A great deal has been written in the medical literature about injectable human growth hormone (iHGH) during the last several years. As a result of the lay press reporting on these medical studies, people with limited disposable income and those on the antiaging bandwagon are looking for noninjectable HGH products that may give them the same effects as the conventional injectable, with the advantage of no injection, nearly one-tenth the price and no prescription needed. HGH, comprised of 191 amino acids linked in a specific sequence, is secreted in pulses from the anterior pituitary gland. These pulses range from 9 to 29 pulses per 24 hours and can be strengthened by exercise and other variables. Most secretions occur during deep sleep, or in response to heavy exertion. Once secreted by the pituitary gland, circulating levels of HGH stimulate production of insulinlike growth factor-1 (IGF-1) from the liver. Most of the positive effects of HGH are mediated by the IGF-1 system, which also includes specific binding proteins. This is a highly regulated system, and several factors play a role in the pulsatile HGH secretion.

Only a few pharmaceutical companies worldwide are capable of producing injectable HGH. Studies show a host of beneficial effects using iHGH. The positive effects have been reported on body composition (lean body mass, fat mass, fluid volume), bone mineral density, muscle strength, exercise performance, cardiovascular health, metabolism (energy expenditure as well as protein, carbohydrate and lipid metabolism), skin, immune function, psychological well-being and quality of life. All studies in the medical literature showing the benefits of restoring HGH used the injectable form. This is an important and often overlooked fact.

No published studies have done a direct head-to-head comparison of injectable verses noninjectable HGH. Until this is done, the only available data are from companies marketing and selling these noninjectable forms. Certainly, nHGH products are available from many sources, but there is much concern about their effectiveness.

Amino Acid Secretagogues
This category of nHGH products uses amino acids as "secretagogues," which stimulate pituitary gland production of HGH. Other proprietary agents are usually part of the powder/tablet mix and give each product a presumed marketing advantage. Although studies show certain amino acids in combination, such as L-lysine and L-arginine, can stimulate pituitary HGH, no published studies show evidence that these other proprietary factors provide additional pituitary HGH secretion.

Pharmaceutical companies are investigating several biosynthetic hexa- and heptapeptides as well as nonpeptide secretagogues, but these are considered drugs. Should any of these find application, there will be a lot of news about them.

The claims and statements made by several companies advertising oral products require careful reading. It is routine to see the benefits of iHGH listed, with the implication that the advertised oral product (nHGH) will have the same benefit.

Walter Essman, M.D., Ph.D., at City University of New York, conducted a study for one company and reported average IGF-1 levels increased by 25%, 46% and 93% at 60, 120 and 180 days, respectively. Thirteen subjects (six females and seven males), ages 47­72, were each given 15gm packets (each containing L-glutamine, L-lysine and L-arginine, plus sugars, citric acid and natural flavoring) to be taken three times a day on an empty stomach for 180 days. Essman concluded that this amino acid formula is an effective HGH secretagogue, and no adverse side effects were noted.

The basis for calling this formula effective was on the elevation of IGF-1 levels. However, there was no control group, and other endpoints for judging effectiveness such as body composition and metabolism were not reported. In addition, because the study has not been published, no one has substantiated the data, which therefore become suspect. New studies should be done using urinary measures of HGH, not IGF-1, for greater accuracy, as IGF-1 levels do not always respond as expected.