Scientific American reports that sermorelin, tesamorelin and a growing list of related compounds are being sold as antiaging elixirs while the clinical evidence behind those claims stays thin and the risks stay serious.

The compounds in question, including sermorelin, tesamorelin, CJC-1295, ipamorelin, GHRP-2 and GHRP-6, are meant to prod the pituitary gland into releasing more growth hormone. Growth hormone levels peak in puberty and then decline by as much as half every seven to 10 years, endocrinologist Brad Anawalt of the University of Washington told the magazine, and that decline is the entire premise the category rests on.

The approvals nobody mentions

Two of the most popular compounds were built for people who are not the ones buying them. Sermorelin was FDA approved in 1997 for growth hormone deficiency in children, discontinued in 2008 and later withdrawn for commercial reasons. We know it raises growth hormone levels, says Alexander Pastuszak of the University of Utah, but there are no large randomized controlled trials in healthy adults testing performance, body composition or longevity.

Tesamorelin was approved in 2010 for HIV-associated lipodystrophy. In a trial of more than 400 people with that condition, visceral fat fell by about 15 percent. Pastuszak notes the goal was reducing fat tissue, not building muscle, and the population studied looks nothing like the longevity clinic clientele. CJC-1295, ipamorelin and the GHRPs have never been FDA approved at all.

Size is not function

Growth hormone itself has more data behind it, and it is a useful cautionary tale. One review found more than 200 older adults gained about 4.6 pounds of lean body mass with a similar drop in fat mass, alongside swelling, joint pain, carpal tunnel and, in some cases, diabetes. What they did not gain was mobility. What you really want is function, says Anne Cappola of the University of Pennsylvania, not how big the muscle is. In athletes, growth hormone raised stationary bike sprint capacity by about 4 percent, and the effect vanished on stopping.

What is in the vial

A recent analysis, not yet peer reviewed, found that between roughly 40 and 70 percent of thousands of gray-market peptide samples tested, sermorelin and tesamorelin among them, failed basic quality criteria. About 15 percent of a tested subset carried measurable endotoxin, a marker of bacterial contamination.

Bottom line

The honest position here is Anawalt's: believe me, he says, if he thought a peptide was going to work, he would recommend it. Until somebody runs the trial in healthy adults, the marketing is running well ahead of the file.