I would say, yes, D is high on my contender list. But as I tell folks too... and I know this is preaching to the choir... there are a slew of other potential things and not to fixate on D as *the* solution. It may not be a factor for you, but personally, knowing what I have seen what happens when we have become deficient, and stay deficient, the consequences can go from crummy lethargy to disaster.
Let us know how your topical use goes tho. I am sitting here at the moment, 'painted' maself...