I love vitamins, in large part because for awhile I was taking a prescription medication that can hinder vitamin B absorption if you take it too long, and nobody told me this, so I wondered why I suddenly had Alzheimer's-like symptoms (inability to form memories, inability to track conversations, inability to retain thoughts longer than minute or two...) until I found that bit of news out online.
I started taking a multi B vitamin and aggressively eating foods with B vitamins in them (which, it turns out, I'd been craving) and all the issues cleared up.
It's not always possible to get all one's nutritional needs through food alone and I am quick to turn to reputable vitamin companies to fill those gaps as needed.
Most Americans are vitamin D deficient despite it being added to just about every prepared food in existence in response to wide spread rickets in the '50s. Most people who are poor are missing pretty essential elements, including magnesium which is a big contributor to developing diabetes.
I am very pro vitamins. Not pro crazy ass supplements like OMG ACAI BERRIES MAGICAL HEAL ALL MAGIC and other flash in the pan, trendy supplements. And when I do take supplements, I try to research to see if they interact with other stuff (for instance, St John's Wart? Makes one very susceptible to sunlight. Or the developing light of a blueprint copier. I got a sunburn from copying blueprints all day one day. NICE.) or have been proven to be no more effective than a placebo (hello, Valerian root.). Of course, I have internet access and can fairly easily weed out the woomeister sites and get an idea of the truth.
Don't, uh, don't go to Whole Foods or other "natural" stores and ask an employee about supplements because a LOT of crap is sold at those stores that is basically homeopathic or otherwise placebo heavy. Or just plain worthless.