WINSTON-SALEM, N.C.—Vitamin D deficiency and cognitive impairment are common in older adults, but there isn't a lot of conclusive research into whether there's a relationship between the two. A new study, published in the Journal of the American Geriatrics Society, has strengthened the connection between the two.

"This study provides increasing evidence that suggests there is an association between low vitamin D levels and cognitive decline over time," said lead author Valerie Wilson, M.D., assistant professor of geriatrics at Wake Forest Baptist. "Although this study cannot establish a direct cause and effect relationship, it would have a huge public health implication if vitamin D supplementation could be shown to improve cognitive performance over time because deficiency is so common in the population."

Wake Forest Baptist Medical Center researchers used data from the Health, Aging and Body Composition (Health ABC) study to look at the relationship between vitamin D levels and cognitive function. The researchers looked at 2,777 well-functioning adults aged 70 to 79 years whose cognitive function was measured at the study's onset and again four years later. Vitamin D levels were measured at the 12-month follow-up visit.

"With just the baseline observational data, you can't conclude that low vitamin D causes cognitive decline. When we looked four years down the road, low vitamin D was associated with worse cognitive performance on one of the two cognitive tests used," Wilson said. "It is interesting that there is this association and ultimately the next question is whether or not supplementing vitamin D would improve cognitive function over time."

However, one of the biggest questions being asked now is whether vitamin D supplementation can treat diseases associated with vitamin D deficiency. Many ongoing studies are testing this hypothesis in cancer, multiple sclerosis, cardiovascular disease and diabetes. (A Gallery from Food Product Design's FoodTech Toolbox, "Vitamin D: Illuminating the Sunshine Vitamin," dives into this topic.)

If so, fortifying foods with vitamin D could prove beneficial, especially with regard to the older population. According to the International Food Information Council's (IFIC) 2013 Functional Foods Consumer Survey, older consumers were most likely to be not at all concerned about not getting all of the nutrients and food components needed for good health, yet 57% of seniors said they would choose either naturally-occurring or fortified foods  to receive nutrients and food components necessary for good health.