Does beef get a bad rap? Red meat has been associated with heart disease, among other health problems, and critics point to the environmental toll taken by industrial beef production. Nicolette Hahn Niman, a longtime vegetarian, wouldn’t disagree. But in her new book “Defending Beef: The Case for Sustainable Meat Production,” the environmental lawyer and Bolinas-based cattle rancher lays out the case for grass-fed beef, which she says is actually nutritious and sustainable.