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Does vitamin D improve symptoms of schizophrenia?

Posted on: March 15, 2017   by  Amber Tovey

A recent randomized controlled trial (RCT) published in the Journal of Pharmaceutical Research found a bolus vitamin D injection did not improve symptoms in chronic stable schizophrenic patients.

While the cause of schizophrenia remains unknown, researchers believe that a combination of genetics and environment contribute to the development of the disorder. Certain factors may increase the risk of schizophrenia, including family history of schizophrenia, older paternal age, malnutrition during pregnancy and drug use during teenage years.

Research shows that people with schizophrenia have lower vitamin D levels than people without schizophrenia. To determine the effects of vitamin D supplementation on the symptoms of schizophrenia, researchers recently conducted a RCT.

A total of eighty patients with stable schizophrenia and residual symptoms were enrolled in the study. Stable refers to the phase of schizophrenia in which symptoms are less severe and even absent. All patients had low vitamin D status as defined by 25(OH)D levels below 30 ng/ml before the study began.

Half of the patients received 600,000 IU of vitamin D injection once along with their antipsychotic regimen, and the other half received their antipsychotic regimen only. The researchers wanted to compare changes of symptom severity at the beginning of the study and again after four months between those who received vitamin D and those who did not.

Here is what the researchers found:

  • The average vitamin D levels significantly increased from 14.7 ng/ml at baseline to 50.5 ng/ml after four months in the vitamin D group (p
  • The average vitamin D levels in the control group significantly decreased from 14.2 ng/ml at baseline to 13.99 ng/ml after four months (p
  • Symptom severity did not decrease significantly in either group (p = 0.5, p = 0.7).
  • Low vitamin D levels were associated with greater symptom severity in the vitamin D group; however, this association was insignificant (p = 0.7)

The researchers concluded,

“…We did not find a relationship between serum vitamin D level changes and the improvement of negative and positive symptoms in schizophrenic patients and more randomized clinical trials are required to confirm our findings.”

The study design was the major strength of the study. A RCT allows researchers to identify whether causality exists, rather than merely association. Furthermore, the study excluded schizophrenic patients with healthy vitamin D levels, permitting researchers to assess the benefits of achieving healthy vitamin D levels.

However, the study also possessed a few limitations to keep in mind. The researchers used a very large bolus dose of 600,000 IU. This highly differs from the Vitamin D Council’s recommended daily supplementation, which better reflects nature’s way for humans to obtain vitamin D from the sun. Also, all patients were stable, meaning they had less severe schizophrenia symptoms. This likely limited the potential improvement of schizophrenic symptoms, seeing as both antipsychotic treatment and vitamin D did not produce any beneficial effects on symptom severity.


Tovey, A. & Cannell, JJ. Does vitamin D improve symptoms of schizophrenia? The Vitamin D Council Blog & Newsletter, March 3, 2017.


Fatemeh, S. et al. Effectiveness of Vitamin D Supplement Therapy in Chronic Stable Schizophrenic Male Patients: A Randomized Controlled Trial. Iranian Journal of Pharmaceutical Research, 2016.

1 Response to Does vitamin D improve symptoms of schizophrenia?

  1. [email protected]

    There is some evidence that large bolus doses might dysregulate 1,25 dihydroxy-D.:

    “Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data”

    Martineau et al, in the bmj

    “Why might use of bolus dose vitamin D be ineffective for prevention of acute respiratory tract infection? One explanation relates to the potentially adverse effects of wide fluctuations in circulating 25-hydroxyvitamin D concentrations, which are seen after use of bolus doses but not with daily or weekly supplementation. Vieth has proposed that high circulating concentrations after bolus dosing may chronically dysregulate activity of enzymes responsible for synthesis and degradation of the active vitamin D metabolite 1,25-dihydroxyvitamin D, resulting in decreased concentrations of this metabolite in extra-renal tissues.38 Such an effect could attenuate the ability of 25-hydroxyvitamin D to support protective immune responses to respiratory pathogens.”

    One would expect that Schizophrenia like autism is affected by levels of 1,25DHD rather than by 25HD then the benefits might not be seen with high bolus doses unless the research includes more detailed analysis of individuals in a regression analysis.

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