Is fiber a vitamin or mineral?

Neither. Fiber is a carbohydrate that humans can't absorb & thus is typically found in fruits, veggies & grains. Check out http://www.Mayoclinic.Com/health/high-fiber-foods/nu00582 for some ideas. It's either soluble or insoluble. It helps us maintain regular bowel function w/o straining excessively. It also slows down sugar absorption. Gradually work your way up to 25g (women) to 38g (men) each day.