A research team has found that Vitamin D insufficiency was associated with faster decline in cognitive functions among a group of ethnically diverse older adults, according to an open-access paper published in JAMA Neurology.*
According to the researchers — Joshua W. Miller, Ph.D., of Rutgers University, New Brunswick, N.J., and coauthors from the University of California, Davis — Vitamin D may influence all organ systems, not just calcium absorption and bone health.
Both the vitamin D receptor and the enzyme that converts 25-hydroxyvitamin D (25-OHD) to the active form of the vitamin are expressed in all human organs, including the brain. So research has increasingly examined the association between vitamin D status and a variety of health outcomes, including dementia and age-associated cognitive decline.
The authors report:
The average 25-OHD level among participants was 19.2 ng/mL, with 26.2 percent of participants being vitamin D deficient and 35.1 percent vitamin D insufficient.
Average 25-OHD levels were lower for African American and Hispanic participants compared with their white counterparts (17.9, 17.2 and 21.7 ng/mL, respectively).
Average 25-OHD levels were lower in the dementia group compared with mild cognitive impairment and cognitively normal groups (16.2, 20.0 and 19.7 ng/mL, respectively.
During an average follow-up of 4.8 years, rates of decline in episodic memory and executive function among vitamin D deficient and vitamin D insufficient participants were greater than those with adequate vitamin D status after adjusting for a variety of patient factors.
Vitamin D status was not significantly associated with decline in semantic memory or visuospatial ability.
The authors note limitations to their study including that they did not directly measure dairy intake, sun exposure or exercise, each of which can influence vitamin D levels.
“Our data support the common occurrence of VitD [vitamin D] insufficiency among older individuals. In addition, these data show that African American and Hispanic individuals are more likely to have VitD insufficiency or