Vitamin D is a group of fat-soluble prohormones (substances which can be converted into hormones) which aid in the intestinal absorption of calcium and phosphorus.
It is often called the "sunshine vitamin" because it is not absolutely necessary to obtain it through eating food. The human body has the ability to synthesize it itself when exposed to sufficient sunlight.
Vitamin D is very important for health because it helps keep bones strong. It also plays a role in muscle movement, neural impulse transmission and immune system function.
Recent research also suggests a connection between vitamin D and depression, although more research is needed before any firm recommendations can be made.
Vitamin D's Link to Depression Risk
In what was probably the largest study conducted on vitamin D and depression to date, a team of University of Texas Southwestern researchers examined the results of almost 12,600 patients who had completed a preventive medical examination at the Cooper Clinic in Dallas, TX between late 2006 to late 2010. The patients' vitamin D status was determined via blood testing and their depression symptoms were assessed using the CES-D questionnaire, a 10-item self-report scale which can be used to detect and evaluate the severity of depression.
What the researchers found when they analyzed the collected data was that the lower a person's vitamin D level was, the greater their risk for currently having depression symptoms, especially if the person had a history of depression. Conversely, those with higher levels had a lower risk for having depression.
This particular study, however, did not assess whether supplementation with the vitamin could help alleviate depression symptoms.
Supplementation May Help Depression Symptoms
Although no large-scale studies have been conducted as of yet to identify whether vitamin D supplementation is a viable treatment for depression, some case reports suggest a connection.
The most recent of these studies was a small, three-person study conducted by Dr. Sonal Pathak, an endocrinologist in Dover, Delaware.
Dr. Pathak noticed that several of her patients who were depressed also were vitamin D-deficient; and, these patients reported having improved energy and mood once she corrected the deficiency. Because of these results, she decided to conduct a small study of the next patients she treated in order to quantify her results.
After identifying three vitamin D-deficient patients to study, she gave them a standardized depression symptoms survey, followed by vitamin D supplementation to correct their deficiency.
When the depression survey was repeating after twelve weeks of supplementation, their symptoms had improved.
Because the study was so small, however, no real conclusions can be drawn. Pathak noted at the The Endocrine Society’s Annual Meeting in Houston, where she presented her results in the summer of 2012, that she hopes to conduct a large-scale randomized study with a control group in the near future.
How Vitamin D Might Help Depression
Various mechanisms have been proposed for how vitamin D might be involved in depression, including its role in regulation of the body's inflammatory response. Increased inflammation from proinflammatory cytokines, such as Interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) has been associated with an increased risk for depression. Vitamin D helps to reduce production of these molecules.
It is also possible that Vitamin D might reduce the risk for depression by influencing certain diseases which have depression as a secondary consequence, such as cancer, cardiovascular disease and multiple sclerosis.
What Does This Mean for You?
Although the jury is still out on whether vitamin D is an effective treatment for depression, it may be worth a discussion with your physician. She can easily order a blood test. Your personal physician can easily order a blood test for vitamin D deficiency and provide you with prescription-strength vitamin D supplements if needed.
Until the research on vitamin D and depression is clearer, self-help measures such as taking an over-the-counter vitamin D supplement; eating more vitamin D-rich foods, like salmon, tuna and vitamin D-fortified milk; and, spending more time in the sun to encourage your body to produce its own vitamin D can't hurt -- in conjuction with more proven depression treatments such as medication and psychotherapy.
"Dietary Supplement Fact Sheet: Vitamin D." Office of Dietary Supplements.. June 24, 2011. National Institutes of Health. Accessed: Dec. 17, 2012.
Endocrine Society. "Treating vitamin D deficiency may improve depression." ScienceDaily. June 25, 2012. Accessed: Dec. 17, 2012.
Hoang, MinhTu T. et. al. "Association Between Low Serum 25-Hydroxyvitamin D and Depression in a Large Sample of Healthy Adults: The Cooper Center Longitudinal Study." Mayo Clinic Proceedings 86.11 (November 2011): 1050-1055.