This trial also includes a sub-study with individuals who have psoriasis. Psoriasis is also an immune-mediated skin disease, and is characterized by scaling skin and inflammation (pain, swelling, heat, and redness). Most psoriasis cause patches of thick, red skin with silvery scales. These patches can itch or feel sore. This sub-study will provide additional information on psoriatic responses to oral vitamin D. (Originally listed separately as ADVN-CATH-03-01).