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Children and B12

B12 deficiency affects all ages.

A baby in the womb can be affected by B12 deficiency and so can a new born.

It is crucial to have your child tested if B12 deficiency is suspected.  There should be no delay in diagnosis and treatment as symptoms in children may not be completely reversible. If you feel you need personalised help please see the contact page for more information. 

The 'What to do next' page is your 'crash course' in B12 deficiency.

We have also developed an app to help determine your risk of B12 deficiency.


The lists below are provided with kind permission of Sally M. Pacholok R.N. & Dr. Jeffrey J. Stuart Co authors of Could it be B12? and Could It Be B12? Paediatric Edition: What Every Parent Needs to Know

Signs & symptoms in infants and children 

  • Developmental delay or regression
  • Apathy - Irritability
  • Hypotonia (decreased muscle tone)
  • Weakness
  • Tremor
  • Involuntary movements
  • Seizures (fits)
  • Ataxia (Neurological disorder affecting balance, coordination and speech)
  • Anorexia and other eating disorders
  • Failure to thrive
  • Poor weight gain
  • Poor head growth
  • Poor socialisation
  • Poor motor skills
  • Language delay
  • Speech problems
  • Lower IQ - Intellectual disability
  • Anaemia
  • Macrocytosis (large red blood cells) Note - need not be present!

Red flags of B12 deficiency in infants, children and teenagers

If your child exhibits any of the following signs or symptoms, insist that your doctor tests for B12 deficiency make sure to get a copy of the results. Please see this link for more information. 

  • Movement problems, including difficulty in walking or writing
  • Mental changes - irritability, altered mood, poor memory, "flat" emotional tone, autistic-like withdrawal
  • Vision problems/abnormalities
  • Slowed weight and height gain
  • Leg pains or other abnormal sensations
  • Fatigue
  • Loss of appetite
  • An abnormally small head circumference in infants or toddlers
  • Apathy, lethargy, or irritability
  • Involuntary movements, such as arm waving in infants or toddlers
  • Tics
  • Grey hairs / premature greying
  • Areas of hypo pigmented skin in a Caucasian child and/or vitiligo, or areas of hyper pigmented skin in a black or Asian child
  • A rooting reflex after eight months of age (this reflex is usually absent after six months of age
  • A history of any surgery (including dental surgeries) involving nitrous oxide. This anaesthetic agent is often administered during dental work or surgeries such as insertion of ear tubes in children with chronic ear infections, can inactivate the body's stores of B12 and cause severe neurological damage
  • Failure to thrive (poor appetite, poor growth and/or weight gain, general poor health)
  • Chronic constipation
  • A diagnosis of developmental delay, autism, cerebral palsy, Intellectual disability, or other neurological disorder
  • Severe food allergies or sensitivities
  • A diagnosis of coeliac disease or gluten enteropathy
  • A thyroid disorder or other autoimmune disorder
  • A history of stroke or a diagnosis of arteriosclerosis
  • A diagnosis of any psychiatric or behavioural disorder including ADHD
  • A diagnosis of Downs Syndrome


Waiting for months on an NHS list to see a paediatrician could mean that the essential window for optimum recovery may be missed. Please visit our Case studies page to read about Tom and JJ. We also have a page to help with writing to your doctor and this blog post details more options too.

There is a separate hydroxocobalamin BNF Guideline for children which should be pointed out to your GP.  

If your child has a vegetarian or vegan diet they have an increased risk of B12 deficiency. Please visit the vegetarian page and the Causes page.

Please also see the Pregnancy page Nitrous oxide administration can have devastating consequences in a B12 deficient patient. 

Please note: Serum B12 levels in symptomatic children can often fall 'within range' please see the NEQAS B12 alert to read about 'false normal' results and the risk of neurological damage without treatment. It is vital that you see a copy of the results. you are legally entitled to these.  Please see this link for more information. 

If your doctor will not provide treatment based on your child's symptoms, further tests must be carried out. For information on homocysteine, MMA and Active B12, please visit the testing page. Prior supplementation of B12 could skew test results so please let your doctor know this.

We have produced a strong organic cotton bag with an image of a child to help you to raise awareness on the street, click here to buy. 

Click here to read about the unreliability of the serum B12 test.

Click here to read journals on B12 deficiency in infants and children.

Click here to read about Inborn errors of B12 metabolism.


You can help us to raise awareness of B12 deficiency in children with our strong organic shopper. Click on the bag below.

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The information below provided with kind permission of Sally M. Pacholok R.N. & Dr. Jeffrey J. Stuart.

Mothers with depleted B12 stores...

...who exclusively breast feed their babies unknowingly put them at great risk for developmental disability or even death. This is a common cause of B12 problems in infants; one study for instance, found that a group of six infants became ill after being nursed by vegetarian mothers. (The other half were born to mothers with undiagnosed pernicious anaemia).

Vegetarian and vegan mothers are devastated and feel tremendous guilt when their children suffer harm due to B12 deficiency, but in reality, most of these tragedies are the fault of doctors who fail to screen pregnant and nursing mothers for this deficiency - and who then often misdiagnose these women's children as intellectually disabled or autistic, rather than considering B12 deficiency when the infants lose their speech, social skills and motor skills.

Documentary on B12

Elissa Leonard's documentary on B12 deficiency features Lennon and JJ, two children who were permanently damaged through lack of early diagnosis and treatment of B12 deficiency.

If you value this website, consider donating. Donations support the free information provided on and it's blog, which help those with B12 deficiency world wide.

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