Jack in the Box Inc., in an apparent concession to activist shareholders and consumer groups, has ruled out buying poultry treated with antibiotics to promote growth.

The pledge was included in a recently updated policy statement posted to the San Diego-based restaurant chain’s website. It added the company is working with its suppliers to eliminate other routine uses of antibiotics, such as for disease prevention, by 2020.

“We encourage continued research into the development of safe and ethical alternatives for the treatment of sick and injured animals,” the policy statement reads, “and we look forward to a time when antibiotics important to human medicine can be phased out of the food-supply chain.”

No mention was made regarding the use of antibiotics in its beef or pork products.

“That’s going to be a little more challenging,” company spokesman Brian Luscomb said in an interview. “That’s something we’ll be looking into.”

Jack in the Box Inc. operates the namesake fast-food chain and Qdoba Mexican Eats restaurants.

The use of antibiotics in U.S. food supplies has gained attention as concerns mount that routine use of such treatments may be a major contributor to antibiotic resistance, which the U.S. Center for Disease Control estimates causes 23,000 deaths annually nationwide.

A California law passed in 2015 restricts the use of antibiotics to treating sick animals or controlling a confirmed outbreak of disease. While it forbids their use for promoting growth or routine disease prevention, the measure has no jurisdiction over the treatment of animals raised in other states.

As recently as September, advocacy groups including Consumer Union and the National Resources Defense Council called out Jack in the Box and other restaurant companies for failing to reduce the use of antibiotics in their meat.

The Green Century Equity Fund announced Dec. 22 it has withdrawn its September shareholder proposal asking the company to adopt a companywide policy ending the non-therapeutic use of medically important antibiotics in Jack in the Box’s meat supply chain.

The fund said in a news release it views the policy as a commercial opportunity for the restaurant chain, asserting that some consumers will seek out foods raised without antibiotics.

The California Public Interest Research Group issued a statement applauding the restaurant company’s decision.

“Jack in the Box does California proud by committing to protect antibiotics,” CALPIRG’s public health program director, Steve Blackledge, said in a news release. “The bottom line is that we simply cannot afford to lose antibiotics as an effective tool in medicine.”