The blogosphere has been swept by an epidemic of debate regarding the new Smart Choices program laid out by the country's major food corporations. Critics point out that Froot Loops, over 40% sugar by weight, gets the green check mark of approval. Proponents claim that it will help consumers navigate the plethora of choices in the grocery store aisles. Since I'm an applied physicist and microbial enthusiast, rather than a nutritionist, I'll offer my unique perspective on the issue:
Growing biofilms in a petri dish isn't easy. The label above is adapted from the mix of nutrients that I use to feed the Bacillus subtilis that I study. It's a pretty odd assortment: the controversial flavor-enhancer MSG, the supposedly sleep-inducing protein tryptophan, the diet drug component phenylanaline, the B-vitamin thiamine, and various metal ions.
Not growing biofilms outside of a petri dish is also difficult. If we aren't careful to keep things sterile in lab, an invasion can sweep through the incubator. Pretty much every surface around you (e.g. your teeth, contact lenses, intestinal linings...) can be a home for a symbiotic coalition of bacteria.
If it's this hard to know exactly what makes a single, well-studied species of bacteria survive (one of the vanishingly small minority that we can actually culture in a lab), I think that we still have quite a ways to go to catalog all the substances in the plant and animal kingdoms that keep us healthy. On the other hand, human beings seem to be pretty adaptable, capable of surviving on diets ranging from raw vegan to arctic carnivore. Evolution may need a little help, though, when it comes to new creations like KFC's Double Down "sandwich" or deep-fried butter.