Michelle Shardell, Ph.D. and Nancy Chiles Shaffer, Ph.D. (pictured)

Image of Nancy Shaffer

Nancy Chiles Shaffer, Ph.D.
Co-Principal Investigator (pictured)
Postdoctoral Fellow, National Institute on Aging

Michelle Shardell, Ph.D.
Co-Principal Investigator
Postdoctoral Fellow, National Institute on Aging

Project Title: “Addressing Disparities in Optimal Vitamin D Levels for Functional Outcomes in Older Adults”

This study addresses an important and clinically relevant topic: health disparities in the effects of serum vitamin D levels on older adults’ ability to perform everyday tasks. The study will pool multiple racially diverse cohort studies of older men and women to identify and validate sex- and race-specific threshold 25-hydroxyvitamin D (25(OH)D) concentrations that predict incident decline in physical function. The impact is that these thresholds can help identify older adults who may benefit from vitamin D supplementation and inform inclusion criteria of future vitamin D trials comprising racially diverse older men and women. This study will also create linkages across a number of large data sets that will facilitate future health disparities studies.

Low vitamin D levels are associated with incident-related bone fractures in older adults. Researchers hope to understand a paradox among African Americans: While they tend to have lower vitamin D levels than Whites do, they also have fractures less frequently. Meanwhile, an ongoing debate surrounds optimal serum vitamin D levels, especially in relation to everyday tasks. One size may not fit all. Given that older African American adults experience a higher incidence of functional decline than their White counterparts do, determining sex- and race-specific vitamin D targets for everyday functioning could potentially improve clinical outcomes for older adults.