Vitamin D: How Winter Causes Depression
The cold presence of Old Man Winter can leave many people feeling blue. Poignantly named, SAD, or seasonal affective disorder affects approximately 10 percent of the population. Beginning in the fall and continuing into the winter months, those suffering from SAD experience a range of depressive symptoms including weight fluctuations, hypersensitivity, low energy, and irritability. SAD can exacerbate symptoms of major depression or only bring on slight changes in mood in the fall and winter. So what makes people experience the winter blues?
Deficiency of Vitamin D
In a collaborative effort, researchers from the University of Georgia College of Education, the University of Pittsburgh, and the Queensland University of Technology in Australia have discovered a possible relationship between vitamin D levels and SAD symptoms. It is already common to find vitamin D deficiencies in people with depression. However, many studies regarding the sun and SAD have demonstrated interesting results. One example is that it takes about eight weeks for the body to process vitamin D from ultraviolet (UV) radiation. It also takes eight weeks for SAD to affect people from the seasonal peak of UV radiation. Basically, less sun means less vitamin D, and less vitamin D could mean depression - Especially over a period of 8-weeks.
Vitamin D: A Mood Booster
While psychologists continue to strengthen research regarding SAD, depression, and vitamin D, one aspect remains positive: vitamin D may help elevate mood, especially during the winter. According to researchers at Loyola University Chicago Marcella Niehoff School of Nursing (MNSON), vitamin D supplementation can improve many health issues, including depression. In Chicago, which is known for its blistering winter weather, “people spend time away from sunlight, which is a natural source of vitamin D,” says Sue Penckofer, PhD, RN, professor, MNSON. Combinations of sunlight, dietary intake of vitamin D, and vitamin D supplementation may reduce the risk for multiple health issues. In fact, light therapy (phototherapy) remains a prevalent treatment for patients diagnosed with SAD.
A Case of 3 Women
Researchers at Loyola want to continue studying the impact of vitamin D on health problems, particularly with regard to mood and diabetes. They plan to assess how vitamin D supplementation improves mood and blood sugar in women. A relationship exists between depression and insulin resistance, and there is support to indicate that vitamin D may diminish insulin resistance.
Sonal Pathak, MD, and endocrinologist at Bayhealth Medical Center in Dover, has taken this evidence a step further. In a study of three women with clinical depression, and either Type 2 diabetes or an underactive thyroid, she found that vitamin D supplementation improved their depressive symptoms. Not only did the participants report an improvement in mood, but scores on the Beck Depression Inventory demonstrated changes from severe to mild depression and from mild to minimal depression for the three women.
The Studies Are Still New
While these results are promising, studies regarding vitamin D deficiency and depression are in their infancy. To find a “real causal relationship” the scientific and psychological communities need to conduct larger and more controlled clinical trials. A review of the evidence by staff at Columbia University Medical Center (CUMC) suggests that no inconclusive data exists that proves vitamin D deficiency causes depression or that its use as a treatment is effective. The CUMC review found that nearly all trials in this field lack methodological strength, meaning the methods for obtaining information and evaluating events are limited. The best methods are to compare pools of participants with vitamin D supplementation to those not receiving supplementation. The CUMC review identifies only seven such trials, with a pool of only 3,200 participants.
Overall, the findings that vitamin D deficiency can cause depression and that vitamin D supplementation can improve depression are technically still “not clinically meaningful”. However, many studies suggest a potential link. What is most promising is that data indicates that vitamin D supplementation, combined with the use of antidepressant medication, can benefit patients diagnosed with clinically significant depression. Then again, vitamin D supplementation may only be an effective treatment for people with a true deficiency.
Jonathan A. Shaffer, PhD, assistant professor of sciences at CUMC hopes this review will shed some light on the need for more thorough studies concerning vitamin D and its potential uses in depression diagnoses and treatments. He proposes that researchers look into more thorough methods of study, including highly controlled designs. Researchers should compare data from participants with supplementation to those without. It is also important to take into account individual dosing and forms of vitamin D supplementation when evaluating the findings. With more clinical evidence, the relationship between vitamin D and depression could shed some valuable light on effective treatments for many individuals.
- Melissa Lavery, M.S.
Columbia University Medical Center. (2014, March 18). No evidence that vitamin D supplements reduce depression, study concludes. ScienceDaily. Retrieved January 11, 2015 from www.sciencedaily.com/releases/2014/03/140318185829.htm
Edwards, D. (2014, December 5). Vitamin D Deficiency Causes Depression and SAD. Retrieved January 11, 2015, from http://www.inquisitr.com/1656231/vitamin-d-deficiency-causes-depression-and-sad/
Endocrine Society. (2012, June 25). Treating vitamin D deficiency may improve depression. ScienceDaily. Retrieved January 11, 2015 from www.sciencedaily.com/releases/2012/06/120625152358.htm
Loyola University Health System. (2010, March 8). Vitamin D lifts mood during cold weather months, researchers say. ScienceDaily. Retrieved January 11, 2015 from www.sciencedaily.com/releases/2010/03/100303162854.htm
Seasonal affective disorder (SAD). (2014, September 12). Retrieved January 11, 2015, from http://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/basics/definition/CON-20021047
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