Cobalamin, or Vitamin B12 (also called cyanocobalamin), works with other B vitamins to turn food into energy. B12 cannot be made by plants or by animals as the only type of organisms that have the enzymes required for the synthesis of B12 are bacteria and archaea.

B12 also guards against heart disease, mental disorders, and anemia, and keeps your immune system strong. Vitamin B12 works closely with folic acid ( vitamin B9) and pyridoxine ( vitamin B6) to convert food into energy.

Vitamin B12 is naturally found in foods including meat (especially liver and shellfish), eggs, and milk products. Fortified breakfast cereals are a particularly valuable source of vitamin B12 for vegetarians and vegans.

While lacto-ovo vegetarians usually get enough B12 through dairy products or eggs, it may be found lacking in those practicing vegan diets who do not use multivitamin supplements or eat B12 fortified foods, such as fortified breakfast cereals, fortified soy-based products, and fortified energy bars. Claimed sources of B12 that have been shown through direct studies of vegans to be inadequate or unreliable include, nori (a seaweed), barley grass, and human gut bacteria.

Several studies[citation needed] of vegans on raw food diets show that raw food offers no special protection against B12 deficiency either. The only known vegan sources of substantial B12, aside from multivitamin supplements and fortified foods, are the Chinese herb Dang Gui (Angelica sinensis) , used for centuries for treating anemia, and certain brands of fortified nutritional yeast.[citation needed]

Interestingly, certain insects such as termites have been found to contain B12.

Cobalamin is also found in many energy drinks.