Vitamin D is a unique neurosteroid hormone and there is solid research evidence that links vitamin D to many brain development and functional processes, for example, neuroimmunomodulation (the connection between the nervous system and the immune function) and neuroplasticity (the ability of the brain to form new synaptic connections, for example when learning new information).
What is more, vitamin D receptors have been found in areas of the brain associated with depression; vitamin D is also linked to serotonin production.
Therefore, it is biologically plausible that a lack of vitamin D can contribute to depression.
In 2018 the British Journal of Psychiatry published a meta-analysis examining 14 different studies that look at the evidence about the relationship between vitamin D deficiency and depression. The analysis showed that lower vitamin D levels were found in people with depression compared to the control group. There was also an increased odds ratio of depression for the lowest v. highest vitamin D groups.
The analysis is consistent with the theory that low vitamin D concentration is associated with depression, however, association does not equal causation. At present, more studies are needed to explore whether vitamin D deficiency directly contributes to depression.
Until results from further studies are available, there seems little harm in recommending that all of us follow the NHS advice to take 10 micrograms of vitamin D per day. Vitamin D is proven to be beneficial for physical health and is likely to be beneficial for mental health also.
Fernwood Clinic Team
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