“Eggs are bad; eggs are good. Fat is bad; fat is good. Meat is bad; meat is … OK? That last food flip-flop made big headlines last week. … How, it was asked, could seemingly bedrock nutrition advice turn on a dime? The answer is that many of the nation’s official nutrition recommendations — including the idea that red meat is a killer — have been based on a type of weak science that experts have unfortunately become accustomed to relying upon. Now that iffy science is being questioned. At stake are deeply entrenched ideas about healthy eating and trustworthy nutrition guidelines.”