Vitamin D for Depression

by | | Gut Brain Axis

More and more people are willing to discuss mental health so let’s look at the role Vitamin D plays in depression.  Most people have insufficient levels of this nutrient whether it’s due to low dietary intake or not enough outdoor exposure to sunshine.  Very low levels affect approximately one billion people while insufficient levels affect many more.  Supplementation is often needed to reach optimal blood levels and several studies show promising results on depression.  Vitamin D is an easy and cost-effective intervention for both physical and emotional health.


Depression is considered the leading cause of disability worldwide, affecting about 121 million people.  Only 25% of people with depression seek support.  Conventional treatment includes antidepressant medication and psychotherapy.  People discontinue their medication due to unwanted side effects, financial reasons, fear of addiction, and the belief that the medication is no longer necessary.  Novel therapies are therefore needed.

Vitamin D is not just a nutrient.  It also acts as a neuro-steroid hormone. In the brain it has biological functions and influences gene expression.  This may explain why those with the lowest levels of vitamin D had the highest rates of depression.


Serotonin is the neurotransmitter related to mood, sexual desire, appetite, sleep, memory, learning, temperature regulation, and social behavior.  An imbalance in serotonin may lead to depression.  This is why selective serotonin reuptake inhibitors (SSRIs) are widely recommended by physicians. Low brain cell production, lack of receptor sites or transport to these sites and a shortage of the amino acid tryptophan can all be causes of a serotonin imbalance.

Interestingly, the active form of vitamin D mediates gene transcription inducing serotonin synthesis in the brain.  Research also indicates that sunlight and serotonin are linked. In fact, serotonin turnover in the brain is lowest in winter and the rate of serotonin production is related to the amount of bright sunlight exposure one has.


Sunlight and Supplements

We definitely need both.  Beta endorphins are not released by supplementing Vitamin D but they are by getting out in daylight.  Even in small amounts these peptides significantly reduce stress and pain.  People with depression have lower levels. UVB sunlight exposure increases serum beta endorphin.  Whether it’s cloudy or sunny, UVB is highest at noon.  By going for a walk mid-day you support your HPA axis and beta endorphin levels thus reducing depression. This is perhaps an evolutionary reward system set-up to encourage regular exposure to daylight.



Low levels of Vitamin D are associated with low grade systemic inflammation in the body.  This recent study of 300,000 people compared elevated cross reactive protein levels (CRP) to low 25-OH-D.  CRP is a blood marker that measures inflammation in the body.  The study concluded that increasing Vitamin D intake the high CRP levels could be corrected.  Inflammation is a cause and contributor of depression which further supports use of Vitamin D as part of mental health support. 




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