The United States has turned its food pyramid upside down — sending a signal far beyond supermarket shelves. That's because the new composition of the country's guidelines form the basis for government nutrition programs, from school cafeterias to the military to hospital food services. US Health Secretary Robert F. Kennedy Jr. presented the new guidelines in January. They are visualized as an upside-down pyramid, with steak, chicken, cheese and dairy now occupying the broad base once held by