I can't believe I just stumbled in here after all this time.
I can't say if vitamins are helpful or not, but I have a real problem getting sick. I don't get sick often, but when I do (Ahem, sounding like the Dos Equis guy here) I usually can't kick the phlegm for at least a few weeks after the rest of the symptoms get better. Often times have to go on Mucinex-D for a couple weeks...once I even lost my voice from it. The phelgm, in turn (for some reason I can't explain) usually causes me to have a bout of acid reflux flareup that can last months. Yes, I have been to the doctor, multiple times, and yes, I do have a prescription for acid reflux pills. As anyone with acid reflux knows, it can disappear for months at a time only to have a flareup that can last...months at a time.
I got sick at the beginning of June with a cold that lasted all of three days. Then had two weeks of phlegm, now I'm still in acid reflux flareup. I only ever get the acid reflux after a cold like this.
Point is, I usually take the Vitamin C "you can't catch a cold" pills religiously during the winter, and whenever my wife gets sick. Just so happens I didn't catch this one in time. But I used to get sick a lot, and suffer a lot, until I started it. Maybe it's a mental placebo, who the heck knows. But I swear by those vitamin tablets. No one can tell me they don't work for me at least.
I read somewhere a while back that your body can only absorb so much in the way of chemicals from one of those tablets. I don't know any exact figures, and I don't remember the source (so take it with a grain of salt), but it was something like, you can only absorb 500 mg of Magnesium from a tablet during a day. So, yeah, you can take a 1000 mg tablet, and think it's better, but it's doing nothing more for you...