CORVALLIS, Ore — March 18, 2015 — A study published in the journal Psychiatry Research shows a relationship between low levels of vitamin D and depression in otherwise healthy young women.

Researchers found that young women with lower levels of vitamin D were more likely to have clinically significant depressive symptoms over the course of a 5-week study.

The results were consistent even when researchers took into account other possible explanations, such as time of year, exercise, and time spent outside.

“Depression has multiple, powerful causes and if vitamin D is part of the picture, it is just a small part,” said David Kerr, Oregon State University, Corvallis, Oregon. “But given how many people are affected by depression, any little inroad we can find could have an important impact on public health.”

Vitamin D is an essential nutrient for bone health and muscle function. Deficiency has been associated with impaired immune function, some forms of cancer, and cardiovascular disease.

The current study was prompted in part because there is a widely held belief that vitamin D and depression are connected, but there is not actually much scientific research out there to support the belief.

The researchers focused on young women in the Pacific Northwest because they are at risk of both depression and vitamin D insufficiency. For the study, the researchers recruited 185 women aged 18 to 25 years to participate in the study at different times during the college school year. Vitamin D levels were measured from blood samples and participants completed a depression symptom survey each week for 5 weeks.

Many women in the study had vitamin D levels considered insufficient for good health, and the rates were much higher among women of colour, with 61% of women of colour recording insufficient levels, compared with 35% of other women. In addition, more than a third of the participants reported clinically significant depressive symptoms each week over the course of the study.

“It may surprise people that so many apparently healthy young women are experiencing these health risks,” Kerr said.

As expected, the women’s vitamin D levels depended on the time of year, with levels dropping during the fall, at their lowest in winter, and rising in the spring. Depression did not show as a clear pattern, prompting Kerr to conclude that links between vitamin D deficiency and seasonal depression should be studied in larger groups of at-risk individuals.

The researchers noted that the study does not conclusively show that low vitamin D levels cause depression. A clinical trial examining whether vitamin D supplements might help prevent or relieve depression is the logical next step to understanding the link between the two.

SOURCE: Oregon State University