Alcohol destroys the body's stores of B6 and if you become deficient in this nutrient you could develop anemia, icky skin conditions, kidney stones and start convulsing. Oh and your brain waves will become abnormal and you'll become extremely irritable. You can also purchase these products through mail order catalogues, the television and the Internet. Those big warehouse stores where you can buy a lifetime supply of anything also carry dietary supplements, but since most supplements have a set shelf life, you should avoid buying your pills in bulk. Take the time to read the supplement labels carefully.
Some companies claim to provide results that are neither accurate nor humanly possible.
Consider poisonous mushrooms. Natural and synthetic vitamins are basically the same thing. Mother Nature created a bunch of crazy stuff, but she managed to stay away from tablet and gelcap production. Basically, synthetic vitamins are just cheaper to make. A vitamin's price doesn't reflect its potency.