Vitamin D3 is an essential steroid for humans to maintain calcium levels and preserve bone density. The creation of vitamin D3 in the body is activated by light and is a well-studied reaction. The ring opening of its steroid precursor 7-dehydrocholesterol, or provitamin D3(PVD), is photo-initiated from UVB and some lower energy UVC wavelengths. Studies have shown a strong wavelength dependence on the final
product formation due to subsequent isomerization reactions. Previtamin D3 is the ring opened metastable intermediate, formed after the absorption of lower energy UVB wavelengths. It will eventually thermally rearrange to form the bioavailable vitamin D3. However, if previtamin D3 interact with a higher energy UVB or lower energy UVC photon this will trigger an isomerization and increase minor product formation, such as tachsterol or lumisterol. In this study the experiments were focused on maximizing previtamin D3 formation in the UCV region by minimizing secondary isomerization. This was accomplished by introducing phenylalanine(PHE), a known UVC absorber into a solution with PVD, for the purpose of converting UVC wavelengths into lower UBV energy. In the process, the energy is made available through energy transfer to initiate the ring opening reaction itself. Through several experiments and date analysis there is strong evidence that when illuminated with lower energy UVC wavelengths the PHE-PVD solution aided in the formation of previtamin D3. A secondary influence caused by phenylalanine was to diminish previtamin D3's secondary isomerization by acting as an inbound energy down-shifter that suppresses isomerization. When a similar mixed solution was illuminated with lower energy UVB wavelengths the formation of previtamin D3 proceeded unimpeded by the phenylalanine.