Back in 2012, Peter Bergman, a resident physician in clinical microbiology at Karolinska University Hospital, and his team aimed to determine if vitamin D supplementation provides a treatment effect for immune compromised patients with frequent respiratory tract infections. In this randomized, double-blind trial, 120 patients who suffered from frequent respiratory tract infections received either 4,000 IU/day of vitamin D or placebo for one year. The researchers discovered significant treatment effects:
Last month, the researchers reanalyzed their data to find even more convincing effects in reducing respiratory tract infections:
Now, in another reanalysis, Bergman et al asked one question to all 124 subjects who completed the study: “How do you rate your overall health during the study year compared with the year before?” The questionnaire contained the predefined answers: 1 = better than before, 2 = worse than before, 3 = no change or 4 = other.
In the 72 subjects who said “better than before”, there was a very significant yearly increase in mean 25(OH)D levels (p<0.001). However, of those 72 subjects, only 43% obtained a final 25(OH)D of > 40 ng/ml. In the 32 subjects who reported feeling the same as before, final 25(OH)D was improved from baseline, but less significantly (p<0.05) and only 22% obtained a final 25(OH)D of 40 ng/ml. In the 14 patients who felt “worse” after the year, final 25(OH)D levels were no different than baseline.
However, what was interesting was the effect of vitamin D supplementation on the 22 patients taking antidepressants. Ten of the subjects on antidepressants felt “better”, and four of them could terminate their antidepressant use. In the figure below, of those four (red lines), three had final 25(OH)D levels > 40 ng/ml (100 nmol/L).
Figure: Well-being in patients with immunodeficiency disorders taking antidepressants (n=22), before and after a 1-year vitamin D study. In patients with a better well being during the study (n = 10) there was an average increase in 25-hydroxyvitamin D (25-OHvitD) levels (p < 0.001). Four patients could terminate their antidepressant therapy during the study (red lines). Of the four patients on antidepressants (red lines) who obtained final serum 25(OH)D of > 40 ng/ml, three could stop there antidepressants. In patients stating no difference (n = 6) or worse well being (n = 6) there was no change in average 25-OHvitD levels (p = not significant).
Due to the very small sample size, these findings remain inconclusive. However, in my practice of psychiatry, I have seen some uncomplicated mild to moderate clinical depression improve with 5,000 to 10,000 IU/day of vitamin D. I have never seen vitamin D help treatment resistant major depression, which are the cases with severe symptoms that have not improved on multiple antidepressants.
In order to conduct a randomized controlled trial that properly evaluates the effect of vitamin D on clinical depression, the patients in the study should have mild to moderate depression that can be treated effectively with antidepressants. All subjects must be vitamin D deficient initially. Doses of vitamin D must be adequate to achieve at least 50 ng/ml (125 nmol/L) in almost all subjects (5,000 to 10,000 IU/day). The most difficult part of the study would be to identify a placebo group with depression that was vitamin D deficient and not treat them. That’s why so few meaningful studies of vitamin D are being conducted: ethically, vitamin D deficient placebo groups cannot be identified and then not treated.