General Mills announced Thursday that it will stop using genetically modified ingredients to make its original Cheerios cereal, the USA Today reported.

Pressure from consumer and activist groups prompted the Minneapolis-based company to manufacture original-flavor Cheerios without genetically modified organisms for the past several weeks. The boxes are expected to appear on shelves soon, General Mills did not specify when, the Associated Press reported.

"We were able to do this with original Cheerios because the main ingredients are oats," Mike Siemienas, a company spokesman, told the Associated Press.

He noted that the oats used to make Cheerios have never contained GMOs. The changes primarily affect the company's sourcing; for example, instead of corn starch from genetically modified corn, the company will now uses non-GM pure can sugar.

"The formula for our Cheerios hasn't changed," Siemienas added. "We believe that consumers will embrace this."

Other Cheerio flavors, such as Apple Cinnamon Cheerios or Multi Grain Cheerios, will not be affected by the change. Siemienas said other varieties of Cheerios are made with ingredients such as corn, making it harder for the company to make them free of GMOs, the AP reported.

"For our other (non-organic) cereals, the widespread use of GM seed in crops such as corn, soy, or beet sugar would make reliably moving to non-GM ingredients difficult, if not impossible," said the company, in a statement. However, most Cheerios varieties sold in Europe are made without GMOs, the USA Today reported.

Todd Larsen, corporate responsibility director at Green America, a green economy activist group, said the change is a big deal for General Mills.

"Cheerios is an iconic brand and one of the leading breakfast cereals in the U.S.," Larsen told the USA Today. "We don't know of any other example of such a major brand of packaged food, eaten by so many Americans, going from being GMO to non-GMO."

One year ago, Larsen's group used social media efforts to rally consumers to pressure the food company to make Cheerios without GMOs. Cheerios was picked, in part, because it's one of the first foods given to many toddlers.