percent. A senior author of the paper, Kenneth Ho, noted that a 4 percent improvement might cut four-tenths of a second from an Olympic athlete's 100-meter dash—enough to turn a last-place finisher into a gold medalist.
The last-to-first comparison was reported widely in the media, along with claims that researchers had at last produced "hard evidence" for the HGH effect. That fit in well with the message of the World Anti-Doping Agency, which provided funding for the study. But other scientists wondered at the paper's conclusions. Previous double-blinded, placebo-controlled studies had found no effect of HGH on muscle strength or bicycling performance, and the 4 percent effect from the Ho paper showed up not in a real 100-meter dash, but on something called a Wingate test, completed on a stationary bicycle. (No one in the field knows exactly how the Wingate test relates to actual sports performance.) The Ho paper also found that HGH had no detectable impact on its subjects' cardiovascular endurance, their ability to lift weights, or their capacity to jump straight up in the air. Finally, the drug did not appear to boost performance in female subjects.
A critique published in the same journal several months later warned that while the media attention to the study might be taken "as a victory in the highly publicized battle against sports doping, it is scientifically inaccurate, unethical and irresponsible." Then the author added: "Ironically, it could also encourage the abuse of doping agents by exaggerating their efficacy."
Evidence for the amazing healing powers of HGH remains obscure as well. (A few studies have found an effect on collagen protein synthesis and fracture repair, but they have not yet been corroborated.) Same goes for the drug's often-cited long-term health risks. The December AP report, for example, writes off some of the drug's purported benefits as having "scant scientific evidence," while listing diabetes, heart disease, and cancer growth among its "suspected side effects." But the research support for these dangers is scant as well. Children treated with growth hormone for legitimate medical conditions seem to have higher rates of certain kinds of cancer, but their overall mortality rates are unchanged. In August 2011, the FDA reviewed data from a large study of HGH that's underway in Europe and concluded that "the evidence regarding recombinant human growth hormone and increased risk of death is inconclusive," recommending that healthcare providers continue to prescribe it where appropriate. (N.B. the FDA considers "anti-aging" an inappropriate use.)
Six years ago, I wrote in Slate that "every star athlete who gets caught with a vial of HGH turns into a spokesperson for the drug." Indeed, these de facto advertisements are just like the ones that drive an underground market in deer-antler spray, holographic energy stickers, negatively charged water, and other mumbo jumbo for which pro athletes seem to have an endless hunger and credulity. HGH may not really improve your game, but that doesn’t matter much when it comes to its popularity. A-Rod just gave this product his endorsement, and that means the drug will sell.
What does this mean for all the nonathletes who are taking the drug for its "anti-aging"—i.e. cosmetic—benefits? They're left to fend for themselves amidst conflicting claims from sleazy clinicians and overzealous anti-dopers. They would be wise to ignore the marketing, wherever it comes from, and decide for themselves whether the potential for cosmetic gain is worth the as-yet-unknown risks.