make us healthier, or are we putting too much faith in a little pill? those are the questions being raised in a new book "vitamania: our obsessive quest for nutritional perfection." a poll found 50% of americans regularly take a multivitamin, and it's big business $32 brake light in 2012. joining me now, the author katherine price. a welcome to you. i just want to clear up semantics here. what's the difference between a vitamin and a dietary supplement? >> i'm very happy you asked that question. that's commonly confused. so there's actually only 13 human vitamins. those are the ones that usually go by letters, the a, c, d, e, k, and then eight b viet minutetaminsvitamins. but only 13 of those. there's a much larger category of products called dietary supplements, about 85,000 products is the last estimate i've seen. they're regulated the same way, but they're not the same. >> can you tell me how we went from 13 vitamins to 85,000 dietary supplements? >> yeah i think we really latched...