[greggyb]

My favorite guidance is Pollan's, "Eat food. Not too much. Mostly plants."[0]

Another piece of guidance I like is this (paraphrased): Eat absolutely anything you want. But make it all yourself. If you want cookies and cake and ice cream, great! Buy flour and sugar and butter and chocolate and milk and cream, and make them yourself.[1]

Now, these don't directly address your point about conflicting research. They give reasonable heuristics that work well, though. Now, clearly you can come up with pathological examples that follow the advice above - any of us could come up with dozens that are reasonable. But being precise and 100% correct is not the point of a heuristic.

[0] https://michaelpollan.com/reviews/how-to-eat/

[1] Paraphrased from an interview in Cooked. The 4-part series was produced for Netflix.

[teslabox]

With regard to salt, I like the advice “salt to taste”: add salt to your food until it taste good. Salt has many roles in the body; it was simplistic and wrong to blame a oerson’s high blood pressure on salt consumption.