> Nutrition is pretty terrible. It seems to me that laymen have zero chance of getting useful advice out of the research, other than "Eat a varied diet, move regularly".

I completely agree, and it also appears to change every other decade.

Suddenly, drinking coffee became healthy, eggs stopped being unhealthy and drinking a glass of wine a day became a major risk for CVD.

Engineers are spoiled when it comes disentangeling relationships between causes and effects because our systems are relatively simple compared to the huge and complicated mess that is human (or, indeed, any) biology.