What is the role of vitamin B12 and how can you avoid having a deficiency?

What is vitamin B12? 

Vitamin B12, also known as cobalamin, refers to a family of 4 substances - 3 of which are present in certain foods. The 4th, called cyanocobalamin, is synthetic.

Cobalt is the central atom in vitamin B12. It can be provided by foods of animal origin and by the intestinal flora, and it is stored mainly in the liver.

Together with vitamin B9, vitamin B12 is involved in the synthesis of DNA and fatty acids, in the production of energy within cells and in the functioning of the nervous system.

What are the symptoms of vitamin B12 deficiency? 

Vitamin B12 deficiency leads to such symptoms as anaemia, shortness of breath, fatigue, tingling in the feet and hands, alternating constipation and diarrhoea, and weight loss.

Anaemia due to vitamin B12 deficiency develops gradually, allowing the body to adjust to the condition. In fact, symptoms can be mild even when the anaemia is severe, and include paleness, weakness and fatigue. Profound anaemia leads to breathing difficulties (dyspnoea), dizziness and increased heart rate.

In some people, vitamin B12 deficiency can lead to confusion, irritability, mood disorders and depression. When the deficiency is severe, it can lead to delirium, paranoia, problems with reasoning and memory, and impaired mental function, including dementia.

Who can be at risk of vitamin B12 deficiency? 

People following a vegetarian, vegan, strict macrobiotic or even flexitarian diet - diets in which meat consumption is significantly reduced or altogether absent - may be exposed to inadequate intakes of vitamin B12.

People who have undergone surgery as treatment for obesity - where part of the stomach has been removed - are also more likely to be affected by vitamin B12 deficiency.

The same applies to patients suffering with Biermer's disease (formerly known as pernicious anaemia).

Elderly people, whose stomach acidity decreases with age, are less able to absorb vitamin B12 from their food and are therefore prone to deficiencies.

How can vitamin B12 deficiency be diagnosed? 

Vitamin B12 deficiency is suspected when blood tests reveal the presence of large red blood cells.

Doctors tend to suspect vitamin B12 deficiency in people with typical symptoms of nerve damage, such as tingling and loss of sensation. To confirm the diagnosis, they measure the level of vitamin B12 in the blood.

Doctors usually also measure folate levels to rule out folate deficiency, as it can also result in the presence of large red blood cells.

In elderly people, if vitamin B12 deficiency is confirmed, no further tests need to be carried out, as the cause (reduced gastric acidity) is generally not serious.

But in younger people, other tests may be carried out to determine the cause of deficiency.

An endoscopy may be performed to see if there is any destruction of the gastric cells producing intrinsic factor.

How is vitamin B12 deficiency treated? 

Elderly people with a deficiency need to take supplements because it is usually due to difficulties in absorbing the vitamin B12 contained in meat. The vitamin from the supplements is more easily absorbed than that present in meat.

Treatment for vitamin B12 deficiency involves taking high-dose supplements of this vitamin. When people are deficient without showing symptoms, they can take an oral supplement. Blood tests should be carried out regularly to ensure that levels return to normal and remain there.

People with very low vitamin B12 levels or symptoms of nerve damage should receive intramuscular injections of vitamin B12. These injections are given daily or weekly over a period of several weeks, until levels return to normal, and can be self-administered. The frequency of administration is then reduced to once a month for an unlimited period of time, until the disorder causing the deficiency is cured.

Anemia due to vitamin B12 deficiency is cured on average within 6 weeks.

However, if severe symptoms due to nerve damage have lasted for months or even years, they may be irreversible. 

Which foods are rich in vitamin B12? 

Including foods rich in vitamin B12 in your diet is the best way to prevent deficiencies. Here is a list of foods naturally rich in vitamin B12: 

Foods of animal origin:

• Red meat,
• Poultry,
  
• Fish and seafood,
  
• Eggs,
  
• Dairy products.

For those following a vegan diet or who cannot consume enough foods of animal origin, here are a few options for foods fortified with vitamin B12:

• Plant milks,
  
• Certain types of breakfast cereal,
  
• Meat substitutes,
  
• Nutritional yeast.