A U.S. Food and Drug Administration official who has led the agency's food policy efforts since 2018 announced his resignation on Wednesday.

Frank Yiannas was also among the top officials leading the agency response to last year's infant formula shortage.

"Today, I informed [FDA] Commissioner [Robert] Califf that I will be resigning my position as Deputy Commissioner for the Office of Food Policy and Response, effective February 24. I am honored to have served the American public, alongside each and every one of you, over these past four years," Yiannas tweeted.

In his resignation letter, Yiannas noted he inherited a "decentralized structure" at the foods program and said it "significantly impaired FDA's ability to operate as an integrated food team and protect the public."

Yiannas' role has included developing policies on food safety and responding to outbreaks, as well as involvement in investigations to trace food-borne illness, product recalls and supply chain innovation.

But the infant formula shortage posed the greatest challenge. In that saga, Abbott Labs stopped production at the largest infant formula factory in the United States following reports of illnesses and deaths in infants who were given formula manufactured there. The U.S. Department of Justice is now investigating Abbott.

Last summer, Califf ordered an independent investigation of the foods program on the heels of the infant formula shortage. An expert panel issued a scathing report on the program last month, finding a "culture, structure, and governance model that detracted from program effectiveness."

Still, Yiannas' efforts on key initiatives helped "create a safer and more digital, traceable food system for our country," the FDA said in a statement to NBC News.

"The FDA remains committed to providing an update on steps to strengthen the Human Foods Program at the end of January and additional updates on the organizational structure, including how responsibilities of Mr. Yiannas' position will be handled moving forward, by the end of February," the statement read.