Vitamins: To take or not to take?

Recently I've shared several conversations with friends about vitamin supplements. One friend wanted to start taking supplements, but was not sure how to avoid synthetic multivitamins and thought that GNC might be her best bet. Another friend shared that she encourages her clients to take multivitamins, but for those who don't she struggles to develop a nutritional plan for them to include as much vitamins and minerals as possible, all the while knowing that they will never get enough from their daily meals. Most of us don't, hence the availability of a variety of vitamins on the market.

For those who take vitamins, how do you know which ones are the best for you? I was recently introduced to a book called the Comparative Guide to Nutritional Supplements and it really opened my eyes to thousands of brands that are out there. I encourage you to check it out and see if you vitamin holds up to the ratings.

For those who don't take vitamins, why? I hear so many things from it not being convenient, not needing them, or not knowing what to take. Are those the primary reasons or are there more?