Women who are currently pregnant or breastfeeding

Use of antibiotics within the last 2 weeks

Use of supplementary vitamin D within the last month

Self-reported, pre-existing history of inflammatory bowel disease, heart disease or diabetes

Students under 18

Tanning/sun exposure \> 60 min at a time in last 4 weeks

No phenobarbital, carbamazepine, spironolactone chronic therapy; or steroid use within the last 2 weeks

Severe allergy to ingredients found in supplements

Vitamin D Intervention and Associated Changes in the Gut Microbiome and Vitamin D Levels in Healthy Adults