I have always wondered why so many facets of "institutional health" are promoted as the status quo even with much contradictory evidence or lack of "common sense".
A couple of things that come to mind:
salt
saturated fats
sugars
I know many instances of this problem have to do with monetary interests. But salt? Who gains from low salt intake? Reputation? Or is it something else.
Taube's theory (about cholesterol, but I think it applies here as well) is that it's "where the light is". Things which are measurable are optimized for even if they're pragmatically pointless.
So a study comes along that finds a correlation between sodium intake and cardiovascular disease. Totally possible. The USDA looks at those numbers and says, we're eating Xmg of salt, we should be eating Ymg. They make a recommendation, years go by, and they look at the numbers again and, hey, salt consumption is down to Ymg! Success!
What about mortality? Who knows. That's not their department.
Not to sound like I'm putting on my tin-foil hat, but a lot of money floats around in this space. It's entirely possible for a segment of the food industry to be viewed the same as cigarette companies if extensive studies show that, for example, eating cereal is actually killing you. No company wants that death sentence, pun not intended :-P
A couple of things that come to mind: salt saturated fats sugars
I know many instances of this problem have to do with monetary interests. But salt? Who gains from low salt intake? Reputation? Or is it something else.