In America, in the year 2015, youthfulness is a national obsession. In the public mind, the advantages of young adulthood (beauty, strength, stamina, sexuality, and good health) greatly outweigh the supposed advantages of age (experience, wisdom, a record of accomplishment, a lifetime of friendships, standing in the community, accumulated wealth and increased earning power). The “baby boom generation” (people born between 1945 and 1955) is approaching retirement with the fear of having accumulated too few assets for that retirement to be comfortable. Many people approaching retirement wonder how they will pay their medical bills, which are sure to mount. Given the public mood, purported methods to delay or reverse the ageing process inevitably attract attention. Of these, the most discussed is human growth hormone (hGH). Proponents of hGH therapy for ageing, including many hGH vendors hoping to improve their own retirements, argue that it has many benefits. It is claimed to increase lean body mass, reduce body fat, improve physical and mental performance, improve the quality of sleep and reverse the decline of the immune system that occurs with ageing. Detractors pointout that the documented benefits of hGH therapy are usually modest, that many studies have failed to find any benefit, and that hGH has welldocumented undesired side effects.
The purpose of this article is to describe the benefits and drawbacks of growth hormone therapy, and to offer a glimpse of how growth hormone functions. However, growth hormone does not exist in a vacuum. Instead, it is one of six hormones whose workings are interrelated. The others are Growth Hormone Releasing Hormone (GHRH), somatostatin, ghrelin, and the insulin-like growth factors I and II (IGF-I and IGF-II). These six hormones are together termed the “growth hormone axis,” or simply the “axis.” This article is thus about the growth hormone axis.
In the course of writing this article, I consulted between 1000 and 1100 research articles, although I certainly did not read them all in detail. There are many more relevant published articles that I did not consult, very probably including many that I am not aware of. I have formed the following opinions:
One. Despite advertising claims, growth hormone does not reverse the ageing process. Ageing is far more profound than a reduction in hormones,
and reversing it would take much more than restoring those hormones. Hence, the most that growth hormone might do is to postpone or temporarily reverse some of the symptoms.
Two. Growth hormone greatly benefits several groups of sick people. Most of the claimed benefits for growth hormone come from studies of these people. Although these people represent a diverse group of illnesses, it is likely that their illnesses all disrupt the normal workings of the growth hormone “axis.” Growth hormone therapy restores the axis to its normal function. Hence, the demonstrated benefits of growth hormone therapy in these people may not apply to healthy people.
Three. Growth hormone and other members of the growth hormone axis may provide the the following benefits to elderly people (in other words, the purported benefits have at least some support): reduced body fat, increased strength and stamina, improved heart performance, lowered blood pressure, improved blood lipid (cholesterol) profile, increased bone density, improved memory and mental function, increased immune system activity, increased sexual potency, and improved sleep. However, these benefits do not always occur, and may be modest when they do.
Four. In some people, growth hormone improves mood and life satisfaction, as well as marital and economic performance. The improvement sometimes lasts indefinitely, and sometimes does not.
Five. Growth hormone is sometimes also claimed to improve the vision, remove wrinkles, and restore hair growth and color. There are indeed connections between growth hormone and blood vessels in the retina, between growth hormone and the skin, and between growth hormone and hair. However, in all three cases the connection is complex, and it is not not necessarily true that more growth hormone is better.
Six. Growth hormone and other members of the growth hormone axis can have strong adverse consequences, as well as beneficial ones. A few examples are: People with acromegaly have a large excess of growth hormone. Such people have many physical ailments, and (unless treated) eventually die of heart failure. Tens of thousands of patients have been treated with growth hormone, and seem not to suffer any statistical increase in cancer. However, evidence suggests that growth hormone and other members of the growth hormone axis can accelerate the growth of many cancers. Cancers in an early state, that could still be stopped by the body’s own defenses, might also be accelerated. ( H5_4 )
Growth hormone and other axis hormones clearly have strong effects on the brain. However, some evidence indicates that high concentrations of growth hormone accelerate mental deterioration in the elderly. Growth hormone promotes blood vessel growth in the retina of the eye. In diabetics, overgrowth of such vessels causes diabetic retinopathy, which can lead to blindness. A promising therapy is to chemically antagonize the growth hormone. Growth hormone and other members of the axis induce immune system activity, and hence could be said to “strengthen” the immune system. However, “strengthening” of the immune system is risky; the induced immune system activity may accomplish nothing useful, and may even attack the body, causing autoimmunity. Elevated levels of growth hormone may reduce rather than increase longevity. Long-lived strains of mice have reduced levels of growth hormone and IGF-I.
Seven. Commercially available growth hormone is a protein that is produced with recombinant DNA techniques. As such, it is regulated by the Food and Drug Administration; it is approved as a treatment for several medical conditions but not as a therapy for ageing, and not as an ergogenic aid for sports. Hence, it can be taken legally by only some people and only by a doctor’s prescription. Growth hormone will not enter the body reliably unless injected. Moreover, a year’s supply of recombinant growth hormone can cost $10,000 or more. Hence, dietary supplements or sprays which increase a person’s growth hormone levels probably do not contain growth hormone itself. Instead, they presumably contain substances that will induce the body to produce more growth hormone. Dietary supplements, including melatonin and creatine, have been reported to increase growth hormone levels in patients. Therefore, some commercial supplements may indeed increase a user’s growth hormone levels.
Eight. The best advice on whether to take such supplements will probably come from a physician specializing in Endocrinology. Such a physician should be certified by the American Board of Medical Specialties as qualified to specialize in Internal Medicine, with a subspecialty in Endocrinology.
Nine. Growth hormone research is an exciting field that deserves continued financial support. It has helped tens of thousands of people. Although it offers only modest benefits to the healthy elderly, continued research may bring much greater benefits.