What amazes me is they talk as if it only happens in nutrition science, but it happens in just about every single area of scientific endeavour. Look at the pushback against h. pylori and ulcers. Also read the book by the guy who discovered the Lucy hominid and the way his reputation was trashed. Science is full of people addicted to their own theories who refuse to accept it when the science moves on. I think the quote (I forget who coined it) about science advancing one death at a time just about sums it up.
Unfortunately the scientific method gets abused more often than we probably know. A lot of it is about research dollars, publication count and academic tenure. Scientists are just as corruptible as every other field of human endeavour, so it amazes me why we're meant to put them on pedestals. Legends in their own lunchtimes, it seems.