Guys, all of this that you mention is very worrying. I have been flying short haul for little over a year and continue to get colds. I have been struck down as we speak with a huge head cold. I only had one 2 months ago. I too also eat very well, exercise religously and take multi vitamins. Does that mean my immune system is deteriorating?? I hope not. Does anyone know of anything they take that has given their immune system a bit of a boost. I really can't stand to get colds and flus every few months and can't imagine it is doing wonders for my overall physical health!