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Vitamin B12 or cobalamin performs several key functions such as red blood cell formation, DNA synthesis, and helps in proper neurological functioning in humans and other animals. This particular vitamin is synthesized by bacteria and can be found in soil. Cobalamin deficiency is often common in vegetarian diets. Non-vegetarians who have an absorptive problem and vegetarians who have no other source for this essential vitamin are often given B12 supplements. Vitamin B12 dietary supplements are given to all age groups of people for pre-emptive as well as prescriptive purposes.

Recommended To Everyone

Only some time ago, it was believed that vitamin B12 supplements were essential for old people but new studies have shown that they are essential for every age group.

A new scientific study published in American Journal of Clinical Nutrition and cited by NIH shows an unexpected deficiency of vitamin B12 in young adults. The Framingham Offspring Study provided evidence that vitamin B12 deficiency in youth is prevalent and that people between age groups (26-49 years, and 65 and older) had similar values of vitamin B12 deficiency in their blood. It was also found that those individuals who were taking vitamin B12 supplements were less likely to suffer from this deficiency. Even rampant gastric troubles, such as an increase or decrease of stomach acid value, can affect the absorption of vitamin B12, which makes the vitamin B12 deficiency to show in every age group. As cited by NIH, about 1.5% to 15% of the general population is suffering from vitamin B12 deficiency in their body due to malabsorption of vitamin B12 from food due to various reasons like pernicious anemia, gastric troubles, age factors and others.

Any essential nutrient is assigned a Dietary Reference Intake Value (DRI). These values include Recommended Daily Allowance (RDA) which estimates daily nutrient intakes in a healthy individual to perform normal functions.

For pregnant women 2.6 mcg and for women who are breastfeeding 2.8 mcg of vitamin B12 is recommended by the Food and Nutrition Board (FNB) at the Institute of Medicine (IOM). IOM is a part of National Academy of Science (now known as National Academies). No upper limits are defined for vitamin B 12 due to its low toxicity. IOM officially maintains that no adverse effects are seen with excessive intake of vitamin B 12.

Role in RBC Count and Hemoglobin/Iron Levels

The role of vitamin B12 in decreased RBC count is significant because its deficiency causes pernicious anemia, a condition in which total RBC count is reduced in the body due to decreased intrinsic factor in the body. The most common deficiency effect seen is pernicious anemia, according to a review published in the journal NEJM, conducted by researchers Ban-Hock Toh and others. This condition is characterized with severe megaloblastic anemia (decrease of red blood cells due to inhibition of DNA synthesis), gastrointestinal symptoms like constipation, diarrhea, and often loss of bowel function (due to defective DNA synthesis). Neurological symptoms like lack of motor control, sensory deficiencies like loss of sensation are also seen (due to accumulation of methylmalonic acid in the absence of vitamin B 12). Prevention of permanent neurological deficiencies can be achieved by taking an active stance which includes early diagnosis and intervention.

Dr Teodoro Bottiglieri (PhD), in an article in journal Nutrition Reviews of Oxford University Press, explains that additional symptoms can include confusion, difficulty in maintaining balance, poor memory, soreness of tongue and mouth.
When RBCs are reduced in pernicious anemia, hemoglobin is also reduced because the total number of circulating RBCs directly affects hemoglobin in the blood.

Another surprising aspect of vitamin B12 deficiency is that it can stay unnoticed, as this deficiency’s side-effects are masked by folic acid within the body. It may be hard to recognize that the body is experiencing vitamin B12 deficiency until the anemia worsens or some neurological effects start to show.
The patients of pernicious anemia can also benefit from oral vitamin B12 as those individuals lack intrinsic factor in their body. In such conditions, oral vitamin B12 absorption in the body is affected. Its deficiency can be controlled by provision of high oral doses of the supplements.

Vitamin B12 and Energy Production

According to an article published in JAMA, B12 is one of eight B vitamins, which is water soluble and can exist in several forms. All of the B vitamins are known for their help with which the body converts carbohydrates (food) into glucose (fuel). The most active form of the vitamins in human metabolic functions are methylcobalamin and 5- deoxyadenosylcobalamin. That’s why vitamin B12 can be used for endurance and athletic performance. Other research has proved that for energy endurance nutrition provision is also important because vitamin B12 helps in the conversion of food into glucose (fuel).

Combination of Vitamin B12 and Folate/Folic Acid

Folate is used by the body during cell division, while forming new DNA. Every day, almost 1% of the RBCs are turned into new cells, giving the body the new RBCs as oxygen carriers to the cells and organs of the body. The role of vitamin B12 is crucial here, as it activates an enzyme called methionine synthase. This enzyme helps the body utilize folate to produce new RBCs. When vitamin B12 is low in the body, the production of new RBCs slows down in bone marrow. This will eventually lead to low levels of iron in the blood because new RBCs are not being replaced.
An important role played by vitamin B12 in combination with folic acid is the regulation of homocysteine (methylation to methionine and synthesis of S- adenosylmethionine). Julie Robertson and colleagues explain, while writing in the journal CMAJ, that homocysteine levels in humans are elevated as a result of the deficiency of B12. Increased elevation of plasma homocysteine is a serious condition known as homosysteinemia. Almost two-thirds of the adults showing symptoms of ‘homosysteinemia’ also present with methylmalonic acidemia which indicates that B12 levels in the body are low. As cited by NIH, high levels of the hormone have been associated with impaired endothelial vasomotor function, lipid peroxidation, promotion of thrombogenesis, and vascular proliferation. As the study in NEJM showed, vitamin B12 along with folic acid is used to lower down the value of homocysteine in the plasma.

Vitamin B12 and Its Role in Regulating Human Mood

Increased homocysteine levels can also mean a decrease in some essential substances which regulate the metabolism of certain neurotransmitters in the human brain, leading to cognitive dysfunction, depression, schizophrenia and multiple sclerosis. Low levels of Vitamin B12 have been seen in nearly one-third of the patients with depression. Vitamin B12 is proven to reduce the homocysteine levels in the body, as per mentioned in the research mentioned above.

Vitamin B12 and DNA/RNA Support

The book ‘The Vitamins: Fundamental Aspects in Nutrition and Health’ details how Vitamin B12 in sync with folic acid helps prevent chromosomal damage and hypomethylation of DNA, which in turn ensures genomic stability in animals and humans alike. Several congenital diseases and disorders with faulty vitamin B12 metabolisms in body have also been indicated. These include methylmalonic aciduria and Imerslund-Grasbeck Syndrome.

Vitamin B12 Deficiency and Its Association with Cancer

In other instances, it has been seen that persistent low asymptomatic levels of vitamin B12 can produce mutations like base substitution in mouse cancer models.

This indicates a potential high risk of cancer in individuals with low cobalamin plasma levels.

Vitamin B12 and Osteoporosis

In some instances reversal in osteoporosis has also been seen when provided with B12 supplements. In osteoporosis the bone mass and density can increase giving rise to multiple health problems. However, in an experimental approach taken by Mary E Melton from the Department of Internal Medicine at University of Michigan, it was seen that when the B12 levels were increased in the patients suffering from osteoporosis, nearly 79%, 17%, and 15% of bone density increased in femoral neck, greater trochnater and lumbar regions respectively over a period of two years.

Vitamin B12 and Nerves

Vitamin B12 is essential in the development of nerve cells and the brain. The ‘myelin sheath’, which covers the nerve cells and ensure the fast nerve-impulse-transmission, vitamin B12 plays a significant role in its formation. Research published in JAMA shows that this vitamin’s deficiency can also cause peripheral neuropathy. Patients with pernicious anemia have also been found to show peripheral neuropathy.

Vitamin B12 and Gastric Disorders

Published in Baillière’s Clinical Haematology, if an individual has undermined gastric absorptive capacity for nutrients due to certain diseases like Crohn’s disease or Celiac disease, it is advised to take vitamin B12 supplements. Initially, disturbance in cognitive functioning is a sign of deficiency in such individuals which can later on exhibit as memory loss or megaloblastic anemia.

Some individuals with low or no stomach acidity, called hypochlorhydria or achlorhydria respectively, can also experience vitamin B12 deficiency.

Vitamin B12 and Post-Surgical Malabsorption

Obesity and eating disorders like binge eating make some people so desperate that they go for different types of weight loss surgeries or removal of part of the stomach. They can suffer from vitamin B12 deficiency. For such individuals, high oral supplements of vitamin B12 according to the condition of their surgery have been advised. A study published in NEJM proves that after total gastrectomy, the absorptive power of vitamin B12 is reduced.

References:

https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/#en41 http://ajcn.nutrition.org/content/71/2/514.long
http://www.nap.edu/catalog/6015/dietary-reference-intakes-for-thiamin-riboflavin- niacin-vitamin-b6-folate-vitamin-b12-pantothenic-acid-biotin-and-choline
http://www.nejm.org/doi/full/10.1056/NEJM199711133372007
http://nutritionreviews.oxfordjournals.org/content/54/12/382.long
http://www.ncbi.nlm.nih.gov/pubmed/17972439?dopt=Abstract
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012244
http://www.cmaj.ca/content/173/11/1360.1.full
http://www.nejm.org/doi/ref/10.1056/NEJMoa060900#t=article
http://journals.lww.com/co-clinicalnutrition/pages/articleviewer.aspx? year=2007&issue=11000&article=00011&type=abstract
http://197.14.51.10:81/pmb/AGROALIMENTAIRE/ The_Vitamins__Fundamental_aspects_in_nutrition_and_health.pdf
http://jama.jamanetwork.com/article.aspx?articleid=656740
http://www.sciencedirect.com/science/article/pii/S0950353605802240
http://www.nejm.org/doi/full/10.1056/NEJM195407292510501

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