In a new study from the journal Psychoneuroendocrinology, researchers found a high prevalence of vitamin D deficiency in suicidal patients, as well as a negative correlation between vitamin D levels and pro-inflammatory markers.
Suicide is a complex event that involves a multitude of genetic, environmental and psychological influences. It is widely known that psychological conditions such as depression, stress, personality disorders, and other forms of mental illness play a major role leading up to a suicide attempt.
What is less understood is how the unique biological markers seen in suicidal patients contribute to suicidal behavior. Previous evidence suggests that inflammation can contribute to depressive disorders, which in turn increases the odds of a suicide attempt.
Taking this a step further, researchers have found that patients who attempt suicide have elevated levels of pro-inflammatory markers such as interleukin-6 (IL-6) and C-reactive proteins when compared to depressed patients who were non-suicidal.
While these studies support the hypothesis that inflammation is an underlying factor in those who attempt suicide, the cause of that inflammation remains unknown.
Researchers of the current study speculated that vitamin D, a known modulator of inflammation, may be involved in the etiology of suicide attempts and could subsequently be a cheap and effective therapy in these patients.
To test their hypothesis, Dr. Cécile Grudet and her research team out of Sweden enrolled participants from three distinct groups.
They recruited 59 patients who had been admitted to Lund University Hospital after a suicide attempt, 17 patients with major depressive disorder but who were non-suicidal, and 14 healthy participants from the surrounding area to serve as a control group.
All participants underwent a structured interview by a psychiatrist in order to detect any psychiatric disorders and determine the severity of these disorders.
Blood samples were then taken within a week after the interview. The researchers used these blood samples to measure the participants’ inflammatory markers, including IL-6, interleukin 1-beta (IL-1β) and tumor necrosis factor alpha (TNF-α), as well as their vitamin D status.
IL-1β is an important inflammatory marker that is associated with pain sensitivity in the . TNF-α is an inflammatory cytokine produced by adipose tissue and is responsible for immune regulation. Improperly functioning TNF-α has been implicated in the development of depression.
The researchers wanted to determine the prevalence of vitamin D deficiency, defined as having levels below 20 ng/ml, and whether this deficiency was correlated with increased inflammatory markers in suicidal patients when compared to non-suicidal depressed patients and the control group.
Here’s what the researchers found:
- Overall, 92% of the suicidal patients had 25(OH)D levels below 30 ng/ml compared to 59% in the non-suicidal depressed patients and 71% in the control group (P < 0.01).
- The average vitamin D level in the suicidal patients was significantly lower than the other groups with an average of 18.8 ng/ml, compared to 24.8 ng/ml in the non-suicidal depressed patients, and 26 ng/ml in the healthy control group (P < 0.05).
- There was no significant difference in vitamin D levels based on psychiatric diagnosis or severity of the disorder.
- A significant negative relationship was observed between vitamin D and IL-1β in the suicide attempters (P < 0.05).
- There was a significant negative correlation between vitamin D and IL-6 in the non-suicidal depressed patients (P < 0.05).
- There was no significant effect of psychiatric medications or anti-epileptic drugs on vitamin D in any of the participants.
The researchers concluded,
“As we and others have previously shown that peripheral and central inflammation is increased in suicidal patients, we here suggest that low levels of vitamin D could be a contributing cause of this inflammation.”
They went on to add,
“As inflammation is suggested to directly be part of the neural mechanisms underlying depressive and suicidal behavior, it should be of high relevance to detect and cure the vitamin D deficiency in these patients.”
The researchers acknowledge a few key factors missing from their analysis. They did not collect data on the participants’ ethnicity, sun exposure behavior, or smoking habits, which may impact their results.
As with other observational studies, the design limits the ability to know for sure whether vitamin D deficiency causes increased inflammation or suicide attempts.
While this research hints at the possibility that vitamin D may influence biological factors relating to suicides, it is important to keep in mind the complex nature of suicidal behaviors. These events often arise from life issues, such as social or financial problems, and may not be able to be controlled through nutritional or medical intervention.
Nonetheless, if biological factors do significantly contribute to risk of suicide attempt then, as the researchers mention, vitamin D may be a cost-effective and easily administered therapy to help in those with suicidal behaviors.
For this reason, clinical trials looking at how vitamin D supplementation to treat deficiency affects suicidal behavior are still needed.