Vitamin B12 is an important building block in the formation of red blood cells - our oxygen carriers. It is necessary for the function and regeneration of nerves and in the metabolism of amino acids, fats and homocysteine, a risk factor for vascular calcification.
How vitamin B12 is absorbed and stored in the body
B12 must be absorbed through food, is found exclusively in animal foods and is then transported into the bloodstream via a special transport route – with the help of the so-called intrinsic factor. There is sufficient storage of B12 in the liver and muscles, so that no deficiency usually occurs with a balanced diet. This depot lasts for several years – the body has set this up so that this vital vitamin is always available in sufficient quantities. For this reason, however, a deficiency only becomes symptomatic years later.
How can a vitamin B12 deficiency develop?
People who follow a meat-free diet need to make sure they take a constant supplement and in individual cases it may be useful to determine B12. If there is a problem in the stomach and intestines with the absorption of vitamin B12, taking it as a tablet will not help to achieve normal levels. In these rare cases, the B12 must then be regularly injected into the muscle as a depot in order to be sufficiently available.
Chronic inflammation in the stomach can lead to too little “intrinsic factor” being produced and then no absorption via the gastrointestinal tract can take place even with sufficient intake. The frequently used diabetes medication metformin can also reduce the absorption of B12 in the small intestine.
Special vitamin B12 requirements during pregnancy, breastfeeding and in old age
Pregnant women and breastfeeding mothers also have a higher requirement and must pay particular attention to getting enough vitamin B12, preferably through their normal diet. B12 deficiency also often affects older people due to a decrease in stomach acid production or the long-term use of acid-blocking medication.
Pernicious anemia: when vitamin B12 absorption is impaired
Pernicious anemia, also known as Biermer’s disease, is an autoimmune disease in which the body’s own immune system attacks certain cells in the gastric mucosa, leading to autoimmune gastritis. In case of suspicion, a gastroscopy is performed and autoantibodies against parietal cells of the stomach and/or intrinsic factor are determined. In this potentially life-threatening disease, the intrinsic factor for the absorption of vitamin B12 in the stomach is completely absent, resulting in a severe long-term vitamin B12 deficiency with consequences for blood formation, neurological disorders and an inflamed tongue.
Briefly explained: What is an intrinsic factor?
Intrinsic factor (IF) is a protein that is formed in the stomach and absorbs vitamin B12 in the intestine. Without it, B12 cannot enter the bloodstream, no matter how much you eat.
Typical symptoms of vitamin B12 deficiency
The impaired blood formation with anemia causes fatigue, weakness, lack of energy and, in severe cases, pallor, rapid pulse, shortness of breath and dizziness. Nerve dysfunction can cause tingling and numbness in the extremities as well as memory problems.
A B12 deficiency can also be responsible for depressive episodes, anxiety disorders and mood swings and can lead to inflammation and ulcers throughout the digestive tract – starting in the mouth with aphthae and inflammation of the tongue (so-called Hunter’s glossitis).
How do you ensure a vitamin B12 deficiency?
An initial suspicion arises when the red blood cells are significantly enlarged in a simple blood count – an MCV > 100 fl is then noticeable – and no explanation for this can be found in the dietary habits.
An enlargement of the red blood cells can also occur as part of a folic acid deficiency, which is why the folic acid value is usually determined in the blood at the same time in these cases.
We determine the concentration of B12 via the so-called holotranscobalamin in the blood, which is the active form of B12 that is absorbed into the cells. A value of > 50 pmol/l indicates a good supply of vitamin B12. For values in the so-called gray area between 35 and 50, the determination of homocysteine and methylmalonic acid may be helpful to confirm a deficiency.
Should you simply take B12 to prevent a deficiency?
It is not advisable to simply take vitamin B12 as a precautionary measure. In case of doubt, a simple blood count will show whether there could be a deficiency without any major costs, and you can then get to the bottom of it if necessary. Overdoses manifest themselves in the form of acne or gastrointestinal complaints such as diarrhea or nausea.
Therapy for a vitamin B12 deficiency
If a vitamin B12 deficiency is detected in the blood via holotranscobalamin, the first question to be clarified is whether there are any dietary causes for this (vegetarian, vegan, malnutrition) or whether there is medication that favors this, such as metformin or acid blockers.
If the cause is suspected here, treatment with high doses of vitamin B12 in tablet form can initially be tried, with regular laboratory checks. If there is no improvement in the blood count over time, a gastroscopy must be performed and the autoantibodies determined.
If a deficiency or lack of intrinsic factor then becomes apparent, with the corresponding changes in the gastric mucosa, vitamin B12 must be regularly injected into the muscle as a depot.
