Personally, I do not take vitamins, or really, pills of any kind. I prefer to be nourished from natural sources rather than a factory. So, I do my best to eat a diversity of fresh vegetables, fruits, and grains.

If you need vitamin A and D, they are plentiful in easy to find foods, and even sunlight.

There may be cases where vitamins are necessary. But I believe in most cases they are not. In fact, even the scientific community has been questioning their value. See: http://www.theguardian.com/lifeandstyle/2013/dec/17/vitamin-supplements-waste-money-scientists