I agree that good food by that definition is likely to exist, but since I don't see a specific reason for it a priori, I don't see any reason that the difference in health should be particularly large. One thing that I would like to see is some scientific evidence rather than anecdotal that there is any significant correlation between certain diets and health outcomes. I believe they exist but I don't currently have strong evidence for that belief, other than "people talk about it like it's true."