Insulin-like growth factor-I acts as an important mediator between growth hormone and growth throughout fetal and childhood development. Its effects and those of the other insulin-like growth factors are modulated by at least six different binding proteins.
The risk of cancer is higher among people with raised concentrations of insulin-like growth factor-I, and it is lower among those with high concentrations of insulin-like growth factor binding protein-3 (the main binding protein).
Support for the link between cancer and this growth factor comes from an understanding of the potential mechanisms. Concentrations of insulin-like growth factor-I could be a surrogate for the activity of sex steroid hormones, which in turn influence the risk of cancer. However, associations between insulin-like growth factor-I and cancers dependent on sex hormones are stronger than those between directly measured concentrations of sex hormones and these cancers.
Insulin-like growth factor-I may increase cell turnover and the susceptibility of cells to malignant transformation both directly and by modulating the effects of sex steroids.
This study establishes a link between an insulin-like growth factor (IGF-1) and elements such as milk intake.
What's the link between multiple pregnancies and IGF-1 levels?
Levels of IGF-1, a hormone that can raise cancer risk when levels are too high, fell as the number of pregnancies increased for women in this study. Women who had been through at least four pregnancies had IGF-1 levels that were 14% lower on average than their peers who had fewer children.
What link was discovered between milk proteins and IGF-1 levels?
It's not clear at this point whether milk, or a particular component of milk, is the culprit. It was found that IGF-1 levels rose along with women's intake of protein, especially from milk. There was no association between IGF-1 levels and vegetable protein intake. Yogurt, cheese and ice cream also had no association with the hormone.
Cancer Epidemiology Biomarkers and Prevention September 2002
No mystery here! A similar report was published in British Medical Journal two years ago.
Interestingly there was no association with the IGF-1 levels and other forms of dairy aside from milk such as yogurt, cheese and ice cream.
Many may not realize that when you drink milk you are consuming IGF-1, along with many other growth factors. Milk from cows treated with synthetic growth hormones such as rBGH have especially high levels of IGF-1. This is one of the many reasons why I advise avoiding milk.
It is also interesting to note that the growth hormone that is so strongly promoted by many anti-aging clinicians may in fact have adverse effects by raising insulin-like growth factor-I. It is probably best for most to avoid the use of growth hormone and rely on more proven and less risky interventions, like a good diet, which reduces insulin levels, and weight training - which can also increase growth hormone.
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