For example, bad fats still play an important role in clogged arteries, but it's more nuanced then that. There are many kinds of fat, and there are other variables in causing fats to clog arteries, such as sugar.

Well, so yes, it does seem that avoiding refined sugar and trans fat and not overdosing on calories, and keeping highly active in terms of exercise, and not being in the same position for too long, and avoiding foods that inflame you (which seems to be very personal), and making sure you get a varied diet of nutrients, is all we know.

I just don't know if that should be framed as a failure. Could just be that it's a hard problem, could be that there are no real pattern to learn about as well. The latter is interesting, because we start our nutrition quest believing nutrition can affect health to a great deal, but that could just as well be false, nutrition could be a very small factor on health.

I think the problem is just the tendency we all have for snake oil, shortcuts and easy way outs. That is where I think this impression of "failing" comes from. That we didn't find something easy to do and that works very well. In that sense, science is characterized by lots of failures.