Given the exhaustion of US farm soils, trace minerals and mineral-dependent enzymes are all but absent from our food supply; vitamin levels are low due to the fact that produce is picked long before it ripens, to accommodate the time required for the delivery chain, so enzymatic action has little chance - the produce may be be large, firm & brightly-colored, but largely tasteless and not exactly nutrient-dense; much of what nutrition remains (beyond the macros) is damaged (if not eliminated) during canning, freeze-drying, transportation and storage.
Witness the herds of over-fed and under-nourished upright bovines we have staggering around.
As for vitamins & scams. They're called vitamins as a contraction of "vital amines" - vital because our bodies can't make them: we must consume them, and in sufficient quantities. There's plenty of good, solid science here, so learn to be an informed consumer In both senses).
There are in fact, plenty of snake-oil salesmen in the supplement business, and vitamins are a big part of the supplement business, and they're easy enough to find - or at least recognise; however, vitamins are not scams. Once again, it's important to know what the major vitamins, minerals and other nutrients are, and what they do for you; otherwise, it's very difficult to be an informed consumer. Learn to think beyond the macros.
For one thing, there are reputable brands, and what you might call 'bar-code' brands - most of these show up as "house" brands, and are what you'll find at the corner drug store, or the grocery; these are generally made, packaged, shipped, stored, bottled, labeled, shipped and stored on a commodity basis. They are minimal potency, w/ no particular care taken in their production & distribution: a low-to-medium-quality product with a shelf-life, a too-low dose, and sometimes in elemental forms that are useless to us (classic example I guess is ferric oxide, put in pre-natal vitamins to make sure pregnant women get enough iron: problem is, our bodies can't make use of ferric oxide, so the only effect is constipation).
The (*ahem*) respectable brands tend to use higher-quality ingredients/raws/extractions, handle them more carefully, tend to spend a lot of money & ingenuity on processing methods that preserve as much as possible the nutritional value of whatever it is, they package their products more carefully, they keep in touch with actual research. My multi is Daily One from TwinLab, without iron. I take one at each of my 3 main meals.
About pissing yellow: that's B-1 (if it's the fluorescent yellow; if it's the dark, stinky yellow, you're dehydrated)): like the rest of the B-complex (and C), it's water-soluble, which means that anything your body hasn't used yet will cycle out in a few hours. Which means it should be re-dosed every few hours, as blood-levels are important (have I heard that somewhere before?).
