I have a B12 deficiency. i take a tablet daily to keep my levels up. I have red hair or did before I had to color the grey. It also has an impact on getting novocaine at the dentist and some other interesting facts re anesthesia and red hair. Novocaine for me must be injected slowly, wait a while for it to take effect, and then keep an eye on it because it can run out fast too. I also have problems with the substance used to dilate my eyes. It takes a long time for them to dilate and hours to "undilate". I don't know if the eyes issue is unique to me or not but red heads and anesthesia has been written about. I must look into that B12 issue.
A study by McGill University in 2003 proved that redheaded women could tolerate pain by up to 25 percent more than people with other hair colours and that they’re harder to sedate. Medical Daily reports redheads also need 20 per cent more anaesthesia than others. Dr Karan notes in a comment, "The link between red hair & pain sensitivity isn't fully understood so some might have a greater pain sensitivity - but important before surgery!" A fellow doctor wrote, "They always need more anesthesia for dental surgery! At least that's what 23 years of practice taught me."

mary ellen