Vitamins and Minerals

What is vitamin B12?

Written by

Lauren Dobischok
16 May, 2022

Medically checked article All HOMED-IQ content is reviewed by medical specialists

Vitamin B12, often referred to as cobalamin, is an essential component of the vitamin B complex. It is found in a number of foods and beverages that we consume on a daily basis. Adequate levels of vitamin B12 are essential as a deficiency can lead to a variety of physical ailments. Have you ever wondered if your vitamin B12 level is in the optimal range? Read on to learn more about vitamin B12 and its importance for the human body.

What is vitamin B12?

Vitamin B12 is the best-known B Vitamin and, like the other B vitamins, it is water-soluble. It is the only B vitamin of which your body has a reserve, located in the liver. This stock can remain in the body for approximately three years, and sometimes even longer. Vitamin B12 is found in certain animal products and is bound to protein in food. The acid in our stomach ensures that the protein of vitamin B12 is decoupled. Later in the small intestine, vitamin B12 binds to a new protein called Intrinsic Factor which is made in the stomach and allows for absorption into the body to occur (Nutrition Center).

What foods contain vitamin B12?

Vitamin B12 is mainly present in animal products, such as :

  • Meat, fish, and poultry 
  • Milk products 
  • Eggs

While less concentrated you can also find the vitamin non animal products, such as:

  • Algae and dried seaweed
  • Fortified breakfast cereals
  • Nutritional yeast

Why is vitamin B12 important?

Vitamin B12 has a number of crucial functions in the human body:

  • Formation of red blood cells: These cells are responsible for transporting oxygen in the blood.
  • Maintenance of brain and nerve cells: Vitamin B12 supports the functionality and health of these cells.
  • DNA production: As an essential building block of our genetic code, vitamin B12 is involved in the synthesis of DNA.
  • Cell metabolism: Vitamin B12 plays a key role in various metabloic processes at the cellular level.

What is a healthy vitamin B12 level?

The target values of vitamin B12 are 150 – 750 pmol/l, or 0.15 and 0.75 nmol/l

In most tests serum B12, also known as total B12 value, is examined. However, a good B12 value does not mean that a deficiency does not exist. For example, it may be that a person falls under the lower limit for vitamin B12, but has no symptoms. Another person may have a value within the healthy range, but still have symptoms of low vitamin B12 (Nederlands Huisartsen Genootschap, 2018). That is why it is important to view the result of a vitamin B12 test in conjunction with existing symptoms that may indicate a vitamin B12 deficiency.

Is too much or too little vitamin B12 harmful?

A deficiency of vitamin B12 can lead to a number of health problems. These include anemia, neurological disorders and difficulties with DNA synthesis. These symptoms can take the form of fatigue, weakness, memory problems and other neurological complaints. On the other hand, while it is rare that excessive intake of vitamin B12, especially through supplements, has harmful effects, as the body normally excretes excess vitamin B12 through the urine. However, some studies suggest that extremely high levels of vitamin B12 in the blood may correlate with an increased risk of death. However, this correlation is still the subject of research.

It is always advisable to discuss the intake of vitamins and food supplements with a doctor to ensure that one is within health-promoting limits (Flores-Guerrero et al., JAMA Network Open, 2020).

The causes of vitamin B12 deficiency

There are various causes for vitamin B12 deficiency. The main causes are as follows:

  • Eating too few animal products (vegans, vegetarians)
  • Problems absorbing vitamin B12 into the body
  • Drinking too much alcohol
  • Long-term intake of antacid tablets
  • Frequent use of laughing gas
  • Diseases, for example an autoimmune disease

What symptoms are associated with a vitamin B12 deficiency?

The symptoms of vitamin B12 deficiency differ per individual. Symptoms can be divided into three groups, namely neurological complaints, psychological complaints and other  complaints (Thuisarts, 2018).

Neurological symptoms:

  • Tingling
  • Reduced sensation in the fingers or toes
  • Struggling to find words: aphasia
  • Difficulty walking, tripping, falling, or bumping into something: ataxia

Psychological symptoms:

  • Depressed feelings and thoughts
  • Confusion
  • Irritability

Other complaints with vitamin B12 deficiency:

  • Pale skin (due to extreme anemia)
  • Feeling weak
  • Fatigue
  • Low appetite, weight loss
  • Burning tongue
  • Nausea
  • Muscle pain
  • Gastrointestinal problems

Are there any diseases related to vitamin B12 deficiency?

It is possible for an autoimmune disease to cause a deficiency of vitamin B12. In that case, the reason is impaired absorption because intrinsic protein is not sufficiently produced in the stomach. In the case of colorectal cancer, stomach cancer, atrophic gastritis, or pancreatic insufficiency there may also be a reduced absorption of nutrients from food, leading to a deficiency.

What can I do if my vitamin B12 level is abnormal?

To ensure adequate vitamin B12 intake it is important to eat a varied and healthy diet. Vegetarians are advised to consume egg or milk products daily, and vegans are recommended to choose products that are fortified with vitamin B12. In the event of a vitamin B12 deficiency, it is of course also possible to take vitamin B12 as a supplement. 

How long does it take for vitamin B12 deficiency to be reversed?

Although this varies from person to person, it takes an average of eight to sixteen weeks before vitamin B12 deficiency is reversed. In severe deficiencies, this can take six months to a year.

Testing Vitamin B12

A simple blood test can indicate the level of vitamin B12 in your blood and can reveal whether any deficiencies exist. It is now possible to test your vitamin B12 level at home using Homed-IQ’s Vitamin Deficiency Test, a test that also measures essential vitamins folic acid and Vitamin D. This vitamin test involves a blood sample collected at home via a finger prick, after which a certified laboratory analyzes the sample and determines the results.

How often should you test your vitamin B12 level?

There is no recommended frequency to test vitamin B12. If an initial test shows that there is a deficiency, you have the option to take action to increase the value. It is then advisable to perform another test after three months to see whether the value has increased.

If you experience symptoms related to a vitamin B12 deficiency and find that they do not disappear within three months after beginning vitamin B12 tablets, it is wise to contact your doctor. Has the deficiency and symptoms disappeared with the use of supplements? In that case, it is possible to take the supplement for another three months and then stop and see whether the symptoms return or not.

Is Homed-IQ’s vitamin B12 test reliable?

Yes, all vitamin B12 tests – like all our other home tests – are processed and analyzed in a certified laboratory. These labs are also used by general practitioners, hospitals and other medical specialists.

Is this vitamin B12 test an alternative to a blood test via the GP?

Yes. A doctor checks vitamin B12 levels using the same laboratory analysis offered by Homed-IQ. The only difference with a home test is that you can take the sample required for the test anonymously, from the comfort of your own home, and at a time of your choosing.

How does the Homed-IQ vitamin B12 test process work?

Homed-IQ’s test process is very simple. After pricking your finger using the supplied lancet, you collect a few drops of blood in a sample collection tube. Next, use the supplied shipping bag and the return envelope to send your sample to the lab for analysis. Your results will be ready within a few days.

About the author

Lauren Dobischok

Lauren is a health scientist and science communicator currently living in the Netherlands. Originally from Canada, she completed a Research Master’s in Health Sciences at the Netherlands Institute of Health Sciences at Erasmus University Rotterdam (NIHES) with a specialisation in epidemiology. Prior to her master’s degree, she completed a Bachelor’s degree in Health Sciences at Simon Fraser University. With a background in public health, her goal is to create accurate scientific content that is easy to understand and empowers people to make informed decisions. Within Homed-IQ, Lauren works as a Product Developer and Content Lead, working closely with physicians and scientists on medical devices for Homed-IQ’s new products and written communications.