I would bet the 500mg 2x a day is what most of us started out on... I just was up-ed to 3x a day (1500mg total) after two months of taking it.
Good luck... if you have bad side effects (stomach upset, diarreha) try taking it without food even though it's recommended with food... everyone is different with the s/e!! I'm better off without food, most need to take it in the middle of a meal.
