Vitamin B12 deficiency: causes, complaints and solutions

A vitamin B12 deficiency is uncommon. The reason for this is the fact that most people have a fair amount of B12 in their bodies. However, a deficiency can cause many complaints, especially complaints related to the nervous system and the production of red blood cells. How can this shortage arise? What are the symptoms of a vitamin B12 deficiency? How is the diagnosis made and more importantly: what can you do about it?

What does vitamin B12 do?

Vitamin B12 is very important for the proper functioning of your nervous system and for the production of red blood cells. Red blood cells ensure that oxygen is transported from your lungs via the blood to the rest of the body. Another name for vitamin B12 is cobalamin.

Causes of vitamin B12 deficiency

A deficiency of vitamin B12, also called vitamin B12 deficiency, can have many different causes. This includes:

Problems with your stomach

‘Intrinsic factor’ is a protein produced by the stomach lining and that is important for the absorption of B12. People who are deficient in this protein cannot absorb vitamin B12 (sufficiently). A deficiency of intrinsic factor can have various causes, such as: partial removal of your stomach (gastric reduction), damaged stomach lining or reduced stomach acid production (particularly in the elderly).

Problems with your small intestine

Vitamin B12 is absorbed in the last part of the small intestine. If you have inflammation in your small intestine – as may be the case with Crohn’s disease -, if part of your small intestine has been surgically removed, or if there is bacterial overgrowth in this part of the intestine, then B12 not properly absorbed. Insufficient B12 is also absorbed in intestinal diseases such as celiac disease.

Other causes

  • Very occasionally, a B12 deficiency can occur due to the use of medication;
  • A reduced intake of vitamin B12 due to avoiding animal products. For example, vegetarians do not eat meat and vegans do not eat animal products at all;
  • Alcoholics are also often deficient in this vitamin, because the kidneys excrete a large portion of vitamin B12 through excessive alcohol consumption.

Symptoms of vitamin B12 deficiency

Symptoms will not quickly occur if your body absorbs too little B12 from your diet. The cause of this lies in the fact that the body has large amounts of B12 in stock. However, if you take in too little for a long time, complaints may arise. Most of these complaints relate to the functioning of the nervous system and the production of red blood cells. With this you can think of:

  • Fatigue;
  • Anemia;
  • A twitching eyelid;
  • Tingling in the hands and feet;
  • Amnesia;
  • Muscle strain;
  • Muscle weakness in the legs;
  • Headache;
  • Mental health problems;
  • Concentration problems;
  • Loss of appetite;
  • Nausea;
  • Intestinal complaints.

However, the list of complaints that can be caused by a B12 deficiency is much longer. The above symptoms are only part of this.


Your doctor can determine whether you have a vitamin B12 deficiency through a blood test. According to the Dutch Association of General Practitioners, the blood value of B12 must be at least 148 pmol/l. In regular care (which includes the general practitioner), people talk about the incidental occurrence of symptoms at values between 148 and 260 pmol/l. However, alternative medicine uses a different minimum limit. It is assumed that a value of less than 300 pmol/l can cause complaints. Additional investigation is often necessary to determine the cause.

Resolve shortage

A deficiency can be resolved in three ways:

  • Through injections;
  • Through pills;
  • By adjusting the diet.

How the shortage can best be resolved depends on the cause. In many cases, additional research will be necessary after a Vitamin B12 deficiency has been diagnosed. Please note that the cause of a deficiency is not always found.

If it turns out that a person eats too one-sidedly or unhealthy, changing the diet can have a positive effect on the amount of vitamin B12 in the blood. Since vitamin B12 is almost exclusively found in animal products such as eggs, fish, meat and dairy products, these are the most important sources.

If your GP cannot prescribe B12 supplements because your blood values correspond to the values that are considered normal in regular care, you can contact an orthomolecular doctor. Since alternative medicine uses different standards, it may be possible that he can prescribe supplements or increase the value of your blood through injections.

You don’t have to be afraid of too much B12. Because it is a water-soluble vitamin, an excess is excreted by the body through the urine.

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