A vitamin? How can that help depression? Say what?

Depression certainly can be a complex area.

Whichever way one choses to look at the causes of depression, it is a very complex area. It appears there is no set treatment that works for every person, obviously because the disease is multifactorial in its development and therefore may require a variety of approaches in treatment. B12 is one vitamin that may assist the reduction of depressive symptoms, and this will be explored in this blog post (adapted from a large literature review I completed in May 2017). I am happy to pass on my full literature review if you would find that helpful (be warned- its wordy)

B12 is a generic term used for a group of compounds known as corrinoids. There are a few types of cobalamin structures in the body including cyanocobalamin and hydrox-cocobalamin. Two forms, methyl-cobalamin and adeno-cobalamin, are active co-enzyme forms within humans (depression11).

B12 sources include animal food products, especially meat, eggs, seafood and poultry. There are smaller amounts in dairy, legumes and mushrooms. The recommended daily intake for B12 for adults is 2.4mcg, although 4-7mcg has also been recommended. During pregnancy and lactation, this need increases by 0.2-0.4mcg. 10-30% of older adults have changes to their gastrointestinal tract that limit their ability to absorb food.

There are many reasons for deficiency of b12. Some are not fully understood, especially the role genes play in vitamin B12 metabolism in the body. It appears the elderly are at particular risk of b12 deficiency with up to 15% affected .

Reasons for b12 deficiency may include: inadequate intake of foods rich in b12 (for example a vegan or a vegetarian diet), impaired pancreatic function, impaired gastric acid function (common with patients on Somac for example), autoimmune issues of the parietal and mucosa cells of the stomach, impaired gastrointestinal function, such as inflammatory bowel disease, parasites and use of nitric oxide, MTHFR gene polymorphism.

Vitamin B12 is an essential element in methyl group transfer and cell division. It is needed for neural cell renewal, maturation and multiplication. It is needed, alongside folate, as an essential cofactor in the metabolism of homocysteine. B12 helps to lower homocysteine levels.

There are two main thB12eories surrounding vitamin B12 and its role in mood. The first is its role in methylation in the central nervous system (CNS). The hypo-methylation hypothesis suggests that B12 (alongside other folate, and b6), has a direct effect on reactions within the CNS including the metabolism of neurotransmitters monoamines (dopamine, norepinephrine, and serotonin), which are essential for a happy psychological status.  The second theory, the homocysteine hypothesis, suggests that B12 is necessary for healthy vascular function, protecting the integrity of the CNS (2). In a 2016 study ,a meta-analysis of nine observational studies showed that patients with homocysteine of 12.5umol/L had a 70% higher risk of depression than patients with homocysteine levels of 12.5umol/L and under (3).


Upon reviewing many scientific journals about B12 and its treating depression, I came across many interesting findings. I won’t share them all here, however. One extreme example of the impact of low b12 on mood and cognitive decline was this example below. I recently have come across a similar case to this and I am working on improving this patient’s wellbeing. Interestingly B12 was NOT tested until I pushed for it to be done, and it was significantly low.

In 2005, a case report was published in the Primary Care Companion, Journal of Clinical Psychiatry (4) outlining the effects of B12 supplements improving depression. Within this case report, a 66 year old African American woman presented to an outpatient clinic following hospitalisation for major depressive disorder with psychosis. Her family reported a 6 month history of poor mood, with other symptoms such as lack of interest in personal hygiene, weight loss, fear, agitation and slow psychomotor activity. She had no prior family history of mental illness or substance abuse. The patient was placed on medications Sertraline 150mg daily and Risperidone 2mg daily. She was in hospital for 10 days. She continued on her medication and presented to the outpatient clinic less than one month after her hospital visit where she had bloods taken. She had a partial remission at this point.

Upon testing the patient’s vitamin B12 level, it was shown to be less than 100pg/ml (range 200-900pg/ml). Afterwards she was treated with a series of B12 injections, whereby her B12 level improved to 500pg/ml. Her mood significantly improved, alongside her sleep, hygiene and energy. She was able to stop taking the Risperidone.

It appears a dosage of 1000mcg of B12, given with folate, shows the best clinical results in these studies, mainly in patients with established B12 deficiency or high homocysteine. The reasons as to why the b12 deficiency is occurring in the patient needs to be addressed.  Depending on the severity of the b12 deficiency, injections may be needed initially, and then oral tablets may provide lasting results.

In general, patients with depression should have any underlying B12 deficiency ruled out as a contributing factor. Active b12 and homocysteine levels should be checked, possibly in addition to their methylation status (SAH, SAM). MTHFR gene polymorphisms should also be checked.

I encourage you to look DEEPER for the reasons for your depression. I see many links with low b12, folate, copper overload, low zinc, gut dysbiosis, heavy metal toxicity, underactive thyroid etc. Never stop prescription medications without your doctors supervision.


The information provided in this talk today/ in this hand out is intended to be general information only and not specific health advice or treatment. Always seek the advice of your registered health care provider with any questions you have regarding any medical condition.

If you or someone you know needs help for any mental/ emotional concerns call Lifeline on 13 11 14, Anglicare Northern Inland, Tamworth on 67018200 or Beyond Blue 1300224636.



  • Gropper S S, Smith J L, Advanced Nutrition and Human Metabolism, 6th Wadsworth: Cengage Learning 2013
  • Byan J, et al, Short-Term Folate, Vitamin B-12 or Vitamin B-6 Supplementation Slightly Affects Memory Performance but not Mood in Women of Various Ages. Available from:
  • De Koning E J et al, Effects of Two-Year Viatmin B12 and Folic Acid Supplementation on Depressive Symptoms and Quality of Life in Older Adults with Elevated Homocystein Concentrations:Additional Results from the B-PROOF Study, an RCT, Nutrients Journal, Basel, Switzerland, Published 2016. Available from: mdpi.com/journal/nutrients
  • Hanna, S, et al, Vitamin B12Deficiency and Depression in the Elderly: Review and Case Report, Prim Care Companion J Clinical Psychiatry, 2009 . Found here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781043/