4 min read

B12 - the Enigmatic Red Vitamin

Oliwia Kaczmarek ✓

Diets Premium Expert • 25.03.2026

✓

Scientifically reviewed by a clinical dietitian: This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.

Diets Premium Expert Oliwia Kaczmarek

min read 4 min

Scientifically reviewed by a clinical dietitian 25.03.2026

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B12 - the Enigmatic Red Vitamin

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Key Takeaways

In today's article, I will focus on vitamin B12, which performs an extremely important function in our body, and its deficiency can be dangerous. Vitamin B12 is also indispensable for athletes as it participates in the production of red blood cells and supports the functioning of iron.

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What is Vitamin B12, also known as the red vitamin

Vitamin B12 is a crucial component of nutrition that is essential for the functioning of the human body. The group of compounds containing cobalt includes adenosylcobalamin, methylcobalamine, hydroxycobalamin, and cyanocobalamin. Modern diets are often poorly balanced, leading to deficiencies in vitamin B12. For this reason, many people must take supplements to ensure adequate intake of this important nutrient. Vitamin B12 is necessary for the proper functioning of the nervous system, as well as for DNA synthesis and red blood cell production. As we age, our bodies lose the ability to absorb vitamin B12, so people over 50 should be mindful of adequate intake of this vitamin.

What constitutes vitamin B12?

Only animal products can serve as a source of vitamin B12, which is an unpleasant piece of news for those who consume a plant-based diet. This can lead to serious health issues such as complications related to anemia. The best sources of vitamin B12 are: - liver; - eggs; - kidneys; - lean meat; - fish; - dairy products. It was once thought that vitamin B12 also occurs in some plant-based products. However, it must be reiterated that this is not vitamin B12, but only a structurally similar compound that blocks the absorption of the proper vitamins.

The operation of Vitamin B12

Vitamin B12 has a substantial impact on our bodies. As previously mentioned, it plays a crucial role in the production of erythrocytes, thereby preventing anemia. Furthermore, as I have previously emphasized, it can regulate menstrual cycles in women with excessive and irregular bleeding. It also has a positive effect on the nervous system, participating in processes that increase brain productivity and improve concentration. This is especially important for young people and people who are mentally active. Moreover, it prevents damage to the nervous system and participates in the synthesis of metionine in the body cells, which refers to the production of amino acids. A lack of Vitamin B12 can disrupt this process, leading to disorders in the digestive system. Vitamin B12 also lowers the level of LDL, also known as bad cholesterol, and improves mood, showing antidepressant effects.

Inadequacy of Vitamin B12

An inadequacy of Vitamin B12 results in a number of serious symptoms. These include: – anemia; – delayed growth rate; – gastrointestinal issues: diarrhea or constipation; – muscle pain; – increased risk of cardiovascular diseases; – hair loss; – dermatological problems: acne, skin inflammation, rashes; – insomnia, mood swings, irritability, anxiety, depression; – motor disorders, dementia, difficulty concentrating and remembering; – numbness and tingling as well as functional impairments of the limbs.

Dosage

I've heard of some trainers aiming to build muscle mass who take Vitamin B12 through intramuscular injections. This results in considerable discomfort. Therefore, I advise against engaging in such practices. It's also worth noting that Vitamin B12 may have allergic effects, hence it should not be taken in excessive amounts. Below are the daily requirements for Vitamin B12: men and women - 2.4 mcg/d, pregnancy - 2.6 mcg/d. Vitamin B12 plays a crucial role, so it's advisable to ensure adequate provision in the body. This is particularly relevant for vegetarians and vegans.