Supplements are bad for you

Don't take your vitamins:

In the first study, Jaakko Mursu and colleagues have been following 38,772 older women since 1986. The women in the study, whose average age was 62 back in 1986, have reported their use of multivitamins and supplements for the past 25 years. The news was not good: the risk of death INCREASED with long term use of multivitamins, vitamin B6, folic acid, iron, magnesium, zinc, and copper. The risk of death only decreased with the use of calcium. They also noted that in other studies, calcium had the opposite effect.
…

In the second study, Eric Klein and colleagues studied 35,533 men over the past 10 years, looking at whether vitamin E or selenium would decrease the risk of prostate cancer. Both supplements have been claimed to have benefits, so the researchers randomly divided the subjects into four groups, giving them daily doses of (1) vitamin E only, (2) selenium only, (3) vitamin E and selenium, and (4) nothing (in the form of placebo pills).

The result: the risk of cancer INCREASED for the men taking vitamin E, selenium, or both. Although the increased risk is small, it is abundantly clear that neither of these supplements is helpful against prostate cancer.
…

Well, there might be the off-chance that in some medical condition vitamins might be helpful – but one needs evidence for that from a proper double-blinded placebo-controlled study.