Vitamin B12 Deficiency: What are the consequences?

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Vitamin B12 Deficiency, Neurons and the Brain

Adequate supplies are essential during the development and maintenance of the brain and the neural network.  Insufficient levels of vitamin B12 in the mother. Vitamin B12 has a vital role in neuronal development, particularly in myelinogenesis. It has been shown that early in vitamin B12 deficiency demyelination of the autonomic nervous system may occur and reduced cardiac sympathetic activity may be observed in children born to mothers with a lower vitamin B12 status. Studies have shown that women with low levels of vitamin B12 (<250ng/L) have two to three times the risk of delivering a child with neural tube defects (NTD) as compared to those with higher levels. Women with pregnancy blood levels of  <150ng/L had almost five times the risk of having babies with NTD  those with high levels of the vitamin. The neural tube forms very early on in pregnancy so it is very important the a women is tested for vitamin B12 deficiency before becoming pregnant. It is important that pregnant mothers supplement with both folate AND vitamin B12. With the advent of folate supplementation in food, vitamin B12 deficiency is the leading cause of neural tube defects in children. Children born of mothers with vitamin B12 deficiency have shown subacute combined degeneration of the spinal chord and developmental delay. Methylation deficiency is postulated as the primary cause of autism in children.

Vitamin B12 has an essential role  in the maintenance of a healthy brain and nervous system.. Methylcobalamin has an essential role in the methylation of myelin basic protein, and in the maintenance of choline, acetylcholine and phosphatidyl choline and essential component of the myelin sheath surrounding the neurons. In addition,  adenosyl cobalamin is an essential component of the energy system in mitochondria and vitamin B12 deficiency can lead to the formation of deformed and poorly functioning mitochondria.

Energy production in neurons is critically dependent upon the last numbers of mitochondria that are present. Lack of adenosylcobalamin has been shown to lead to mitochondrial storage disease, and generation of high levels of MMA, which is associated with a deficiency of adenosylcobalamin. MMA has been shown to be neurotoxic and leads to incorporation of unusual lipids into the myelin sheath. Deficiency of vitamin B12 leads to thinning of the myelin sheath. It has also been shown that neuron conduction speeds are correlated with the levels of vitamin B12. Methylcobalamin is required for the synthesis of methylarginine in myelin basic protein. Lack of methylation of MBP has been associated with improperly folded MBP and poor association of MBP with the myelin sheath.

Vitamin B12 deficiency impacting on neuronal health can produce classic signs of vitamin B12 deficiency and particularly axonal degeneration of spinal cord, unsteadiness of gait, ataxic gait, particularly in dark, positive Romberg, positive Lhermittes, Loss of motor control over some or all of toes, loss of motor control over part or all of feet, loss of sense of joint position, sudden electric like shocks/pains shooting down arms, body, legs shooting down from neck movement, sudden “ice pick” pain
decreased reflexes, brisk reflexes, foot drop, tripping over toes, injuring toes catching top of toes on floor, general feeling of weakness, incontinence, loss of taste and many other signs of peripheral neuropathy

It has recently been found that methylation of histones is an essential part of the development of short term memory, which may explain why some of the early signs of continued vitamin B12 deficiency is the loss of short term memory .

MRI imaging of the brain of elderly patients has shown considerable shrinkage of the brain with time, which has been reduced and even stopped by high dose vitamin B12 supplementation in combination with folate and vitamin B6..

Neuronal damage due to vitamin B12 deficiency has been associated with conditions such as multiple sclerosis, dementia, Alzheimer's disease, Parkinson's disease, as well as the brain fog and poor mini-mental scores seen in many patients with Chronic Fatigue Syndrome.. Generation of methylmalonic aciduria due to a deficiency in  adenosylcobalamin, which is neurotoxic, has been correlated with the development of various neuropathologies.

Vitamin B12 Supplementation and brain health

It is very important that during pregnancy and during the suckling period that mothers maintain adequate levels of vitamin B12 for the brain and spinal chord of the developing fetus.  Many of the mental issues associated with ageing are potentially due to reduced intake, and or uptake of vitamin B12, leading to sub-clinical vitamin B12 deficiency. In these individuals the progressive loss of vitamin B12 may be helped with standard vitamin supplements, however, if deficiency is implied or symptomology suggests deficiency high dose vitamin B12 administered by injection or by transdermal delivery such as with TransdermOil technology is strongly recommended.

Further Information on assessment of brain health

An excellent site for assessment of general brain health can be found at