Vitamin D affects most physiological systems, including the brain. Research has found that vitamin D helps regulate serotonin and dopamine production through vitamin D receptors. In the brain, both dopamine and serotonin function as neurotransmitters, or chemicals released by nerve cells to send signals to other nerve cells.
Low levels of dopamine and serotonin are thought by many to be major contributors to the development of depression. Thus, researchers have hypothesized that vitamin D plays a crucial role in depression. Past research has confirmed this hypothesis by reporting that vitamin D helps treat depression. Though, skepticism remains as other studies have reported mixed findings.
Approximately 1 in 10 people in Korea suffer from depression. Because women are at a 2-3 fold increased risk of experiencing depression than men, this is a critical health problem of Korean females.
Recently, researchers aimed to understand whether a relationship exists between vitamin D status and depressive symptoms in young Korean female workers. The researchers identified a gap in knowledge as the role of vitamin D in depression has not been thoroughly studied in Korean individuals, a population who suffers from vitamin D deficiency at an alarming rate. According to the data from the Korea National Health and Nutrition Examination Survey (KHANES 2010-2011), only 28.3% of people 10 years of age or older were considered to be sufficient in vitamin D (as defined by levels of 20 ng/ml or higher).
The researchers conducted medical examinations, anthropometric measurements and blood tests of 1054 female workers. The Korean version of the Center for Epidemiologic Studies Depression Scale (CES-D), a widely accepted depression scale, was used to assess depressive symptoms. The researchers compared vitamin D levels to the presence of depressive symptoms.
Here is what they found:
- The average vitamin D levels was 9.07 ng/ml.
- 68.4% were considered vitamin D deficient, as defined by levels less than 10 ng/ml.
- 33.9% were considered depressed.
- After adjusting for potential confounding factors, the vitamin D deficient individuals were 55% more likely to have depression than the vitamin D sufficient individuals.
The researchers concluded,
“This study is significant in that amidst a serious widespread deficiency of serum vitamin D, a high prevalence of depressive disorder, and a lack of previous studies investigating the association between serum vitamin D and depressive symptoms in Korean subjects, the study has determined the level of serum vitamin D in a large number of Korean female workers and its association with depressive symptoms.”
As always, it’s important to acknowledge the study’s limitations. The study design was cross-sectional, meaning it only proves correlation, not causation. The researchers compared depressive symptoms in those with vitamin D levels below 10 ng/ml to those with levels above 10 ng/ml; it’s likely that an individual requires a vitamin D status far above 10 ng/ml (the Vitamin D Council recommends a status of 40-80 ng/ml) to help acquire some protective benefits of vitamin D for depression.
Tovey, A. & Cannell, JJ. Low vitamin D status linked to depressive symptoms in Korean female workers. The Vitamin D Council Blog/Newsletter, January 2016.