Why it's not a good idea to keep vitamin B12 a secret: case report of psychosis in Bangalore

"Memory loss and confusion are common presenting symptoms in B12 deficiency followed by depression, delirium, psychosis, personality changes, mania and dementia."

Researchers from Department of Psychiatry at the National Institute of Mental Health and Neurosciences in Bangalore (India) have just published a case report of a dairy-free vegetarian (dairy-free as of one year) with severe vitamin B12 deficiency. This man suffered from psychosis as well as other symptoms such as not being able to walk normally anymore. These symptoms were caused by his vitamin B12 deficiency, and they are somewhat typical symptoms of severe vitamin B12 deficiency that have been reported before.

It is likely that this man followed a vegan or near-vegan diet (speculation): He probably had been a vegetarian for many years before taking the step of excluding dairy-products from his diet (speculation). 

This man did not have anemia. He received intramuscular vitamin B12 injections and after two weeks his symptoms started improving. 

Here you can read his case description:

"Case history
A 26 year old gentleman presented with recent onset of behavioural change along with cognitive decline since past 2 months. He belonged to middle socio-economic strata from an urban background. He had well-adjusted premorbid personality, nil significant family and past history. On clarification of history, the symptoms had started 2 months ago with decreased social interaction, withdrawn behaviour, and reduced sleep. These behaviours worsened over next one month along with emergence of unprovoked irritability, anger outburst, persecutory ideas, hallucinatory behaviour and hypervigilance. Additionally, patient also developed recent memory deficits, poor concentration, and executive dysfunction [problems with thinking/feeling/behaviour caused by brain damage] and gait disturbances [inability to walk normally]. Personal history of patient revealed that he was a strict vegetarian and also had not taken milk products since 1 year. On bedside examination he was conscious, oriented, there was generalised skin hyperpigmentation with normal vital signs. Central nervous system [brain] examination showed brisk deep tendon reflexes, bilateral extensor planter response and wide based gait. His Mini Mental Status Examination (MMSE) score was 18/30. Other systemic examinations were normal. The blood investigations of the patient are summarised in Table 1. Patient had very low Vitamin B12 levels and elevated serum homocysteine. Magnetic Resonance Imaging (MRI)-brain showed hyperintense signal changes on T2WI and FLAIR images involving posterior columns of the upper cervical cord and symmetrical signal changes in bilateral periatrial white matter (Fig. 1). The clinical presentation was diagnosed as leukoencephalopathy [brain white matter disease] with organic psychosis secondary to [= caused by] vitamin B12 deficiency. Patient was treated with parenteral cobalamin 1000 mcg i.m and Tab. quetiapine 100 mg HS. Patient’s psychotic symptoms and behavioural problems decreased over 2 weeks and cognitive deficits started improving over next one month. He was referred to rehabilitation services for gait training. He was advised to continue parental [they mean: parenteral = injections] vitamin B12 supplements on a monthly basis and to taper the Tab. quetiapine during the followup."

"The change in dietary pattern to strict vegetarianism along with neurological signs and symptoms prompted an assay for vitamin levels."

Many long-term vegans, including "leaders" in the vegan/animal rights "movement" downplay the issue of vitamin B12 deficiency in vegans who do not make sure to consume vitamin B12 (from supplements or from fortified foods in sufficient amounts). Many long-term vegans will tell you that (1) it takes YEARS to develop low vitamin B12 levels [only true if you have very high vitamin B12 stores in your liver] and (2) that they themselves either do not take B12 supplements or only started taking B12 supplements YEARS AFTER becoming vegan [irrelevant - they are not you, and you cannot see their arteries or brains from inside].
Downplaying the issue of vitamin B12 in vegan diets is dangerous misinformation. And it is arguably unethical to provide new vegans or vegan-curious individuals with such "information". Whether it is well-meant or not is irrelevant. This kind of information can ruin someone's life, or many people's lives, can cause them years or decades of suffering from which they might never recover. Severe vitamin B12 deficiency can even lead to death, especially so in vegan babies (luckily not common, but possible). It could potentially lead to life imprisonment for vegan parents of such vegan babies in case they died. Praying that this will not happen, will not work. The only chance we have in order to prevent such tragic and utterly unnecessary cases of "leading our fellow vegans to the B12 slaughter" is science-based nutrition information: Every human (and all other mammals as far as I'm aware) must consume vitamin B12 in sufficient amounts. Like any other vitamin deficiency, vitamin B12 deficiency whether mild or severe will lead to physiological impairments which can then cause mental and/or physical health problems.
Severe vitamin B12 deficiency will damage your nervous system (Nervous system: brain, spinal cord, and all other nerves). 
Vitamin B12 deficiency - even mild deficiency - will likely damage your arteries and promote atherosclerosis.

Apart from the potential harm caused for the people themselves who chose to become vegan and chose to not consume vitamin B12 (because they have been misinformed/lied to or because they are religious/other types of fanatics), cases such as these will harm farm animals indirectly by discrediting the vegan "movement" as a bunch of certifiably insane hippies who want to live in a "cuddly dog and pig fantasy world" and/or who cannot reason, and therefore cannot be taken seriously.
(No offence to self-identified hippies or people with emotional attachments to cuddly individuals but as soon as you cause harm to others, it is not your personal choice anymore, it is political.) 

Mukku SSR, Suhas S, Thippeswamy H, Ganjekar S, Arvind HR, Chaturvedi SK: Mixed neuropsychiatric clinical manifestations associated with vitamin B12 deficiency. Asian J Psychiatr. 2018 May 23;36:25-27. doi: 10.1016/j.ajp.2018.05.026 . [Epub ahead of print]