It is well-known that the serum vitamin D level is decreased in patients with depression compared with non-depressed controls.
Although the underlying mechanism leading to decreased vitamin D levels in depressed patients has not been established, it has been theorized that vitamin D receptors in the limbic system, cerebellum, and cortex have an effect by modulating intra-neuron levels of Ca++ in the brain.
The results of the current study suggest that “supra-normal” levels of vitamin D may thus be required to overcome the Ca++ effect, although immunoinflammatory processes may also be involved, albeit to a lesser degree.
Additional well-designed studies are warranted to determine whether vitamin D causes depression or vice versa, and the dose, duration, and safety of vitamin D supplementation.
This was an 8-week double-blind clinical trial involving 56 patients (18-60 years of age) with mild-to-moderate depression. The patients were randomized to receive 50,000 IU of cholecalciferol every 2 weeks or placebo. The serum 25(OH)D, iPTH, IL-1β, IL-6, and hs-CRP levels, as well as the Beck Depression Inventory II score were determined prior to and after treatment.
After the 8-week treatment with cholecalciferol, the serum 25(OH)D level was increased compared to placebo (40.83 vs. 5.14 mmol/L). The Beck Depression Inventory II score was decreased further in the treatment group than the placebo group (-11.75 vs. -3.61).
The IL-1β, IL-6, and hs-CRP levels were not significantly different between the treatment and placebo groups post-treatment.