I've been asthmatic since being pregnant at age 26. On medications including steroids and inhalers. Just to make a long story shorter, I began with Vitamin C with bioflavanoids and rosehips (ascorbic acid alone did not seem to help). Vit C 1000 worked many times if I caught an attack early enough, but, omega 3s helped even better so I added them. Another real difference I found was when I went organic. A lot of things improved for one, but, it seems also my asthma as well.
Haven't had a problem in years, eating all kinds of foods, but, organic, in particular organic dairy and grass fed meats. I do now have raw organic Apple Cider Vinegar most everyday as well. Just to add, since going organic, my son's allergies that he had for years since he was a teenager, now in his 30's, have subsided as well. I use all natural household cleaning products as well such as baking soda and vinegar. Kind of "detoxing" as much as I can. Hope that helps anyone.