Prepared by Francisca Soto-Aguilar Bralic. MD, Ms Nutrition, Ms Global Public Health
Vitamin B12 (cobalamin) is a water-soluble vitamin essential for red blood cell formation, neurological function, and DNA synthesis. This vitamin is produced by microorganisms that live in the guts of animals, so dietary sources can be scarce (for any dietary pattern), especially in people who do not eat animal-based foods regularly. Deficiency in children can result in developmental delays, anemia, and neurological impairments. This guideline is intended to assist clinicians in evaluating and supplementing vitamin B12 in pediatric populations based on the Recommended Dietary Allowances (RDA) and clinical scenarios, with a special focus on children following plant-based diets.
Recommended Dietary Allowances (RDA) for Vitamin B12 for children
| Age Group | RDA (µg/day) |
|---|---|
| Infants 0-6 months | 0.4 µg* |
| Infants 7-12 months | 0.5 µg* |
| Children 1-3 years | 0.9 µg |
| Children 4-8 years | 1.2 µg |
| Children 9-13 years | 1.8 µg |
| Adolescents 14-18 years | 2.4 µg |
* Adequate Intake (AI) used when RDA not established
Diagnosis of Vitamin B-12 Deficiency
Optimal monitoring of B12 status includes dosage of serum homocysteine (HCY), methylmalonic acid (sMMA), and holo-transcobalamin II, along with serum total vitamin B12.
Normal B12 status is defined as holo-transcobalamin II > 45 pmol/L, sMMA < 271 nmol/L, and HCY < 10 µmol/L.
Serum total B12 is the most common and widespread method to define B12 status and should be considered optimal above 360 pmol/L, if holo-transcobalamin II is not available, as up to this level there is no increase in the markers of functional B12 deficiency.
Risk Factors for Deficiency
Health professionals should periodically assess vitamin B12 status in children with the following risk factors:
- Maternal deficiency (especially, but not only, in vegan/vegetarian mothers)
- Vegan or vegetarian diet
- Malabsorption syndromes (e.g., pernicious anemia, Crohn’s disease)
- Gastrointestinal surgeries (e.g., ileal resection)
- Long-term use of medications such as metformin, proton pump inhibitors
- Inborn errors of metabolism affecting B12 transport or processing
Supplementation Recommendations by Age Group
Infants (0-12 months)
- Infants of B12-deficient mothers: Assess and monitor deficiency signs and symptoms, supplement 1-10 µg/day orally or via formula fortified with B12 as soon as the mother’s deficiency is diagnosed (before 6 months of age), and consider taking serum B12 tests for a more comprehensive assessment. Mother intake and supplementation of vitamin B12 should also be corrected to improve breast milk concentrations for breastfeeding infants, and a B-12 fortified formula should be used for formula fed infants.
- Formula-fed infants of B-12 sufficient mothers: Typically do not require supplementation if formula is B12-fortified and there is no suspicion of mother’s B-12 deficiency during her pregnancy. At 6 months of age, when starting complementary feeding, infants following plant-based diets (vegetarian and vegan) should begin a B-12 supplement with 12 ug of vitamin B12 per day.
- Infants with vitamin B12 deficiency: Supplement with 12 ug of vitamin B12 3 times per day or a single daily dose of 250 ug for at least 1 month (if deficiency is severe or signs or symptoms of deficiency appear, consider hospital admission, parenteral supplementation and close monitoring of medical complications).
- Parenteral route may be considered instead of, or on top of, oral supplementation if preferred or if there are absorption disorders.
Children 1-3 Years
Routine supplementation is not needed for healthy omnivorous children.
At-risk children (including children following plant-based diets): 12 µg/day oral cyanocobalamin supplement is recommended. Children who eat B-12 fortified foods can meet their requirements in a plant-based diet when their intake of these foods is 3 times per day. However, given the complexity to achieve this intake and the importance of this nutrient in the children’s healthy development, a supplement is recommended as the primary source of vitamin B-12.
In deficiency: Therapeutic doses of 1000 µg/week IM or high-dose oral (250–500 µg/day), reassess after 1–2 months. See table with doses below.
Supplementation tables for maintaining normal B-12 levels and for deficiency treatment
| Daily Single Dose | Daily Multiple Dose | Weekly Dose | |
|---|---|---|---|
| Pregnant and lactating women | 50 µg 1 | 2 µg × 3 | 1000 µg × 2 |
| Children aged 6 months to 3 years | 5 µg | 1 µg × 2 | – |
| Children aged 4 to 10 years | 25 µg | 2 µg × 2 | – |
| Children aged 11 years and above | 50 µg | 2 µg × 3 | 1000 µg × 2 |
1 during pregnancy, taking this dose in two separate halves can increase B12 bioavailability.
| Serum B12 < 75 pmol/L | Serum B12 between 75 and 150 pmol/L | Serum B12 between 150 and 220 pmol/L | Serum B12 between 220 and 300 pmol/L | |
|---|---|---|---|---|
| Pregnant and lactating women | 1000 µg/day for 4 months | 1000 µg/day for 3 months | 1000 µg/day for 2 months | 1000 µg/day for 1 month |
| Children aged 6 months to 3 years | a daily single dose of 250 µg or 3 daily doses of 10 µg for 4 months | a daily single dose of 250 µg or 3 daily doses of 10 µg for 3 months | a daily single dose of 250 µg or 3 daily doses of 10 µg for 2 months | a daily single dose of 250 µg or 3 daily doses of 10 µg for 1 month |
| Children aged 4 to 6 years | 500 µg 4 times/week for 4 months | 500 µg 4 times/week for 3 months | 500 µg 4 times/week for 2 months | 500 µg 4 times/week for 1 month |
| Children aged 7 to 10 years | 500 µg 6 times/week for 4 months | 500 µg 6 times/week for 3 months | 500 µg 6 times/week for 2 months | 500 µg 6 times/week for 1 month |
| 11 years and above | 1000 µg/day for 4 months | 1000 µg/day for 3 months | 1000 µg/day for 2 months | 1000 µg/day for 1 month |
Forms of Vitamin B12 found in common supplements
- Cyanocobalamin: Most common, stable, cost-effective and more evidence for dosing
- Methylcobalamin
- Hydroxocobalamin: Longer-lasting, used in parenteral therapy
Monitoring and Follow-up
- Reassess vitamin B12 levels and clinical response 4–8 weeks after starting supplementation. In severe cases of deficiency, a closer assessment is encouraged (e.g. after 3-5 days after starting supplementation)
- On top of serum Vitamin B-12, monitor MMA (methylmalonic acid) and homocysteine levels if available, especially in subtle deficiencies.
- For long-term management, ensure ongoing dietary assessment and support.
Safety and Toxicity
- Vitamin B12 has no established upper intake level due to low toxicity.
- High doses (up to 1000 µg/day) are generally well-tolerated, including oral therapy.
Special Considerations
- Neurological symptoms: Treat aggressively; do not delay IM treatment.
- Vegan families: Educate on fortified foods and B12 supplements.
- Food fortification: Encourage use of B12-fortified cereals, plant milks and other B12-fortified foods.
References
- Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington (DC): National Academies Press (US); 1998. 9, Vitamin B12. Available from: https://www.ncbi.nlm.nih.gov/books/NBK114302/
- Baroni L, Goggi S, Battaglino R, Berveglieri M, Fasan I, Filippin D, Griffith P, Rizzo G, Tomasini C, Tosatti MA, Battino MA. Vegan Nutrition for Mothers and Children: Practical Tools for Healthcare Providers. Nutrients. 2018 Dec 20;11(1):5. doi: 10.3390/nu11010005. PMID: 30577451; PMCID: PMC6356233.