How Vitamin B12 Deficiency Affects The Body?

Vitamin B-12 deficiency is caused by a nutritional deficiency, which can lead to serious neurologic and hematologic (megaloblastic anemia) disorders. It is much easier to overcome this deficiency by consuming dietary supplements or fortified foods which can help to improve vitamin B-12 levels. If decreased absorption is the reason for B-12 deficiency, it is generally considered more effective to get B-12 supplementation through injections rather than by mouth, as this allows the nutrient to enter into the body’s tissue directly. Vitamin B-12 shots can overcome many of the disorder, sometimes it can be reversed, particularly in the early stages.

How Vitamin B12 Deficiency Affects The Body?

How Vitamin B12 Deficiency Affects The Body?

Vitamin B-12 and Cognitive Function

Vitamin B-12 deficiency has been associated with a few neurocognitive disorders. Dementia is the best example of such disorder characterized by memory loss and behavioral changes. Scientific research suggests that B-12 deficiency caused the consequence of an elevated level of plasma homocysteine, which leading to the onset of dementia.

Vitamin B-12 and Anemia

Malabsorption is the major reason for the cause of pernicious anemia, atrophic gastritis, and postgastrectomy syndrome. Intrinsic factor is a secretory protein that combines with vitamin B-12 in the stomach and enhances the absorption function through the small intestine and then to the circulatory system (bloodstream). Without intrinsic factor, vitamin B-12 can’t be absorbed and leaves your body as waste. Certain drugs like proton pump inhibitors i.e. H2 blockers; and antibiotics, anticonvulsants, colchicine, metformin, and N2O can injure stomach cell resulting in poor or no synthesis of intrinsic factor.

Vitamin B-12 deficiency anemia caused by a lack of intrinsic factor is called pernicious anemia. Megaloblastic anemia caused by vitamin B-12 deficiency is referred to as pernicious anemia. Megaloblastic anemia is that results from inhibition of DNA synthesis during red blood cell production.

Vitamin B-12 and Peripheral Neuropathy

A lack of vitamin B-12 can cause damages to the myelin sheath that surrounds and protect nerves. Without this protection, nerves cease to function properly and conditions such as peripheral neuropathy occur. Peripheral neuropathy can cause chronic fatigue in the body and usually, the feet and hands are more affected, which shows tingling sensation and numbness.

Vitamin B-12 and Depression

Both folate and vitamin B-12 has a significant role in producing brain chemicals that affect mood and other brain functions. Recent literature has identified links between vitamin B12 deficiency and depression. Vitamin B12 supplementation with antidepressants significantly improved depressive symptoms in a cohort study conducted in the USA.

Vitamin B-12 and Stroke

The role of vitamins in stroke prevention has been studied for many decades. It is known that B-12 deficiency causes a high level of plasma homocysteine. Homocysteine-lowering therapy with appropriate doses of folic acid, Vitamin B6, and Vitamin B12 supplementation would reduce the incident risk of cardiovascular diseases which also includes stroke.

The Most Important Deleterious Effect Caused Due To Vitamin B12 Deficiency Are Summarized Below:

  • It represses the synthesis of DNA
  • It suppresses the energy metabolism
  • It affects the lipid metabolism (development of cell membranes, development of myelin sheath, protection of nerves in central nervous system and brain)
  • The synthesis of hormones and neurotransmitters is inhibited
  • It discontinues detoxification (homocysteine, cyanide, nitrous oxide and many more)

The Groups At Risk For A Vitamin B12 Deficiency Include Mainly:

  • Older persons
  • Vegetarians/vegans
  • Persons with gastrointestinal diseases
  • Persons with raised vitamin B12 requirements (pregnant women, breastfeeding women, patients with autoimmune diseases or an HIV infection)
  • Persons under long-term treatment with proton pump inhibitors, metformin or H2 blockers
  • Patients with renal diseases.


At present, the incidence of a vitamin B12 deficiency has received much attention. Older persons, patients on long-term medication and those with neurological disorders can all benefit from adjuvant Vitamin B12 administration.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:June 29, 2018

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