In a definitive critical review, scientists at Children's Hospital and Research Center Oakland have found convincing biological and behavioural evidence indicating a vital link between vitamin D and brain development and function.
Joyce C. McCann, Ph.D., assistant staff scientist and Bruce N. Ames, Ph.D., senior scientist at Children's Hospital Oakland Research Institute (CHORI), have also said that there is a need for vitamin D supplementation in groups chronically deficient in this vitamin.
"This critical analysis of vitamin D function and the brain is a model of careful thinking about nutrition and behaviour. One wishes that all studies of nutritional supplements or requirements were this thoughtful. Drs. McCann and Ames deftly show that while vitamin D has an important role in the development and function of the brain, its exact effects on behavior remain unclear. Pointing to the need for further study, the authors argue for vitamin D supplementation in groups at risk", said Gerald Weissmann, MD, Editor-in-Chief of the FASEB Journal.
Vitamin D has long been known to promote healthy bones by regulating calcium levels in the body. Lack of sufficient vitamin D in very young children results in rickets, which can be easily prevented by vitamin D supplements. Besides this vitamin D has also has an important role in protecting against autoimmune diseases, including multiple sclerosis and type I diabetes, as well as some forms of cancer, particularly colorectal and breast.
Vitamin D is present in only a few foods (e.g., fatty fish), and is also added to fortified milk, but our supply typically comes mostly from exposure to ultraviolet rays (UV) in sunlight.
The results of this review indicated that vitamin D is involved in brain function and there is a wide distribution of vitamin D receptors throughout the brain. The researchers have also discuss vitamin D's ability to affect proteins in the brain known to be directly involved in learning and memory, motor control, and possibly even maternal and social behavior.
The review also discusses studies in both humans and animals that present suggestive though not definitive evidence of cognitive or behavioural consequences of vitamin D inadequacy. The authors discuss possible reasons for the apparent discrepancy between the biological and behavioral evidence, and suggest new, possibly clarifying avenues of research.
Many vitamin D experts advise that the currently recommended level of vitamin D intake is much too low and should be raised to protect against bone fractures and possibly cancer in addition to rickets.
The authors have suggested that despite uncertainty regarding all of the deleterious effects of vitamin D inadequacy, the evidence overall indicates that supplementation, which is both inexpensive and prudent, is warranted for groups whose vitamin D status is exceptionally low, particularly nursing infants, the elderly, and African Americans.
Their findings will be published in the Federation of American Societies for Experimental Biology (FASEB) Journal.