Which Beans Are Healthiest?

The question I dislike most, after "Which is your favorite bean?", is "Which bean is healthiest?"

There's a side of me that couldn't care less. Beans have so much going for them and we know they're healthy, so let's relax. But the reality is a lot of people are very concerned about health and diet and for them I pass on this link, sent to me by my online friend Andie, to an article in Real Age. They claim darker beans are higher in nutrients but compared to what and by how much? And is this true of all varieties or just Phaseolus vulgaris? What about limas or tepary? It's not much to go on, but the recipe for Roasted Corn, Black Bean, and Mango Salad might be a winner.