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Vitamin B12 in a child's diet - function, occurrence, deficiency, and supplementation
Kacper Nowak
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Diets Premium Expert • 18.03.2026
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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 Kacper Nowak | min read 4 min | Scientifically reviewed by a clinical dietitian 18.03.2026 |
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Key Takeaways
Vitamin B12 is the sole vitamin compound that is produced solely within prokariotic cells. Simultaneously, it is indispensable in the daily diet of humans and animals to prevent the development of malignant forms of anemia.
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Cobalamin, commonly referred to as Vitamin B12
Cobalamin is also known as Vitamin B12 due to the central position of a cobalt atom in this compound. The earliest mentions of Cobalamin date back to 1920 when Whipple and colleagues discovered that administering raw liver to dogs with uremia accelerated their recovery. In 1934, Minot and Murphy discovered that a substance in the liver, together with iron, prevented the development of uremia. All three scientists researching this organ were awarded the Nobel Prize in 1934. Fourteen years later, Rickes and his team isolated a reddish compound from the liver, which they named Vitamin B12 and later Cobalamin.
The action of vitamin B12
Vitamin B12, much like folic acid and iron, is vital for the production of erythrocytes, cells responsible for the transportation of oxygen and carbon dioxide in the body, which ensures proper oxygenation of tissues and the possibility of numerous metabolic processes. Vitamin B12 also plays a crucial role in the transformation and metabolism of proteins, carbohydrates, fats, and the synthesis of DNA, amino acids, and bone marrow proteins. It is indispensable for the proper functioning of the nervous system as it participates in the construction of myelin sheaths and neurotransmitters as well as the correct operation of the digestive tract. Furthermore, the contribution of cobalamin in preventing atherosclerosis, multiple sclerosis, and heart diseases is significant.
Inadequate amount of vitamin B12 in children - potential causes and consequences
Vitamin B12 deficiency may occur in young children, as this is the time when the supply of cobalamin stored in the liver during fetal life can become depleted. However, if we expand the child's diet appropriately with meat, fish, eggs, milk, and dairy products, this situation should not occur. In children who follow a vegan or vegetarian diet and in those who have impaired DNA absorption in the digestive tract, insufficient cobalamin may occur along with the diet, which should be supplemented by introducing dietary modifications or consulting with specialists. A vitamin B12 deficiency promotes the occurrence of megaloblastic anemia (due to a deficiency of vitamin B12 and folic acid), as it inhibits the maturation and division of red blood cells. Lack of sufficient cobalamin increases the susceptibility of DNA to damage and promotes neurological diseases (ataxia, paralysis of the limbs, polyneuritis, lethargy).
Availability of Vitamin B12
Vitamin B12 is mainly present in animal-derived products since it does not naturally occur in plants. In addition, cobalamin can be produced by microorganisms found in the digestive tract of herbivores (e.g. cows) and in small amounts by the bacterial microflora of the intestine in humans. The most common sources of vitamin B12 are listed in the table below. Food product Vitamin B12 content [µg] Drinking milk 2.0% and 3.2% Full milk powder Natural yogurt 2% Full fat cheese Cottage cheese Eggs Beef liver Chicken liver Lean turkey breast Fresh cod Fresh salmon 0.4 2.4 0.5 1.7-2.2 0.9 1.6 110.0 35.0 0.7 1.0 5.0 Important According to the opinion of the Expert Group from 2016, published in the Medical Standards for pediatrics, concerning the nutrition of infants after completing 6 months of age, lean, cooked meat should be introduced into the infant's diet in a portion of 10 g daily, so that before completing 1 year of age, the child consumes double the original portion. In the case of offal (liver, liver), these should be introduced into the diet only after completing 3 years of age. Eggs can be given whole from 9 months of age.
Supplementation of Vitamin B12 – recommended
In a study conducted by Sochacka-Tatar, which assessed the nutrition of pre-school children, it was found that in the Krakow group of children studied, the need for vitamin B12 in the food consumed was exceeded twice. The likely cause of this phenomenon is high meat intake, which is a source of cobalamin (protein demand was also exceeded in the study). Unnecessary supplementation is not required and should not be used too frequently. However, in children who do not consume animal products such as meat and fish, eggs and dairy products, i.e., those following a vegan diet, supplementation with vitamin B12 is recommended to avoid deficiencies. Similarly, in cases of diseases accompanied by signs of poor absorption of nutrients in the digestive tract. In these situations, after consulting a specialist, supplementation of vitamin B12 is recommended to avoid dangerous deficiencies and the occurrence of malignant anemia. Supplementation of vitamin B12 is and should be used in Addison's disease, Biermer's disease, anemia with vitamin B12 deficiency, polyneuritis, and liver diseases.
Kacper Nowak
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