What is Follistatin?
Follistatin is a single-chain glycosylated protein found to possess notable benefits in various health conditions ranging from diabetes to multiple myopathies. More recently, its potential uses have been studied in regard to metabolic diseases due to its various known beneficial effects, including several that are relevant for muscle health and regeneration.
Follistatin – known as FST) is a member of the tissue growth factor β family of proteins, which antagonises (or works to reduce the effect of) a number of its family members including activin A, growth differentiation factor 11 and myostatin – an important signalling molecule in skeletal muscle atrophy [1]. It was discovered in ovarian follicular fluid and characterised as a pituitary follicle-stimulating hormone (FSH) suppressor.
Both isoforms of natural occurring follistatin – FST288 and FST315 – occur in the body. FST315 is the more prevalent isoform; FST288 accounts for less that 5% of the mRNA it encodes [2].
What Are The Benefits of Taking Follistatin?
Follistatin is produced in a wide range of tissues and has been shown to provide defence against a range of stresses [3]. It is also a muscle regulator as it can inhibit the activity of myostatin, a protein that regulates skeletal muscle mass [4].
From the therapeutic point of view, follistatin has also been used as a systemic therapeutic agent promoting muscle regeneration after different models of injury. Extensive in vivo analyses revealed that weekly administration of follistatin increased body weight and lean muscle mass in normal mice and stimulated the parameters of muscle injury/atrophy repair by changing the early inflammatory phase and increasing the macrophage density, thus restoring myofibres and muscle function. [1].
With respect to metabolic health, there is evidence that follistatin has decreased abdominal fat content, enhanced glucose clearance and improved plasma lipid profiles in mice, which might be of clinical relevance for the treatment of the metabolic syndrome as well as for fat-restriction protocols [5].
However, there haven’t been any human studies, and more studies are needed to truly understand the benefits of follistatin in humans. If you want to try supplementing follistatin, please discuss this with a licensed physician.
What are the Risk Factors of Taking Follistatin?
Follistatin is readily available on the black market, often labelled as ‘follistatin 344’ or ‘follistatin 315’ (even when it technically is that substance, it’s rarely pure as described in the formulation). In one study, of 17 nutritional supplements marketed as containing follistatin 315 or follistatin 344, only nine actually contained follistatin, with several others containing human growth-promoting peptides [5].
Furthermore, follistatin acts as a potent antagonist of the myostatin pathway and, as such, can increase muscle mass. However, the follistatin impact on the pituitary activin-inhibin axis and the inhibition of FSH release position the agent to date as dangerous for uncontrolled use [6].
In order to comprehend how follistatin compares to MK-677, another peptide involved in muscle building, read above to find out more.
Conclusion
Follistatin might be beneficial against metabolic disease or help with muscle development, but there is very little evidence to support it, since all studies have been on animals. More research is needed to verify whether it can be used to treat these conditions and what the limitations are.
Most importantly, if you’re considering taking these supplements, weigh the risks carefully and discuss them with a fully qualified medical practitioner, as they are often under-researched, side-effects are poorly understood, and some peptides are illegal to purchase in certain countries.