I received a question asking if there is a hazard to taking too many vitamins.
My shortest answer would be apart from damage to your pocketbook, there are no large health hazards to taking too many vitamins. Unless advised by a health professional for a particular health problem there is no value to going overboard "megadosing" vitamins and minerals. There are a couple vitamins with unique features that might comprise a health problem if they were to be overdosed. One of these would be niacin. It is one of the B-vitamins, and is commonly recommended or prescribed for managing high cholesterol. The risk with it is in very large doses it can have a toxic effect on the liver. If you get itchy all over, look a little more yellow in the whites of your eyes, hear voices, or experience serious hot flashes frequently you may be getting too much niacin. Reducing or eliminating niacin will cause the symptoms to diminish or disappear.
A second toxic vitamin is Vitamin A. Normal adults would have to take in excess of probably 25,000-30,000 units for a long time (more than a year) to collect any negative hits health-wise. I'm referring to pure Vitamin A -- not Beta-carotene for which it is impossible to overdose.
Iron is a toxic mineral. Men rarely need supplemental iron. Menstruating women have a need for 15-20 mg of iron daily, particularly during and for a few days after periods. Iron increases your free radical damage, so it's best to avoid it beyond true need for it. Too much iron has been associated with increased colon cancer risks. Excess iron could also cause you to get stuck in the scanners at the airport. (LOL - I am joking.)
The very best source for nutritional supplementation comes from food. Whacky idea! A wide variety of variously colored vegetables are the most nutrient dense foods on the planet. The second best source is from supplements made from whole foods, (e.g. Juice Plus.) Finally, the least useful source is a synthesized multi-vitamin tablet that you commonly find on the grocery store shelf. The actual brand names will remain nameless as the companies would probably sue me for saying their products are trash and pretty worthless.
I have to say I am not very good at being consistent for long periods with the pill popper lifestyle. The supplements I take with the most regularity include Juice Plus, a B-50 complex, a probiotic, and a revolving assortment of varied adrenal supplements (for aiding stress.) If I'm getting sick, I'll take Vitamin C, Echinacea, Mitake/Shitake mushrooms, and Zinc.