Individuals who have low vitamin D levels could be more susceptible to developing dementia.
Researchers from the University of Exeter undertook a study where they analysed blood samples from more than 1,600 people who were aged 65 or older.
At the beginning of the trial, all the participants had neither the degenerative disease, nor any sign of stroke. After six years, it transpired individuals who had moderately low levels of the sunshine vitamin were 53 per cent more likely to develop dementia and had a 69 per cent higher chance of experiencing Alzheimer's disease.
Those who had an even greater lack of vitamin D were noticeably more susceptible to cognitive decline. The chances leapt to 125 per cent for dementia and 122 per cent for Alzheimer's.
The next step is to hold clinical trials to ascertain whether or not consuming foods that are rich in the nutrient - or even taking supplements - could be effective in halting or even curing the degenerative condition.
Dr David Llewellyn, who led the research, said: "We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer's disease, but the results were surprising - we actually found that the association was twice as strong as we anticipated."
Foods such as oily fish tend to have high levels of the nutrient, but individuals can also expose themselves to sunlight to ensure they are not depriving their body of the vitamin.
While these results are encouraging, Dr Llewellyn added that caution was necessary as this was still the initial stages. He stated these findings do not show that low levels of vitamin D bring about cognitive decline.
Research communications manager at Alzheimer's Society Dr Clare Walton told BBC News that there could be another "unknown factor" that is responsible for an individual having both dementia and low levels of the sunshine vitamin.
She called for clinical trials to find out if higher levels of the nutrient could lower the risk developing this condition.
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