A recent search in Pub Med reveals over 87,000 publications on growth hormones in the conventional medical literature. Yet mainstream medicine and the media continually remark how under-studied this hormone is. In addition, there are 384 double-blind placebo-control studies on growth hormone, some of which are highlighted below.
A landmark study by Dr. Rudman from Harvard [NEJM 323:1-6 July 5, 1990] looked at hGH’s effects on body composition in the elderly. In essence, Dr. Rudman studied 12 elderly men in a nursing home, ages ranging from 61-80 years old, that were given 3 injections of hGH per week at a high dose of 5mg/day. As a control, 9 elderly men received placebo.
The positive results of the study were:
- 14% decrease in body fat (3.5kg/7 pounds loss)
- 8.8% increase in lean body mass
- Increased bone density (from -1.1 to -0.9)
- Increased skin thickness
The negative side effects were edema and increased blood sugar.
In the article, Dr. Rudman remarked that he knew just from walking into the nursing home who was on the [hGH] hormone and who was on the placebo. Unfortunately, the investigators’ fear of the side effects caused them to abandon their investigation.
Dr. Rudman’s study soon received disbelief and was later re-produced by Dr. Papadakis at the University of California San Francisco [Ann Intern Med 1996:124:708-716].
The repeat study revealed similar results within six months, including:
- decrease in fat mass of 13.1%
- increase in lean mass of 4.3%
- increase in bone mineral content of 0.9%
- increase in skin thickness of 13.4%
- increase in muscle strength of 10%
- increase in oxygen consumption of 2.5%
What Is Human Growth Hormone?
If we had any say, the human growth hormone definition in the dictionary would show its synonym as “repair hormone.”
hGH is a natural hormone (not steroids as some mistakenly believe) and is produced in the human body by the pituitary gland. Like all other hormones, it is a messenger. If levels are too low or too high, there are undesirable effects. A human growth hormone deficiency can cause widespread damage.
What does growth hormone do for memory, bone loss, the heart, the immune system, weight loss, and cancer? The following research results might surprise you.
hGH and Memory
A 2000 study by Dr. Nyberg showed that growth hormone was responsible for improving cognitive capabilities, memory, alertness, motivation, and work capacity (Nyberg, F., et al., “Growth hormone in the brain: characteristics of specific brain targets for the hormone and their functional significance,” Frontiers in Neuroendocrinol 2000; 21(4):330-348).
hGH and Alzheimer’s
Numerous clinical studies have proven that growth hormone has protection against the mechanism that causes Alzheimer’s Disease by exerting cytoprotection against A beta amyloid plaques that induce neuronal cell death [Takako Niikura et al. Insulin-Like Growth Factor 1: IGF-1 Protects cells from Apoptosis by Alzeheimer’s V6421 Mutant Amyloid Precursor Protein through IGF-1 Receptor in an IGF-Binding Protein-Sensitive Manner. The Journal of Neuroscience, March 15, 2001, (21(6):1902-1910)].
hGH and Bone Density
hGH has been shown to increase the formation and strength of cortical bone, thus decreasing and even reversing osteoporosis. [Sugimoto, T., et al., “Effect of recombinant human growth hormone in elderly osteoporotic women,” Clin Endocrinol (Oxf) 1999; 51(6):715-124; Baum, H., et al., “Effects of physiologic growth hormone therapy on bone density and body composition in patients with adult-onset growth hormone deficiency. A randomized, placebo-controlled trial,” Ann Intern Med 1996; 125(11):883-90)]
hGH and the Heart
Growth hormone improves cardiac contractility, cardiac output, and ejection fraction. A 1999 study showed how hGH improved cardiac function after myocardial infarction by stimulating contractility and promoting tissue remodeling.
The same study showed how growth hormone facilitates glucose metabolism, lowers insulin levels, increases insulin sensitivity, and improves the lipid profile. [Ren, J., et al., “Insulin-like growth factor 1 as a cardiac hormone: physiological and pathophysiological implications in heart disease,” Journ Mol Cell Cardiol 1999; 31(11):2049-61]
hGH and the Immune System
Insulin Growth Factor-1 (IGF-1) is a powerful hormone of growth created by growth hormone in the liver. IGF-1 is needed for lymphocyte maturation and function. Decline in T and B cells are restored with hGH. IGF-1 restores a damaged immune system. [Burgess, W., et al., “The immune-endocrine loop during aging: role of growth hormone and insulin-like growth factor-1,” Neuroimmunomodulation 1999; 6(1-2):56-68]
hGH and Weight Loss
Growth hormone decreases fat (adiposity) by inhibition of lipoprotein lipase, which enhances lipolysis and improves dyslipidemia. [Nam, S., et al., “Growth hormone and adipocyte function in obesity,” Horm Res 2000; 53(Suppl 1):87-97)]
hGH and Cancer / Contraindications
Does hGH Cause Cancer?
“Extensive studies of the outcome of GH replacement in childhood cancer survivors show no evidence of an excess of de novo cancers, and more recent surveillance of children and adults treated with GH has revealed no increased in observed cancer risk.” [Jenkins PJ et al. Does growth hormone cause cancer? Clin Endocrinol (Oxf). 2006 Feb;64)2):115-21]
The package insert of hGH specifies that growth hormone should not be used in patients with “Proliferative retinopathy” or “active malignancy.”
However, the president of the Growth Hormone Research Society states that “There are no data to support this labeling. Current knowledge does not warrant additional warning about cancer risk.” There is no evidence that hGH increases cancer recurrence or de novo (new) cancer or leukemia. There is an increased risk of cancer, however, in low growth hormone adults. [ Journal of Clinical Endocrine Metabolism, May 2001]
A review of the existing literature regarding growth hormone and cancer by Shalet states that tumor recurrence is not greater than in patients not on hGH and that there is no increase in cancer in children on hGH replacement, concluding that there is “No evidence of an increased risk of malignancy, recurrent or de novo.” [Shalet, S., et al., “Growth hormone therapy and malignancy,” Horm Res 1997; 48 (Suppl 4):29-32]
One study that does connect growth hormone with cancer is by Dr. Jenkins in [Journal of Clinical Endocrinology and Metabolism, 2000, volume 85: pages 3218-3221]. Jenkins concluded that there is a positive influence of IGF-1 in cancer development, and this is supported by the considerable evidence that patients with acromegaly are at an increased risk of cancer, especially colorectal.
Jenkins failed to realize, however, that in acromegalic patients the IGF-1 levels are much greater than that of normal values. We believe that it’s the imbalance of hormones that allows mutated cells to proliferate.
A quote from a 1999 New England Journal of Medicine article states that there is “No evidence that GH replacement therapy affects the risk of cancer or cardiovascular disease.” [Vance M. et al. GH Therapy in Adults and Children. New England Journal of Medicine October 14, 1999)]
A remarkable study of children with brain tumors being treated with cranial radiation therapy who were given growth hormone (180 patients treated with hGH and 891 not treated with hGH) revealed the following:
- Decreased risk of recurrence – 0.60 RR
- Decreased risk of mortality – 0.55 RR