B12 Use Vitamin

Vegetarians who choose to use a vitamin B supplement either as a single supplement or in a multivitamin must remember to use the supplements regularly for them to be effective. Vitamin B is a water soluble vitamin. Water soluble vitamins dissolve in water. After the body uses these vitamins leftover amounts leave the body through the urine.Typically However deficiency can result from being unable to use vitamin B.

Vitamin B-12 (cobalamin)
... prolonged use of acid-suppressing drugs such as cimetidine (Tagamet), ranitidine (Zantac) and omeprazole (Losec) can lead to a serious vitamin-B12 deficiency. ...

MedlinePlus Herbs and Supplements: Vitamin B12
However, deficiency can result from being unable to use vitamin B12. ... control pill use is stopped, normalization of vitamin B12 levels usually occurs. ...