Yep, I take extra vitamins and magnesium for it and it helps a lot. I guess it has to do with the swelling CF can cause and the different salts that it messes with. I had this and really bad muscle cramps, but the magnesium really helped me. They offer me anti-inflammatories, but I don't want to add more drugs until I really need too.
I also make an herbal tea that seems to help: (in parts by weight 1/10ths of an oz will make a good trial batch) 3 spearmint, 1 rosehips, 1 sage, 2 ginko (stemmed), 1 rosemary, 1 clove, 1 red clover, 1 chamomile. Then I break them up separately with a mortar and pestal so that they are in well broken up, but not a fine powder and the mix them all in a container. I add about 2 teaspoons per liter of hot water. A pinch of stevia (or 1 part premixed) for sweetening since I am diabetic and let it steep for about 30 minutes. There are also good pre-made products or recipes available online. There is probably a psychological component to it, but tea helps me so there ya go.