Maybe "betrayed" was a strong term. I understand that in some ways it was worse before and also elsewhere but when taken as a whole, the American medical system and its hubris definitely did the people a disservice.
Does anyone think that the food companies actually believed that sugar and starch mixed with water was better than mothers milk? No, they knew it was a lie from the outset. Just the same way that the tobacco companies knew that smoking causes cancer yet they fought to keep that info under wraps.
The docs happily accepted monies from those companies to play along.