Vitamin D to ENhance TraUma REcovery

Inclusion Criteria: * ≥ 18 years and ≤ 65 years of age * Admitted to ED within 24 hours of motor vehicle collision * Plan to discharge to home from the emergency department * Stated willingness to comply with all study procedures and availability for the duration of the study (with the exception of the blood draw sample collected in the ED, which is optional) * Has a smartphone with continuous service \>1 year * Able to speak and read English * Alert and oriented, and capable of engaging in informed consent * Willing to take on-time dose of study medication (6 capsules of Vitamin D or placebo) * Non-Hispanic white or non-Hispanic black * Point of care Vitamin D level \<100 ng/ml * During ED admission pain severity must be at least 4/10 or higher Exclusion Criteria: * Substantial comorbid injury (e.g., long bone fracture) * Pregnancy/breastfeeding * Prisoner status * Chronic daily opioid use prior to MVC (\>20 mg oral daily morphine equivalents) * Active psychosis, suicidal ideation, or homicidal ideation * Plans for hospital admission * Known chronic kidney disease, stage 4 or higher (GFR≤29) * Intubated and sedated at time of enrollment * Inability to provide informed consent (receipt of sedative, hypnotic agent making the patient non-decisional for consent) * Vitamin D supplements in excess of 800 IU daily * Any other history or condition that would, in the site investigator's judgement, indicate that the patient would very likely be non-compliant with the study or unsuitable for the study (e.g., might interfere with the study, confound interpretation, or endanger patient)