How is Dementia Risk now linked to Vitamin D Deficiency?
By comparing images of the brain’s gray matter, white matter and volume with genetic data, a team of scientists from Australia and the United Kingdom linked vitamin D3 measurements of over 290,000 Britons with an increased risk of dementia. [1]
Volunteers were followed for over 10 years, completing surveys and brain neuroimaging. They were asked about lifestyle, sun behavior, socio-economic status, and any prolonged illness.
Scientists had earlier studies of the human genome to rely on in their search for vitamin D3 -related biomarkers. The most current Genome-Wide Association Study determined that more than 140 genetic variants are associated with 25(OH)D, [vitamin D3], using UK Biobank data.
A weighted Genetic Risk Score was calculated using 35 of the variants and weights from the Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits (SUNLIGHT).
They found:
The highest risk of both dementia and stroke were seen for those with the lowest concentrations of vitamin D3, less than 50nmol/L*.
Using the subject’s baseline D3 measurements, brain neuroimaging analysis and health outcomes, this study showed that up to 17% of cases of dementia could be prevented by increasing D3 levels to greater than 50nmol (*or 20ng/ml U.S.)
Scientists found that “categories [of genes] associated with lower brain volume tended to reflect a higher rate of dementia and stroke”. This confirms a 2014 systematic review which determined that D3 deficiency is associated with lower brain volume in the hippocampus.
Image: Interior organs of the brain
Preserving Brain Volume is crucial to how you spend the rest of your life, no matter what age.
The hippocampus is the area of the brain that was observed to be affected by low volume and D3 deficiency, in this study.
According to John Hopkins Medicine:
“The hippocampus supports memory, learning, navigation, and perception of space.
It receives information from the cerebral cortex and may play a role in Alzheimer’s disease.”
https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-of-the-brain
This study is important because of the 920,000 people in the UK suffering from dementia [7 million in the US]. As dementia rates increase there are foreseeable added impacts on family members and health care providers. Within the next 20 years, the UK numbers could increase to 2 million [9 million in the US].
Of Note – The study’s authors discovered evidence of the Threshold Effect – meaning the association of D3 and dementia is strongest when correcting a severe D3 deficiency (less than 50nmol/L). There is decreased impact when the D3 threshold has been met with diet, sunlight, or supplements.
Is preventing dementia possible? If your vitamin D3 is low at 50nmol/L there is the almost 1 in 5 chance that improving your D3 status would help prevent dementia. This one study is not considered generalizable to everyone since the study population was mostly older, white, and female.
Mendelian Randomization (MR) is the genetic approach used that tested for underlying causality by examining specific genetic indicators, in this case, testing for 35 of the 140 genetic subvariants already known to be impacted by D3 deficiency.
This study is the first time MR was used to test for causal effects of increasing D3 concentrations when there is severe deficiency.
The Genetic Connection
The study authors looked at 35 out of the140 known gene pairs whose expression are known to be affected by vitamin D3 deficiency.
The gene’s “expression” is the way it is “switched on” to make vital bodily proteins; each of us has nearly 20,000 protein coding genes.
Genes can be compared to volume controls, so their activation makes them “louder”, more expressive.
Support those genes with adequate nutrition.
Image: A graphic example of a strand of human DNA as pairs of proteins from the National Library of Medicine DNA Images.
Nanograms (ng), at 1 billionth of a gram, were too small to measure until the invention of the electron microscope in the 1980s. Since then, Dr. Michael Holick, the first person to measure D3 in ng, has published over 200 scientific papers and several books about the importance of D3 in many vital bodily functions.[2] For comparison -
· 100,000 ng = thickness of a book page
· 7,000 ng = width of one red blood cell
· 2 ng = size of a DNA molecule
Increasing vitamin D3 concentrations to greater than 20ng/ml could have beneficial health impacts for dementia and other chronic disease. With 7 million in the US already affected by dementia, 17% represents 1.2 million individuals and their caregivers.
References: 1. American Journal of Clinical Nutrition, April 22, 2022. 2. Holick, MF, The Vitamin D Solution, 2011, Plume Press, Penguin Books, USA.
