Vitamin B12 (Cobalamins): Multitalents for Cell Formation, Energy, and Nervous System Strength

These compounds play a key role in energy production, nerve function, and blood formation. Since they occur almost exclusively in animal-based foods, they are considered a “critical” nutrient—especially for people following a vegan or vegetarian diet.

In this article, you will learn why vitamin B12 is so important, what the consequences of a deficiency can be, and how to ensure an optimal supply.

We Are Many – The Main Forms of Vitamin B12 at one Glance¹

“Vitamin B12” is not a single molecule but a whole group of chemically related compounds collectively referred to as cobalamins. The term is commonly used as a synonym, but it actually encompasses all substances with the same biological activity.

An overview of the most important forms:

·       Cyanocobalamin – the most commonly used synthetic form in dietary supplements.

·       Hydroxocobalamin – frequently used medically by injection, as it can be stored in the body for longer.

·       Methylcobalamin – the active coenzyme form in cellular metabolism.

·       Adenosylcobalamin – another biologically active form, essential for energy production in the mitochondria.

All these forms belong to the cobalamin group, whose central structural element is a cobalt ion – hence the name. This diversity explains why different terms are used in literature and clinical practice.

For Body and Mind – The Key Functions of Vitamin B12²

Unlike other B vitamins, vitamin B12 can be stored in the liver for years. Nevertheless, regular intake is essential, as the body cannot produce it on its own.

Main functions:

•        Protection of the nervous system: Builds and maintains the myelin sheaths.

•        DNA synthesis and cell division: Works closely with folate. 

• Energy and vitality: Contributes to energy metabolism.

•       Homocysteine reduction: Supports cardiovascular health.

Signs and Causes of Vitamin B12 Deficiency³

A deficiency often develops gradually, since body stores can last for years. However, when it occurs, the consequences can be severe:

·       Persistent fatigue and weakness

·       Tingling, numbness (neuropathies)

·       Psychological changes (e.g., depressive symptoms)

Possible causes can be:

•    Strict vegan or vegetarian diet without supplementation

•  Malabsorption due to gastrointestinal diseases (e.g., Crohn’s disease, celiac disease)

•  Intrinsic factor deficiency (pernicious anemia)

• Medications such as proton pump inhibitors or metformin 

• Increased demand during pregnancy and breastfeeding

Vitamin B12 – Medical Applications

From these facts, the medical applications of vitamin B12 follow logically:

•  Support of blood formation: B12 is indispensable in the treatment of pernicious anemia (Langan et al., 2011).

• Cardiovascular health: Together with folate and B6, B12 lowers elevated homocysteine levels, which are associated with atherosclerosis and stroke (Lonn et al., 2006).

• Neurology: Supplementation can be beneficial in polyneuropathies, dementia, and depression (Moore et al., 2012).

• Prenatal development: Deficiency increases the risk of nervous system malformations in the unborn child (Molloy et al., 2009).

Vitamin B12 – Daily Requirements and Reference Values⁴

As with many B vitamins, the values given here are considered minimum intake levels—the lower limit required to avoid deficiency, not necessarily the amount for optimal supply.

According to the German Nutrition Society (DGE), the requirements are as follows:

•            Adults: 4.0 µg/day

•          Pregnant women: 4.5 µg/day

•          Breastfeeding women: 5.5 µg/day

• Children (depending on age): between 1.5 and 3.5 µg/day

How to Cover the Requirement ...

Foods Rich in Vitamin B12⁵

Examples include:

Plant-based foods contain no relevant vitamin B12. For this reason, supplementation or the consumption of fortified foods is essential, e.g. for people following a vegan diet.

Supplementation Options⁶ ⁷

Other groups who benefit from targeted supplementation include pregnant women, breastfeeding women, and the elderly.

Vitamin B12 supplements are available as:

•         Tablets

•         Lozenges

•         Drops.

In cases of malabsorption, injections (usually hydroxocobalamin) are the standard therapy.

FAQ –  Frequently Asked Questions About Vitamin B12

1. Does vitamin B12 status affect mental health?

Yes, studies show that low vitamin B12 levels are also associated with cognitive decline and memory problems. Supplementation can help slow the progression of cognitive impairment.

2. Can vitamin B12 increase energy levels in healthy people?

Vitamin B12 is essential for energy metabolism. However, supplementation only improves performance in cases of deficiency.

3. How reliable are blood tests for detecting vitamin B12 deficiency?

Standard serum B12 tests can be misleading, as they measure total B12 but not the active forms. More accurate markers include holotranscobalamin (active B12), methylmalonic acid (MMA), and homocysteine.

4. Is vitamin B12 absorbed equally well from food and supplements?

Absorption from food requires stomach acid and intrinsic factor, which may be impaired in older adults or people with gastrointestinal conditions. Supplements often bypass this step and are therefore more reliable.

5. What can cause impaired absorption of vitamin B12?

o   Stomach problems, e.g., chronic gastritis or reduced stomach acid production with age.

o   Intrinsic factor deficiency, as in pernicious anemia, where the protein required for B12 absorption in the small intestine is lacking.

o   Intestinal diseases, such as Crohn’s disease, celiac disease, or after small intestine surgery.

o   Medications, such as proton pump inhibitors, metformin, or certain antibiotics, which can impair absorption.

6. Can vitamin B12 be overdosed?

Vitamin B12 is considered very safe. There is no established tolerable upper intake level (UL), since even very high doses have not shown toxic effects in studies. Excess amounts are usually excreted in the urine. Side effects (such as rosacea) are therefore extremely rare.

Vitamin B12 – The Essential Energy Vitamin

From nerve protection and mental clarity to blood formation and lasting vitality – vitamin B12 is indispensable. Those following a plant-based diet, as well as pregnant and older individuals, should pay special attention to their intake. Ensuring optimal levels can make a decisive difference for long-term health.

For more information, feel free to read our other blog articles—also on B vitamins—and visit our online shop. There you will also find the volumes of our Codex Humanus and the Medizinskandale series, where B vitamins are also discussed.

Sources:

·  ¹ ² ⁶      https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

·       ³      https://www.ncbi.nlm.nih.gov/books/NBK441923/

·       ⁴      https://www.dge.de/wissenschaft/referenzwerte/vitamin-b12/

·       ⁵      https://www.vitalstoff-lexikon.de/Vitamin-B-Komplex/Cobalamin-Vitamin-B12/Lebensmittel

·       ⁷      https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/

·       Langan, R. C. et al. (2011): “Update on vitamin B12 deficiency,” Am Fam Physician.

·       Lonn, E. et al. (2006): “Homocysteine lowering with folic acid and B vitamins in vascular disease,” N Engl J Med.

·       Moore, E. et al. (2012): “Cognitive impairment and vitamin B12: a review,” Int Psychogeriatr.

·       Molloy, A. M. et al. (2009): “Maternal vitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic Acid fortification,” Pediatrics.