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Why is it a good idea to get tested for a vitamin B12 deficiency?

Why is it a good idea to get tested for a vitamin B12 deficiency?Vitamin B12 is required for the production of red blood cells, and the importance of the nutrient for the nervous system is often overlooked. Factors like vegan diets, ageing processes, low stomach acid, and use of anti-diabetic medication increase the risk of a vitamin B12 deficiency. Pernicious anemia is a life-threatening autoimmune disease where people are unable to absorb vitamin B12 from their diet. Typical symptoms of the condition are fatigue, poor memory, nerve damage, impaired fertility etc. and because these problems are insidious, it may be difficult to link them to the root cause. Many people are misdiagnosed as being stressed or having dementia. However, according to an article published in MedicalNewsToday, it may have detrimental consequences for your health if the vitamin B12 deficiency is not treated in ample time.

Vitamin B12 is important for the formation of red blood cells, the energy levels, nervous system, brain, immune system, and cell division. Vitamin B12 is found strictly in animal food sources like meat, fish, eggs, and dairy products. We humans absorb vitamin B12 in our small intestine with help from a carrier compound called intrinsic factor. Vitamin B12 is stored in the liver, which is why months or even years may go by before actual deficiency symptoms occur as a result of eating a strictly plant-based diet or for other reasons

Vitamin B12 deficiencies are widespread and can cause a number of symptoms

An estimated 15 percent of the American population lacks vitamin B12. The condition can cause either few or many symptoms that are linked to anemia and disturbances in the nervous system. These symptoms are often insidious and may occur in varying levels of severity. Pay attention to the following:

  • Fatigue and difficulty with concentrating
  • Poor memory that is often misdiagnosed as dementia
  • Depression
  • Uncomfortable tingling or prickling in the fingers and toes (needles and pins sensation)
  • Red and irritated tongue
  • Heart palpitations
  • Impaired sense of taste
  • Unsteady balance
  • Irreversible nerve damage
  • Difficulty with becoming pregnant
  • Children of mothers that were vitamin B12-deficient during their pregnancy risk stunted growth, anemia, and mental retardation in worst case

Pernicious anemia

Pernicious anemia is a type of anemia that is a result of not being able to absorb vitamin B12 from the diet. It is an autoimmune disease where the immune system erroneously produces antibodies against the cells in the gastric mucosa that makes intrinsic factor, the carrier compound for vitamin B12. It is typically older people that lack intrinsic factor. Pernicious anemia may also occur as a result of chronic infection in the stomach or in the wake of ulcer surgery where the surgeon removes a large part of the stomach, including the mucosa that makes intrinsic factor. Pernicious anemia may cause symptoms such as:

  • Fatigue and muscle weakness
  • Constipation
  • Loss of appetite
  • Paleness
  • Weight loss

High levels of folic acid may mask a vitamin B12 deficiency

Lack of vitamin B12 and folic acid often occur simultaneously. Nonetheless, elevated blood levels of folic acid may mask a vitamin B12 deficiency, thereby aggravating the symptoms.

Who is particularly likely to lack vitamin B12?

Low stomach acid increases the risk of vitamin B12 deficiency, which is because the stomach acid helps release the vitamin from the food we ingest, thereby making it easier for the body to absorb it. The following population groups are likely to lack vitamin B12:

  • Older people
  • Vegans and vegetarians
  • Children
  • Diabetics – especially if they use metformin
  • Patients with celiac disease, Crohn’s disease, and other conditions that reduce nutrient uptake
  • Patients that have undergone gastric by-pass surgery
  • Breastfeeding women
  • Patients that take chloramphenicol and antacids such as proton pump inhibitors

How do you test vitamin B12 levels?

Normally, the physician draws a blood sample in order to test levels of vitamin B12, and this is often part of a more comprehensive standard blood test. One can also test vitamin B12 with a urine sample. It is important to inform your doctor if you take any medicine or supplements that may affect the result.

Interpretation of blood samples

According to the article in MedicalNewsToday, vitamin B12 levels are the following (and differ slightly from Danish values):

  • Normal: 200-900 ng/ml (nanograms per milliliter or nmol/liter). People with values below the lower part of this range should be tested again, especially if they have symptoms.
  • Low: Under 200 ng/ml. This is a sign of vitamin B12 deficiency, pernicious anemia, or an overactive thyroid gland. People with low levels often have neurological symptoms
  • High: Above 900 ng/ml. High levels can be harmless. However, they may also indicate liver or kidney problems, diabetes, or specific types of leukemia. A doctor or relevant specialist should normally be consulted in order to get a proper diagnosis.

Treating vitamin B12 deficiency with high-quality supplements

In the case of severe vitamin B12 deficiency, it is possible to begin with injections of the nutrient, as this often cures different symptoms rather fast. If the vitamin B12 deficiency is related to the diet, it is necessary to make dietary changes or to take a supplement of vitamin B12.
Vitamin B12 lozenges are highly assimilable because the nutrient is absorbed directly by the oral mucosa. A supplement should contain at least 2.5 micrograms, which is the daily reference intake level for the nutrient. For the treatment of pernicious anemia, which is a lifelong condition, one must receive continuous vitamin B12 injections because of the lack of intrinsic factor.

  • If vitamin B12 deficiency and pernicious anemia are not treated in ample time the symptoms may become disabling and the nerve damage irreversible.
  • The nerve damage is caused, among other things, by the fact that vitamin B12 is vital for the production of myelin that protects the nerve cells by forming a protective sheath around them. You can compare this sheath to the plastic cover on an electric wire.
  • The most common disabling neurological symptoms are fatigue, memory loss, and difficulty with concentrating


Jayne Leonard. What is the purpose of a vitamin B12-level test? MedicalNewsToday. 2020

Heidi Seage. Vitamin B12-mangel: Hvad er perniciøs anæmi, og hvorfor er det så farligt? 2019

Ebba Nexø. Vegetarer risikerer at få for lidt B12-vitamin. marts 2018

Trinity College Dublin. Many older adults are deficient in vitamin B12 and folate. ScienceDaily June 26, 2018

Vanita R Aroda et al. Long-Term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. Endocrine Society 2016

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