vitamin D – Protects against cognitive decline and dementia based on observational data on the circulation of 25-hydroxyvitamin D (25(OH)D).
An estimated 55 million people suffer from dementia worldwide, a number that is expected to increase as the world’s population ages. To find treatments that can slow or stop the disease, scientists need to better understand the factors that can cause it.
One nutritional factor that has received much attention is vitamin D, an essential fat-soluble vitamin and prohormone acquired through diet and outdoor exposure. The enzyme 1α-hydroxylase (cytochrome P450 [CYP]; CYP27B1) is required to convert 25-hydroxyvitamin D3(25(OH)D3), the major circulating form of vitamin D, to 1,25-dihydroxyvitamin D(1, 25(OH)2D) biologically active, the form that binds to the nuclear vitamin receptor (VDR) to exert its biological function.
Tufts University researchers have completed the first study to examine vitamin D levels in brain tissue, specifically in adults suffering from various rates of cognitive decline. They found that members of this group with higher levels of vitamins in the brain had better cognitive functions.
Vitamin D contributes to many functions in the body, such as the immune response and the maintenance of healthy bones. Dietary sources include fatty fish and fortified beverages (such as milk or orange juice); a brief exposure to sunlight also provides a dose of vitamin.
The team examined brain tissue samples from 209 participants in the Rush Memory and Aging Project, a long-term study on Alzheimer’s disease that began in 1997. The Rush University researchers assessed the cognitive function of the participants, older people without signs of cognitive decline, as they aged, and analyzed irregularities in their brain tissue after death.
In the Tufts study, the researchers looked for vitamins in four brain regions: two associated with Alzheimer’s disease-related changes, one associated with blood flow-related forms of dementia, and a region with no known relationship to cognitive decline. related to Alzheimer’s disease or vascular disease. They found that vitamin was present in brain tissue and that elevated levels of vitamin D in all four brain regions were correlated with better cognitive function.
However, vitamin D levels in the brain were not associated with any of the physiological markers associated with Alzheimer’s disease, including amyloid plaque buildup, Lewy body disease, or evidence of microscopic or chronic stroke. This means that it is not yet clear how exactly vitamin D might affect brain function.
However, experts caution against taking large doses of vitamin supplements as a preventative measure. The recommended dose of vitamins is 600 IU for people between 1 and 70 years of age, and 800 IU for the elderly; excessive amounts can be harmful and have been linked to the risk of falls.
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