So now you know why many synthetic vitamins and supplements don't do much. It sits there, until it is later found in the septic waste tanks (see comments here reproduced below).
(Kim here's the Reference for the septic tank story.
"Absorption is the key to everything. How much you swallow means very (VERY) little. Dr. Jonathan Wright was informed by a patient who was a septic tank cleaner that many septic tanks of 'pill-poppers' have layers of pills at the bottom, a clear example of taking something that went on through and was never absorbed." - Robin)