Vitamin B12 belongs to group of vitamins B. It is a water soluble vitamin, necessary for proper functioning of the brain, maintenance of the nervous system, synthesis of the red blood cells, and growth and development in children. Vitamin B12 is also known as cobalamin because it contains cobalt. Vitamin B12 is also important for maintaining and increasing levels of energy and it is needed to make DNA in cells in the body.
Vitamin B12 can be found in plants and animal sources. However, plants and animals are not able to produce this vitamin on their own but it is synthesized by bacteria, microorganisms, yeast and fungi which are present in the large intestine of animals. It can also be obtained from dietary supplements. The body can store small amounts of vitamin B12 while most of it is stored in the liver. Absorption of vitamin B12 depends on the certain type of protein called glycoprotein, which is produced by the cell lining of the stomach. This is known as intrinsic factor and people who are unable to produce it cannot absorb vitamin B12.
Deficiency of vitamin B12 is very rare but if it occurs it is due to lack of intrinsic factor, insufficient intake of this vitamin which usually occurs in people who eat vegan diet and older people. Pernicious anemia can cause vitamin B12 deficiency because it destroys the cells in the stomach that absorb the vitamin. Deficiency of vitamin B12 leads to weakness, tiredness, lightheadedness, pale skin, bleeding gums, depression, memory disorders, heart palpitations, and diarrhea or constipation.
List of Food Sources of Vitamin B12
Animals are better source of vitamin B12 than plants. This vitamin is stored in liver of the animals thus animal liver is the best source of vitamin B12, particularly liver of the calf and snapper. Also, beef, boiled eggs, scallops and cow’s milk are rich in this vitamin. Fish are also good source of this vitamin such as tuna, shrimps, sardine and salmon. Plants, on the other hand, do not store this vitamin and amount of it depends on microorganisms that live in soil on which the plants grow. Vegetables and fruits do not contain enough of this vitamin and vegetarians and vegans must find other sources since they don’t eat meat and animal products. But vegans can ensure sufficient intake of vitamin B12 from fermented soy products such as tempeh, tamari, natto, mosi and shoyu. Seaweeds and algae contain this vitamin too as well as shellfish, clams, mussels and oysters. Good sources of vitamin B12 are cheese, milk, yeast extract and fortified breakfast cereals.