1. Vitamin D C3-epimer levels are proportionally higher with oral vitamin D supplementation compared to ultraviolet irradiation of skin in mice but not humans. Ghaly S, Bliuc D, Center JR, Clarke MW, Jones AP, Trend S, Kermode AG, Neale RE, Hart PH. J Steroid Biochem Mol Biol. 2019 Feb;186:110-116. Epub 2018 Oct 5. PMID: 30296587. DOI: doi: 10.1016/j.jsbmb.2018.10.002