Some researchers thought that insufficient levels of vitamin D may play a role in depression, but the findings of a large study of more than 18,000 adults aged 50 or older in the US have found no evidence to that effect.
Dr. of the Psychiatry Department of Massachusetts General Hospital. Olivia I. Okereka and the study’s lead author said in a news statement, “There was no significant benefit from the supplement for this purpose. It did not prevent depression or improve mood.”
The study noted, “The findings do not support the role of supplemental vitamin D3 in the prevention of depression in adults.”
There were 609 cases of depression or clinically relevant depressive symptoms in the vitamin D3 group and 625 cases in the placebo group.
Participants filled out annual questionnaires, and researchers conducted face-to-face interviews with approximately 1,000 participants.
The study was a randomized controlled trial (RCT), which is considered the gold standard of scientific research. It was also a “double blind”, meaning neither participants nor researchers knew who took vitamin D and who had a placebo. It consisted of a large sample population with approximately equal numbers of men and women and high racial and ethnic diversity.
“One scientific issue is that a very large number of study participants are needed to tell whether or not you are actually helping to prevent the development of depression.”
“With about 20,000 people, our study was statistically driven to address this issue.”
Limitations included the fact that surveys were conducted only annually and that symptoms of depression were self-reported. However, it was similar for both the vitamin D group and the placebo group. Furthermore, the findings were not applicable to younger adults or children.
Brian Powers, a dietitian at University College London Hospital, said it was pleased to have the so-called “negative results” accepted for publication.
“Was not included with the research,” Power said, adding that there is a longstanding issue of publication bias, with statistically significant findings unevenly published in studies.
“This conclusion should be reiterated to increase the belief that there is no effect. By doing so we will not waste resources in the future.”
The study stated that previous observational studies had found a favorable relationship between vitamin D and depression, but stated that a link to this RCT and others in a “rigorous experimental setting” was not found.
Like all vitamins, D is an essential micronutrient, which is required in small amounts for normal cell function, growth and development. The primary function of vitamin D is to help the body absorb calcium and phosphate, thus keeping muscles and teeth healthy and making bones stronger and less likely to break.
The body makes vitamin D when the skin is in direct sun exposure. Indirect exposure, such as the sun shining through a window, will not produce vitamin D clouds. Shade, living at high altitude and away from the equator also affect your body’s production.
Dr. of Brigham and Women’s Hospital “Vitamin D is essential for bone and metabolic health, but randomized trials have cast doubt on other presumed benefits,” said Joanne Manson.
For countries such as the UK where the skies are often cold, additional supplementation may be necessary during the months of October through March, according to the UK National Health Service.