- MD is a renewable resource, generated by the Force-user's body
- MD is contained in, though perhaps not entirely limited to, the blood stream
- It would theoretically be possible to boost Force-use by "enricing" the blood of a Jedi by exracting several pints of his blood and re-injecting it when a boost is needed
- A great loss of blood should lead to a reduction in Force-abilities
That being said, although Anakin (and therefore Vadar) had a very high MD count, Vadar's injuries and cybernetic transplants should render him less powerful a Force-user.
Like I said, random Star Wars thoughts.