Vitamin E
Vitamin E as a dietary supplement is proved by science (through randomized trials, not observational) to INCREASE the risk of dying. So it does the opposite of it aims to do on the label. In other words, those who take Vitamin E, die 4% more based on the scientific randomized study below.
Thus Vitamin E supplement use is actively discouraged by scientists behind these studies.
Here's a more detailed video on that study discussion from the University of California San Francisco Department of Medicine: