Robert F. Kennedy Jr. delivered a stark ultimatum to major food company CEOs in a closed-door meeting this week: Ban certain artificial dyes from your products or the government will do it for you.

Mr. Kennedy told executives of major food companies that he wants synthetic colors removed from their products. “Decision time is imminent,” a trade group warned its members.

Health and Human Services Secretary Robert F. Kennedy Jr. directed large food corporations to remove artificial dyes from their foods or have the government step in to do it for them. Kennedy on Monday asked leaders of PepsiCo,