Although the mechanism has not been fully elucidated, it has been speculated that some ingredients in Coca-Cola® play a key role in bezoar dissolution. Such hypotheses include enhanced bezoar digestion by the mucolytic effect of sodium bicarbonate and/or by the acidifying effect of carbonic acid and phosphoric acid. Destruction of the bezoar may also be assisted by the carbon dioxide bubbles, which penetrate into the bezoar through the microscopic pores on its surface. Diet Coke®, Coca-Cola Light®, and Coca-Cola Zero® all contain these ingredients. Since the clinical success of bezoar dissolution by Diet Coke®, Coca-Cola Light®, and Coca-Cola Zero® was documented in previous reports, several authors have speculated that these sugar-free beverages have the same effect of bezoar dissolution as the regular version of Coca-Cola®.