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Vitamin D and Emerging Science: Cellular Aging and Cognitive Health

Vitamin D and Emerging Science: Cellular Aging and Cognitive Health

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Vitamin D is rightly regarded for its crucial role in supporting healthy bones, but its influence extends far beyond the skeletal system. As a regulator of gene expression for more than 3% of the human genome, vitamin D’s extraskeletal (acting outside of the skeletal system) potential is vast. This hormone-like vitamin is involved in a wide array of biological functions, including immune health, cardiovascular function, metabolic balance, muscle strength, and blood sugar metabolism.1

A plethora of research is showing that vitamin D participates in multiple aspects of cellular metabolism and cellular differentiation. Its influence on immune function extends to the innate and adaptive immune system, and it also has anti-inflammatory effects. In the area of cardiovascular health, numerous studies point to an increased risk of cardiovascular events with lower vitamin D levels. Similarly, elevated vitamin D levels decrease the likelihood of hypertension.2

Two unique areas of emerging science surrounding vitamin D include aging and cognitive health. As additional research is conducted in these areas, it is becoming clear that vitamin D plays a significant role in keeping cells healthy, vital, and youthful, as well as in maintaining brain function with advancing age.

 

Vitamin D and Aging

Telomeres are end caps on chromosomes that have received increased attention over the years because of their association with cellular aging and their relationship to the development of age-associated chronic conditions. In general, longer telomere length is associated with a reduced risk of chronic conditions and better cellular health. Thus, telomere length may be a potential marker of biologic aging. Telomere dysfunction in cells occurs for several reasons and is often a result of the aging process itself.3 Cardiovascular disease and diabetes, among others conditions, are characterized by an increased rate of telomere shortening, which indicates an increased effect of these disease conditions on the aging of the body.4

Vitamin D insufficiency has been linked to the onset and prevalence of numerous chronic health issues, and it is well-known that vitamin D impacts many aspects of cellular aging through its influence on various aspects of cellular metabolism. In many studies, researchers have found vitamin D to be associated with telomere length, a possible explanation for vitamin D’s potential role in delaying cellular aging.4

A newly published study led by Mohsen Mazidi of the Chinese Academy of Sciences (Beijing, China) evaluated telomere length in association with serum levels of 25-hydroxyvitamin D in participants of the National Health and Nutrition Examination Survey (NHANES).5 The study sample included 4,347 participants with an average age of 42.7 years. The authors found that for each increment increase in serum 25-hydroxyvitamin D levels (25(OH)D; a common measure of vitamin D status), there was a corresponding increase in telomere-to-single-copy gene ratio, a measure of telomere length, in both women and men. After adjusting for smoking status, BMI, and physical activity levels, however, the significant relationship went away. Despite the presence of confounding factors, the authors concluded that serum levels of vitamin D had a possible positive association with telomere length in this sample, which should be investigated further.

Taking the previous analysis a step further, researchers from Harvard Medical School (Boston, MA) and the University of Tromsoe–The Arctic University of Norway (Tromsoe, Norway) also used NHANES data from 2001-2002 and stratified their analysis of telomere length by age, dividing the subjects into young adults (age 20-39), middle age (40-59), and older age (greater than 60) segments.6 Measuring leukocyte telomere length via polymerase chain reaction techniques, the investigators found that middle-aged adults with 25(OH)D concentrations above 50 nmol/L had significantly longer telomeres than those with levels below 50 nmol/L, further suggesting genomic instability in those with lower levels of vitamin D. An earlier analysis conducted by Jason Liu and colleagues from the Harvard School of Public Health (Boston, MA) looked at participants from the Nurses’ Health Study.7 Included in the analysis were 1,424 participants who had plasma samples taken in 1989–1990. The researchers found that higher serum levels of 25-hydroxyvitamin D were significantly associated with longer telomere length. 

While the studies highlighted above indicate that vitamin D concentrations are associated with positive benefits for telomeres, a previous study assessed the impact of vitamin D supplementation on telomerase activity in African American participants. Telomerase is an essential enzyme that functions to maintain telomere length. Led by Haidong Zhu of Georgia Health Sciences University (Augusta, GA), this four-month double-blind placebo-controlled study enrolled 57 healthy African American men and women.8 Each month, participants were supplemented with 60,000 IU vitamin D3 or a placebo. As plasma 25(OH)D levels increased substantially in the supplementation group from baseline to the end of the four-month period, telomerase activity significantly increased by an average of 19%. This remained unchanged from baseline in the placebo group, indicating that vitamin D supplementation could support the function of this important enzyme in the study population. 

These studies suggest that vitamin D is an important nutrient for healthy cellular aging. Higher levels of vitamin D may, therefore, have a protective effect on cellular health and have implications for aging as well as prevention of several chronic conditions.

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