From canola oil to colorful dyes, the US food industry is girding for a shift away from the ingredients that made American diets among the cheapest in the world.

Robert F. Kennedy Jr. has often used his influential position to weigh in on public health issues, but during a congressional hearing he dodged questions about whether children should be vaccinated.

Kennedy, who heads the federal government's health department, said his opinions on vaccines were "irrelevant."