What Is Vitamin B12?

Vitamin B12, also called cobalamin, is one of eight B vitamins and is essential to human life, supporting the nervous system and cardiovascular system. Most healthy individuals will obtain enough from their diet alone, as it can be found in meat, seafood and animal products, such as milk.

How Is Vitamin B12 Used?

Vitamin B12 is a cofactor in DNA synthesis, meaning it acts as a helper molecule to create new DNA and keep cells healthy. It plays an important role in the formation of red blood cells and myelin, the fatty substance that forms sheaths surrounding nerve cells, insulating the “wires” along which the nervous system’s electrical impulses travel.

Human brain

How Much Vitamin B12 Do You Need per Day?

According to the Mayo Clinic, adults should consume 2.4 micrograms of B12 each day. Individuals with risk factors for cobalamin deficiency should consult their physician for more detailed recommendations.

Benefits of Vitamin B12

Maintaining healthy levels of vitamin B12 may have a number of benefits, including

  • Preventing anemia
  • Supporting healthy pregnancy
  • Supporting bone health
  • Reducing osteoporosis risk
  • Improving mood
  • Preventing memory loss

What Causes Vitamin B12 Deficiencies?

The ability to absorb vitamin B12 declines as we age, especially in individuals over 60 years old. Individuals with certain autoimmune and digestive disorders are more likely to suffer from a vitamin B12 deficiency.

Senior woman experiencing neurological symptoms of B12 deficiency

Potential risk factors for cobalamin deficiency include:

  • Family history of B12 deficiency
  • Surgery leading to removal/restriction of the stomach or intestine, such as gastric bypass surgery
  • Autoimmune diseases, including type 1 diabetes
  • Crohn’s disease
  • HIV
  • Certain medications, including proton-pump inhibitors
  • Highly restrictive diets, such as strict veganism
  • Advanced age

What Are the Symptoms of Vitamin B12 Deficiency?

Man experiencing depression and fatigue from B12 deficiency

Early signs of a possible vitamin B12 deficiency include:

  • Weakness
  • Numb or tingling sensation in extremities
  • Difficulty walking
  • Elevated heart rate
  • Smooth and tender tongue
  • Fatigue (lack of energy)
  • Nausea
  • Decreased appetite
  • Weight loss
  • Irritability
  • Diarrhea

Vitamin B12 deficiency is rare in healthy individuals, but when it occurs it is important that it be addressed swiftly. Prolonged deficiency can lead to pernicious anemia and fatigue, with more severe deficiencies impairing neurological function. 

woman suffering from tinnitus due to B12 deficiency

More severe B12 deficiencies that go untreated can lead to

  • Tinnitus
  • Severe joint pain
  • Memory problems
  • Depression
  • Anxiety
  • Poor muscle function
  • Ataxia
  • Changes in reflexes
  • Infertility
  • Delayed growth/development in children

The Benefits of Vitamin B12 Injections

Vitamin B12 injection needle

In cases of severe vitamin B12 deficiency, frequent intramuscular injections of large doses of a form of cobalamin may be used to restore vitamin levels to healthy amounts, followed by smaller and less frequent maintenance doses of injections or oral supplements. They can also be used to prevent future deficiencies.

Vitamin B12 injections are an excellent way to supplement cobalamin, as they bypass the digestive system. This allows for greater bioavailability and absorption, particularly in individuals who have difficulty absorbing it from their diet.

Supplemental cobalamin is available in multiple forms, including methylcobalamin and hydroxocobalamin. Individuals considering B12 injections should discuss their options with a physician before beginning a course of treatment.



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