Treating vitamin D deficiency may help cure depression, according to researchers.

A new small study, presented at The Endocrine Society's 94th Annual Meeting in Houston, found that women with moderate to severe depression experienced dramatic improvement in their symptoms after being treated for their vitamin D deficiency.

Participants did not change their antidepressants medications or any other environmental factors that could affect their depression symptoms, leading researchers to conclude that treatment for vitamin D deficiency had a beneficial effect on depression.

"Vitamin D may have an as-yet-unproven effect on mood, and its deficiency may exacerbate depression," researcher Dr. Sonal Pathak , an endocrinologist at Bayhealth Medical Center in Dover, Delaware said in a statement. "If this association is confirmed, it may improve how we treat depression."

The study consisted of three women who were between the ages of 42 and 66.  All three women had previously been diagnosed with major depressive disorder and were taking antidepressants.

The women were also being treated for either Type 2 diabetes or hypothyroidism.

Researchers said that because the women had risk factors associated with vitamin D deficiency, like low vitamin D intake and poor sun exposure, they each were given a 25-hydroxyvitamin D blood test that confirmed that they did not have enough vitamin D.

The women were placed on an oral vitamin D replacement therapy for right to 12 weeks to restore their vitamin D levels to a normal status.

After being treated, researchers reported that all three women reported significant improvement in their depression, as found using the Beck Depression Inventory, a 21-item questionnaire that measures the severity of sadness and other symptoms of depression.

A score of 0 to 9 indicates minimal depression, 10 to 18 indicates mild depression, 19 to 29 corresponds with moderate depression, and 30 to 63 was equivalent to severe depression.

Pathak said that one woman had her depression score improve from severe depression to only mild depression.  Another participant who had moderate depression exhibited only minimal symptoms of depression after vitamin D replacement therapy, and the third woman when from moderate depression to mild depression.

Previous studies have also found that vitamin D improved mood and depression, but researchers noted that larger more randomized studies are needed to prove whether there was really a causal relationship between vitamin D and mood.

"Screening at-risk depressed patients for vitamin D deficiency and treating it appropriately may be an easy and cost-effective adjunct to mainstream therapies for depression," Pathak said.