“An international research partnership between the University of Georgia, the University of Pittsburgh, USA, and the Queensland University of Technology in Australia conducted a review of more than 100 leading articles and found a relationship between vitamin D and seasonal depression (1). The investigations showed that rather than being one of many factors, vitamin D could have a regulative role in the development of seasonal affective disorder (SAD). Seasonal affective disorder is believed to affect up to 10 percent of the population, depending upon geographical location, and is a type of depression related to changes in season. People with SAD have the same symptoms every year, starting in fall and continuing through the winter months. 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. 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.
Vitamin D is also involved in the synthesis of serotonin and dopamine within the brain, both chemicals linked to depression. 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. Studies have also found depressed patients commonly had lower levels of vitamin D. Vitamin D levels varied according to the pigmentation of the skin. People with dark skin often record lower levels of vitamin D. 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.
Adequate levels of vitamin D are essential in maintaining bone health, with deficiency causing osteomalacia in adults and rickets in children. Vitamin D levels of more than 50 nanomoles per liter are recommended by the U.S. Institute of Medicine. What we know now is that there are strong indications that maintaining adequate levels of vitamin D are also important for good mental health. Queensland is known as the Sunshine State in Australia but that does not mean all Queenslanders get enough vitamin D. This research is of international importance because no matter where you live, low levels of vitamin D can be a health concern.”
Based on: University of Georgia. UGA Today. Vitamin D deficiency, depression linked in UGA-led international study. Published online December 2014.