Vitamin D does not prevent depression in adults nor can it improve a person’s mood, study reveals
Vitamin D is sometimes called the “sunshine vitamin” because the skin can naturally create it when exposed to sunlight. While some believe that insufficient levels of vitamin D may play a role in depression, researchers now show that it does not protect against depression in middle-aged or older adults in one of the largest studies of its kind.
“There was no significant benefit from the supplement for this purpose. It did not prevent depression or improve mood,” writes Olivia I Okereke from the Massachusetts General Hospital’s Psychiatry Department in the analysis published in JAMA. Okereke is the lead author of the report and principal investigator of the study. The study’s senior author, JoAnn Manson, from the Brigham and Women's Hospital, says that while vitamin D is known to be essential for bone and metabolic health, “randomized trials have cast doubt on many of the other presumed benefits.”
According to the authors, numerous prior studies have shown that low blood levels of vitamin D (25-hydroxy vitamin D) were associated with a higher risk for depression in later life, but there have been few large-scale randomized trials necessary to determine causation. The current study has delivered what may be the “definitive answer to this question,” emphasizes the research team.
“Depression is often undertreated in older persons, who frequently experience residual symptoms even with treatment. Thus, late-life depression prevention is a public health priority. Observational data have shown associations between low levels of serum 25-hydroxyvitamin D and higher late-life depression risk; and having a low level of 25-hydroxyvitamin D has been hypothesized to play a role in the etiology of seasonal affective disorder. However, within a framework for the prevention of mental disorders, it is uncertain whether supplementation with vitamin D3 would benefit all persons (universal prevention), or only those at high risk due to subclinical symptoms (indicated prevention) or due to depression risk factors (selective prevention),” say the team. Accordingly, they decided to test the effects of vitamin D3 supplementation on late-life depression risk and mood scores.
The analysis included 18,353 men and women aged 50 years or older. Half the participants received vitamin D3 (cholecalciferol) supplementation for an average of five years, and the other half received a matching placebo for the same duration.
Called VITAL-DEP (Depression Endpoint Prevention in the Vitamin D and Omega-3 Trial), the study was an ancillary study to VITAL, a randomized clinical trial of cardiovascular disease and cancer prevention among nearly 26,000 people in the US. From that group, the research team studied over 18,000 men and women who did not already have any indication of clinical depression to start with, and then tested whether vitamin D3 prevented them from becoming depressed. “One scientific issue is that you actually need a very large number of study participants to tell whether or not a treatment is helping to prevent the development of depression. With nearly 20,000 people, our study was statistically powered to address this issue,” explains Okereke.
The results were clear, say experts, who found that vitamin D does not reduce the risk of depression in adults. Among the randomized participants, the researchers found the risk of depression or clinically relevant depressive symptoms was not significantly different between those receiving active vitamin D3 supplements and those on placebo, and no significant differences were seen between treatment groups in mood scores over time.
“There were 609 cases of depression or clinically relevant depressive symptoms (incident and recurrent) in the vitamin D3 group (12.9 out of 1,000 person-years) and 625 cases in the placebo group (13.3 out of 1,000 person-years). There were no significant differences between groups in depression incidence or recurrence. No significant differences were observed between treatment groups for change in mood scores over a median follow-up of 5.3 years,” write authors. They add, “The findings do not support a role for supplemental Vitamin D3 in depression prevention among adults.”
According to the research team, however, it is not time to throw out the vitamin D yet, “at least not without your doctor's advice.” “Some people take it for reasons other than to elevate mood,” says Okereke.