Updated

Coca-Cola is dropping a controversial ingredient from its Powerade sports drink, after a similar move by PepsiCo's Gatorade last year.

The ingredient, brominated vegetable oil, had been the target of a petition by a Mississippi teenager, who questioned why it was being used in a drink marketed toward health-conscious athletes. The petition on Change.org noted that the ingredient is linked to a flame retardant and is not approved for use in Japan or the European Union.

In response to customer feedback, PepsiCo said last year it would drop the ingredient from Gatorade. At the time, Coca-Cola declined to say whether it would remove the ingredient from the two flavors of Powerade that contain it as well.

But this week, bottles of Powerade in fruit punch and strawberry lemonade flavors being sold in the Detroit, Michigan; Omaha, Nebraska, New York and Washington, D.C. areas no longer list the ingredient. Some bottles still list it, however, suggesting Coca-Cola Co. may have started phasing it out recently.

A representative for the Atlanta-based company confirmed Sunday that its Powerade brands are "BVO-free." But no details were immediately available on when the change would be complete or how the drinks were reformulated.

Powerade's website still lists brominated vegetable oil as an ingredient for its fruit punch and strawberry lemonade flavors.

The Food and Drug Administration says brominated vegetable oil is used as a stabilizer for flavoring oils in fruit-flavored drinks. Coca-Cola has said in the past that it uses it to "improve stability and prevent certain ingredients from separating."

The decision by Coca-Cola to remove brominated vegetable oil from Powerade is just the latest evidence that food makers are coming under pressure for the ingredients they use. While companies stand by the safety of their products, some are making changes in response to the movement toward foods that people believe are natural.

Earlier this year, for instance, Subway said it would remove an ingredient dubbed the "yoga mat chemical" from its breads. The ingredient, azodicarbonamide, is approved for use by the FDA and can be found in a wide variety of breads. The petitioner, Vani Hari of FoodBabe.com, said she targeted Subway because of its image for serving healthy food.

Likewise, brominated vegetable oil can also be found in several other drinks.

But the Mississippi teenager, Sarah Kavanagh, said she targeted Gatorade and Powerade in petitions because they're designed for athletes, who are likely more concerned about what they're putting into their bodies. Her Powerade petition had more than 59,000 online supporters while the Gatorade one had more than 200,000.

"Consumers are coming together quickly and efficiently to influence the world's biggest beverage companies in an unprecedented manner," said Pulin Modi, senior campaign manager for Change.org.

As Americans cut back on soda, sports drinks have become more important for Coca-Cola and PepsiCo Inc., which is based in Purchase, New York.

Although Coca-Cola has long dominated rival PepsiCo on the soda front, it lags the company in the growing sports drink category. According to the industry tracker Beverage Digest, Gatorade has 64 percent of the sports drink market.