Vitamin B-12 is a water-soluble vitamin. Water-soluble vitamins are easily dissolved in water, and unlike fat-soluble vitamins, are not generally stored in the body. Vitamin B-12 is the exception because it can be stored in your liver long term. You must regularly get vitamin B-12 from your diet because the human body cannot make it. Older adults need more vitamin B-12 because the body's ability to absorb the vitamin decreases with age.
Vitamin B-12 is sometimes referred to as cobalamins since several forms of vitamin B-12 exist, all of which contain the mineral cobalt. There are only two "forms of vitamin B-12 that are active in human metabolism - Methylcobalamin and 5-deoxyadenosylcobalamin," according to the National Institutes of Health.
Functions and Roles
Vitamin B-12 has several important roles in keeping the body healthy. It is needed for the production of red blood cells, it is needed to form DNA, it helps maintain the central nervous system and it aids in metabolizing fat and protein.
Only animal based foods provide the body with vitamin B-12. Meat, poultry, eggs, shellfish, milk and dairy products are all good sources. In comparison, unfortified plant based foods such as fruits, vegetables and grain products do not contain vitamin B-12. Products such as rice and soy milk or soy meat substitutes fortified with vitamin B-12 offer a vegetarian alternative. Additionally, vitamin B-12 can be obtained from dietary supplements and prescription medications.
"Vitamin B-12 deficiencies often develop gradually over many years," according to the Centers for Disease Control and Prevention. Deficiencies can occur when the body is unable to absorb vitamin B-12 due to decreased production of gastric acids and enzymes, common in older adults and in people who have had parts of their stomach or small intestine surgically removed. Since vitamin B-12 is found only in animal products, strict vegetarians and vegans who do not use supplements are also at risk for deficiency. If left untreated, vitamin B-12 deficiencies could lead to megaloblastic anemia and even neurological disorders.