Vitamin B12 Deficiency



Vitamin B12 Deficiency in Pregnant Mothers


Vitamin B12 (cobalamin), is necessary for development of the foetus and neonate. Studies have shown that during pregnancy there is a significant drop in the level of vitamin B12 in the serum of the mothers, which progressively drops further during the course of the pregnancy and while the mothers are breast-feeding. Overt vitamin B12 deficiency may occur in pregnant women who have lower levels of vitamin B12 at the start of their pregnancy, or who are vegetarian or vegan, have Crohn of coeliac disease, who are on Metformin™ for diabetes, or who have undergone gastric bypass surgery. More recently it has been shown that functional vitamin B12 deficiency may also be present in women who are obese.


Low serum levels of vitamin B12 have been linked to negative impacts on cognitive function, and on motor development, and poor growth outcomes in the developing neonate. Vitamin B12 deficiency in mothers has also been linked to autism in the off-spring.


Obvious signs of deficiency in the neonate include:


In addition, babies of mothers who are deficient in vitamin B12 may have lower cognitive scores one year after birth, even if the deficiency is detected. Following the birth of the child, low levels of vitamin B12 in the serum of the mothers may be linked to fatigue and depression, although further studies are required to confirm this.


Critically, loading of the brain of the child occurs primarily in the foetus and up to 17% of vitamin B12 that crosses the placenta goes to the brain of the developing foetus (See).


Absolute levels of vitamin B12 are rarely checked in pregnant mothers, rather, levels of iron and macroscopic testing of the blood for obvious signs of deficiency are performed, and generally folate and iron supplementation is suggested. Surprisingly there are not even any recommendations on supplementation of mothers during pregnancy in the UK, and despite numerous papers on the negative impacts of vitamin B12 deficiency in the neonate, a recent report from the UK claimed that "There is also no evidence that vitamin B12 is associated with an increased risk of congenital malformations of other adverse foetal effects". This statement from the UK is almost unbelievable in light of the evidence of decreased levels of vitamin B12 seen in the brains of children with Autism, and also the association of vitamin B12 deficiency and developmental delay and adverse neurological outcomes in the neonate.


Childbearing  women are particularly vulnerable to the adverse effects of poor nutrition on mood because pregnancy and lactation are major nutritional stressors to the body. Thus, the developing foetus gains its vitamin B12 (and also other nutrients) from the mother with additional supplementation obtained from the mother's colostrum and milk. As a result, during pregnancy and lactation the nutrient reserves of the mother are particularly stressed, and the lack of recovery postpartum may increase a woman's risk of depression. Several studies have shown that the foetus is able to actively accumulate vitamin B12 with a resultant drop in the mother's serum levels. There is a direct correlation between the vitamin B12 status of the mother and the vitamin B12 status of the new-born. Vitamin B12 levels in colostrum and milk are also directly correlated with those of the mother.  Whilst mothers may not show overt signs of vitamin B12 deficiency (such as macrocytic anaemia), they may give birth to babies who are vitamin B12 deficient. Other signs of vitamin B12 deficiency such as unusual fatigue, nausea, numbness of the fingers and feet are generally ascribed to the "pregnant condition" rather than to vitamin B12 deficiency. Babies born of vitamin B12 deficient mothers will have lower vitamin B12 levels in their liver and serum at birth, and in turn receive lower amounts of vitamin B12 in the milk from their mother, and as such are at increasing risk of becoming vitamin B12 deficient. Breast-feeding mothers have been shown to have a further reduction in vitamin B12 levels, and there is a real possibility that this greatly reduced level of vitamin B12 in the mother may lead to post natal depression. Maternal supplementation with B12 has been associated with better cognition and higher expressive language in their children, whilst lower B12 and associated elevations in homocysteine in the mothers have been shown to be negatively associated with expressive language and gross motor development and the development of Autism. Several studies have shown that vitamin B12 supplementation of mothers using standard multivitamin supplement does not reduce the chances of vitamin B12 deficiency in the neonate (Guez et al, 2012). Children born of B12 deficient mothers can show poor weight gain, feeding difficulties, severe pallor, muscle hyptonia and somnolence, delayed developmental mile-stones and have a higher chance of being diagnosed with autism later in life.


Vitamin B12 Deficiency in Vegetarian Mothers


Children born of vegan and vegetarian mothers often have moderate to severe vitamin B12 deficiency (Guez et al, 2012; Roed et al, 2009; Agrawal and Nathani, 2009; Chalouhi et al, 2008; Lucke et al, 2007; Strucinska 2002; Rendle-Short et al 1979; Michaud et al, 1992; Specker 1994; Renault et al 1999; Ueland and Monsen 2003; Weiss et al, 2004; Jarosz et al, 2004; Baatenburg et al 2006; Kollee 2006; Yajnik 2006; Cetinkaya etal, 2007; Fadyl and Inoue 2007; Mathey et al, 2007;Dror and Allen, 2008; Honzik et al, 2010; Kocaoglu et al, 2014; Bravo et al, 2014; Bousselamati et al. 2018) Despite these deficiencies being well documented, for more than 30 years, many vegetarian and vegan mothers do not supplement before, during or after pregnancy, nor do their health professionals check them for deficiency.


Maternal serum B12 levels are closely correlated with the vitamin B12 levels in the mother's milk


Vitamin B12 deficiency in the milk has been found to be measurable by an increase in MMA levels in the urine of the mothers, and B12 levels in the mothers are mirrored in MMA levels in the infants  (reprod from Specker et al, 1990) .

As one would expect increased urinary MMA in babies was inversely correlated with serum vitamin B12 levels in the infants (reprod from Specker et al, 1994).


Summary Vitamin B12 Deficiency in vitamin B12 deficient Mothers


Children born of vitamin vegan, vegetarian or otherwise vitamin B12 deficient mothers will be vitamin B12 deficient. The extent of deficiency in the baby will be related to extent of deficiency in the mother. The extent of developmental delay seen in the children will be reflective of the extent of vitamin B12 deficiency observed in the mothers.





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The statements on this site compose a compendium of generally recognized signs of vitamin B12 deficiency, and problems that can then ensue They also are formulated from a summary of relevant scientific publications. In addition they may contain some forward looking statements of a general nature.
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