This is a prose nonfiction book about food and food aversions throughout history. Britney Spears loathes meatloaf and “all lumpy stuff.” Arturo Toscanini hated fish. Ayn Rand despised salads. Alexander Theroux’s Einstein’s Beets is a study of the world of food and food aversions. The novelist and poet probes the secret and mysterious attitudes of hundreds of people―mostly …