Vitamin D: Role In Depression
Seasonal Affective Disorder (SAD) is a depressive illness that has been linked to a biochemical imbalance in the brain prompted by shorter daylight hours and a lack of sunlight in winter. Symptoms can include, but are not limited to: fatigue, lack of interest in normal activities, social withdrawal, craving foods high in carbohydrates, and weight gain. Increased exposure to sunlight can improve symptoms of SAD and in more extreme cases light therapy (phototherapy) has proven an effective treatment option.
New information is developing out of an international research partnership between the University of Georgia College of Education, the University of Pittsburgh and the Queensland University of Technology in Australia, who reported their findings in the November 2014 issue of the journal Medical Hypotheses. Stewart and Michael Kimlin from QUT's School of Public Health and Social Work conducted a review of more than 100 leading articles and found a relationship between vitamin D and seasonal depression. “Vitamin D could have a regulative role in the development of SAD," said Alan Stewart of the University of Georgia College of Education.
This should not be completely surprising information, as it is known that vitamin D and vitamin D responsive elements are concentrated in the hypothalamus, a region that includes the circadian timing systems and much of its neural circuitry. Based on the team's investigations, Stewart went on to state that vitamin D was likely to be a contributing factor in seasonal depression for numerous reasons. “We believe there are several reasons for this, including that vitamin D levels fluctuate in the body seasonally in direct relation to seasonally available sunlight," he said. "For example, studies show there is a lag of about eight weeks between the peak in intensity of ultraviolet radiation and the onset of SAD, and this correlates with the time it takes for UV radiation to be processed by the body into vitamin D.”
The Importance of Vitamin D
Vitamin D levels in the central nervous system have also been shown to affect the production of both serotonin and dopamine, chemicals know to directly correlate with the incidence of depression. Kimlin, a Cancer Council Queensland Professor of Cancer Prevention Research, stated that, “Evidence exists that low levels of dopamine and serotonin are linked to depression, therefore it is logical that there may be a relationship between low levels of vitamin D and depressive symptoms.” He went on to add that, "Studies have also found depressed patients commonly had lower levels of vitamin D."
Vitamin D is different from other essential vitamins because our own bodies can manufacture it with sunlight exposure. People with darker skin, however, often record lower levels of vitamin D, according to researchers, because they are unable to absorb as much of the vitamin through sun exposure as a person with fairer skin would. Adults who have darker skin pigmentation or frequently wear sun protection during outdoor activities are often vitamin D deficient. "Therefore it is suggested that persons with greater skin pigmentation may experience not only higher risks of vitamin D deficiency, but also be at greater risk of psychological and psychiatric conditions," he said.
Vitamin D is known to be essential for the formation, growth, and repair of bones and for normal calcium absorption and immune function. It may reduce the risk of Multiple Sclerosis, aid in maintaining cognitive ability, and help maintain a healthy body weight. It has been shown to reduce the severity and frequency of asthma symptoms as well as reduce the risk of developing rheumatoid arthritis in women. It has also been linked a decreased risk of developing cancer and heart attack.
"What we know now is that there are strong indications that maintaining adequate levels of vitamin D are also important for good mental health," Kimlin said. "A few minutes of sunlight exposure each day should be enough for most people to maintain an adequate vitamin D status."
Conclusion: Vitamin D is an essential nutrient with wide-reaching impacts on physiological and potentially mental health.
- Laura Wells
Nordqvist, C. (2014, September 3). What is vitamin D? What are the benefits of vitamin D? Retrieved December 2, 2014, from http://www.medicalnewstoday.com/articles/161618.php
Seasonal Affective Disorder. (n.d.). Retrieved December 2, 2014, from http://www.psychiatry.org/seasonal-affective-disorder
University of Georgia. (2014, December 2). Vitamin D deficiency, depression linked in international study. ScienceDaily. Retrieved December 2, 2014 from www.sciencedaily.com/releases/2014/12/141202111148.htm
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