It'd take a helluva lot of evidence to persuade me that eating grains is bad, because... heck, grains are tasty, and the vast majority of humans who have lived over the last five thousand years have had grain-based diets with no obvious ill effects.
Well, sugar, ice cream, cola - they are all tasty too.
Anyway, if you're interested in looking into ill effects of grain-based diets, there's a couple of links with some evidence.