Wearing blue scrubs and a 1,000-watt smile, Nikesha McPherson arrives for her annual visit to the home of an octogenarian couple in Plainfield, New Jersey. This time she’s going to pitch Margarita and Alfonso Varon on the benefits of brown rice. The nurse practitioner barely gets a sentence into her spiel before Margarita, 83, interrupts her with a long roll of laughter that bounces off the beige walls covered in family photos.