Vitamin D is a precursor to the hormone calcitriol. Vitamin D3 is synthesized in the skin from a cholesterol derivative after exposure to ultraviolet sunlight. Vitamins D2 and D3 can be obtained from dietary sources including oily fish, eggs and meat. The active hormone of vitamin D has multiple functions in the body such as maintaining calcium levels, stimulating immune system function and modulating cell growth. Vitamin D deficiency has been associated with the increased incidence of several disorders, including depression, but few studies have evaluated the therapeutic benefits of vitamin D supplementation or its mechanism of action.
Depression Incidence
A study in the July 2010 issue of "The Journal of Clinical Endocrinology and Metabolism" reports that women and men with vitamin D deficiency are 2 times and 1.6 times more likely to develop depression, respectively. In contrast, a recent study in the "The British Journal of Nutrition" reports that vitamin D deficiency was not correlated to the incidence of depression in an adult population of the United States. Therefore there is still some controversy over the correlation between low levels of vitamin D and depression warranting studies that actually define a mechanism by which vitamin D affects mood.
Depression Symptoms
Results from a clinical trial study published in the December 2008 issue of the "Journal of Internal Medicine" purports that overweight and obese men treated with 20,000 or 40,000 international units of vitamin D per week for 1 year had significantly decreased symptoms of depression.
Hyperparathyroidism
Hyperparathyroidism is a disorder in which the parathyroid glands secrete excessive levels of parathyroid hormone, which is the primary regulator of calcium levels in the blood. Vitamin D deficiency can lead to hyperparathyroidism because the often accompanying low calcium levels stimulate parathyroid hormone release. A primary symptom of hyperparathyroidism is depression. A study the "Archives of General Psychiatry" reports that 33 percent of elderly patients with major depressive disorder had vitamin D deficiency and high levels of parathyroid hormone.
Neuron Protection
A review in the journal "Psychoneuroendocrinology" notes that vitamin D does act on neuronal cells and modulates the production of chemicals in the brain that regulate the survival and growth of neurons. The exact mechanisms of how vitamin D acts on neuronal cells to affect mood are unknown, but this review also notes that vitamin D imbalances may play a role in depression and other brain diseases like Parkinson's and epilepsy.
References
- "Journal of Internal Medicine"; Effects of Vitamin D Supplementation on Symptoms of Depression in Overweight and Obese Subjects: Randomized Double Blind Trial; R. Jorde et al.; December 2008
- "Archives of General Psychiatry"; Depression is Associated with Decreased 25-Hydroxyvitamin D and Increased Parathyroid Hormone Levels in Older Adults; W.J. Hoogendijk et al.; May 2008
- "The Journal of Clinical Endocrinology and Metabolism"; Serum 25-Hydroxyvitamin D and Depressive symptoms in Older Women and Men; Y. Milaneschi et al.; July 2010
- "The British Journal of Nutrition"; No Associations Between Serum Concentrations of 25-Hydroxyvitamin D and Parathyroid Hormone and Depression Among US Adults; G. Zhao et al.; July 2010
- "Psychoneuroendocrinology"; Vitamin D, a Neuro-immunomodulator: Implications for Neurodegenerative and Autoimmune Diseases; D.A. Fernandes de Abreu et al.; December 2009
Member Comments