Vitamin D Supplementation and Muscle Function in Older Adults

Trial of Vitamin D Supplementation and Neuromuscular Function in Older Adults

The purpose of this study is to see if vitamin D supplementation improves muscle function in older adults.

This study is a 12-month, double-blind randomized placebo controlled trial in older (65-89 yrs) men and women with initial 25(OH)D concentrations of 18-<30 ng/mL to determine the effect of increasing 25(OH)D concentrations to ≥30 ng/mL through vitamin D3 supplementation on 1) change in neuromuscular functions that are established risk-factors for falls in older adults; and 2) changes in the underlying physiological mechanisms over 4 months in a subset of randomly selected participants. Participants will be randomized to 2000 IU/d of vitamin D3 or placebo. Lower extremity muscle strength and power, physical performance, and postural sway will be assessed at baseline, 4 months and 12 months and falls assessed monthly. Muscle biopsies of the vastus lateralis will be taken at baseline and 4 months to assess muscle fiber type, contractility, and denervation, and number and differentiation stage of satellite cells.

Inclusion Criteria:

• Age ≥65 to <90 years
• SPPB <=10
• Initial serum 25(OH)D concentration of 18 to <30 ng/mL
• Not dependent on a walker
• Able to provide own transportation to study visits
• Not involved in another intervention study
• Willing to provide informed consent and adhere to the protocol

Exclusion Criteria:

• Serious or uncontrolled chronic disease including: insulin-dependent diabetes; cancer requiring treatment in past year, except non-melanoma skin cancers; acute coronary event (within the last 6 months), uncontrolled angina, heart failure (stage 3-4), PAD, or stroke (within the last 6 months); uncontrolled hypertension (BP>200/110 mmHg); chronic respiratory disease requiring the use of oxygen; uncontrolled endocrine/metabolic disease; neurological (e.g., Parkinson's disease) or hematological disease; liver or renal dysfunction (eGFR <45 mL/min/1.73m2); and musculoskeletal impairments severe enough to preclude functional testing
• Evidence of impaired cognitive function (MoCA <18)
• Taking prescription vitamin D2 or taking >1000 IU/day of vitamin D3 (from all sources); taking an oral corticosteroid (i.e., prednisone at 7.5mg/d for 3 mos or equivalent); taking hormone replacement therapy
• Inability or contraindications to consume daily vitamin D supplements (e.g., hypercalcemia, sarcoidosis, history of kidney stones in last 5 years)
• Knee or hip surgery within the last 6 months or planned knee or hip surgery within the next year
• Unwillingness to undergo a muscle biopsy or use of anti-coagulants
• Unintentional weight loss of ≥5% or more in the past 3 months
• BMI >40 kg/m2
• If the PI feels the participant is unlikely to follow the protocol