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Alzheimer's Disease Health Center

Low Vitamin D Levels May Boost Alzheimer's Risk

But it's too soon to recommend supplements, dietary changes for prevention
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WebMD News from HealthDay

By Kathleen Doheny

HealthDay Reporter

WEDNESDAY, Aug. 6, 2014 (HealthDay News) -- Older adults with too little vitamin D in their blood may have twice the risk of developing Alzheimer's disease as seniors with sufficient levels of the "sunshine vitamin," a new study finds.

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.

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.

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.

Dementia describes a decline in memory and thinking that interferes with daily life. Alzheimer's is the most common form of dementia in old age, affecting about 5 million Americans, according to the Alzheimer's Association.

For this study, researchers looked at mentally healthy men and women who participated in the U.S. Cardiovascular Health Study between 1992-93 and 1999. Their blood samples were collected at the start, and their mental status was assessed roughly six years later.

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