There are other tbings besides vitamin c that one can take to boost immunity, such as zinc, vitamin A, and numerous herbs. I am not questioning that vitamin c is useful, although 8 grams a day isn't 4x as useful as 2 grams a day. Even at 4 grams a day, most is probably excreted and not utilized. Vitamin c has some anti inflamatory effects as well, although there are a number of herbs that are antiinflamatory. Years ago I did take around 10 grams of vitamin c a day, but discontinued that, as I felt it really wasn't much more beneficial than taking 2 or 3 grams a day.