NEW YORK — PepsiCo says it’s dropping aspartame from Diet Pepsi in response to customer feedback and replacing it with sucralose, another artificial sweetener commonly known as Splenda.

The decision comes as Americans keep turning away from popular diet sodas. Competitor Coca-Cola said that sales volume for Diet Coke, which also uses aspartame, fell 5 percent in North America in the first three months of 2015.

Executives at Coke and Pepsi blame the declines on perceptions that aspartame isn’t safe. That’s even though the Food and Drug Administration says aspartame, best known by the brand names Equal and NutraSweet, is “one of the most exhaustively studied substances in the human food supply.”

Reformulated Diet Pepsi will start hitting shelves in August. The change only applies to the U.S. market and will affect all varieties of Diet Pepsi, such as Caffeine Free Diet Pepsi. It will not apply to other PepsiCo drinks, such as Diet Mountain Dew.