Cobalamin (aka Vitamin B12) is a unique vitamin compound because it is the only essential piece of the diet which includes the element cobalt. B12 deficiencies and inadequate consumption are quite common, even in developed countries. Other states of the body like low stomach acid production or use of medications like proton pump inhibitors for GERD may actually decrease absorption rates significantly. Inabilities to properly methylate vitamins in the liver like as seen with MTHFR mutations can also increase need for B12 or require supplementation of methylated B12. Cobalamin deficiencies are typically seen in those who consume little to no animal products (as plants do no contain B12 in a bioavailable form, sorry, spirulina is not a source of real cobalamin) and who do not supplement or consume fortified foods. Consumption of meat may not be enough to provide B12 in adequate amounts if one lacks the ability to properly extract the vitamin from food. An outright deficiency of B12 is serious business and can cause severe and sometimes permanent neurological damage, and therefore should be a nutrient of concern for certain people. The RDA is 2.4 mcg per day, quite a small amount, but may be difficult to achieve for some without supplementation.

Functions

  • Conversion of homocysteine to methionine
  • Coenzyme for various processes
  • Necessary for proper energy metabolism
  • Required for brain and nerve functioning

Primary deficiency symptoms and diseases

  • Anemia
  • Lethargy
  • Abnormal nerve and brain functioning and damage (long term)
  • Low B12 status over many years may contribute to increased risk of heart disease through inefficient conversion of homocysteine to methionine

Food sources

It should be noted that while marketers claim that supplements like spirulina contain a plant based B12, they actually contain analogues which are not used properly by the body and may increase the need for B12.

  • Liver
  • Meats
  • Seafood
  • Eggs
  • Dairy
  • Dirty water (don't drink bacteria contaminated water to get B12)

Supplementation

Vitamin B12 supplements will vary slightly based on their type, but typically you'll see two forms available on the shelf. They are often in ridiculously high doses, but since it is water soluble, there is little risk of over consumption. An option for some people is to get B12 injections from a doctor.

  • Cyanocobalamin (most common, very shelf stable)
  • Methylcobalamin (more common now, but lacks stability over the long term. May be required by those with methylation problems)
  • Hydroxycobalamin (most often in the form of injections)

Who needs it most?

  • Strict vegans and vegetarians
  • Those with gastrointestinal disorders
  • People with malabsorption issues
  • Elderly
  • People with pernicious anemia

Other tips

  • If you don't consume animal products, then take a B12 supplement. Leaving dirt on your fruits and vegetables or trying to rely on bacteria in water or your gut for this vitamin is asking for a deficiency.
  • B12 can be stored by the body, so daily consumption is not always necessary and levels tend to slowly decline over time with inadequate consumption. This is why many people claim to feel fine despite not consuming B12 regularly.
  • It is not an "energy" supplement. Usually when people feel increases in energy from B12 it is because they were deficient or are experiencing a placebo effect. This can also be confounded by the fact that many "energy pills" also contain things like stimulants in addition to B12.