​Doomsday survivalists have over the years have earned a reputation for stockpiling medical supplies, guns and ammo—essentially gathering whatever resources and expertise necessary for self-sufficiency in the event of the apocalypse. That ethos has now drawn a group of survivalists that call themselves preppers to an unlikely superfood that's just beginning to take hold in North America: moringa. Moringa Oleifera is an unassuming shrub that grows in hot, dry tropical climates around the globe, and is prized for its high level of nutrients—especially protein. "The biggest reason is because it is a great food source," David Wentworth, who publishes expertprepper.com,...