Vitamin D Supplementation and Physical Function in Older Adults

A growing body of evidence suggests that vitamin D status is important in biologic processes
involved in the maintenance of physical function. However, whether remediation of vitamin D
insufficiency will improve physical function and the potential mechanisms involved are
unclear. Previous vitamin D supplementation trials have produced mixed results with respect
to physical function; however, most trials did not specifically recruit individuals who were
vitamin D insufficient nor is the potential mechanism of action understood well enough to
appropriately select those individuals most likely to benefit. To advance our understanding
of the role of vitamin D in physical function, the investigators will conduct a feasibility
pilot study to collect key information to help design a full-scale randomized trial to
determine whether vitamin D supplementation will delay declines in physical function. The
primary goals of the pilot study are to determine cost-effective strategies for identifying
persons at high risk for functional decline with insufficient vitamin D levels, determine the
serum vitamin D response to a vitamin D supplementation regimen designed to attain sufficient
vitamin D levels, and provide preliminary data of key functional measures (balance, short
physical performance battery (SBBP) and muscle power) for the future larger study design. A
secondary goal is to begin to examine potential mechanisms by which vitamin D supplementation
may enhance physical performance and muscle contractility by exploring the effects of vitamin
D supplementation on changes in skeletal muscle gene expression using microarrays.

Inclusion Criteria:

- Short Physical Performance Battery (SPPB) score of ≥ 4 to < 10

- Vitamin D insufficient (serum 25(OH)D ≥ 10 to < 25 ng/mL)

Exclusion Criteria:

- Serious or uncontrolled chronic disease including: insulin-dependent or uncontrolled
diabetes; cancer requiring treatment in past year, except non-melanoma skin cancers;
past or current ischemic heart disease, uncontrolled angina, heart failure, peripheral
artery disease (PAD), or stroke; chronic respiratory disease; uncontrolled
endocrine/metabolic disease; neurological or hematological disease; liver or renal
dysfunction; and severe musculoskeletal impairment

- Impaired cognitive function (MMSE ≤ 24)

- Dependent on a cane or walker

- Use of anti-coagulants

- Unwillingness to undergo a muscle biopsy

- Taking prescription vitamin D2 or OCT vitamin D3 supplements of > 1000 IU/d

- Inability or contraindications to consume daily vitamin D and calcium supplements

- Weight loss of ≥ 5% or more in the past 6 months

- Involved in any other intervention