GM: Let’s talk about the optimal diet. There’s a theory out there that we’re all different and we should choose our diet according to our blood type or our genetic makeup or our personality type or our astrological sign, and that the optimal diet is one thing for one person and a vastly different thing for another person. Is there any truth to the idea that different people need wildly different diets, or are we mostly alike in what we ought to be eating?

PP: We’re shockingly alike. The only thing that differentiates us significantly is food allergies. My attorney, who died a couple years ago at sixty-one, was in his fifties when I met him. He had been allergic to cherries, peaches, and apricots ...

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