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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

New randomized controlled trial: Vitamin D helps in depression

A new randomized controlled trial out of Iran and published in the Journal of Clinical Psychopharmacology reports that vitamin D may help depression.

Past research has shown a definite association between low vitamin D levels and depression. However, clinical trials have shown mixed results, thus raising need for further research. The researchers in this study led by Dr Hassan Mozaffari-Khosravi wanted to know if a single injection of vitamin D could help improve symptoms in those who suffered from mild to moderate depression.

One-hundred and twenty people were recruited from specialist clinics at Yazd Shahid Sadoughi University of Medical Sciences and enrolled into the study. They only enrolled people between the ages of 20 to 60, had presented depression at specialist clinics, scored higher than a 17 on the Beck Depression Inventory II test (BDI) and had a vitamin D level lower than 16 ng/ml.

The BDI is a 63 point self-assess scale, with a score of 63 indicating severe depression, a score of 0 indicating no depressive symptoms. Scores in the range of 11-16 indicate mild depression, while scores 17-20 indicate the need for psychological consultation, so all participants scored at least just above mild depression.

The researchers evenly divided the participants into three groups. One group to receive a single shot of 300,000 IU of vitamin D (300k), another group to receive a single shot of 150,000 IU (150k) and another group to receive nothing, serving as a control group. The third group did not receive a fake shot, so this was not a double blind study, just a randomized controlled trial.

Here were the baseline findings:

  • Mean vitamin D levels were very low. The mean level was 10.1 ng/ml in the control group, 9.2 ng/ml in the 150k group, and 8.5 ng/ml in the 300k group.
  • Mean BDI scores were similar among groups, ranging from 26.4 to 27.5.

The researchers then administered the vitamin D. After three months, the researchers had participants take the BDI again to assess depression to see if improved vitamin D levels helped at all. Here is what they found:

  • Mean vitamin D levels increased to 24 ng/ml in the 300k group, 21.8 ng/ml in the 150k group and stayed low in the control group at 11.3 ng/ml.
  • The severity of depression improved in all groups, as assessed by decreasing BDI. However, the 300k group improved the most.
  • BDI decreased by 9.3 points in the 300k group (26.7 to 17.4).
  • BDI decreased by 6.8 points in the 150k group (27.5 to 20.6).
  • BDI decreased by 2.1 points in the control group (26.4 to 24.3).

The difference in BDI decrease between the 300k group and the 150k group and the difference in BDI decrease between the 150k group and the control group was not statistically significant. However, the difference in BDI decrease between the 300k group and the control group was statistically significant, suggesting that vitamin D may have had an effect in improving depression.

The authors conclude,

“The findings of this study showed that first, vitamin D deficiency in patients with depression has a high prevalence; second, the correction of vitamin deficiency improves depression in these patients; and third, the single dose of 300,000 IU of vitamin D is safe and more effective than 150,000 IU.”

The greatest limitation in this study was that the trial wasn’t double blinded, so we don’t know if there was an extended placebo effect in the people that received shots compared to the control group that didn’t  However, the fact that the 300,000 IU vitamin D group showed statistically significant improvement in depression over the control group and the 150,000 IU group did not, hints that the vitamin D shots were not just a placebo effect and that the more vitamin D administered, the better the improvement.

There were some strengths in this study compared to previous randomized controlled trials looking at vitamin D and depression. In a study out of Norway last year, researchers wanted to see if 40,000 IU/week improved depression and found that it didn’t. However, their participants for the most part did not suffer from depression. They also used the BDI scale and found the median participant started at only 4 points, compared to the mean of about 27 points in this Iranian study. Thus, there were few depressive symptoms to improve upon in the Norway study. In this Iranian study, participants suffered from mild to moderate depression, so there was much more room for improvement.

The Vitamin D Council does not recommend the use of single loading doses like the ones used in this study. After three months, vitamin D levels were still low in the 300,000 IU group. Rather, the Vitamin D Council recommends use of daily maintenance doses of 5,000 IU/day in adults to achieve levels of 50 ng/ml. Please see our ‘How do I get the vitamin D my body needs’ page for more information.

Also visit our patient friendly summary on depression for an overview on the subject. Note that the summary is a little outdated now, as there have been a couple of trials on depression and vitamin D since we last updated it.


Mozaffari Khosravi H, et al. The Effect of 2 Different Single Injections of High Dose of Vitamin D on Improving the Depression in Depressed Patients With Vitamin D Deficiency: A Randomized Controlled Trial. J Clin Psychopharm 2013.

  About: Brant Cebulla

Brant Cebulla was a staff member for the Vitamin D Council from May 2011 to April 2014. He has keen interests in nutrition and exercise.