Vitamin B12 deficiency: symptoms, diagnostics and treatment
Vitamin B12 is essential for the formation of red blood cells, DNA synthesis, and a healthy nervous system. A deficiency occurs much more frequently than thought and can have major consequences.
A B12 deficiency occurs more often than people think. The symptoms often develop gradually and the clinical picture is varied. A deficiency is easily overlooked. The normal value for vitamin B12 in the blood is 150-600 pmol/l, but unfortunately, a 'normal' vitamin B level does not rule out a vitamin B12 deficiency. During pregnancy and breastfeeding, and with aging, the vitamin B12 requirement is increased. With a vitamin B12 deficiency, methylation processes in the cell decrease and the level of homocysteine in the blood rises, which is a risk factor for cardiovascular disease.
Vitamin B12 is very safe. Whether you need extra B12 supplements depends on many factors. In addition to the value in the blood, we use the OligoScan to look at the value in the cells.
is the optimal B12 value that we use at HPV Health. The standard Dutch threshold of 140 pmol/l is often too low to detect subtle deficiencies.
How can a vitamin B12 deficiency develop?
The absorption of B12 from food is a complex process. Vitamin B12 from food is bound to proteins. In the stomach, B12 is released by stomach acid and pepsin. B12 then binds to intrinsic factor (IF), a protein produced by the stomach wall. This B12-IF complex is absorbed in the last part of the small intestine (ileum). After that, B12 is transported in the blood by transcobalamin.
Absorption can be disrupted at any point in this process. Consider:
- Reduced stomach acid production (e.g., due to antacids)
- Too little intrinsic factor (e.g., in autoimmune gastritis)
- Intestinal diseases affecting the ileum (e.g., Crohn's disease)
- Medication use (metformin, PPIs)
- Vegan or vegetarian diet without supplementation
- Genetic variants in methylation (MTHFR mutation)
Severe symptoms of B12 deficiency (A-criteria)
The following complaints are considered serious signs of a vitamin B12 deficiency:
- Chronic fatigue that does not improve with rest
- Concentration, memory, and word-finding difficulties
- Allergic complaints
- Autoimmune diseases
- Anemia
- Loss of strength in arms and legs
- Prickling, tingling, or numbness in hands and feet
- Severe psychological problems, including dementia and psychosis
Less specific complaints (B-criteria)
In addition to the severe symptoms, the following less specific complaints can indicate a B12 deficiency:
- Hair loss
- Mucosal problems
- Loss of appetite
- Depression
These complaints are often attributed to other causes, but can improve when the B12 deficiency is corrected.
Diagnostics: how do you determine a B12 deficiency?
Determining a B12 deficiency requires more than just measuring the serum B12 value. We recommend a combination of tests:
| Test | What is measured | Why it is important |
|---|---|---|
| Serum B12 | Total vitamin B12 in the blood | Initial screening, but can be false-normal |
| Active B12 (holotranscobalamin) | The bioavailable form of B12 | More accurate than serum B12 |
| Methylmalonic acid (MMA) | Rises in functional B12 deficiency | Confirms a deficiency at the cellular level |
| Homocysteine | Amino acid that rises with B12 and folate deficiency | Indicator for methylation activity |
Normal serum B12 values do not rule out a functional deficiency. Therefore, measuring MMA and homocysteine is essential for a reliable diagnosis.
Treatment of B12 deficiency
Treatment steps
Confirm diagnosis
Extensive blood testing with serum B12, active B12, MMA, and homocysteine.
Start oral supplementation
Active forms such as methylcobalamine or dibencozide.
Potential injections
In case of severe deficiency or reduced absorption via the intestine, B12 injections are used.
Monitoring and adjustment
After 3-6 months, values are checked again and the plan is adjusted.
Active forms of B12
Not everyone can properly convert the inactive form (cyanocobalamin) into the active form. This is especially true for people with an MTHFR mutation. In that case, we recommend the active forms directly:
- Methylcobalamine: the methylated form, directly available to the body
- Dibencozide (adenosylcobalamine): primarily works at the mitochondrial level
Homeopathic support can be used as a supplement in some cases.
B12 and the immune system
Vitamin B12 plays an important role in the production of white blood cells and the DNA synthesis of immune cells. A B12 deficiency can weaken the immune system, making the body less effective at fighting viruses, including HPV.
At HPV Health, we consider the status of vitamins and minerals important. Correcting a deficiency contributes to an optimally functioning immune system.
Do you recognize these symptoms?
A B12 deficiency is highly treatable. During a consultation, we map out your B12 status and create a targeted supplementation plan.
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Why do you use different normal values than my general practitioner (GP)?
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Does a B12 deficiency affect my HPV treatment?
Are B12 injections better than tablets?
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