Most B12 supplements (multi or individual) are cyncocobalamin which is only 2 per cent absorbed by liver. 98 per cent is excreted in urine!!-look for methlycobalamin when using b12. I was fired from GNC for giving customer info on passing drug test with Strip. They will not let you sell detox drinks unless asked for by name. However they carry products as the cost is 5 and they charge 50. 1000 per cent profit!!!!