The importance of vitamin D to human health has been thoroughly studied, revealing that this super hormone does far more than aid calcium absorption and bone health. New vitamin D research emerges regularly, revealing new benefits. Researchers at Rutgers University and the University of California, Davis, published a new study in the journal JAMA Neurology that adds to these benefits and suggests low vitamin D levels are associated with accelerated cognitive decline in the elderly.
While labeled as a vitamin, vitamin D is actually a steroid hormone primarily obtained through sun exposure or supplementation. Interest in vitamin D hastened when scientists estimated that it controlled approximately 2,000 genes, or 10 percent of the entire human genome. Its ability to influence genetic expression — the process whereby genetic material (DNA) becomes useful products (usually proteins), which perform essential functions — makes it one of the most critical nutrients for human health.
Without optimum levels of vitamin D you are at greater risk of a host of diseases including diabetes, depression, cardiovascular disease, cancer, infections, autoimmune conditions, and neurologic diseases. The problem is an estimated 1 billion people have insufficient vitamin D levels, and 64% of healthy adults in America have vitamin D levels that prevent their cells and tissues from performing at their best.
Both the vitamin D receptor and the enzyme that converts it to its active form are expressed in all organs within the human body. Indeed, nearly every tissue and cell in the human body has receptors for vitamin D, further illuminating its importance — meaning these tissues and cells require vitamin D to function optimally.
Joshua W. Miller, PhD, of Rutgers University, and his colleagues from the University of California, Davis, evaluated how vitamin D levels correlated with cognitive function among elderly persons. The average age of the study participants was 75.5, and the populations included both males and females, Caucasians, African Americans and Hispanics. Approximately half of the participants had normal cognitive function at the beginning of the study, while 17.5 percent had dementia and 32.7 percent had mild cognitive impairment.
The study authors discovered that 61.3 percent of the participants had deficient or insufficient vitamin D levels. Deficiency was defined in the study as serum (blood) levels of vitamin D of less than 12 ng/mL. Insufficient levels were defined as 12 to less than 20 ng/mL.
Average serum vitamin D levels were lower among those with dementia even when compared to those with mild cognitive impairment (116.2 and 20.0 ng/mL, respectively). Interestingly, African Americans and Hispanics had lower average serum levels when compared to their counterparts (17.9, 17.2 and 21.7 ng/mL, respectively). In addition, vitamin D deficient and vitamin D insufficient persons experienced greater rates of decline in episodic memory — memory of specific events — and executive function — higher level cognitive skills used to control other cognitive abilities and behaviors — compared to those with adequate vitamin D status (20 to less than 50 ng/mL).
While the study has limitations such as not directly measuring sun exposure, exercise, and supplementation (all of which can affect vitamin D levels), it does suggest that lower vitamin D levels are associated with significantly faster declines in cognitive function.
The study also adds to the mounting body of evidence that suggests supplementing with vitamin D may be a necessity for optimal health and peak vitality. Depending on current serum levels and geographic location, it may be necessary to supplement with up to 10,000 IU daily — with physician approval — to achieve optimal levels.
