It’s not that health authorities weren’t warned. “They are not acting on the basis of scientific evidence, but on the basis of a plausible but untested idea,” Dr. Edward H. Ahrens Jr., a top specialist at Rockefeller University and prominent critic of the growing doctrine on dietary fats and cholesterol, cautioned back in the ’80s. In the face of urgent pressure to offer a solution to the rising tide of heart disease, however, he turned out to be the Cassandra of his day.

Today, we are poised to make the same mistakes. The committee’s new report also advised eliminating “lean meat” from the list of recommended healthy foods, as well as cutting back on red and processed meats. Fewer protein choices will likely encourage Americans to eat even more carbs. It will also have policy implications: Meat could be limited in school lunches and other federal food programs.

It’s possible that a mostly meatless diet could be healthy for all Americans — but then again, it might not be. We simply do not know. There are no rigorous clinical trials on such a diet, and although epidemiological data exists for adult vegetarians, there is none for children.