2. • Vitamin B-12 (cobalamin) plays an essential role
in red blood cell formation, cell metabolism,
nerve function and the production of DNA, the
molecules inside cells that carry genetic
information .
• Food sources of vitamin B-12 include poultry,
meat, fish and dairy products. Vitamin B-12 is
also added to some foods, such as fortified
breakfast cereals, and is available as an oral
supplement. Vitamin B-12 injections or nasal
spray might be prescribed to treat vitamin B-12
deficiency .
3. • Vitamin B-12 deficiency is not common in the U.S.
However, people who follow a vegetarian or
vegan diet might be prone to deficiency because
plant foods don't contain vitamin B-12. Older
adults and people with digestive tract conditions
that affect absorption of nutrients also are
susceptible to vitamin B-12 deficiency
• Left untreated, a vitamin B-12 deficiency can lead
to anemia, fatigue, muscle weakness, intestinal
problems, nerve damage and mood disturbances.
• The recommended daily amount of vitamin B-12
for adults is 2.4 micrograms.
4. • C₆₃H₈₈CoN₁₄O₁₄P
• Vitamin B₁₂, also known as cobalamin, is a
water-soluble vitamin involved in metabolism.
It is one of eight B vitamins. It is required by
animals, which use it as a cofactor in DNA
synthesis, in both fatty acid and amino acid
metabolism
5. • Vitamin B12, or cobalamin, is naturally found in
animal foods. It can also be added to foods or
supplements. Vitamin B12 is needed to form red
blood cells and DNA. It is also a key player in the
function and development of brain and nerve
cells.
• Vitamin B12 binds to the protein in the foods we
eat. In the stomach, hydrochloric acid and
enzymes unbind vitamin B12 into its free form
• From there, vitamin B12 combines with a protein
called intrinsic factor so that it can be absorbed
further down in the small intestine
6. • Fish, shellfish
• Liver
• Red meat
• Eggs
• Poultry
• Dairy products such as milk, cheese, and yogurt
• Fortified nutritional yeast
• Fortified breakfast cereals
• Enriched soy or rice milk
7. • The RDA for adults is 2.4 μg/day of vitamin
B12. Because 10 to 30 percent of older people
may be unable to absorb naturally occurring
vitamin B12, it is advisable for those older than
50 years to meet their RDA mainly by
consuming foods fortified with vitamin B12 or
a vitamin B12-containing supplement.
8. • Measuring vitamin B12 in the blood is actually
not the best way to determine whether someone
is deficient, as some people with a deficiency can
show normal B12 blood levels. Blood levels of
methylmalonic acid, a protein breakdown
product, and homocysteine are better markers
that capture actual vitamin B12 activity. These
values increase with a vitamin B12 deficiency. It is
estimated that up to 15% of the general
population has a vitamin B12 deficiency. [1]
9. • High doses of vitamin B-12, such as those used
to treat a deficiency, might
cause: Headache. Nausea and
vomiting. Diarrhea.
10. • Vitamin B12 binds to the protein in the foods
we eat. In the stomach, hydrochloric acid and
enzymes unbind vitamin B12 into its free
form. From there, vitamin B12 combines with
a protein called intrinsic factor so that it can
be absorbed further down in the small
intestine.
11. • Avoiding animal products. People who do not eat
meat, fish, poultry, or dairy are at risk of
becoming deficient in vitamin B12, since it is only
found naturally in animal products. Studies have
shown that vegetarians have low vitamin B blood
levels. [5] For this reason, those who follow a
vegetarian or vegan diet should include B12-
fortified foods or a B12 supplement in their diets.
This is particularly important for pregnant
women, as the fetus requires adequate vitamin
B12 for neurologic development and deficiency
can lead to permanent neurological damage.
12. • Lack of intrinsic factor. Pernicious anemia is
an autoimmune disease that attacks and
potentially destroys gut cells so that intrinsic
factor is not present, which is crucial for
vitamin B12 to be absorbed. If vitamin B12
deficiency ensues, other types of anemia and
neurological damage may result. Even the use
of a high-dose B12 supplement will not solve
the problem, as intrinsic factor is not available
to absorb it.
13. • Inadequate stomach acid or medications that
cause decreased stomach acid. A much more
common cause of B12 deficiency, especially in
older people, is a lack of stomach acid, because
stomach acid is needed to liberate vitamin B12
from food. An estimated 10-30% of adults over
the age of 50 have difficulty absorbing vitamin
B12 from food. [1] People who regularly take
medications that suppress stomach acid for
conditions like gastroesophageal reflux disease
(GERD) or peptic ulcer disease—such as proton-
pump inhibitors, H2 blockers, or other antacids—
may have difficulty absorbing vitamin B12 from
food. These drugs can slow the release or
decrease production of stomach acid.
14. • In theory this can prevent the vitamin from being
released into its free usable form in the stomach;
however, research has not shown an increased
prevalence of a deficiency in people using these
medications. Anyone using these medications for
an extended time and who are at risk for a
vitamin B12 deficiency for other reasons should
be monitored closely by their physician. They
may also choose to use fortified foods or
supplements with vitamin B12, as these forms
are typically absorbed well, and do not require
stomach acid.
15. • Intestinal surgeries or digestive disorders that
cause malabsorption. Surgeries that affect the
stomach where intrinsic factor is made, or the
ileum (the last portion of the small intestine)
where vitamin B12 is absorbed, can increase
the risk of a deficiency. Certain diseases
including Crohn’s and celiac disease that
negatively impact the digestive tract also
increase the risk of deficiency.
16. • Vitamin B12: Fact sheet for professionals. Office of Dietary Supplements.
https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional.
Accessed Jan. 9, 2021.
• Fairfield KM. Vitamin supplementation in disease prevention.
https://www.uptodate.com/contents/search. Accessed Jan. 9, 2021.
• Means RT Jr, et al. Causes and pathophysiology of vitamin B12 and folate
deficiencies. https://www.uptodate.com/contents/search. Accessed Jan.
9, 2021.
• Cyanocobalamin. IBM Micromedex.
https://www.micromedexsolutions.com. Accessed Jan. 9, 2021.
• Methylcobalamin. Facts & Comparisons eAnswers.
https://www.wolterskluwercdi.com/facts-comparisons-online/. Accessed
Jan. 9, 2021.
• Vitamin B12. Natural Medicines.
https://naturalmedicines.therapeuticresearch.com. Accessed Jan. 9, 2021.
17. • U.S. Department of Health and Human Services. Vitamin B12 Fact
Sheet for Health
Professionals. https://ods.od.nih.gov/factsheets/VitaminB12-
HealthProfessional/ Accessed 1/21/19.
• Meyer HE, Willett WC, Fung TT, Holvik K, Feskanich D. Association of
High Intakes of Vitamins B6 and B12 From Food and Supplements
With Risk of Hip Fracture Among Postmenopausal Women in the
Nurses’ Health Study. JAMA network open. 2019 May
3;2(5):e193591-.
• Malouf R, Evans JG. Folic acid with or without vitamin B12 for the
prevention and treatment of healthy elderly and demented
people. Cochrane Database of Systematic Reviews. 2008(4).
• Balk EM, Raman G, Tatsioni A, Chung M, Lau J, Rosenberg IH.
Vitamin B6, B12, and folic acid supplementation and cognitive
function: a systematic review of randomized trials. Archives of
internal medicine. 2007 Jan 8;167(1):21-30.
• Rizzo G, Laganà A, Rapisarda A, La Ferrera G, Buscema M, Rossetti P,
Nigro A, Muscia V, Valenti G, Sapia F, Sarpietro G. Vitamin B12
among vegetarians: status, assessment and supplementation. Nutrients. 2016 Dec;8(12):767.
