A new study finds that levels of Vitamin D are low among people with depression. The discovery adds to a recent appreciation of the health potential of the vitamin, a nutrient that the body makes from sunlight and that is also found in fish and fortified milk.
Low levels of vitamin D already are associated with a range of health condition including osteoporosis, cardiovascular diseases, neurological ailments and many other disorders. However, experts do not agree on the ideal level of the vitamin and even if supplements can improve health.
In the new study — published in Mayo Clinic Proceedings — researchers believe they have confirmed that an inverse relationship does exist between vitamin D and depression. The issue turned muddy after smaller studies produced conflicting results about the relationship between vitamin D and depression.
Major depressive disorders affect nearly one in 10 adults in the U.S.
“Our findings suggest that screening for vitamin D levels in depressed patients – and perhaps screening for depression in people with low vitamin D levels – might be useful,” said Dr. E. Sherwood Brown, professor of psychiatry at UT Southwestern and senior author of the study. “But we don’t have enough information yet to recommend going out and taking supplements.”
Researchers examined the results of almost 12,600 participants from late 2006 to late 2010. Brown and colleagues found that higher vitamin D levels were associated with a significantly decreased risk of current depression, particularly among people with a prior history of depression.
This could reflect the fact that vitamin D levels are influenced by getting ultraviolet-light exposure, often by exercising in the outdoors — a behavior that reduces depression. Further, high Vitamin D levels could occur because a person has a strong self-worth and follows a healthy diet.
Among the study participants, researchers discovered low vitamin D levels were associated with depressive symptoms, particularly those with a history of depression. Because of this, investigators believe assessing Vitamin D levels among primary care patients with a history of depression may be an effective screen for potential relapse.
The study did not address whether increasing vitamin D levels reduced depressive symptoms. And, experts have not determined the exact relationship — whether low vitamin D contributes to symptoms of depression, whether depression itself contributes to lower vitamin D levels, or chemically how that happens.
However, vitamin D may affect neurotransmitters, inflammatory markers and other factors, which could help explain the relationship with depression, said Brown.
Vitamin D levels are now commonly tested during routine physical exams, and they already are accepted as risk factors for a number of other medical problems: autoimmune diseases; heart and vascular disease; infectious diseases; osteoporosis; obesity; diabetes; certain cancers; and neurological disorders such as Alzheimer’s and Parkinson’s diseases, multiple sclerosis, and general cognitive decline.
Source: UT Southwestern Medical Center