Vitamin D pills could stave off Alzheimer’s disease, according to new research.
Brains of older people with higher levels of the nutrient function better, say nutritionists.
The main natural source is sunlight but wrinkly skin is less efficient at converting it, meaning older individuals are more likely to be deficient.
Corresponding author Dr Sarah Booth said: “This research reinforces the importance of studying how food and nutrients create resilience to protect the ageing brain against diseases such as Alzheimer’s and other related dementias.”
The number of cases worldwide will triple to more than 150 million by 2050. And with no cure in sight, there is an increasing focus on preventive measures such as lifestyle.
Dr Booth and colleagues examined post mortem samples of brain tissue from 209 participants in the Rush Memory and Ageing Project that began in 1997.
It is the first analysis of its kind, comparing vitamin D levels in adults who suffered from varying rates of cognitive decline.
Lead author Professor Kyla Shea said: “Many studies have implicated dietary or nutritional factors in cognitive performance or function in older adults, including many studies of vitamin D, but all of them are based on either dietary intakes or blood measures of vitamin D.
“We wanted to know if vitamin D is even present in the brain, and if it is, how those concentrations are linked to cognitive decline.”
The team at Tufts University in Massachusetts found more vitamin D in all four regions looked at correlated with better mental skills.
Two areas are associated with changes linked to Alzheimer’s, one with dementias due to to blood flow and the other without any associations with brain or vascular diseases.
Participants’ cognitive function was assessed at the outset and as they aged - with irregularities in their brain tissue identified after death.
No connection was found between vitamin D levels and any of the physiological markers associated with Alzheimer’s disease.
These included rogue amyloid beta proteins that gather in plaques, Lewy body disease or chronic or microscopic strokes.
This means it is still unclear exactly how vitamin D might affect brain function.
Prof Shea said: “Dementia is multifactorial, and lots of the pathological mechanisms underlying it have not been well characterised.
“Vitamin D could be related to outcomes that we didn’t look at yet, but plan to study in the future.”
Vitamin D is also known to vary between racial and ethnic populations, and most of the participants in the original cohort were white
The researchers are planning followup studies using a more diverse group of subjects to look at other brain changes associated with cognitive decline.
They hope their work leads to a better understanding of the role vitamin D may play in staving off dementia.
Experts caution people not to use large doses of vitamin D supplements as a preventive measure.
The recommended dose of vitamin D is 600 IU (international units) for under 70s and 800 for those older.
Excessive amounts can cause harm, and have been linked to the risk of falling.
Prof Shea said: “We now know that vitamin D is present in reasonable amounts in human brains, and it seems to be correlated with less decline in cognitive function.
“But we need to do more research to identify the neuropathology that vitamin D is linked to in the brain before we start designing future interventions.”
The study was published in the journal Alzheimer’s & Dementia.
