I often read on here about people who never get sick with anything, cold, flu etc. because of the way their immune system is functioning. I have the opposite problem, I seem to be unable to fight off anything that comes my way, and I get sick longer and more severely than others who catch the same thing. Are there any supplements or other things to do to help this problem? I have had problems with food poisoning, colds, flus, stomach flus, etc.