White Paper: The Effect of Fortetropin™ on Muscle

Clinical effects on lean body mass, fat mass and muscle size; Implications for use and proposed mechanism of action.

 View the whitepaper with the study results


Muscle tissue is increasingly recognized as a key marker for overall health and wellness. The preservation of muscle mass and muscle quality is considered central to the management of the symptoms of aging and many chronic illnesses. Composing 50% of tissue in the human body, skeletal muscle is essential for high performance mobility and contributes to many metabolic processes in the human body, including thermoregulation, glucose homeostasis and insulin resistance. Research is beginning to recognize the link between increased longevity and increased lean body mass rather than body mass index alone. Lean muscle mass is essential for individuals at all stages of life and has the potential to improve not only longevity, but also the quality of one’s lives.


The importance of muscle has lead many researchers to examine the mechanisms and pathways for muscle health and regeneration. One key regulator is a protein called myostatin. Myostatin, a member of the transforming growth factor- beta (TGF-β) superfamily is an inhibitor of cell cycle progression, and thus impairs satellite cell activation. In 1997, an article in the journal Nature first described the discovery of a novel member of the transforming growth factor-β (TGF-β) superfamily of growth and differentiation factors. This factor was expressed specifically in adult skeletal muscle and referred to as growth differentiation factor- 8 (GDF-8). Since the initial discovery of myostatin, several naturally occurring “double-muscling” phenotypes have been reported in different cattle breeds, dogs, and even humans.

Skeletal muscle is the primary producer of myostatin, where it is secreted into the blood stream and acts as a negative regulator of muscle differentiation and growth. The protein begins as a 375 amino acid dimer that is cleaved by proteases to a 109 amino acid active domain. The active form of the protein binds to activin type II receptors, ActRIIA and ActRIIB. Binding to the receptors initiates a signaling cascade that results in an increase in protein breakdown and subsequent inhibition of protein synthesis.

Myostatin exerts an effect on both muscle hypertrophy and hyperplasia, increasing both the number of muscle fibers and in fiber sizes. Hypertrophy refers to the enlargement of a tissue or organ due to the enlargement of its component cells. In contrast, hyperplasia refers to an increase in the number of cells or a proliferation of cells.


While the inhibition of myostatin has recently become a target for drug development, a naturally occurring myostatin inhibitor, Fortetropin, has been identified and developed as a safe and effective bionutritional product. Fortetropin is a bioactive proteo-lipid complex composed of > 250 proteins, > 50 lipids, a variety of peptides and other bioactive molecules created using a proprietary process that retains the biological activity of the mixture.


In a double blind, randomized placebo controlled, parallel, single-dose study, the effects of Fortetropin on serum myostatin levels were measured. There were 12 healthy adult males in each arm. A dose of 6.6 grams was given in the active arm. Blood measurements were at 6, 12, 18 and 24 hours. No study related adverse events were reported during the study. Results demonstrated greater than 30% decrease in serum myostatin levels compared to baseline during the 24 hours period.

At the University of Tampa, a double-blind, placebo controlled trial examined the effects of Fortetropin on skeletal muscle growth, lean body mass, strength, and power in recreationally trained individuals who rely heavily on satellite cell activation. Forty-five subjects were then divided into placebo, 6.6g and 19.8g dosing arms of Fortetropin daily for a period of 12 weeks. All exercise sessions were conducted and monitored by trained personnel. Standardized diets consisted of roughly 54% CHO, 22% Fat, 24% PRO. There were no differences in total calories and macronutrients between groups. Dual Emissions X-ray Absorptiometry was utilized to measure lean body mass and fat mass. Direct ultrasound measurements determined muscle thickness of the quadriceps.

Results demonstrated a statistically significant increase in both muscle thickness and lean body mass in subjects taking Fortetropin compared to placebo. Strength and power endpoints, as measured bench press, leg press and Wingate power, significantly increased from baseline in all study groups. One unexpected finding was a statistically significant decrease in fat mass in subjects in the 19.8 g arm. This finding, which has potentially broad implications for metabolism and weight management, bears further investigation and studies are currently being planned. No study related adverse events were reported during the study.


Increases in muscle mass and quality and the concomitant increases in strength and power which accompany those gains can provide very meaningful therapeutic results for the management of age-related sarcopenia as well as cachexia and other myopathic conditions. Fortetropin represents the only proven natural myostatin inhibitor clinically available to increase muscle mass and lean body mass. Further studies are planned to examine its role in the treatment of many disease states in various dosing regimens and delivery mechanisms. Improving lean body mass should be a therapeutic objective in the management of aging and chronic illness and all individuals seeking optimal wellness.