Data from the third US National Health and Nutrition Examination Survey revealed that people with vitamin D deficiency were at a 85 percent increased risk of having current depressive episodes, compared with people with sufficient levels, according to findings published in the International Archives of Medicine.
“It is not known, whether vitamin D deficiency leads to the depression or depression leads to the vitamin D deficiency,” write the researchers from Georgia State University. “Further studies are needed in deciphering the precise role of vitamin D in psychosomatic disorders.
“Although the direction of the cause and effect relation between depression and vitamin D deficiency is not known clearly at this time, in public health perspective, the coexistence of vitamin D and depression in the US population at large is a concern,” they add.
“It is important to identify persons who are at risk for vitamin D deficiency and/or for depression and to intervene early because these two conditions have enormous negative consequences on long term health.”
D and depression
And the World Health Organization (WHO) forecasts that within 20 years more people will be affected by depression than any other health problem; it ranks depression as the leading cause of disability worldwide, with around 120 million people affected.
This is not the first time that vitamin D has been linked to symptoms of depression. Dutch scientists reported in 2008 in the Archives of General Psychiatry that low levels of the vitamin and higher blood levels of the parathyroid hormone (PTH) were associated with higher rates of depression among 1,282 community residents aged between 65 and 95.
Furthermore, a review by Bruce Ames and Joyce McCann from the Children's Hospital and Research Center Oakland highlighted the role of the vitamin in maintaining brain health, noting the wide distribution of vitamin D receptors throughout the brain.
According to the review (FASEB Journal, Vol.22, pp. 982-1001), the vitamin has been reported to affect proteins in the brain known to be directly involved in learning and memory, motor control, and possibly even maternal and social behaviour. Depression in the elderly is highly prevalent and can increase the risk of medical illnesses, worsen the outcome of other medical illnesses, and may increase mortality.
Vijay Ganji Ph.D., R.D and his Georgia State co-workers analysed data from 7,970 US residents aged between 15and 39. Assessments of depression were performed using the National Institute of Mental Health’s Diagnostic Interview Schedule.
Results showed that people with blood levels of vitamin D of 50 nanomoles per liter or less were at an 85 percent increased risk of having current depressive episodes in persons, compared with people blood levels of at least 75 nanomoles per liter.
“The mechanism through which vitamin D plays a role in metal health is not clearly understood,” said the researchers. “Active vitamin D enhances glutathione metabolism in neurons, therefore, promotes antioxidant activities that protect them from oxidative degenerative processes.”
The researchers also not that vitamin D is involved in gene expressions for the production of neurotransmitters like dopamine.
The researchers stress however that their results do not prove that vitamin D deficiency causes depression, and called for additional studies to decipher the association between vitamin D and depression.
Source: International Archives of Medicine
2010, 3:29 doi:10.1186/1755-7682-3-29
“Serum vitamin D concentrations are related to depression in young adult US population: the Third National Health and Nutrition Examination Survey”
Authors: V. Ganji, C. Milone, M.M. Cody, F. McCarthy, Y.T. Wang