New research suggests older adults with vitamin D deficiencies could experience more rapid cognitive decline than those with healthy vitamin D levels. 

Vitamin D is known for the role it plays in bone health, but this new research demonstrates the way it benefits the brain, Rutgers University reported. The important vitamin can be acquired through sun exposure, foods such as fish and egg yolks, and supplements.

"There were some people in the study who had low vitamin D who didn't decline at all and some people with adequate vitamin D who declined quickly," said Joshua Miller, professor of nutritional sciences at the Rutgers School of Environmental and Biological Sciences. "But on average, people with low vitamin D declined two to three times as fast as those with adequate vitamin D."

To make their findings, the researchers conducted research between 2002 and 2010 at the Alzheimer's Disease Center at the University of California-Davis. The study included 382 people between the ages of 60 and 90 who were assessed for vitamin D levels and cognition once a year over a five-year period. The ethnically and racially diverse patient sample showed individuals with darker skin were more likely to have lower levels of vitamin D because the melanin in their skin was more likely to block out the ultraviolet rays that synthesize the vitamin. Despite these findings, low vitamin D was associated with faster cognitive decline regardless of race or ethnicity. The findings suggest people over the age of 60 should consult their physicians about taking vitamin D supplements.

"Some people may have had melanoma or fear getting it," Miller said. "Or, they may live in climates where the sun isn't powerful enough, or do work that keeps them out of the sun. That's where supplements come in."

In the future the researchers plan to conduct randomized controlled clinical trials to further assess the link between vitamin D levels and cognitive decline.

The findings were published in a recent edition of the journal JAMA Neurology.