Most of you that actually compete know that you take various supplements, whereas creatine, protein powder, flax oil, and much more. Some products are commodities and some products people swear they work great.
As for the pros, yes, many do take supplements, protein powder, etc - whether or not it is from the brand they represent is a different story. But if someone represents a brand, they usually get some of the products for free (monthly allotment) so of course they tend to use them.
However, for what works with one person may not work with another.