IGF-1 is commonly known to help build muscle or as something to avoid when dealing with cancer. However, IGF-1 is also crucial in healing and tends to be low in those with chronic inflammation. Learn all about how this growth factor works here.

What is Insulin-Like Growth Factor 1?

Insulin-Like Growth Factor 1 (IGF-1) is a hormone that is similar in structure to insulin and works with Growth Hormone to reproduce and regenerate cells.

Growth Hormone, made by the pituitary gland, stimulates the liver to produce IGF-1 and IGF-1 subsequently stimulates growth in cells throughout the body, leading to growth and development (as in the womb and through adolescence), strengthening of tissues (improving bone density, building muscle), and healing (skin, bones, gut lining, etc.), depending on what the body needs [1].

IGF-1 is so crucial to development that if it is not present in adequate amounts during the time when a child is developing, short stature may result.

IGF-1, Overall Health, and Longevity

In several organisms such as fruit flies, worms, and rats, IGF-I is involved in the control of lifespan.

In most studies in mice, inhibiting Growth Hormone/IGF-I results in an increase in lifespan (up to 55%). However, in humans, the association between IGF-I levels and life expectancy doesn’t hold up [2].

Unlike lab animals, humans are exposed to various infections, stress, and other environmental factors that IGF-1 might help.

Several population-based studies describing a relationship between IGF-I and risk of dying were published with conflicting results. Two studies showed a higher risk with higher IGF-I levels, while three showed higher risk with lower IGF-I levels. And in six studies there was no clear association at all [2].

Having either low or high IGF-1 was associated with higher cancer mortality in older men. This was one small study, and though its results were intriguing, they would need to be repeated before they can be taken as conclusive [3].

In a meta-analysis of twelve studies done in 2011 with 14,906 participants, the risk of dying from all causes was increased in subjects with low as well as high IGF-1 levels [4].

People with low IGF-1 were at a 1.27X increased risk of dying from all causes, while those with higher levels were at a 1.18X increased risk.

The activity of IGF-I is influenced by at least six binding proteins (IGFBP). The most abundant is IGFBP-3, which binds more than 90% of IGF-1 in the circulation. Although IGF-I and IGFBP-3 are typically well-correlated, there is speculative evidence that IGF-1 has an independent impact on disease risk, for example, on cancer [