One way that vitamin supplements can be bad for you is when you take more tablets than are suggested for use. A healthy diet ought to provide for the vitamins your body needs without resorting to vitamins, but many people think that the vitamins will make up for a poor diet, or take the place of some vitamins in foods that you don't eat. Some people think that if one pill is good, a second would be better, so they take more than they should. With some vitamins this can actually make you ill because you are effectively getting an overdose. I believe it is best to rely on a good diet of foods.
As of 2014, what we know for certain is that most vitamin supplements don't do much of anything for you. And now, there's news that some vitamin supplements might actually contribute to higher rates of cancer and Parkinson's disease. While there's still research to be done, I think I'll err on the side of caution and continue to get my vitamins from fruits, vegetables, and other natural sources.
I do not believe vitamin supplements are bad for you. Vitamin supplements can be good for a person, especially if they do not get the proper nutrients in daily life. With that said, taking several vitamins, doubling up, or somehow not following the directions for these medicines can be dangerous.
Vitamin supplements are not bad for you. Many doctors and pediatricians recommend vitamin supplements when people are either unable or unwilling to get the vitamins and minerals that they need from their food consumption. Like anything else though, moderation is the key. People need to be informed on how much of each vitamin and mineral they need and how much is harmful.