I have always wondered about the absorption rate of vitamins. I have had several doctors tell me that when you ingest pills that the body releases 90% of them in the urine and you do not get the full benefit of it. This looks promising. Good article
That's because the body only uses what it needs. A simple multi has thousands of times the RDA of the B complex. And a vit like C is water soluble so you're going to pee it out whether you eat it or inject it.