From an anti-aging viewpoint, GH is thought to exert beneficial effects though maintaining various tissues and organs of the body that would otherwise slowly degenerate with the passing years. Indeed, levels of GH peak during the teen years, then begin to decline starting at age 40. Many older people are clinically deficient in GH, and much of the ills associated with aging are often linked to GH deficiency. As noted, however, the active anabolic effector of GH is IGF-1. When people who are deficient in GH undergo GH therapy, IGF-1 always rises significantly. This rise in IGF-1, however, could present problems. Among the many functions of IGF-1 are a stimulation of cellular division and a preservation of cells through inhibiting a type of cellular suicide called apoptosis. The basis of cancer is uncontrolled cell division, and some studies link higher levels of IGF-1 with a greater incidence of certain cancers, such as cancers of the breast, colon, and prostate. While the mechanism makes sense, the relationship of IGF-1 to cancer is still not clear. For one, most active IGF-1 is bound to proteins, and cannot exert effects on the cell until it is freed from its binding protein. Another factor is that most older people, in whom cancer rates tend to be higher, also have low levels of both GH and IGF-1. A recent study followed 633 older men for 18 years, and found that the men with the highest levels of IGF-1 also showed the highest rates of cancer deaths. Other studies, however, have not shown any such association. One difference in the new study was that the study subjects were older than in previous studies. In the new study, the subjects average age was 74. Based on this finding, the authors of the study suggest that IGF-1 may play a role in cancer in older men. In younger men, IGF-1 is known to protect both heart and brain tissues. The authors also suggest that in light of the association between elevated IGF-1 levels and cancer in older men, perhaps GH therapy may be not as beneficial as some people believe. What they didn't mention was that long-term studies of GH therapy in older men show no elevated rates of cancer in the men. This can be attributed to the fact that even though IGF-1 levels increase with GH therapy, so does the IGF-1 binding protein, thus protecting cells from any adverse effects of a rise in IGF-1, although the beneficial effects on mind and body likely remain.
Major JM, et al. Insulin-like growth factor-1 and cancer mortality in older men.J Clin Endocrin Metab2010;95:1054-1059.
©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
