An orally administered adsorbent which, when orally administered to livestocks and men, is capable of effectively adsorbing and removing nitrogen-containing compounds such as creatinine and the like. The orally administered adsorbent comprises clay particles of a layered structure having a cation-exchange capacity of not smaller than 50 milliequivalent/100 g, wherein a suspension formed by dispersing the clay particles in the deionized water at a concentration of 5 (w/v)% has a pH (25° C.) of not larger than 7.0, and has a proton emission capacity EH calculated according to the following formula, EH=(B-A)x10<；SUP>；4 <；/SUP>；wherein A is a hydrogen ion concentration (g ions/L) of the above suspension, and B is a hydrogen ion concentration (g ions/L) of a suspension formed by dispersing the clay particles in a 1 wt% saline solution at a concentration of 5 (w/v)%, of not smaller than 0.5.
