What is IGF-1?
July 3, 2013
IGF-1 has been receiving more media attention lately, especially in the sport world, yet many people are still unaware of this important hormone. It is often outshined in conversation by the effects of its well-known counterpart, HGH (or human growth hormone).
Dr. Ragno M.D. explains, “IGF-1 production is directly under the control of growth hormone. In fact, very little of the effect of growth hormone has on our bodies comes directly from growth hormone –the majority of it comes directly from IGF-1.”
So, how much of a role does IGF-1 play in our life?
IGF-1, also known as insulin-like growth factor 1, is a protein encoded by the IGF-1 gene. Insulin-like growth factor 1 is a naturally occurring hormone, produced mainly by the liver as an endocrine hormone.
Natural IGF-1 production renders a wide-range of effects, so it is important to understand how IGF-1 actually works within our body.
How Does IGF-1 Work?
Insulin-like growth factor 1 received its name due to structural similarities related to insulin. IGF-1’s activity is mediated by its receptor, insulin-like growth factor 1 receptor (IGF1R), which is present in many different cell types and tissues.
When IGF-1 binds to its receptor, intracellular signaling is initiated. In other words, this activates the AKT signaling pathway, a protein that plays an important part in cellular processes like glucose metabolism; stimulates cell growth in skeletal muscle, cartilage, bone, nerves, skin; and inhibits cell death.
IGF-1 is directly affected by the growth hormone. So, by increasing growth hormone levels, IGF-1 levels also increase.
How to Naturally Increase IGF-1 Levels
IGF-1 levels decline with age, being at its highest in adolescence and puberty. And, ingredients containing IGF-1, such as deer velvet, have been under scrutiny due to its banned status by sport associations. But, you don’t need to take banned substances to increase IGF-1 levels. There are natural ways to increase both HGH and IGF-1.
A clinical study reveals whey protein is an excellent way to increase IGF-1 levels.
Fifty-one subjects received either 42 g protein or a 70 g carbohydrate supplement 2 times a day and participated in alternating resistance training and running 5 times a week. Researchers reveal the protein group experienced higher IGF-1 levels in plasma than those in the carbohydrate group.
Brief Intense Exercise
A short bout of intense exercise, more so than low intensity exercise, is also proven to increase IGF-1 bioavailability.
Ten males were studied on 3 different occasions: once under resting conditions and once during each 10 minute low- and high-intensity training. Research reveals IGF-1 bioavailability increased during both training intensities, but was greater during higher intensity.
Low-Fat Milk Supplementation
Low-fat milk also has been linked to increasing IGF-1 levels.
In a case study, researchers collected plasma samples from 14,916 men from the period 1982-1983. Results show dairy low-fat milk was positively associated with higher IGF-1 plasma levels. Additionally, researchers concluded “intake of low-fat milk was associated with lower risk of colorectal cancer.”
What Are Benefits Associated With IGF-1
According to clinical studies, IGF-1 offers many different benefits. IGF-1 benefits are not strictly related to physical enhancement, although there are several physical benefits. Higher IGF-1 levels are also associated with intellectual and sensory gains.
IGF-1 May Positively Contribute to Hearing Loss.
Studies indicate animals that suffer from low IGF-1 bioavailability lose auditory neurons. Researchers indicate neuronal loss due to IGF-1 deficiency is brought about by apoptosis (cell death) of the auditor neurons.
Also, when treated with topical IGF-1 application via gelatin hydrogels, men suffering from sudden sensorineural hearing loss experienced auditory level recovery. Researchers noted major increases were experienced within 4 weeks after the treatment.
IGF-1 May Be Associated with Strength and Exercise
A clinical study suggests IGF-1 increases muscle size by regulating satellite muscle cell activity. Satellite muscle cells are responsible for muscle cell proliferation.
Twenty-six older men and women underwent progressive resistance training. Greater strength increases were experienced in patients with higher IGF-1 levels.
However, research indicates that although higher levels of IGF-1 are shown to increase post-exercise, “the cellular mechanism(s) linking exercise to increased IGF-1 is unclear.”
Higher Levels of IGF-1 Are Associated with Better Cognition
In a Harvard Medical School study, IGF-1 plasma levels were measured in 590 women. Ten years after initial measuring, telephone-based general cognition tests were administered to patients. These tests included verbal memory, category fluency, and attention. After research was collected and analyzed, researchers concluded higher IGF-1 levels may be associated with better general cognition.
Side Effects Associated with IGF-1
- Prostate Overgrowth
- Increased Cancer Risk
The common saying, “everything in moderation” holds true when talking about IGF-1 levels. Reasonable IGF-1 levels are beneficial to overall health, and in excess may cause previously mentioned side effects.
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