Medical professionals have long understood that Vitamin D can contribute to good physical health and emotional well-being, and in recent years, researchers have begun to explore this nutrient’s potential impact on more complex mental health concerns such as depression and schizophrenia.
Some experts report vitamin D deficiencies as a risk factor for depression and schizophrenia. Others caution the evidence does not support these claims.
What Is Vitamin D?
Vitamin D is an organic chemical naturally produced by the human body. It’s also present in certain foods and dietary supplements. In addition, exposure to sunlight can increase the circulating levels of vitamin D in the body.
Vitamin D promotes bone strength by helping the body absorb and maintain appropriate levels of calcium and phosphorate. Vitamin D deficiencies can lead to bone problems such as rickets, osteomalacia, and osteoporosis.
According to Harvard T.H. Chan School of Public Health, the health benefits of vitamin D may also include:
- Reducing cancer cell growth
- Controlling the spread of infections
- Limiting inflammation
- Supporting the immune system
- Lowering the risk of heart attack and stroke
- Protecting against cognitive decline and the onset of dementia
- Decreasing the likelihood of type 1 diabetes and multiple sclerosis (MS)
A few foods, such as beef liver, mushrooms, and egg yolks, have small amounts of naturally occurring vitamin D. Because many people in the United States don’t eat enough of these foods, manufacturers add vitamin D to certain products. Commonly fortified products include some brands of milk, cereal, and orange juice.
Although people can also take dietary supplements to get additional vitamin D, the National Institute of Health urges caution, as an overabundance of this chemical can cause a host of health problems, such as:
- Confusion
- Nausea and vomiting
- Kidney stones
- Muscle weakness
- Kidney failure
- Abnormal heart rate
Is Vitamin D Linked to Depression?
As we noted at the end of the previous section, confusion is one of the potential negative effects of too much vitamin D. Other mental health effects of vitamin D appear to be linked to deficient amounts of the chemical.
For example, in January 2020, the Indian Journal of Psychological Medicine published a review of existing literature on the link between vitamin D and depression. The team that conducted this review assessed 148 articles before choosing 61 for inclusion in their report. Their findings included the following:
- Several studies found that lower amounts of vitamin D correlated with a higher risk of depression.
- Researchers have noted that low levels of serum vitamin D concentration in pregnant people is associated with an elevated risk of postpartum and antepartum depression.
- Some studies found that patients with depression improved after receiving vitamin D supplements, but other studies found no differences between patients who were given supplemental vitamin D and those who were not.
- Researchers have not yet established a cause-effect relationship between low levels of vitamin D and depression.
“The evidence clearly supports a relationship between vitamin D and depression, though the directionality of the association can be contested …” the researchers wrote. “Many gaps in evidence remain, and this must be addressed through future trials that employ uniform assays, dosing protocols, and outcome measures.”
Can Supplemental Vitamin D During Infancy Help?
The studies that were included in the January 2020 review from the previous section were not conclusive about the potential mental health benefits of vitamin D supplements. However, a May 2023 JAMA Open Network study found that infants who received higher than standard amounts of supplemental vitamin D prior to age 2 had lower rates of certain mental health concerns four to six years later.
This study, which was conducted by a research team from Helsinki Finland, involved 346 subjects who completed the entire process:
- 169 infants received 400 international units (IU) of supplemental vitamin D, considered the standard level, from age 2 weeks to 24 months.
- 177 infants received 1,200 IU of supplemental vitamin D, or three times the standard recommended level, for the same period.
The research team conducted follow-up assessments between the ages of 6 and 8. This assessment included parent-completed questionnaires. The results included the following:
- 11.8% of children in the 400 IU group and 5.6% of those in the 1,200 IU group had “clinically significant internalizing problems,” such as anxiety and depression.
- 9.5% of the 400 IU group and 9.0% of the 1,200 IU group demonstrated externalizing problems, which can include aggression and rule-breaking.
In other words, elevated levels of supplemental vitamin D during infancy appeared to reduce the rate of childhood anxiety and depression by about 53%, while behavioral concerns did not seem to be affected by vitamin D levels.
Can Vitamin D Deficiencies Cause Schizophrenia?
The month prior to the publication of the Finnish research from the previous section, the Journal of Neurochemistry featured a study that explored the link between vitamin D and schizophrenia.
This study, which was conducted by a team from the Queensland (Australia) Brain Institute, focused on the following:
- The team hypothesized that vitamin D deficiencies during brain development may impair the development of dopamine signaling circuits.
- This impairment may, in turn, cause the abnormal brain functions that experts have observed in people with schizophrenia.
To test their hypotheses, the Australian researchers took the following steps:
- They developed lab-grown cells that mimicked the process that should occur during the embryonic developmental stage.
- They placed some of these cells in a culture that contained vitamin D hormones.
- They allowed another set of the cells to grow in an environment that was free of vitamin D.
“What we found was the altered differentiation process in the presence of vitamin D not only makes the cells grow differently, but recruits machinery to release dopamine differently,” Professor Darryl Eyles, the study’s corresponding author, said in a May 2023 article that was released the same day that the study was published.
These changes, Eyles noted, may be the source of the dopamine abnormalities that affect people with schizophrenia.
Eyles is a recognized expert in this field, having previously published multiple studies on vitamin D, schizophrenia, and related topics. These research efforts have provided considerable insights into the neurodevelopmental factors that may lead to certain mental health concerns later in life.
However, it is important to note that neither Eyles nor any other researchers have yet established a definitive cause-effect relationship between abnormal levels of vitamin D and elevated rates of schizophrenia or other complex mental health concerns.
Are Vitamin D Proponents Misleading the Public?
Headlines and short summaries of studies involving vitamin D and mental health can give the false impression that researchers have identified the root causes for certain disorders. As we alluded to at the end of the previous section, even strong associations are not proof of cause-effect relationships.
Some researchers believe studies widely overstate vitamin D’s role in mental health disorders.
In a March 2023 Scientific American article, epidemiologist Brian Lee of Drexel University expressed his educated doubts about the veracity of recent claims involving vitamin D and mental health. Referring to a study on vitamin D’s ability to prevent suicide and self-harm, Dr. Lee said:
“Imagine if getting a little vitamin D pill would reduce the mental health burden around the world. That would be incredible, right? That’s the kind of pipe dream I think people are chasing with this research.”
Ingrid Wickelgren, who wrote the Scientific American article, noted that several studies have found no connection between vitamin D and various mental health concerns:
- A five-year study that involved more than 18,000 older adults found that supplemental vitamin D made no observable difference in rates of depression.
- A randomized trial from 2021 that included 149 young people with psychosis determined that vitamin D had “no effect at all” on reducing symptoms.
- An Australian study of more than 400,000 people found no link between psychiatric disorders and genetic variants associated with vitamin D deficiencies.
Other experts express doubts about the effect of vitamin D. These include the authors of a November 2021 review in the Journal of Clinical Medicine.
The team that conducted this review found little evidence to support calls for the increased use of supplemental vitamin D. In their own words:
“None of the high-quality studies … which evaluated outcomes other than depression, supported the hypothesis that vitamin D supplementation effectively ameliorates mental health issues, while they present conflicting evidence for depression.”
John McGrath, a psychiatrist and epidemiologist who led the Australian study mentioned in the Scientific American article, told the publication changes in vitamin D may be the result of mental health symptoms, not the causes of the disorders themselves. Here’s his point of view:
“If you have an illness like depression or maybe vulnerability to suicide, and then you change your behaviors, you get less vitamin D because of your changed behavior. Low [vitamin] D may be one of those bystander or proxy markers that just goes along with your behavior.”
What Does This Mean for Mental Health Treatment?
None of the research discussed in this article have changed in how we treat mental health disorders. Even if future scientific investigations confirm the studies that suggest a link between vitamin D deficiencies and mental illness, researchers are unlikely to implement these findings in a therapeutic environment for quite some time.
If you or someone that you care about experiences symptoms of a mental health disorder, effective help is available now.
Crownview Psychiatric Institute offers the personalized care and comprehensive programming. Our programs can empower you or your loved one to achieve improved health and better quality of life.
To learn more about how CPI can help, please visit our Contact Us page or call our center today.
Gianna Melendez
Jodie Dahl, CpHT