(RxWiki News) Vitamin D is essential for building strong bones. But new evidence suggests that it may also play an important role in protecting against cognitive decline.
A new study from Rutgers University and the University of California found that cognitive function declined when older adults had insufficient vitamin D levels.
"Low VitD status was associated with accelerated decline in cognitive function in ethnically diverse older adults, including African American and Hispanic individuals who exhibited a high prevalence of VitD insufficiency or deficiency," wrote lead study author Joshua W. Miller, PhD, a nutritionist and professor at the Rutgers School of Environmental & Biological Sciences, and colleagues. "It remains to be determined whether VitD supplementation slows cognitive decline."
Vitamin D is a nutrient found in some foods that is needed for many of the body's essential functions — muscles need it to move, nerves need it to carry messages between the brain and the body, and the immune system needs it to fight off invading bacteria and viruses. Together with calcium, vitamin D also helps maintain strong bones.
The body makes vitamin D when the skin is directly exposed to sunlight. According to the National Institutes of Health, most people meet at least some of their vitamin D needs this way.
Dr. Miller and colleagues noted that cells in the brain are sensitive to vitamin D levels.
For this study, Dr. Miller and team looked at 382 patients over the span of eight years. Most of the patients were white women with an average age of 75.
Almost half were cognitively normal when the study began, while 33 percent had mild cognitive impairment and 17.5 percent had dementia.
Dementia is a general term for a decline in mental ability severe enough to interfere with daily life. Alzheimer's disease is the most common form of dementia.
Of these patients, about 26 percent were found to be deficient in vitamin D. About 35 percent did not have sufficient levels but were not considered deficient.
On average, black and Hispanic patients had lower vitamin D levels than white patients. The patients with dementia had the lowest vitamin D levels when compared to the other groups.
Patients with deficient or insufficient vitamin D levels also had more cognitive problems during the follow-up period than those whose levels were adequate. The most common of these were problems with episodic memory and executive function performance.
Episodic memory is the ability to recall personal life experiences, while executive functions include decision-making abilities and judgment.
According to Dr. Miller and team, low vitamin D levels may also increase the risk of high blood pressure and heart disease.
This study was published Sept. 14 in the journal JAMA Neurology.
The National Institutes of Health funded this research. No conflicts of interest were disclosed.