Oh really? I didnt know that. I had a blood test and my b12 was low 300s. Started taking pills for a couple weeks. Had recently moved and wanted another opinion since first doc just told my odd muscle twitching and mental fatigue was nothing to worry about. So I saw a new doc who did seem alarmed by my low b12. but she wanted to do another blood test. fast forward a month which was yesterday and found out the new b12 reading was in 500s. but I had been taking b12 every day including the morning of the 2nd blood test. I asked if that would affect my reading but she never really answered.