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IGF-1

Insulin-like growth factor-1 (IGF-1) is an anabolic derivative of growth hormone that is thought to mediate cell growth and muscle protein synthesis. Supplements that increase IGF-1 are thought to promote muscle hypertrophy.

Research analysis led by Kamal Patel.
All content reviewed by the Examine.com Team. Published: Jul 5, 2013
Last Updated:

Things To Know & Note

Also Known As

Insulin-like growth factor-1

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect igf-1
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Minor High See all 6 studies
An increase in IGF-1 hormone levels may exist following DHEA supplementation, although this has only been investigated in older persons.
grade-b Minor High See all 3 studies
There is an increase in IGF-1 concentrations if the subject is deficient in zinc, but no increase otherwise.
grade-b - High See all 5 studies
While any protein sources has the potential to increase IGF-1 when included in the diet, colostrum is no different than whey protein at doing so. The IGF-1 that is present in colostrum naturally appears to be fully digested in the intestinal tract and does not reach the blood.
grade-b - Very High See all 5 studies
Insufficient evidence to support a role of creatine in increasing IGF-1
grade-b - Very High See all 3 studies
Supplementation does not appear to significantly influence circulating IGF-1 concentrations, although equol (a possible metabolite of formononetin) has been associated with a reduction not observed to a significant degree in most trials on red clover extract.
grade-c Minor - See study
IGF-1 appears to be minimally increased relative to placebo (7.8%) following two weeks supplementation of betaine and when tested after exercise in a fasted state.
grade-c Minor - See study
An increase in IGF-1 concentrations has been noted with supplementation of ursolic acid three times daily (150mg) in exercising subjects.
grade-c - - See study
No demonstrated effects on IGF-1 concentrations following the usage of citrulline supplementation
grade-c - - See study
No detectable alterations in IGF-1 for eurycoma extract
grade-c - - See study
No significant alterations in circulating IGF-1 concentrations
grade-c - - See study
No significant changes in IGF-1 seen with carnitine supplementation; IGF-2 also appears unaffected
grade-c - - See study
No significant influence on IGF-1 levels
grade-c - - See study
No significant influence on circulating IGF-1 nor IGF-2 levels
grade-c - - See study
No significant influence of velvet antler on IGF-1
grade-c - - See study
Does not appear to inherently alter circulating IGF-1 levels