Nutrionism (meaning mainstream health science?)

Nutritionism is basically the idea that specific components of food potentially make them healthy or unhealthy.

So assuming for the sake of argument that saturated fat is unhealthy, nutritionism would hold that it's a good idea to substitute canola oil for corn oil.

I have seen such studies analyzed with alternative explanation convincingly by, for example, Uwe Ravnskov, Malcom Kendrick, Chris Masterjohn or Denise Minger, and wonder if there is more convincing evidence they atre excluding

That's an interesting question, but not one I've ever given much specific thought to.