Vitamin B12 deficiency living in children
Informed by recognized medical guidance
Overview
Vitamin B12 deficiency means your body does not have enough vitamin B12, a nutrient that helps make red blood cells and keeps your nerves healthy. In children, it can affect growth and development.
Key facts
- Vitamin B12 is found mostly in animal foods like meat, fish, eggs, and dairy.
- The body needs B12 to make healthy red blood cells and keep the nervous system working.
- Low B12 can cause tiredness, weakness, and problems with thinking and moving.
Vitamin B12 deficiency is not very common in children, but it can happen, especially in those who eat a strict vegan diet or have certain health conditions that affect nutrient absorption.
It affects children of all ages, but it is more common in those who are breastfed by mothers with low B12, eat a vegan or vegetarian diet, or have digestive disorders like celiac disease or Crohn's disease.
Symptoms
- Sudden trouble walking or moving
- Seizures
- Unconsciousness or difficulty waking up
- ⚠Severe tingling or numbness in legs or arms that comes on quickly
- ⚠Extreme weakness or inability to stand
- ⚠New confusion or acting very differently
Common symptoms
- Feeling very tired or weak
- Pale or yellowish skin
- Shortness of breath during play or exercise
- Dizziness
Symptoms in children
- Slow growth or weight gain
- Delayed milestones like walking or talking
- Irritability or mood changes
- Poor appetite or feeding problems
Symptoms in older adults
- Confusion or memory problems
- Numbness or tingling in hands and feet
- Difficulty walking or balance problems
Causes
Main causes
- Not eating enough B12-rich foods (common in vegan or vegetarian diets)
- Problems absorbing B12 from food, such as in celiac disease or after bowel surgery
- Breastfeeding from a mother with low B12 levels
Risk factors
- Strict vegan diet in the child or breastfeeding mother
- Digestive conditions like Crohn's disease, celiac disease, or atrophic gastritis
- Long-term use of medicines that reduce stomach acid
When to see a doctor
See a doctor urgently if:
- Your child has signs of nervous system problems, like trouble walking, numbness, or confusion.
- Your child is very pale, breathless, or extremely tired.
Book a routine appointment if:
- Your child has been eating a vegan diet and you want to check their B12 levels.
- Your child has ongoing stomach problems or poor growth.
Diagnosis
A doctor will ask about symptoms, diet, and health history, and then order a blood test to check B12 levels and other related markers.
Tests that may be done
- Blood test for vitamin B12 level
- Blood test for methylmalonic acid (MMA) and homocysteine, which can show B12 deficiency even when B12 is borderline
- Complete blood count (CBC) to check for anemia
What to expect at your appointment
The diagnosis is usually straightforward with a blood test. The doctor may also check for underlying causes like digestive issues. Treatment often starts quickly once the deficiency is confirmed.
Treatment
Treatment involves replacing the missing B12 and addressing any underlying cause. Most children respond well to treatment.
Self-care at home
- Include B12-rich foods like meat, fish, eggs, and dairy if the diet is not restrictive.
- If your child is vegan, you can add fortified foods like plant milks, breakfast cereals, and nutritional yeast.
Medical treatments
Treatment options include high-dose B12 supplements taken by mouth or given as a shot (injection) by a healthcare provider. The choice depends on the cause and severity. Injections may be used if there is a problem with absorption. Always follow your child's doctor's advice on which treatment is best.
When is surgery considered?
Not applicable. Vitamin B12 deficiency is treated with supplements, not surgery.
Living with this condition
Most children with B12 deficiency feel better within weeks of starting treatment. Regular blood tests may be needed to make sure levels stay normal.
Lifestyle tips
- Ensure your child gets enough B12 from food or fortified products every day.
- Keep a food diary if needed to track B12 intake.
- Tell all healthcare providers about the diagnosis, including school nurses or dietitians.
Diet and exercise
A balanced diet with B12-rich foods is important. If your child is vegan, talk to a dietitian. Exercise and play are encouraged as energy levels improve.
Mental health and emotional wellbeing
Low B12 can affect mood and cause irritability. After treatment, children often become happier and more energetic. If mood changes persist, talk to your doctor.
Prevention
Yes, in many cases. A diet that includes enough B12 – either from animal foods or fortified products – can prevent deficiency. Breastfeeding mothers who are vegan should take B12 supplements to protect their baby.
Vaccines
No vaccine prevents B12 deficiency.
Screening programmes
Routine screening is not needed for all children, but it may be recommended for those at higher risk, such as children with a vegan diet or chronic digestive problems.
Complications
If left untreated
- Anemia (low red blood cells) causing fatigue and pale skin
- Nerve damage leading to numbness, weakness, or trouble walking
- Growth delays and slower development in children
Long-term outlook
With early treatment, most children recover fully and have no long-term problems. If treatment is delayed, some nerve damage may take longer to heal, but improvement is still very possible. The outlook is generally excellent with proper care.
Find support
International organisations
- World Health Organization (WHO) – Nutrition
Local organisations
- NHS – Vitamin B12 deficiency · UK
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 29, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.