Lesser Known Causes of Chronic Constipation in Children

Chronic constipation is fairly common amongst children but it’s important to point out, it’s not normal. While our first assumption is its usually caused by reduced fibre and water intake, there are a few other factors which may causing these gastrointestinal symptoms (1). 


Vitamin B12 

Recent evidence suggests that Vitamin B12 deficiency in children occurs more often than originally assumed (2). The clinical manifestations of vitamin B12 deficiency in children varies from developmental delays to digestive complaints (2,3). While constipation alone may does not automatically indicate B12 deficiency, it can occur due to the autonomic nervous system dysfunction associated with vitamin B12 deficiency (3). Gastric emptying of solids and liquids depends on complex neurohormonal interactions which rely on vitamin B12 (3). 


Other Symptoms of Vitamin B12 deficiency 

  • Weakness

  • Fatigue

  • Lack of appetite

  • Delay in growth

  • Developmental delay or even regression

  • Irritability

  • Tingling or burning sensation (in extremities)

  • Hypotonia (low muscle tone)

  • Reduced tactile sensation

  • Seizures

  • Ataxia (lack of muscle control)

  • Symptoms of paralysis

  • Involuntary movements

  • Concentration problems

  • Memory disorders

  • Personality changes

  • Depression

  • Hyperpigmentation of the skin

  • Vomiting

  • Diarrhea and/or intestinal symptoms

  • Jaundice

  • Headache (2)


Reasons for Vitamin B12 deficiency 

Severe deficiency usually results from a failure of physiological absorption seen in an autoimmune disease known as pernicious anaemia. However, there are a number of other causes for vitamin B12 deficiency which range from mild to severe. Most commonly deficiency is due to reduced dietary intake or failure to render dietary B12 bioavailable (2,4). Malabsorption can occur due to a number of factors including, reduced stomach acid (may be due to acid reducing medications), reduced pancreatic function, bacterial overgrowth (SIBO), Crohn’s disease, coeliac disease, small intestinal surgery and Imerslund-Gräsbeck syndrome (2).  


Natural food sources of B12 are limited to foods of animal origin, meaning that it is often a micronutrient in short supply particularly in vegetarian and vegan populations (4).


Cow’s milk allergy or cow’s protein hypersensitivity

Cow’s milk allergy has many symptoms including diarrhoea and eczema. Constipation, while less frequent can also be a consequence of cow’s milk allergy (1). Evidence suggests that removing cow’s milk products from children with chronic constipation is associated with improvements in 80% of children. This is also be due to the connection between cow’s milk protein hypersensitivity and constipation (1). Whether the chronic constipation is caused by hypersensitivity to the cow’s milk protein or an allergy, an elimination diet (removing all cow’s milk products) may be helpful in either identifying or ruling out cows milk as a cause (1). 


You may have already had your child tested for a cow’s milk allergy via a skin prick test. While his test is extremely useful it only rules out an IgE-mediated food allergy (1). Therefore, even if your child’s skin prick test was negative this does not rule out cow’s milk allergy. 



Dealing with chronic constipation may not be as simple as upping fibre and hydration. Food allergies and sensitivities, such as cows milk and vitamin B12 deficiency are the less obvious contributors of constipation in children that certainly warrant further investigation. Constipation in children can be multifactorial and it’s important to work with your healthcare practitioner to properly assess and identify the individually factors that may be at play.



1. Dehghani S, Ahmadpour B, Haghighat M, Kashef S, Imanieh M, Soleimani M. The Role of Cow’s Milk Allergy in Pediatric Chronic Constipation: A Randomized Clinical Trial. Iran J Pediatr. 2012;22(4):468-474.

2.Visser P. Vitamin B12 Deficiency in Children | Stichting B12 Tekort [Internet]. Stichting B12 Tekort. 2020 [cited 29 September 2020]. Available from: https://stichtingb12tekort.nl/english/vitamin-b12-deficiency-in-children/

3. Yağcı M, Yamaç K, Acar K, Cingi E, Kitapçı M, Haznedar R. Gastric emptying in patients with vitamin B12 deficiency. European Journal of Nuclear Medicine and Molecular Imaging. 2002;29(9):1125-1127. 

4. Green R. Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood. 2017;129(19):2603-2611.


Written By Brittany Darling



Brittany Darling