Vitamin D & The Mood - Can single deficiency cause depression?

Updated: Jul 21, 2021

VITAMIN D IN MENTAL HEALTH (Anxiety & Depression)

Mental health is a highly stigmatised topic. Most mental health conditions are complex and multifactorial. While sometimes there is a direct cause such as a significant emotional turmoil, a trauma, grief or significant physical stressor, in many cases, the cause of anxiety or depression is unknown. Vitamin D remains one of the most central nutrients explored in connection to depression and anxieties; however, it also remains a source of many controversies in this area.

Our primary source of vitamin D is sunlight. When the skin is exposed to it, a cascade of complex biochemical signals results in the synthesis of a molecule called Calcitriol (Active Vitamin D). In the past, it has been assumed that the only role of vitamin D3 was calcium metabolism in the digestive system and bone health; however, research has now demonstrated many other effects.


More recent research has identified vitamin D deficiency in depression, anxiety disorders, psychosis, Parkinson’s disease, autism, premature cognitive decline and other forms of mental health problems. The human blood-brain barrier (selectively permeable layer protecting the brain from toxins and dangerous metabolites) allows for vitamin D to pass through. This has been a significant finding that indicated that there has to be a use for vitamin D in the brain that we did not know about before. And indeed, receptors for vitamin D (VDR- Vitamin D Receptor) have been found across multiple parts of the human brain, some of which are listed below:

  • Cerebellum – key motoric coordination and fine-tuning centre

  • Hypothalamus – major hormonal regulation centre

  • Thalamus – a communication hub relaying information between different brain areas

  • Amygdala – the core of the Limbic system, the key emotional & survival regulatory centre.

  • Brain Cortex - one of the largest areas responsible for hundreds of functions including sensory reception, logics, rational thinking, motoric skills and association regulation

  • Hippocampus – stores short-term information to long-term memory.

  • Cingulate cortex – brain centre involved in motor control, memory, attention, emotional processing, executive control, working and learning.


The above suggests that, hypothetically, being vitamin D deficient may alter a variety of brain centres and have a negative impact on our thinking, learning, attention span, long term and short term memory, neuroplasticity, and even coordination and emotional regulation including the mood. It appears that the impact of vitamin D in the brain starts as early as from birth. Children born to mothers chronically deprived of vitamin D were found to have a lower attention span than babies with normal levels. They scored worse on a variety of psychomotor tests, and they have increased risk of language impairment. The risk of autistic spectrum disorder (autism) appears to be increased in vitamin D deficiency, although studies on this topic are conflicted (and I have not come even close to reviewing all of them).

These children also appear to be at higher risk of developing eating disorders later in life compared to those who were not deficient.


Considering that we have a vast amount of receptors for vitamin D all over our brain, it would only make sense to assume that deficiency state will have a profound impact on our emotional wellbeing which is often impacted in depression. Depression is a complex and multifactorial condition. There is not one single cause that could be attributed although a variety of biochemical, emotional, psychological and even spiritual factors and contributors are known.

Much research has been done on the relationship between depression and vitamin D. One of the largest studies from 2013 assessing data from 31,424 participants across 13 large studies found that vitamin D deficiency increased the risk of depression by 31%. Several other, smaller studies have produced fairly conflicting results; however, it appears that the majority of them indicate that indeed lack of vitamin D seems to predispose the individual for increased risk of depression.

There were a few key findings here:

  • The optimal level at which the risk is the lowest is between 50-80 ng/ml or 125-200nmol/L depending on the measured unit (a blood test can often be requested by the local doctor)

  • Regular daily supplementing appears to be superior to mega-dosing once a week or once a month. Daily dosage below 4000 International Units appears to be more suitable. Personally, I advise my clients 2,000 daily for maintenance and more if we see a deficiency on tests

  • Vitamin D supplementation appears to be more beneficial in Major Depression rather than mild or moderate.

In summary, people suffering from depression may greatly benefit from optimising their vitamin D levels. A visit to the doctor or private testing would be advised and then subsequent supplementation to ensure ideal levels of 50-80ng/ml (125-200nmol/L).


Several Factors may (or may not) be involved in anxieties

  • hyperarousal of the central nervous system caused by chronic stress

  • neuro-inflammation

  • oxidative damage caused to the nervous system (a side-effect of stress)

  • macro-changes in certain brain areas, some may grow, and some may shrink

  • a variety of signalling molecules are also involved but that would be beyond the scope of this article

Vitamin D has a protective function for the central nervous system. It acts as an antioxidant. It can reduce inflammation in neurons. It also supports neuroplasticity and reshaping which are crucial in anxiety treatment as often new synaptic (nerve centre hub) connections have to be created to help the person to “see things in a different light” such as when they are undergoing cognitive behavioural therapy or other forms of mental health treatment. As such, it should, theoretically at least, be able to improve anxieties; however, the research is not as convincing as previously.

There is significantly fewer research data on vitamin D in anxieties comparing to depression. While there are a few small studies indicating mixed results, overall we are missing larger, more rigorous studies to be clear whether there is any effect. Same with depression; however, we may suggest that because vitamin D has such a profound implication on so many brain areas, it is safe to assume that it may be relevant to ensure optimal levels for people suffering from chronic anxieties however on its own (without other forms of nutritional or mental health protocols) it may not be enough.


  • Vitamin D is a hormone-like substance produced in our body when we are exposed to light. We may also receive it from the diet such as fish, eggs, meat or dairy.

  • Vitamin D appears to have an essential function in vital regulatory centres of the brain with an impact on cognitive processes, emotional wellbeing, judgement, psychomotor skills and much more

  • Vitamin D appears to be somewhat helpful in depression. For people suffering from depression, their levels of vitamin D in blood should be checked and then supplementation encouraged should their levels fall below 50ng/ml or 125nmol/L.

  • In anxieties, the role of vitamin D has not been clearly established as the research data are a bit all over the place.

  • Vitamin D has profound therapeutic benefits for the human body beyond just mental health. Everyone should have their levels checked at least once a year, especially those living in cold and dark climates. People suffering from depression or anxieties should make their best effort to optimise their levels and work with their doctors or another health specialist to obtain the most accurate data.


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