Vitamin B12 - Methylcobalamin

Vitamin B12 is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement and a prescription medication. It plays an essential role in the production of your red blood cells and DNA, as well as the proper functioning of your nervous system.

Vitamin B12 exists in several forms and contains the mineral cobalt, so compounds with vitamin B12 activity are collectively called “cobalamins”. Methylcobalamin and 5-deoxyadenosylcobalamin are the forms of vitamin B12 that are active in human metabolism. Vitamin B12 is naturally found in animal foods, including meats, fish, poultry, eggs and dairy. However, it can also be found in products fortified with B12, such as some varieties of bread and plant-based milk.

Vitamin B12 deficiency can be slow to develop, causing symptoms to appear gradually and intensify over time. It can also come on relatively quickly. Given the array of symptoms a vitamin B12 deficiency can cause, the condition can be overlooked or confused with something else. Vitamin B12 deficiency symptoms may include:

Unfortunately, B12 deficiency is common, especially in the elderly. You’re at risk of deficiency if you don’t get enough from your diet or aren’t able to absorb enough from the food you eat.

People at risk of a B12 deficiency include:

Unfortunately, symptoms of a vitamin B12 deficiency can take years to show up, and diagnosing it can be complex. A B12 deficiency can sometimes be mistaken for a folate deficiency.

Low levels of B12 cause your folate levels to drop. However, if you have a B12 deficiency, correcting low folate levels may simply mask the deficiency and fail to fix the underlying problem.