IGF-1 = insulin-like growth hormone

To start with the advertising claims, here's what this wonderful supplement may do to your body:
http://www.igf-1plus.com/ (they do have a cool 3D structure of the molecule :) ) states 23 beneficiary effects, ranging from sharpened mental alertness to reduced inflammation & decreased pain in arthritis and correction of impotence. It is also said to combat several deseases and the perfect substance for "gaining muscle and losing fat". In other words, yet another drug on thee list of ultimate fantastic wonder treatment.
My information is that IGF-1 supplements are produced by genetically modified micro-organisms (for bulk production), but it's also possible to induce production in the liver.

Yeah, right!
Call me skeptical if you want, but after a certain dose of human physiology lectures at university and spending a couple of years in the medical circuit as a patient myself, I've lost any little bit of faith in such claims. So, what do the researchers themselves say about IGF-1 ? My main source for the information written below is the "Growth Hormone & IGF Research" scientific magazine (readable online at http://www.harcourt-international.com/journals/ghir/default.cfm)

Insulin-like growth factors (IGFs) are produced in the brain and participate in brain development via activation of the type 1 IGF receptor. IGF binding proteins (IGFBP-1) modulate the cellular action of IGFs and some are expressed in the fetal brain. IGF tests can be used in the diagnosis of GH hypersecretion or hyposecretion (i.e. too much or insufficient production). Further, there are indications that there's a role for IGF-I measurement as an index of nitrogen balance and in monitoring remission of breast cancer under treatment with and oestrogen receptor antagonist. (how? why?)
This for what it affects, but the interesting part of course is: what happens if you have too much of it, or insufficient levels?

Research results
In accordance with the common practice in the pharmaceutical area, animal tests with transgenic mice and rats are being carried out.
First, the IGFBP-1 overproduction in mice fetuses: effects include reproductive defects, ante- and perinatal mortality and post-natal growth retardation and there were some cases of head enlargement. The width of the cerebral cortex was reduced in homozygotes (the transgene mice, not the control group), with disorganized neuronal layers. Similar anomalies have been reported in mice with disruption of the IGF-1 gene and in a model of transgenic mice over-expressing IGFBP-1 in all tissues, including the brain. Conclusion: the results indicate that (at least) hepatic over-expression of IGFBP-1 may have endocrine effects on brain development. This makes me wonder if pregnant women taking the IGF-1 drug expose their fetus to these threats. Browsing through the magazine's database, there was no report that mentioned if they tested this hypothesis on animals.
Secondly, the previously mentioned weight loss. Weight change was positively correlated with serum free IGF-I, but not with total IGF-I. It is proposed that in rats the (glucocorticoid-induced) weight loss may in part be due to suppression of circulating free IGF-I.
Third, deficiency in IGF-1 is related to infertility, delayed bone development, retarded post-natal growth, reduced adult weight and growth deficiency (http://www.bioscience.org/knockout/igf-1.htm).

Ok, ok, I made a selection of the research results I've illustrated here, but there certainly wasn't scientific back-up of the mentioned claims in the ads. Further, by no means you can ever say that when you have the situation of a deficiency + IGF-treatment (or any drug treatment) up to normal levels (which is beneficiary), the same postive correlation may be measured when going from normal levels up to an overdose!!

See also human growth hormone by factgirl

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