I have never heard of a person whose asthma improved significantly through dietary change. If such a person exists I would love to hear about her/him. I know that I have been eating paleo, but I still can't take a walk in cold air without wheezzing and becoming short of breath.
Jean,
Have a look at Dr. John Briffa's article re nutritional ways to help with asthma... on the whole, he is very close to and supportive of paleo eating principles.
http://observer.guardian.co.uk/foodmonthly/story/0,9950,1166266,00.html
Dedy