In all seriousness, the army's views on supplements differ. For example, in practice i know loads of people (officers and soldiers) that take all kinds of supplements, creatine promax etc.
However, i know certainly at RMAS that supplements of any kind are banned, this even extends to Red Bull and other energy drinks. Just be careful what you are taking and dont get caught out.
So gone are the days of a can of red bull and two asprin before the start of the endurance race?? Shame, Im off to phase 1 soonish and was hoping to instill the same values that were thrust upon me by the best soldier I have ever met.