the conventional wisdom of vitamins

I am skepticl about the 'conventional' wisdom of taking vitamins. you hear on all the newsshows---now listen carefully---'clearly', 'obviously', 'evidently', 'studie's show', 'apparently'---when a master chemist who is world-renowned says one vit. c pill could cure a shipload of Englishmen of Scurvy. I belive that much of it is marketing and it's hard to separate the wheat from the chaff. yes, we want to think that a one-a day or a more complicated regimin will keep us protected, but i doubt it. my grandparents lived to be in their 90's and never ate a salad in their lives. lot's of people didin't. not to say that extends your life, but it may not matter. Not to say you should eat ho'ho's and cupcakes everyday! we recoil from that but is it based on science, conventional wisdom (which is subject to change)? I doubt very much that bc is related to something we ate or didn't eat. It could be from what's IN what we ate, genes and environment, or a virus. Now, i am seeing alot of women driking soy powders (isolates---not what people in Asia eat), taking multi-vits, eating soy (no proof), i enjoyed a cup of gelato last week. No BVGH! HA! But milk----oh, you bad, bad girl!