It is well known that vitamin D maintains bone health; there is increasing appreciation that this vitamin may serve important roles in other organs and tissues, including the brain. Vitamin D deficiency is widespread among the elderly, it is important to understand how the range of serum vitamin D levels that mimic those found in humans (from low to high) affects the brain during aging from middle age to old age.
In order to find out how vitamin D affects the brain in middle-aged and elderly adults, Dr. D. Allan Butterfield, PhD, Professor in the Department of Chemistry and Sanders-Brown Center on Aging at the University of Kentucky, Lexington, and lead author, along with colleagues used 27 male F344 rats (used in various studies such as aging) and divided the rats into three groups and were fed isocaloric diets (carbohydrates) containing low (100 IU/kg food), control (1000 IU/kg food), or high (10,000 IU/kg food) vitamin D beginning at middle age (12 months) and continued for a period of four to five months.
The researchers compared the effects of the low, control and high food diets on oxidative and nitrosative stress measures in posterior brain cortices.
The low vitamin D group showed an elevation of 3-nitrotyrosine compared to control and high-VitD-treated groups. Nitrotyrosine is identified as an indicator or marker of cell damage, inflammation as well nitric acid production. The rats developed free radical damage to the brain and many different brain proteins were damaged as identified by redox proteomics. The proteins included, 6-phosphofructokinase and triose phosphate. These rats also showed a significant decrease in cognitive performance on tests of learning and memory.
“These results suggest that dietary VitD deficiency contributes to significant nitrosative stress in brain and may promote cognitive decline in middle-aged and elderly adults,” write the researchers.
According to Professor Butterfield "Given that vitamin D deficiency is especially widespread among the elderly, we investigated how during aging from middle-age to old-age how low vitamin D affected the oxidative status of the brain.” "Adequate vitamin D serum levels are necessary to prevent free radical damage in brain and subsequent deleterious consequences."
He recommends persons consult their physicians to have their vitamin D levels determined, and if low that they eat foods rich in vitamin D, take vitamin D supplements, and/or get at least 10-15 minutes of sun exposure each day to ensure that vitamin D levels are normalized and remain so to help protect the brain.
This study is published in Free Radical Biology and Medicine.