There were 40% fewer dementia diagnoses in people taking vitamin D supplements in one study.
Of the nearly 2,670 people who developed dementia in the study, 75% did not take vitamin D.
Previous research linked low vitamin D levels to dementia and stroke.
People who take vitamin D supplements may have a lower risk of developing dementia, a new large-scale study suggests.
Taking vitamin D supplements was associated with longer dementia-free lives in the study published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring on Wednesday.
The study, conducted by researchers in the UK and Canada, involved more than 12,000 participants with an average of 71, all of whom were free of dementia at the start of the study. About 4,600 (or 37%) of the participants reported taking vitamin D supplements. These include calcium-vitamin D, cholecalciferol and ergocalciferol.
Ten years after the start of the study, nearly 2,670 participants developed dementia. Of the dementia patients, only 679 (or 25%) took vitamin D supplements, while about 2,000 (or 75%) did not.
Researchers found that the group of participants who reported taking vitamin D supplements had 40% fewer dementia diagnoses than the rest of the cohort. Women and people with normal cognition, as opposed to those who show signs of memory loss and loss of congitive ability, known as mild cognitive impairment, were especially less likely to develop dementia with vitamin D supplementation.
The group of participants who took vitamin D supplements were more educated, less likely to suffer from depression, included more women and fewer black people. Having dark-colored skin reduces the amount of vitamin D your skin produces, according to the National Institutes of Health.
“Overall, we found evidence that earlier supplementation could be particularly beneficial, before the onset of cognitive decline,” Zahinoor Ismail, a professor at the University of Calgary and the study’s lead author, said in a news release.
The paper is limited because researchers have only observed the link between supplements and dementia using self-reported data, not by randomly assigning participants to take either vitamin D or a placebo, said Byron Creese, a lecturer in neuroscience at the University of Exeter and the study. co-author, in the press release. Trials that randomly assign placebos or treatments without participants knowing which one they are using are considered the “gold standard” in scientific research.
Previous research has shown a link between low vitamin D levels and dementia. An Australian analysis last year, using data from 300,000 UK Biobank participants, found that low levels of vitamin D were associated with an increased risk of dementia and stroke. and the risk was highest in people who were deficient in the vitamin.
The study cannot prove that vitamin D reduces the risk of dementia
Experts in the field who did not work on the study stressed its limitations. Susan Fairweather-Tait, professor of mineral metabolism at the University of East Anglia, UK, said the findings are not strong enough to draw firm conclusions about the link between vitamin D and dementia, partly because it only looked at vitamin D supplementation, not how much a person got in other ways, such as sunlight and food.
Gill Livingston, professor of psychiatry of the elderly at UCL, UK, said the groups taking and not taking vitamin D were “strikingly different”. She said it’s important to recognize that some participants had MCI, with research suggesting that about 40% of such people eventually develop dementia, and it would be expected that dementia rates in people with MCI would be higher in the study. And the findings are further complicated by the fact that those who took the supplements were more likely to be white and less likely to be depressed.
Professor Tara Spiers-Jones of the UK Dementia Research Institute at the University of Edinburgh said the study cannot prove that taking vitamin D supplements lowers the risk of dementia as they “could lead healthier lifestyles overall and something else could cause the lower risk of dementia”. .”
Vitamin D supplements can help when exposure to sunlight is limited
Humans typically get vitamin D from the sun, but foods such as fatty fish and beef liver are high in vitamin D. Federal dietary guidelines recommend that healthy adults consume a total of about 600 international units of vitamin D per day.
In some countries where people have limited exposure to sunlight in the winter months, such as the UK, vitamin D supplements are recommended. The only way to find out if you have a vitamin D deficiency is through a blood test.
Nutritionists previously told Insider to consult a doctor before taking vitamin D supplements, as taking too much can lead to constipation, nausea, vomiting, confusion and muscle cramps.
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