Myostatin, a myokine and potent antagonist of growth in skeletal muscle, increases with aging and muscle wasting diseases.[135] In contrast, follistatin counteracts the growth-limiting effects of myostatin.[135][136] Thus, the follistatin to myostatin ratio is an important determinant of the anabolic state of muscle tissue, with greater ratios favoring muscle growth.
A pilot study using six middle-aged subjects (41+/-5 years) of average weight given 1mg/kg (-)-epicatechin twice a day for seven days noted that follistatin to myostatin ratio increased by 49.2+/-16.6%.[137] Importantly, the increase in follistatin to myostatin ratio also correlated with a bilateral increase in hand strength of around 7%.[137] Moreover, when (-)-epicatechin is fed orally to mice at 2mg/kg daily (in two divided doses of 1mg/kg) for two weeks, the 18% increase in myostatin and 30% decrease in follistatin which normally occur with aging were prevented. Young mice given the same dose of (-)-epicatechin showed a 15% reduction of myostatin with no influence on follistatin.[137]
The (-)-epicatechin found in dark chocolate has been shown to promote muscle anabolism in both aging mice and middle-aged humans by increasing follistatin to myostatin ratio in skeletal muscle. This suggests that cocoa extract supplementation may be helpful for conditions associated with muscle loss, such as during aging (sarcopenia) and muscle wasting diseases.
Gutierrez-Salmean G1, et al Effects of (-)-epicatechin on molecular modulators of skeletal muscle growth and differentiation . J Nutr Biochem. (2014)