Vitamin B12 Factsheet

What is vitamin B12?
Vitamin B12 also called cobalamin is an essential water-soluble vitamin vital for maintaining healthy central nervous system, formation of red blood cells, proper metabolism and production of DNA and RNA. Vitamin B12 is one of the 8 Vitamin B groups and has the largest and most complex chemical structure of all the vitamins.

How is Vitamin B12 absorbed in the body?
To get into the bloodstream, B12 must be escorted by a protein called intrinsic factor, produced by cells of the stomach. During digestion process, hydrochloric acid in the stomach releases B12 from protein in food which B12 is bound to. After this, vitamin B12 combines with a protein made by the stomach called intrinsic factor and is absorbed by the body.

What is the Importance of Vitamin B12?
- Vitamin B12 and folic acid help iron work better to make healthy red blood cells in the body. The human body produces millions of red blood cells every minute. A deficiency leads to a characteristic kind of anemia but a high intake of folate can compensate for B12 deficiency in this matter. However, it is also important to note that in complete isolation from vitamin B12 our bodies can not absorb folic acid and therefore it must be present for folic acid to do it job aswell.
- Vitamin B12 is needed to support the normal function of nerve cells, and to manufacture myelin, the insulating material that surrounds some of our nerve cells and speeds neural transmission. A deficiency of vitamin B12 can limit your ability to think clearly and impaire brain function. Elderly people with low vitamin B12 are more likely to suffer from brain shrinkage and cognitive decline. Studies show that the vitamin helps reduce age related changes to the brain that happen over time.
- Vitamin B12 plays an important role in supplying essential methyl groups for protein for DNA replication synthesis. Methylation of DNA may be important in cancer prevention.
- Production of S-adenosylmethionine (SAMe), a compound involved in immune function and mood is also dependent upon B12 and folic acid which help in methionine synthase.
- For our cells to multiply properly, an adequate level of vitamin B12 is required. vitamin B12 deficiency can mimic all of the effects of aging as we can’t generate new, healthy cells.
- Vitamin B12 (with folic acid and vitamin B6) also helps the body lower amino acid Homocysteine levels, which have been found to increase the risk of heart disease and stroke.

What is vitamin B12 food source?
B12 is naturally found in many non-vegetarian products people eat like chicken, eggs, beef, seafood, lamb, as well as dairy products. Because B12 can only be manufactured by bacteria it is found naturally in animal products and not in plant foods although some plant foods can contain 'insignificant' amounts of it. B12 may also come in a fortified form in plant foods such as some cereal.

How much vitamin B12 do I need?
The National Institutes of Health recommend that healthy adults get 2.4 micrograms of vitamin B12 daily. Women who are pregnant need 2.6 micrograms and women who are breastfeeding, 2.8 micrograms.

What are the forms of Vitamin B12?
Methylcobalamin and 5-deoxyadenosyl cobalamin are the forms of vitamin B12 used in the human body. The form of cobalamin used in most supplements, cyanocobalamin, is readily converted to 5-deoxyadenosyl and methylcobalamin in the body.

Who is most susceptible to Vitamin B12 deficiency?
- The human body stores several years' worth of vitamin B12 in the liver, so nutritional deficiency of this vitamin is rare in meat eating individuals. However, people who are on strict vegetarian diets, and particularly vegan ones that exclude dairy products, are more likely to suffer from a vitamin B12 deficiency.
- B12 deficiency may also be caused by a lack of intrinsic factor.
  * Elderly people common after age 50 are also at a high risk for B12 deficiency, because the body loses its ability to absorb the necessary vitamin properly as we age.
  * Many disorders of the stomach, such as gastritis, IBS, Chrohn’s disease, celiac disease as well as gastrointestinal surgeries can interfere with the production of intrinsic factor.
  * Medications that affect the stomach – such as aspirin, antacids, proton-pump inhibitors and commonly used diabetes medication, metformin (Glucophage) – can also interfere with intrinsic factor production.
- Some prolonged illnesses such as HIV – patients who are not taking in proper amounts of B12 are also prone to deficiency.
- In rare cases, genetic mutations can limit the ability to metabolize B12 as well, in which case you will need to get the active form, called methylcobalamin, instead of the more common cyanocobalamin.

What are the symptoms of Vitamin B12 deficiency?
Vitamin B12 deficiency causes tiredness, weakness, mood changes, constipation, loss of appetite, weight loss, and megaloblastic anemia. If the deficiency continues untreated the patient may have neurological signs and symptoms such as tingling or numbness of the fingers, tingling or numbness of the toes, general muscle weakness, tender calves, difficulty walking properly (staggering), irritability, depression, confusion, forgetfulness and dementia-like symptoms. In the long term, an unchecked vitamin B12 deficiency can lead to permanent nerve damage.
If you’re suffering from serious symptoms like chronic fatigue, depression or anemia, then talk with your physician to see if a shortage of vitamin B12 might be the problem.

What serious diseases can Vitamin B12 deficiency lead to?
Vitamin B12 deficiency may lead to an elevated rate of DNA damage and altered methylation of DNA, both of which are important risk factors for cancer.
A series of studies in young adults and older men indicated that increased levels of homocysteine and decreased levels of vitamin B12 in the blood were associated with a biomarker of chromosome breakage in white blood cells. In a double-blind, placebo-controlled study, the same biomarker of chromosome breakage was minimized in young adults who were supplemented with 700 mcg of folic acid and 7 mcg of vitamin B12 daily in cereal for two months. 
Alzheimer's disease and Dementia
A case-control study of 164 patients with dementia of Alzheimer's type included 76 cases in which the diagnosis of Alzheimer's disease was confirmed by examination of brain cells after death. Compared to 108 control subjects without evidence of dementia, subjects with dementia of Alzheimer's type and confirmed Alzheimer's disease had higher blood homocysteine levels and lower blood levels of folate and vitamin B12. 
Observational studies have found as many as 30% of patients hospitalized for depression are deficient in vitamin B12. A population-based study in 3,884 elderly men and women with depressive disorders found that those with vitamin B12 deficiency were almost 70% more likely to experience depression than those with normal vitamin B12 status.