Vitamin D and Mental Health

Sunlight Exposure Is Often Our Main Source of Vitamin D

Vitamin D has long been associated with bone health. More recently, data has started to suggest that vitamin D plays an invaluable role in immune function with individuals who are deficient being at a significantly higher risk for respiratory infections like colds and flu. While data on vitamin D and mental health has long been somewhat mixed, the latest analyses are starting to find significant benefits.

Of the mental health benefits of vitamin D, probably the strongest are related to:

  • Depression
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Schizophrenia

Vitamin D and Depression

A recent meta-analysis looked at the correlation between vitamin D deficiency and depression (Wilczyński 2022). Vitamin D deficiency correlated with a 1.5 times increased risk of a depression diagnosis. However, the authors state that the results of their study do not indicate if vitamin D causes or contributes to depression directly. 

A meta-analysis on trials administering vitamin D as a treatment for depressive symptoms found significant effects (Srifuengfung 2023). For adults, the effect size was moderate, indicating a reasonably sized benefit in reducing depression symptoms with vitamin D supplementation. However, for children the effect size was still positive but quite small. Of note, for children, only one study was included in the analysis. The included study didn’t assess levels of vitamin D and likely treated both deficient and sufficient children with vitamin D supplementation. Similarly, more than half of the studies in adults didn’t measure vitamin D levels and included subjects without vitamin D deficiency. It’s quite likely that the results from vitamin D for treating depression would be even stronger if limited to populations that were deficient.

Vitamin D and ADHD

Similar to depression, children with ADHD are more likely to have vitamin D deficiency. A meta-analysis from 2019 showed that ADHD children had lower levels than healthy controls. On average, children with ADHD had levels of vitamin D that met the criteria for vitamin D deficiency (Kotsi 2019).

Intervention studies that supplemented vitamin D to children with ADHD also found benefits, although the available evidence is limited (Gan 2019). Of the four published randomized controlled trials reviewed in the most recent meta-analysis, two included children whose average vitamin D levels were deficient, one didn’t measure vitamin D levels and one had children that had vitamin D levels that were well within the normal range. In all of the studies, vitamin D was combined with standard medication treatment. Overall, vitamin D showed a modest improvement in ADHD symptoms.  

A more recent trial added vitamin D to standard medication for six weeks (Dehbokri 2019). The authors noted significant improvements for inattention, with the best results found in children who were initially deficient. 

Vitamin D and Schizophrenia

Vitamin D Gel Caps

Schizophrenia is a challenging condition to treat. Symptoms of schizophrenia have both positive and negative components. “Positive” symptoms include hallucinations, delusions, hyperactivity and behavioral abnormalities. “Negative” symptoms include symptoms similar to depression, including loss of pleasure in daily activities, lack of motivation, diminished facial expressions and reduced amount of speech.

Similar to both depression and ADHD, schizophrenia patients have been found to have lower levels of vitamin D as compared to healthy individuals. In fact, one of the most recent analyses found that schizophrenia patients were twice as likely to be vitamin D deficient as compared to controls (Zhu 2020).

Standard medications for schizophrenia generally help more with positive symptoms. While often recalcitrant to treatment, negative symptoms are still of significant concern to patients. A meta-analysis of different nutritional interventions found that vitamin D was one of the treatments that can provide benefits for negative symptoms in schizophrenia (Sarris 2022).

On the Use of Vitamin D for Treatment

Vitamin D is a prohormone, it’s not actually a vitamin. When considering vitamin D supplementation, levels should typically be assessed before supplementation. If testing finds low levels, oral supplements are the simplest way to raise levels. After treatment has been initiated, I generally recommend retesting at six months.

As a fat soluble vitamin, vitamin D builds up slowly in the body. Typically by six months, whatever dose is being used has reached a plateau and you can expect a person’s level to stay around that level with continued supplementation unless they have a large change in regular sunlight exposure. Most people need between 2000 and 5000 iu per day, but it depends on the levels found upon testing. 

If interested in vitamin D, talk with your doctor to get your levels checked. While there is prescription vitamin D, it is usually as vitamin D2, the form of vitamin D found in plants. Vitamin D2 appears to be somewhat less effective than vitamin D3, the standard form found in humans. Most over-the-counter supplements contain vitamin D3 and are preferred over D2 whenever possible.    


Vitamin D appears to provide support for a number of different mental health conditions, including depression, ADHD and schizophrenia. Considering the safety of the vitamin when used properly, for anyone struggling with mental health concerns, testing vitamin D levels and treating as appropriate may play a part in helping to reduce symptoms. 

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