Past studies have suggested that vitamin D deficiency may lead to depression. In response, other studies propose that increasing vitamin D levels with supplements may reduce depressive symptoms. But new research, published in the journal Psychosomatic Medicine, has found no evidence that vitamin D supplements reduce depression.
The research team, led by Dr. Jonathan A. Schaffer of the Columbia University Medical Center (CUMC) in New York, NY, conducted a systematic review of clinical trials that looked at how vitamin D supplementation affected depression.
The team identified seven trials involving 3,191 participants that looked at the effects of vitamin D supplementation against depression and compared this with no vitamin D supplementation.
The investigators say that almost all trials were "characterized by methodological limitations" and only two studies included participants who had clinical depression at study baseline.
The researchers found that vitamin D supplementation itself had no overall impact on depression.
However, further investigation revealed that for patients with clinical depression, particularly those who were taking standard antidepressant medication, vitamin D supplementation may help reduce depressive symptoms.
But Dr. Schaffer says that before this association can be confirmed, new trials that monitor the effects of vitamin D supplements in these patients need to be conducted.
For now, the researchers say vitamin D supplementation may only be beneficial for individuals with vitamin D deficiency.
Dr. Schaffer adds:
"Although tempting, adding vitamin D supplements to the armamentarium of remedies for depression appears premature based on the evidence available at this time."
He hopes that this research will encourage other investigators to create new trials that will determine whether vitamin D supplements can help reduce depression once and for all.
Vitamin D supplements: to take or not to take?
As well as hailing vitamin D supplements for their potential to reduce depression, past research has suggested they can improve breast cancer survival rates, as well as reduce the risk of heart attack, stroke and cancer.
Vitamin D is important for our body. It helps regulate the absorption of calcium and phosphate in our bones and aids communication between cells.
The main source of vitamin D is from the sun, although some foods - such as oily fish, eggs and fortified fat spreads - contain the vitamin.
But when it comes to using vitamin D supplements, some studies have raised concerns regarding their health benefits.
Earlier this year, Medical News Today reported on a study published in The Lancet Diabetes and Endocrinology, which concluded that vitamin D supplements are unlikely to reduce the incidence of heart attack, heart disease, stroke, cancer and bone fractures.
Last year, other research came to a similar conclusion. Investigators from the International Prevention Research Institute in France stated that low vitamin D levels are a consequence of ill health, not a cause - a suggestion they say casts doubt over the benefits of vitamin D supplements against disease prevention.
With such mixed views, we compiled a feature that looked in more detail at whether vitamin D supplements are good for our health.