What IGF-1 is, what 'HGH releaser' supplements contain, and what the evidence shows, including the one published trial of GenF20 Plus and why its main result was not significant.
IGF-1 (insulin-like growth factor 1) is the blood marker doctors use to judge growth hormone activity. "HGH supplements" contain no growth hormone; they are amino acid and herb blends marketed to make your body release more of its own. Evidence that they work is weak: Mayo Clinic says research does not show such supplements raise HGH, and the one published trial of GenF20 Plus found no significant IGF-1 increase versus placebo across all participants.
Human growth hormone (HGH) is released by the pituitary gland in pulses, much of it during sleep. It signals the liver to make IGF-1, which carries out many of growth hormone's effects. Because HGH levels swing through the day, IGF-1 is the more stable marker used in blood tests.
Products sold as HGH supplements or releasers contain amino acids such as L-arginine, L-glutamine, L-ornithine and GABA, often with herbs like Tribulus or astragalus and animal extracts like deer antler velvet or colostrum. Arginine has raised growth hormone in studies using several grams, but products in this category typically contain far less: GenF20 Plus lists 130 mg of L-arginine per serving and HyperGH 14x lists 520 mg a day. In 2005 the FTC said it knew of no competent evidence that HGH pills or sprays raise growth hormone.
GenF20 Plus is one of the few products with a published placebo-controlled trial (2015, 61 adults completing 12 weeks). IGF-1 rose more on GenF20 Plus than on placebo, but the difference was not statistically significant across all participants; a significant result appeared only in a post hoc analysis of people aged 40 and over. Body fat, lean mass, energy, sleep and libido did not differ from placebo, and growth hormone itself was not measured. HyperGH 14x, marketed to people who train, has no published trial of its own.
L-arginine and GABA can lower blood pressure, and arginine interacts with nitrates, ED drugs, blood pressure and diabetes medicines. If you have a history of cancer or diabetes, or are pregnant, talk to your doctor before taking any product marketed to raise growth hormone or IGF-1. Prescription growth hormone is a different thing entirely; see our guide to HGH supplements vs HGH injections.