The sunshine could reduce the risk of dementia, a major trial suggests. The new study found that a severe lack of vitamin D among over 65s appears to more than double the risk of the condition.
Published online Aug. 6 in the journal Neurology, this is believed to be the largest study yet to find an association between low levels of vitamin D and dementia.
Scientists said they were surprised by the dramatic findings, which suggest that increasing intake of vitamin D, which comes from sun exposure, and oily fish and eggs, could delay or prevent conditions such as Alzheimer’s disease.
The research based on more than 1,600 adults over age 65 found the risk for Alzheimer´s and other forms of dementia increased with the severity of vitamin D deficiency.
But the findings aren´t enough to recommend seniors take vitamin D supplements to prevent mental decline. "Clinical trials are now urgently needed in this area," said study researcher David Llewellyn, a senior research fellow in clinical epidemiology at the University of Exeter Medical School in England.
Another expert agreed. "This shows you there is a link between vitamin D and the development of Alzheimer´s," said Keith Fargo, director of scientific programs and outreach for the Alzheimer´s Association, one of several funding sources for the study. "What it doesn´t show you is that [cause-and-effect] link."
Whether dietary changes or getting more sun exposure would help isn´t known, Fargo said. "We don´t know if increasing vitamin D levels would decrease the risk of Alzheimer´s," he added.
Vitamin D is essential for maintaining bone health. It is also thought to moderate cell growth and help control immune function and inflammation. Vitamin D can be obtained through food, through the skin after exposure to sunlight and from supplements.
Participants´ vitamin D blood levels reflected vitamin D from food, supplements and sun exposure. Dietary sources include fatty fish such as salmon, tuna or mackerel, as well as milk, eggs and cheese.
During the follow-up, those with low levels of vitamin D were about 1.7 times more likely to develop dementia than those with normal levels. Those with severely low levels were about 2.2 times more likely than those with normal levels to develop dementia, the study found.