Vitamin D is a hormone made by the kidneys essential for the growth of healthy bones because it helps regulate calcium levels in the blood. The body uses vitamin D for various functions, but its main contribution is calcium and phosphorus absorption. Since the skin makes vitamin D in response to UV light exposure, most people get their vitamin D from sunlight rather than food.
Scientists at the University of South Australia have discovered a link between vitamin D deficiency and an increased risk of stroke and dementia. According to the study, raising the hormone levels may prevent a significant percentage of dementia cases.
Unfortunately, it’s estimated that up to a billion people globally lack sufficient vitamin D. Along with weaker muscles and bones, vitamin D deficiency can result in an increasingly long list of other diseases and ailments, including colorectal cancers, autoimmune diseases, and even opiate addiction. In addition, studies reveal that pregnant women with insufficient vitamin D levels may increase the risk that their offspring would grow up to have autism or schizophrenia.
Researchers from UniSA have now expanded that list of illnesses in the latest study published on April 22, 2022, in the American Journal of Clinical Nutrition. The team compared vitamin D levels with incidences of stroke and dementia by analyzing data from 294,514 people in the UK Biobank project. While controlling for variables including gender, age, ethnicity, lifestyle, and other health issues, they used a method called nonlinear Mendelian randomization to determine if the genetic variation had a causal effect on the disorders.
The research team discovered that low vitamin D levels – classified as being under 25 nmol/L, or half of what is considered a healthy amount – were linked to decreased brain sizes as measured via neuroimaging and higher chances of dementia and stroke. In addition, genetic studies revealed a causal relationship between vitamin D deficiency and dementia, with patients at 25 nmol/L having a 54% higher risk of developing the condition than those at 50 nmol/L.
Professor Elina Hyppönen, the study’s senior investigator, concluded:
“Our study is the first to examine the effect of very low levels of vitamin D on the risks of dementia and stroke, using robust genetic analyses among a large population. In some contexts, where vitamin D deficiency is relatively common, our findings have important implications for dementia risks.
Indeed, in this UK population, we observed that up to 17% of dementia cases might have been avoided by boosting vitamin D levels to be within a normal range.”
The latest study provides yet another reason for maintaining enough vitamin D levels by controlled, routine sun exposure or, in the near future, through genetically modified tomatoes.
