# Vitamin B12: Who Really Needs It and Who Just Thinks They Do

> Vitamin B12 is the most frequently overlooked nutrient deficiency. Who is affected, what are the signs and what really matters when supplementing?

Vitamin B12 is an essential micronutrient whose importance is often misunderstood. While some people supplement reflexively, others ignore the potential risks of a deficiency. Yet for certain population groups, an adequate supply of B12 is indispensable to avoid long term and sometimes irreversible health damage.

## The Role of Vitamin B12 in the Body

Cobalamin, better known as vitamin B12, is involved in two critical enzymatic processes: **methylation** and the conversion of methylmalonyl-CoA to succinyl-CoA. Methylation is crucial for **DNA synthesis** and the regulation of homocysteine levels. The second function is important for **fatty acid metabolism** and the myelination of nerves. The European Food Safety Authority (EFSA) confirms that B12 contributes to normal nervous system function, blood formation and the reduction of fatigue.

## The Gradual Development of a Deficiency

The human body is able to store vitamin B12 for several years. As a result, a deficiency often only becomes **noticeable with a delay**, typically after two to five years of inadequate intake. Early signs of a B12 deficiency can be unspecific and include **fatigue, concentration problems, tingling in the extremities, pale skin** and low mood. The gradual nature of the deficiency makes early detection difficult without targeted diagnostics.

## Risk Groups for B12 Deficiency

Certain groups of people have an increased risk of vitamin B12 deficiency. **Vegans** are particularly at risk, since biologically active B12 is found almost exclusively in animal products. **Vegetarians** can also develop a deficiency if they consume little dairy and few eggs. In **people over 50**, the production of intrinsic factor declines, which impairs B12 absorption. Medications such as **metformin** and **proton pump inhibitors (PPIs)** can also interfere with B12 absorption by reducing stomach acid or inhibiting uptake in the gut.

## Forms and Dosage of Vitamin B12

There are various forms of vitamin B12. **Cyanocobalamin** is an inexpensive and stable form that the body has to convert. **Methylcobalamin**, on the other hand, is an already active form that can be used directly. For basic daily coverage, 10 to 50 µg is generally recommended. It is important to note that algae such as spirulina or chlorella are **not reliable B12 sources**, since they often contain B12-like pseudovitamins that can actually interfere with the absorption of real B12.

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## Frequently Asked Questions

**How do I recognize a vitamin B12 deficiency?**
A vitamin B12 deficiency can manifest through symptoms such as fatigue, concentration problems, tingling in the hands and feet, and low mood. An accurate diagnosis is made through a blood test, ideally of the holotranscobalamin value.

**Which foods contain vitamin B12?**
Vitamin B12 is mainly found in animal products such as meat, fish, eggs and dairy. Plant foods generally contain no biologically active B12.

**Is an overdose of vitamin B12 dangerous?**
Vitamin B12 is water soluble, and excess amounts are normally excreted via the kidneys. An overdose is therefore rare and considered harmless, but the recommended dosage should not be exceeded unnecessarily.

## Sources

EFSA NDA Panel (2015), Scientific Opinion on Dietary Reference Values for cobalamin.
Pawlak R et al. (2013), Eur J Clin Nutr - How prevalent is vitamin B12 deficiency among vegetarians?
Herrmann W & Obeid R (2008), Dtsch Arztebl Int - Causes and early diagnosis of vitamin B12 deficiency.