That’s the latest theory. Here’s an explanation:
http://dsdaytoday.blogspot.com/2011/10/whole-grains-reduce-mineral-absorption.html
We’ve only been eating grains, whole or otherwise, for a very, very short portion of the evolutionary life of modern humans.
Sorry, misunderstood. Thought you were claiming processed foods were the traditional ones!
Grains and high concentrations of carbs were by definition only an occasional food before agriculture.