[robg]

Unfortunately, human research isn't as simple - you actually have to worry about the health consequences as well as the benefits. But correlations can be very meaningful. For instance, cross-cultural studies w/r to diets can be illuminating even as there are no experiments being run. Still, I'd place my bets, and my life, on fresh foods - high in anti-oxidants - over processed ones. The beauty is it ain't rocket science. And better, good diets can control and even inhibit pathologies (diabetes, heart disease, etc.).

[streety]

I don't think the problem is one of complexity as such but more of being more complex than people imagine. Very few people have any knowledge of high energy physics, so only those who actually know what they're talking about offer an opinion, but everyone knows about food and diets, so everyone has an opinion.