A study finds a link between levels of one vitamin in the brain and how well people maintain their cognitive abilities.
Higher levels of vitamin D in the brain are associated with better cognitive performance and a slower decline in thinking abilities as people age.
Research has repeatedly linked sufficient vitamin D levels with a lower risk of dementia (1, 2, 3).
One study has estimated that maintaining adequate vitamin D could potentially prevent nearly one in five cases of dementia (Navale et al., 2022).
The evidence, however, is not consistent, as other research has found no association (also: Owusu et al., 2018).
The latest study approached the question differently by examining vitamin D directly in the brain, an area that has received relatively little research.
Professor Sarah Booth, one of the study’s authors, said the findings highlight the need to understand how nutrients and diet may help the ageing brain withstand diseases such as Alzheimer’s and other forms of dementia.
Vitamin D markers
The researchers followed 290 older adults and examined their brain tissue after death to determine how much vitamin D was present.
Dr Kyla Shea, the study’s first author, explained that previous research has generally relied on people’s diets or measurements of vitamin D in their blood when investigating its relationship with cognitive function.
The researchers therefore wanted to establish whether vitamin D is actually found in the human brain and, if so, whether brain concentrations are related to changes in cognition over time.
The results showed that participants with greater concentrations of vitamin D in their brains tended to have better cognitive function.
There was no corresponding association between brain vitamin D levels and the physical changes in the brain typically associated with Alzheimer’s disease.
As a result, the researchers cannot yet say exactly why vitamin D might be associated with better cognitive health.
Dr Shea noted that dementia involves multiple biological processes, many of which are still poorly understood. Vitamin D may therefore be connected with other aspects of brain health that were not examined in this study and could be investigated in future research.
How much vitamin D?
The findings do not mean that people should start taking large doses of vitamin D to protect against dementia.
Current recommendations are 600 IU of vitamin D per day for adults under 70 and 800 IU for those aged over 70.
Dr Shea said the study establishes that vitamin D is present in the brain at meaningful levels and that greater amounts are associated with less cognitive decline.
However, she stressed that more research is needed to determine which changes in the brain are associated with vitamin D before treatments or other interventions can be developed.
The study was published in the journal Alzheimer’s & Dementia (Shea et al., 2022).
