Cobalamin (Vitamin B12) deficiency and prevention

The Biomarker Handbook is a curated series that seeks to provide readers with insights on each biomarker we cover in our blood test packages and its relation to our body.


Vitamin B12 deficiency is relatively common, but in epidemiologic surveys, a great majority of cases are subclinical cobalamin deficiency (SCCD), rather than classical clinical deficiency. And because SCCD usually does not present with any symptoms, the only way to know if you have vitamin B12 deficiency is through screening for your blood vitamin B12 level.

One source of data suggests that 16% of the US population are vitamin B12 deficient.

The importance of tracking these biomarkers

SCCD does not have any clinical expression, therefore diagnosis depends solely on biomarker screening, whose optimal application is very important but remains unsettled.

Vitamin B12 is a key water-soluble vitamin. It plays an important role in red blood cell and DNA production, and proper functioning of the nervous system.

It is very important to track your level of vitamin B12 because this deficiency can lead to osteoporosis, anaemia, haematological disorders, cerebrovascular and cardiovascular diseases, and irreversible neurological damage.

Signs and symptoms to watch out for

In the classical vitamin B12 deficiency, these symptoms can arise:

Weakness and fatigue

This is a common symptom of cobalamin deficiency. When vitamin B12 is deficient in your body, you are unable to produce adequate numbers of red blood cells, which carries oxygen all over the body. Your body may even produce abnormal (in size and colour) red cells. As a result, your body fails to efficiently transport oxygen to the cells, causing the person to feel tired and weak.

Pale skin, heart palpitations, and shortness of breath

Vitamin B12 deficiency, when associated with anaemia, can cause pale skin, and your heart is in overdrive mode (pumping harder as your oxygen carrying capacity is reduced from the anaemia) leading to palpitations and shortness of breath to make up for the anaemia.


Paresthesia is a sensation of pins and needles. Hands and feet of the sufferer may have prickling sensation. This is a serious side-effect of long-term deficiency of vitamin B12, which causes nerve damage.

Changes to mobility

As mentioned earlier, Vitamin B12 deficiency, if left untreated, may damage nervous system and alter the way a person walks or moves. It may also affect balance and coordination, making the person more prone to falling.

Other symptoms include:

  • Smooth tongue
  • Mouth ulcers
  • Mood changes
  • Vision problem
  • High temperature
  • Loss of appetite
  • Constipation, gas, or diarrhoea

In general, your risk of developing vitamin B12 deficiency is increased if:

  • Your diet contains little to no natural B12 food sources. Vegetarians who don’t eat dairy products and vegans, who don’t eat any foods from animals, may fall into this category.
  • You are pregnant, and you are not taking any multivitamins. Vitamin and Folic acid supplements are especially important during pregnancy.
  • You have intestinal problems or other medical conditions that interfere with vitamin absorption. Abnormal bacterial growth in your stomach or surgery to your intestines or stomach can interfere with the absorption of vitamin B-12.
  • You abuse alcohol. Alcohol interferes with the absorption of vitamins.
  • You take certain prescription medications that can block absorption of vitamins. Antacids and some drugs used to treat type 2 diabetes may interfere with B-12 absorption.

Ways to balance cobalamin (Vitamin B12) deficiency

The best way to improve or prevent vitamin B12 deficiency is consuming foods rich in vitamin B12.

The foods include:

  • Organ meats, such as liver
  • Meat and poultry
  • Eggs, milk and other dairy products
  • Fish
  • Shellfish
  • Certain fortified cereals, grains, and yeasts.

Additionally, you may need to take vitamin B12 supplements. They are generally safe, as any excess vitamin B12 is excreted in the urine. Those who are at risk of developing B12 deficiency should consider taking supplements. Remember that certain antacids and diabetic medication (metformin) can affect the absorption of the supplement.

When should you see a doctor?

If you think you have anaemia, sensations of pins and needles, weakness, fatigue, heart palpitations, shortness of breath, see your doctor. Vitamin B12 or cobalamin deficiency if left untreated can negatively affect your health with anaemia, nerve damage (irreversible), psychological (depression, anxiety) or heart effects.

What further testing are needed to check for illness related to vitamin B12?

If vitamin B12 deficiency is detected in your blood test, the doctor may need to perform additional tests to determine the cause and type of deficiency:

Antibodies test. This detects presence of antibodies to intrinsic factor. Presence of these antibodies indicate pernicious anaemia.

Other vitamins and minerals. Being vitamin B12 deficient, you will benefit from a comprehensive vitamin and mineral work up including vitamin D, iron studies, folic acid, calcium, magnesium, phosphorous, sodium, potassium.

Full blood count. Being vitamin B12 deficient, you are at risk of developing a megaloblastic anaemia which can be diagnosed with a full blood count and blood film.

To conclude, cobalamin is essential to the human body. It is needed for the body to make red blood cells, synthesise DNA, regulate nerves function, and perform other functions. The human body does not produce vitamin B12 naturally, therefore, it must be taken from food or supplements. Vitamin B12 deficiency may cause anaemia, nerve damage, psychological and neurological diseases. Certain people are at higher risk of developing vitamin B12 deficiency, and need to improve their dietary intake and consider taking supplements.

If you want to find out more about managing a vitamin B12 deficiency and how you can balance cobalamin levels, take a look at our lifestyle article here!

Interested in other biomarkers? Check out the rest of The Biomarker Handbook.

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