Vitamin B12 Deficiency during Infancy
by Anne Eglash MD, IBCLC, FABM
What are risk factors for vitamin B12 deficiency during infancy, and what symptoms would they have?
Dietary vitamin B12 is found primarily in animal products including dairy, eggs, meat, and fish. Vegans and some vegetarians have limited B12 intake from food sources such as mushrooms and nori. Vitamin B12 is derived largely from dietary animal products such as dairy products, eggs, meat, and fish. Vegans have limited dietary B12 options because vegetables such as mushrooms and nori have very little B12. Prenatal vitamins contain vitamin B12, but a significant percentage of pregnant and lactating individuals don’t take vitamins.
Low vitamin B12 intake during pregnancy leads to low fetal stores of B12 and low levels in breastmilk.
Vitamin B12 is vital for infant growth and development, and particularly for brain health.
This week’s study reviews data from published cases and describes biochemical and clinical information on infants diagnosed with vitamin B12 deficiency, to raise awareness of this condition for early diagnosis.
The authors’ literature review yielded 102 publications from countries in 6 different continents, reporting on 292 published cases of infant B12 deficiency from 1962-2022.
They found that clinical signs of vitamin B12 deficiency in infants typically occur in the first few months of life, often manifesting symptoms of developmental regression, irritability, feeding difficulties, low tone, and movement disorders. Although infant symptoms may start early, the diagnosis of vitamin B12 deficiency is often made significantly later.
- Most case reports of infants with vitamin B12 deficiency were breastfed.
- The most common clinical symptom of vitamin B12 deficiency among infants was a movement disorder.
- Most infants with vitamin B12 deficiency were diagnosed with failure to thrive.
- The average age of initial symptoms of vitamin B12 deficiency was 4 months.
- The average age of diagnosis was 2-3 months after initial symptoms.
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Abstract
Pooled data from published reports on infants with clinically diagnosed vitamin B12 (B12) deficiency were analyzed with the purpose of describing the presentation, diagnostic approaches, and risk factors for the condition to inform prevention strategies. An electronic (PubMed database) and manual literature search following the PRISMA approach was conducted (preregistration with the Open Science Framework, accessed on 15 February 2023). Data were described and analyzed using correlation analyses, Chi-square tests, ANOVAs, and regression analyses, and 102 publications (292 cases) were analyzed. The mean age at first symptoms (anemia, various neurological symptoms) was four months; the mean time to diagnosis was 2.6 months. Maternal B12 at diagnosis, exclusive breastfeeding, and a maternal diet low in B12 predicted infant B12, methylmalonic acid, and total homocysteine. Infant B12 deficiency is still not easily diagnosed. Methylmalonic acid and total homocysteine are useful diagnostic parameters in addition to B12 levels. Since maternal B12 status predicts infant B12 status, it would probably be advantageous to target women in early pregnancy or even preconceptionally to prevent infant B12 deficiency, rather than to rely on newborn screening that often does not reliably identify high-risk children.
This is the most robust study thus far characterizing the initial symptoms and signs among infants with B12 deficiency and age at first diagnosis. Most affected infants were breastfed by mothers with low B12 levels, resulting either from a diet lacking in B12 or impaired B12 absorption.
Most infants displayed clinical symptoms of B12 deficiency within the first 6 months of life. Anemia was common, with hypotonia (low tone) as the most prevalent neurologic symptom. Other neurologic signs were failure to thrive, irritability, lethargy, and movement disorders. An increased risk of infant B12 deficiency was associated with maternal vegan or vegetarian diets.
The authors recommend, based on their analysis, screening symptomatic infants for low serum B12, elevated methylmalonic acid, and total homocysteine levels to diagnose B12 deficiency.
Angela Bakos
I am not sure why choice “b” is not included in the answer.
IABLE
Hi, although movement disorders occur among infants with B12 deficiency, the most common symptom is hypotonia (low tone).
Thanks for reading the question!
Linda Ruiz
thank you. this has helped me become more aware to discuss with my vegan mothers. I’m also going to get some nutritional yeast to try as cheese replacement.
Helen Tennant
Is there any evidence that women that have had a gastric gastric bypass surgery would have Low Vit B12 ?
Therefore low in breastmilk causing slow and low weight gain in infants .
Thank you
IABLE
Yes, people who have gastric bypass surgery are at high risk for several vitamin deficiencies. They should be followed by a bariatric center or by their primary care physician to monitor vitamin levels and to receive dietary guidance.
Helen tennant
Thank you for confirming this.
Is there any recent research articles available about low Vit B12 causing low weight gain ?