A review of 67 studies involving 230000+ people found that the vitamin supplements mayn't cut risk of dying. Even more, some supplements may increase mortality.
The study examines effect of Vitamin A, Vitamin C, Vitamin E and selenium intake with varying doses.

The study found that Vitamin A, Vitamin E and beta-carotene increases death risk. Vitamin C and selenium seem to not affect death risk.
Also Vitamin C is reported to not increase longevity.

NEW YORK (Reuters Health) - A person's level of vitamin C may predict his or her likelihood of having a stroke, according to a long-term study of some 20,000 middle-aged and older residents of Norfolk, United Kingdom

(http://www.reuters.com/article/healthNews/idUSCOL27365920080122)