I take about 10 grams of Vitamin C per day (spread out through the day not all at once) plus 2 B complex vitamins, among others. I take a large handful of vits about twice a day lol
I also workout at least 4-5 times per week. Getting your heart rate up forces immune cells to travel around the body much faster than usual.
If I do get sick, I double my Vit C intake, and I'm usually over it in about 48 hours. But I HATE getting sick. My hubby has gotte sick about 6 times in the past three months (yes, he's decided to start taking vit c lol). I haven't been sick in 2 years, and I don't catch hubby's colds or anything else he brings home from work!