Vitamin B12, part of the vitamin B family, is mainly responsible for red blood cell formation and healthy neurological function. Primary causes of a vitamin B12 deficiency are intestinal disorders, which can result in the vitamin not being absorbed, or extreme or continual mental stress. Common symptoms of deficiency include weight loss, loss of appetite, fatigue, weakness and possibly tingling or numbness in your hands and feet. B12 supplements are used to treat deficiencies; those with intestinal disorders need to take B12 by injection, but most others can take the vitamin by tablet.
Ask your doctor to test your vitamin B12 levels to see if you are deficient and should take supplements; this is done through a simple blood test. Obtain instructions from your physician on the amount of B12 to take daily if your tests indicate that you are low; the recommended daily allowance for B12 is 2.4 micrograms per day.
Purchase vitamin B12 at a pharmacy or vitamin store. Though B12 usually is included in a B-complex vitamin, if your are low, you may want to take a supplement that contains only B12 to ensure that you are getting the proper dose.
Place a B12 tablet under your tongue and allow it to fully melt; unlike other vitamins, B12 is absorbed more efficiently when allowed to melt in your mouth rather than swallowed whole. There is a slight sweet and fruity taste to B12 tablets.
Take B12 in the morning, unless your doctor has advised otherwise; many people take their vitamins with their breakfast, but any time in the morning will work. Take B12 with or without food.