PepsiCo’s deal to buy Poppi will help it address rapid growth in the health and wellness soda market, including a new brand from rival Coca-Cola, as the legacy soda rivals engage in a new battlefront—the gut health wars.

Pepsi enters the "healthy" soda wars and buys prebitotic soda brand Poppi for nearly $2 billion, and fans of the beverage are concerned the formula will change.

PepsiCo said Monday that it is buying prebiotic soda brand Poppi for nearly $2 billion. While soda consumption has broadly fallen over the last two decades in the U.S., prebiotic sodas, fueled by industry newcomers Poppi and Olipop,