Vitamin B12 is a water- soluble vitamin, also known as cobalamin. it plays a vital role in brain function and the production of DNA and red blood cells. Chemically, vitamin B12 can exist in several different forms, but all of them contain the mineral cobalt.

Vitamin B12 helps your body use fat and carbohydrates for energy and make new protein. It is also important for normal blood, cells and nerves.

The vitamin can be stored in the liver for a long time, so its may take a few years for a deficiency to develop. Deficiency is common, especially in people who follow a vegetarian or vegan diet. In fact, its thought that up to 90% of people following these diets have a deficiency, this is because B12 is only found naturally in animal foods. However, vegans and vegetarians are not only ones who are deficient, some meat eaters may not absorb B12 very well. Unlike other vitamins, the absorption of vitamin B12 depends on a protein produced in your stomach, called intrinsic factor. Intrinsic factor binds to vitamin B12, so that you can absorb it into the blood. People who do not produce enough intrinsic factor can become deficient. Deficiency is particularly common in elderly people, because the ability to absorb vitamin B12 can also decrease with age.

Other people at risk of deficiency include those who have had intestinal surgery, weight loss surgery and those with diseases that affect the gut, such as Crohn’s disease or celiac disease.