Effect of Vitamin D on Myostatin and Muscle

Myogenesis is the formation of muscular tissue.

A myoblast is like a stem cell, but is already more specific than a stem cell, it can then differentiate (become more specialized) to give rise to muscle cells.

Muscle fibres form from the fusion of myoblasts into multi-nucleated fibres called myocytes (also known as a muscle cells or muscle fibres). After differentiation Myoblasts that do not form muscle fibres de-differentiate back into satellite cells. These satellite cells remain adjacent to a muscle fibre and are used for muscle growth and repair in the future.

So that being said, which I hope is easily understandable, it should be known that there is a negative regulator of muscle growth that inhibits myoblast differentiation into mature muscle fibres, it’s called ‘Myostatin’ and it is the only ‘negative’ regulator of muscle mass that the human body produces. Myostatin function is more prominent in fast twitch muscle and functions as an inhibitor of satellite cell proliferation as well. Now this is a bad thing for hard core trainers as fast twitch fibres contribute most to muscle strength and have greater potential for increase in mass, it is predominantly what we train to get bigger and stronger in the Gym.

But why do we produce Myostatin? Well your body has to balance its need for additional strength against other functions. Probably one of the biggest functions the body has to balance is its need for temperature regulation. Humans must maintain a stable body temperature of around 98.6 degrees Fahrenheit (37 degrees Celsius) in order to function optimally. We produce heat in proportion to our lean muscle mass, and we dissipate heat in proportion to our body surface area. If you create muscle growth you will produce an increase in muscle volume that is roughly 300% greater than the increase in body surface area that goes with it. When this happens your cooling efficiency drops substantially. So one of the main reasons for your body to limit muscle growth is to maintain a steady body temperature, and every time you try to put on size in the gym your body is fighting against you with Myostatin so that you don’t overheat.

It hardly seems fair, we fight so hard to put on muscle and the body fights against us it doesn’t seem to know about air-conditioning and driving with the windows down, it also doesn’t understand that we want bigger muscles to look good naked and we know how to stay cool in this modern era. Is there anything we can do about this?

Enter Vitamin D

It has been found that adequate vitamin D actually encourages Myoblast differentiation, not only that but it down regulates Myostatin production pretty cool eh? But wait there is more, it also increases Follistatin which is a Myostatin-binding protein that can inhibit Myostatin activity, and promote muscle growth. And as if all of that isn’t enough it was also found that Vitamin D significantly increased the diameter and size of muscle fibres, now we are talking business.

So if you’re serious about putting on muscle then perhaps you should be looking at your vitamin D intake a little more closely, it may be the most important and cheapest supplement you can take to boost your gains.

The study

1,25(OH)2Vitamin D3 Stimulates Myogenic Differentiation by Inhibiting Cell Proliferation and Modulating the Expression of Promyogenic Growth Factors and Myostatin in C2C12 Skeletal Muscle Cells

http://www.ncbi .nlm.nih.gov/pm … les/PMC3138228/

And here are the main take outs from it which I have made a bit more readable

We demonstrated that the Vitamin D effect on C2C12 skeletal muscle cell line involves 1) an up-regulation of IGF-II expression, 2) a down-regulation of IGF-I expression, 3) an up-regulation of Follistatin expression (a Myostatin inhibitor), and 4) specifically and most importantly a decrease in the expression of Myostatin, the only known negative regulator of muscle mass.

Moreover, addition of Vitamin D significantly increased the mean diameter and size of the muscle fibres

…..our study demonstrates, for the first time, that Vitamin D administration to C2C12 skeletal muscle cells reduced the expression of Myostatin, the only negative regulator of muscle mass known to date. Specifically, the decrease in Myostatin expression is more evident at d 7 than at d 4, which is in agreement with our previous findings, where we demonstrated that Myostatin expression is more pronounced at later stages in myoblast cell differentiation.

Follistatin is a Myostatin-binding protein that can inhibit Myostatin activity in vitro (in the test tube) and promote muscle growth in vivo (in the living). It has been demonstrated that Follistatin antagonizes (acts against) Myostatin by a direct protein interaction, preventing Myostatin from executing its inhibitory effect on muscle development. In the present study, we demonstrate, for the first time to our knowledge, a direct effect of Vitamin D on increasing Follistatin expression related to muscle differentiation. Our result reinforces the pro-myogenic effect of Vitamin D on skeletal muscle differentiation by decreasing Myostatin at the steady-state mRNA and protein level and possible by inhibiting Myostatin activity through an increase in Follistatin expression.
In summary, the data presented in this article demonstrate a direct effect of Vitamin D on myogenic cell differentiation by promoting a direct pro-myogenic effect by increasing IGF-II and Follistatin expression and by an indirect pro-myogenic effect, decreasing Myostatin expression.