Tricalcium phosphate & magnesium stearate are two ingredients found in multivitamins that interfere with your body's absorption of nutrients. Magnesium stearate is a preservative that slows the solubility and tricalc phosphate actually blocks your body's ability to absorb minerals (such as, get this, iodine-so taking a multivitamin will prevent you from losing weight. Little known fact!) ...Also, many vitamins in powdered and tablet forms contain oxidised forms of nutrients. Examples of this include magnesium oxide, zinc oxide, and so forth-these generally do not dissolve in water (which is, think about it, what our bodies are primarily composed from). So they are poorly absorbed. Then, there are chemicals, such as aspartate which like the name implies, is related to (and toxic in a similar way as is) aspartame. If you have a poor diet (lacking in a variety of raw ORGANIC [that part is very important as you will get the nutrients from the soil-with food that is sprayed with pesticides, the nutrient content is weakened] foods) and you must take vitamins and minerals, the best way to get them is in hard forms. By this I mean citrates, chlorides, and bicarbonate forms.
reference: http://www.nutritional-supplement-truths.com/bioavailability-of-nutritional-supplements.html
