Food and Behaviour Research

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Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms.

Dror DK, Allen LH. (2008) Nutr Rev.  66(5) 250-5. 

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Severe vitamin B(12) deficiency produces a cluster of neurological symptoms in infants, including irritability, failure to thrive, apathy, anorexia, and developmental regression, which respond remarkably rapidly to supplementation.

The underlying mechanisms may involve delayed myelination or demyelination of nerves; alteration in the S-adenosylmethionine:S-adenosylhomocysteine ratio; imbalance of neurotrophic and neurotoxic cytokines; and/or accumulation of lactate in brain cells.

This review summarizes the current knowledge concerning infantile vitamin B(12) deficiency, including a pooled analysis of case studies of infants born to mothers with untreated pernicious anemia or a strict vegetarian lifestyle and a discussion of the mechanisms that may underlie the manifestations of deficiency.


Vitamin B12 can be obtained only from animal-derived foods, or by supplementation. Vegan diets therefore lead to deficiency unless the diet is adequately supplemented with B12.

This review summarises the importance of vitamin B12 for brain development in pregnancy and infancy, and includes an analysis of 30 cases of severe vitamin B12
 deficiency during pregnancy in vegan women with pernicious anemia.

round 60% of the infants born to these women had severe developmental delays and 37% had cerebral atrophy.

Following supplementation to replete B12, many of the neurological symptoms in these infants improved. However, follow-up showed that 50% of the infants still had developmental delays even with repletion of B12, indicating that the brain damage they had suffered was not fully reversible.

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