citric acid is one of the products produced in long chain of events that eventually converts glucose into ATP. citric acid produces products that generate a majority of the ATP. well, as with most chemical reactions, an equilibrium is present, and if you apply a stress to one side of the equation, the equilibrium shifts.
so if you load up with citric acid, perhaps the stress on the system causes process with run in reverse (as in may equilibrium equations) generating AcetylCoA, which results in a buildup of acetylCoA, resulting in a buildup of pyruvate, ...., blah, blah, blah, resulting a buildup of F6P, G6P, and eventually glucose.
but... i would suspect the influx would have to be very great to have such an effect (that is, a LOT of citric acid).
some people have reported (via ketostix) that diet pepper kicked them out of ketosis... no one at this time had determined whether it was due to the citric acid or the aspartame... everyone has a different view on this. Best bet is to drink one then ketostick it to see how your keto levels adjust to it. GL