[loceng]

Similar attitudes exist, or perhaps we could call them myths, exist for meat - that you don't get all of the nutrients you need if you only eat meat.

In part I'm sure it's perpetuated, for every diet, by whatever industry or industrial complex wants to create "news" and attention for themselves - which can include creating misinformation against the opposite.

Superfoods that are fads is an easy example, also, you don't ever hear about the healthiest fat weight loss diet - which is water fasting - because a company generally can't make money off of telling you to not eat.

I agree with you that through evolution there would have been different sources of food for different groups, with more or less meat/animal sources available, and so there will be different lineages of evolution that thrive with certain foods and where those same foods may be harmful to others.

There hasn't been adequate research done for diet, to factor in all variables that are important - including starting state of health of someone's GI tract. To do a proper, holistic and fully inclusive research, will be a big and expensive undertaking. And observational studies isn't adequate research IMHO, as they miss important nuances and help perpetuate whatever ideology someone is pushing/cheering for.