Résumé
Vitamin D, also known as the "sunshine hormone", is essential to human health. Vitamin D deficiency and depression are global health problems. Given the high prevalence of vitamin D deficiency, evaluation of vitamin D status is interesting, not only for diagnosing deficiency but also for evaluating the efficacy of treatment based on vitamin D supplementation. Many factors link vitamin D to depression. From the clinical observation of a correlation between low vitamin levels and the onset, percentage and severity of symptoms, to their close relationship in various systems, particularly the body's immune and nervous systems. While the nature of this relationship (cause, consequence, concomitance) has yet to be determined, there are sources of evidence to support this association: the neuroprotective properties of vitamin D and its role in the neurotransmission of monoamines which are defective in depression, an increase in the expression of vitamin D receptors in brain areas known to play a key role in mood regulation, and the immunomodulatory, anti-inflammatory and antioxidant roles of vitamin D in the association between depression and inflammation. Inthe same vein, interest in vitamin D supplementation for the prevention and treatment of depression has also been growing recently. The improvement of depressive symptoms through improvements in depression scores, mood, well-being, and inflammation has been observed in many patients who have received vitamin D supplementation.