This is almost like an urban myth in the world of energy supplements but the bottom line is there really is a lack of research to back up the audacious claim that capsules will absorb better than powders and liquids. However, the idea that is out in the world is that liquids and powders are superior as they are absorbed better because there is no barrier between your stomach and the supplement itself. Yet, most capsules will be designed to break down within the first five or 10 minutes upon entering the stomach.
Remember, your stomach is very acidic and the components that enter into it will be broken down rather quickly. Either way, this is far from the most important concern so do not worry about it too much.