Researchers analyzed participants in the Rush Memory and Aging Project (MAP) — an ongoing longitudinal study that aims to identify risk factors for Alzheimer’s disease and other cognitive decline disorders — before and after death to see how their vitamin D levels affected their later cognitive functioning. years.
All MAP participants without known dementia at the time of enrollment agreed to participate in annual assessments and organ donation at the time of death. The average age of the participants in this study was 92 years at the time of death.
Total serum vitamin D levels [25(OH)D] and global cognitive functions were assessed antemortem, while vitamin D3, 25(OH)D3 and 1,25(OH)D3 (the active form of vitamin D3) were measured in four brain regions (central temporal cortex, mid-frontal). cerebral cortex, cerebellum and anterior watershed) post mortem.
The main form of vitamin D3 in the brain (and thus the form the researchers focused on in their analysis) was 25(OH)D3. It’s worth noting that there are two types of vitamin D – D2 and D3, and brain levels of vitamin D2 (the form found in most fortified food sources) were not measured in this study.
Ashley Jordan Ferira, Ph.D., RDN, vice president of scientific affairs at Mindbodygreen, clarifies this limitation: “Vitamin D3 is found in animal sources and major algae and lichens, while vitamin D2 comes from plant sources such as yeast and irradiated mushrooms. If a healthcare provider is accidentally measured serum 25(OH)D3, but ruled out irradiated mushrooms or vitamin D2 supplementation, the lab results did not match your intake. Total serum 25(OH)D is the best way to measure the whole picture.”
Although the results of this study remain relevant to dementia research, it is important to keep this discrepancy in mind when reading the results.